All examples working again.

dm/src/main.rs

@@ -2,7 +2,7 @@ mod repl;
 mod run;
 
 use crate::repl::repl;
-use crate::run::run;
+use crate::run::compile_and_run_script;
 use clap::{Parser, Subcommand};
 use std::path::PathBuf;
 
@@ -42,7 +42,7 @@ fn main() {
             show_ir,
             register_count,
         } => {
-            run(script, *show_asm, *show_ir, *register_count);
+            compile_and_run_script(script, *show_asm, *show_ir, *register_count);
         }
         SubCommand::Repl { register_count } => {
             repl(*register_count);

dm/src/repl.rs

@@ -8,6 +8,7 @@ use dmc_lib::lexer::Lexer;
 use dmc_lib::parser::parse_expression;
 use dmc_lib::symbol_table::SymbolTable;
 use dmc_lib::token::TokenKind;
+use dmc_lib::types_table::TypesTable;
 use dvm_lib::vm::constant::{Constant, StringConstant};
 use dvm_lib::vm::function::Function;
 use dvm_lib::vm::operand::Operand;
@@ -97,24 +98,30 @@ fn compile_expression(
     let mut expression = parse_result?;
 
     let mut symbol_table = SymbolTable::new();
+    let mut types_table = TypesTable::new();
 
     // "fake" scopes
     symbol_table.push_module_scope("__repl_module");
-    symbol_table.push_function_scope("__repl_function");
+    let function_scope_id = symbol_table.push_function_scope("__repl_function");
 
-    expression.gather_declared_names(&mut symbol_table)?;
+    expression.init_scopes(&mut symbol_table, function_scope_id);
 
     symbol_table.pop_scope(); // function
     symbol_table.pop_scope(); // module
 
-    expression.check_name_usages(&symbol_table)?;
-    expression.type_check(&symbol_table)?;
+    let diagnostics = expression.check_static_fn_local_names(&symbol_table);
+    if !diagnostics.is_empty() {
+        return Err(diagnostics);
+    }
+
+    expression.type_check(&symbol_table, &mut types_table)?;
 
     // synthesize a function
     let mut ir_builder = IrBuilder::new();
     let entry_block_id = ir_builder.new_block();
 
-    let maybe_ir_expression = expression.to_ir_expression(&mut ir_builder, &symbol_table);
+    let maybe_ir_expression =
+        expression.to_ir_expression(&mut ir_builder, &symbol_table, &types_table);
 
     // if Some, return the value
     ir_builder
@@ -126,8 +133,8 @@ fn compile_expression(
 
     let mut ir_function = IrFunction::new(
         "__repl".into(),
-        &[],
-        expression.type_info(),
+        vec![],
+        expression.type_info(&symbol_table, &types_table),
         entry_block.clone(),
     );
 

dm/src/run.rs

@@ -5,8 +5,10 @@ use codespan_reporting::term::termcolor::{ColorChoice, StandardStream};
 use dm_std_lib::add_all_std_core;
 use dmc_lib::constants_table::ConstantsTable;
 use dmc_lib::diagnostic::Diagnostic;
+use dmc_lib::intrinsics::{insert_intrinsic_symbols, insert_intrinsic_types};
 use dmc_lib::parser::parse_compilation_unit;
 use dmc_lib::symbol_table::SymbolTable;
+use dmc_lib::types_table::TypesTable;
 use dvm_lib::vm::constant::{Constant, StringConstant};
 use dvm_lib::vm::function::Function;
 use dvm_lib::vm::operand::Operand;
@@ -14,45 +16,46 @@ use dvm_lib::vm::{CallStack, DvmContext, call};
 use std::path::PathBuf;
 use std::rc::Rc;
 
-pub fn run(script: &PathBuf, show_ir: bool, show_asm: bool, register_count: usize) {
+pub fn compile_and_run_script(
+    script: &PathBuf,
+    show_ir: bool,
+    show_asm: bool,
+    register_count: usize,
+) {
     let input = std::fs::read_to_string(script).unwrap();
 
     let mut files: SimpleFiles<&str, &str> = SimpleFiles::new();
     let script_file_id = files.add(script.to_str().unwrap(), &input);
 
-    let parse_result = parse_compilation_unit(&input);
-    let mut compilation_unit = match parse_result {
-        Ok(compilation_unit) => compilation_unit,
+    match run(&input, show_ir, show_asm, register_count) {
+        Ok(_) => {}
         Err(diagnostics) => {
             check_and_report_diagnostics(&files, script_file_id, &diagnostics);
-            unreachable!();
         }
-    };
+    }
+}
+
+fn run(
+    input: &str,
+    show_ir: bool,
+    show_asm: bool,
+    register_count: usize,
+) -> Result<(), Vec<Diagnostic>> {
+    let mut compilation_unit = parse_compilation_unit(&input)?;
 
     let mut symbol_table = SymbolTable::new();
+    symbol_table.push_module_scope("global scope");
+    insert_intrinsic_symbols(&mut symbol_table);
+    let mut types_table = TypesTable::new();
+    insert_intrinsic_types(&symbol_table, &mut types_table);
 
-    match compilation_unit.gather_declared_names(&mut symbol_table) {
-        Ok(_) => {}
-        Err(diagnostics) => {
-            report_and_exit(&diagnostics, script_file_id, &files);
-        }
-    }
+    compilation_unit.init_scopes(&mut symbol_table);
+    compilation_unit.gather_symbols_into(&mut symbol_table)?;
+    compilation_unit.check_names(&mut symbol_table)?;
+    compilation_unit.gather_types_into(&symbol_table, &mut types_table)?;
+    compilation_unit.type_check(&symbol_table, &mut types_table)?;
 
-    match compilation_unit.check_name_usages(&symbol_table) {
-        Ok(_) => {}
-        Err(diagnostics) => {
-            report_and_exit(&diagnostics, script_file_id, &files);
-        }
-    }
-
-    match compilation_unit.type_check(&symbol_table) {
-        Ok(_) => {}
-        Err(diagnostics) => {
-            report_and_exit(&diagnostics, script_file_id, &files);
-        }
-    }
-
-    let (ir_classes, mut ir_functions) = compilation_unit.to_ir(&symbol_table);
+    let (ir_classes, mut ir_functions) = compilation_unit.to_ir(&symbol_table, &types_table);
 
     if show_ir {
         for ir_function in &ir_functions {
@@ -117,6 +120,8 @@ pub fn run(script: &PathBuf, show_ir: bool, show_asm: bool, register_count: usiz
     if let Some(value) = result {
         println!("{}", value);
     }
+
+    Ok(())
 }
 
 fn check_and_report_diagnostics(

dmc-lib/src/ast/assign_statement.rs

@@ -6,8 +6,10 @@ use crate::error_codes::{ASSIGN_LHS_IMMUTABLE, ASSIGN_MISMATCHED_TYPES, ASSIGN_N
 use crate::ir::ir_assign::IrAssign;
 use crate::ir::ir_set_field::IrSetField;
 use crate::ir::ir_statement::IrStatement;
+use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol::expressible_symbol::ExpressibleSymbol;
 use crate::symbol_table::SymbolTable;
+use crate::types_table::TypesTable;
 
 pub struct AssignStatement {
     destination: Box<Expression>,
@@ -26,68 +28,68 @@ impl AssignStatement {
         &self.destination
     }
 
-    pub fn gather_declared_names(
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable, container_scope: usize) {
+        self.destination.init_scopes(symbol_table, container_scope);
+        self.value.init_scopes(symbol_table, container_scope);
+    }
+
+    pub fn check_constructor_local_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        [
+            self.destination
+                .check_constructor_destination_names(symbol_table, class_symbol),
+            self.value
+                .check_constructor_local_names(symbol_table, class_symbol),
+        ]
+        .into_iter()
+        .flatten()
+        .collect()
+    }
+
+    pub fn check_method_local_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        [
+            self.destination
+                .check_method_local_names(symbol_table, class_symbol),
+            self.value
+                .check_method_local_names(symbol_table, class_symbol),
+        ]
+        .into_iter()
+        .flatten()
+        .collect()
+    }
+
+    pub fn check_static_fn_local_names(&self, symbol_table: &SymbolTable) -> Vec<Diagnostic> {
+        [
+            self.destination.check_static_fn_local_names(symbol_table),
+            self.value.check_static_fn_local_names(symbol_table),
+        ]
+        .into_iter()
+        .flatten()
+        .collect()
+    }
+
+    pub fn type_check(
         &mut self,
-        symbol_table: &mut SymbolTable,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
     ) -> Result<(), Vec<Diagnostic>> {
         let mut diagnostics: Vec<Diagnostic> = vec![];
 
-        match self.value.gather_declared_names(symbol_table) {
+        match self.value.type_check(symbol_table, types_table) {
             Ok(_) => {}
             Err(mut value_diagnostics) => {
                 diagnostics.append(&mut value_diagnostics);
             }
         }
 
-        match self.destination.gather_declared_names(symbol_table) {
-            Ok(_) => {}
-            Err(mut destination_diagnostics) => {
-                diagnostics.append(&mut destination_diagnostics);
-            }
-        }
-
-        if diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(diagnostics)
-        }
-    }
-
-    pub fn check_name_usages(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        let mut diagnostics: Vec<Diagnostic> = vec![];
-
-        match self.value.check_name_usages(symbol_table) {
-            Ok(_) => {}
-            Err(mut value_diagnostics) => {
-                diagnostics.append(&mut value_diagnostics);
-            }
-        }
-
-        match self.destination.check_name_usages(symbol_table) {
-            Ok(_) => {}
-            Err(mut destination_diagnostics) => {
-                diagnostics.append(&mut destination_diagnostics);
-            }
-        }
-
-        if diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(diagnostics)
-        }
-    }
-
-    pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        let mut diagnostics: Vec<Diagnostic> = vec![];
-
-        match self.value.type_check(symbol_table) {
-            Ok(_) => {}
-            Err(mut value_diagnostics) => {
-                diagnostics.append(&mut value_diagnostics);
-            }
-        }
-
-        match self.destination.type_check(symbol_table) {
+        match self.destination.type_check(symbol_table, types_table) {
             Ok(_) => {}
             Err(mut destination_diagnostics) => {
                 diagnostics.append(&mut destination_diagnostics);
@@ -97,40 +99,73 @@ impl AssignStatement {
         // check destination is l value
         match &*self.destination {
             Expression::Identifier(identifier) => {
-                let expressible_symbol = identifier.expressible_symbol();
+                let expressible_symbol = symbol_table
+                    .find_expressible_symbol(identifier.scope_id(), identifier.name())
+                    .unwrap();
+
+                let is_mut = match &expressible_symbol {
+                    ExpressibleSymbol::Field(field_symbol) => field_symbol.is_mut(),
+                    ExpressibleSymbol::Variable(variable_symbol) => variable_symbol.is_mut(),
+                    _ => false,
+                };
 
                 // check mutable
-                if !expressible_symbol.is_mut() {
-                    let secondary_label = SecondaryLabel::new(
-                        expressible_symbol.source_range().start(),
-                        expressible_symbol.source_range().end(),
-                        Some("Destination (declared here) is immutable.".to_string()),
-                    );
-                    let diagnostic = Diagnostic::new(
+                if !is_mut {
+                    let secondary_label =
+                        if let Some(source_range) = expressible_symbol.source_range() {
+                            Some(SecondaryLabel::new(
+                                source_range.start(),
+                                source_range.end(),
+                                Some("Destination (declared here) is immutable.".to_string()),
+                            ))
+                        } else {
+                            None
+                        };
+
+                    let mut diagnostic = Diagnostic::new(
                         "Destination is immutable and not re-assignable.",
                         self.destination.source_range().start(),
                         self.destination.source_range().end(),
                     )
                     .with_primary_label_message("Attempt to mutate immutable destination.")
                     .with_reporter(file!(), line!())
-                    .with_error_code(ASSIGN_LHS_IMMUTABLE)
-                    .with_secondary_labels(&[secondary_label]);
+                    .with_error_code(ASSIGN_LHS_IMMUTABLE);
+
+                    if let Some(secondary_label) = secondary_label {
+                        diagnostic = diagnostic.with_secondary_labels(&[secondary_label]);
+                    }
+
                     diagnostics.push(diagnostic);
                 }
 
                 // check assignable
-                let lhs_type = expressible_symbol.type_info();
-                let rhs_type = self.value.type_info();
+                let lhs_type = match &expressible_symbol {
+                    ExpressibleSymbol::Field(field_symbol) => {
+                        types_table.field_types().get(field_symbol).unwrap()
+                    }
+                    ExpressibleSymbol::Variable(variable_symbol) => {
+                        types_table.variable_types().get(variable_symbol).unwrap()
+                    }
+                    _ => panic!(),
+                };
+
+                let rhs_type = self.value.type_info(symbol_table, types_table);
                 if !lhs_type.is_assignable_from(rhs_type) {
-                    let secondary_label = SecondaryLabel::new(
-                        expressible_symbol.source_range().start(),
-                        expressible_symbol.source_range().end(),
-                        Some(format!(
-                            "Destination declared here is of type {}.",
-                            lhs_type
-                        )),
-                    );
-                    let diagnostic = Diagnostic::new(
+                    let secondary_label =
+                        if let Some(source_range) = expressible_symbol.source_range() {
+                            Some(SecondaryLabel::new(
+                                source_range.start(),
+                                source_range.end(),
+                                Some(format!(
+                                    "Destination declared here is of type {}.",
+                                    lhs_type
+                                )),
+                            ))
+                        } else {
+                            None
+                        };
+
+                    let mut diagnostic = Diagnostic::new(
                         &format!(
                             "Mismatched types: right-hand side {} is not assignable to left {}.",
                             rhs_type, lhs_type
@@ -143,8 +178,12 @@ impl AssignStatement {
                         rhs_type, lhs_type
                     ))
                     .with_error_code(ASSIGN_MISMATCHED_TYPES)
-                    .with_reporter(file!(), line!())
-                    .with_secondary_labels(&[secondary_label]);
+                    .with_reporter(file!(), line!());
+
+                    if let Some(secondary_label) = secondary_label {
+                        diagnostic = diagnostic.with_secondary_labels(&[secondary_label]);
+                    }
+
                     diagnostics.push(diagnostic);
                 }
             }
@@ -168,29 +207,39 @@ impl AssignStatement {
         }
     }
 
-    pub fn to_ir(&self, builder: &mut IrBuilder, symbol_table: &SymbolTable) {
+    pub fn to_ir(
+        &self,
+        builder: &mut IrBuilder,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+    ) {
         let destination_symbol = match &*self.destination {
-            Expression::Identifier(identifier) => identifier.expressible_symbol(),
+            Expression::Identifier(identifier) => symbol_table
+                .find_expressible_symbol(identifier.scope_id(), identifier.name())
+                .unwrap(),
             _ => unreachable!("Destination must be a mutable L value"),
         };
 
         let ir_statement = match destination_symbol {
             ExpressibleSymbol::Field(field_symbol) => {
+                let field_type = types_table.field_types().get(&field_symbol).unwrap();
                 let mut_field_pointer_variable =
-                    get_or_init_mut_field_pointer_variable(builder, field_symbol).clone();
+                    get_or_init_mut_field_pointer_variable(builder, &field_symbol, field_type)
+                        .clone();
                 let ir_set_field = IrSetField::new(
                     &mut_field_pointer_variable,
                     self.value
-                        .to_ir_expression(builder, symbol_table)
+                        .to_ir_expression(builder, symbol_table, types_table)
                         .expect("Attempt to convert non-value to value"),
                 );
                 IrStatement::SetField(ir_set_field)
             }
             ExpressibleSymbol::Variable(variable_symbol) => {
-                let vr_variable = variable_symbol.borrow().vr_variable().clone();
+                let vr_variable = builder.local_variables().get(&variable_symbol).unwrap();
                 let ir_assign = IrAssign::new(
-                    vr_variable,
-                    self.value.to_ir_operation(builder, symbol_table),
+                    vr_variable.clone(),
+                    self.value
+                        .to_ir_operation(builder, symbol_table, types_table),
                 );
                 IrStatement::Assign(ir_assign)
             }
@@ -203,12 +252,26 @@ impl AssignStatement {
 
 #[cfg(test)]
 mod tests {
+    use crate::ast::compilation_unit::CompilationUnit;
+    use crate::diagnostic::Diagnostic;
     use crate::error_codes::{ASSIGN_LHS_IMMUTABLE, ASSIGN_MISMATCHED_TYPES, ASSIGN_NO_L_VALUE};
     use crate::parser::parse_compilation_unit;
     use crate::symbol_table::SymbolTable;
+    use crate::types_table::TypesTable;
+
+    fn compile_up_to_type_check(
+        compilation_unit: &mut CompilationUnit,
+        symbol_table: &mut SymbolTable,
+        types_table: &mut TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
+        compilation_unit.init_scopes(symbol_table);
+        compilation_unit.gather_symbols_into(symbol_table)?;
+        compilation_unit.check_names(symbol_table)?;
+        compilation_unit.gather_types_into(symbol_table, types_table)
+    }
 
     #[test]
-    fn finds_mismatched_types() {
+    fn finds_mismatched_types() -> Result<(), Vec<Diagnostic>> {
         let mut compilation_unit = parse_compilation_unit(
             "
             fn main()
@@ -219,52 +282,41 @@ mod tests {
         )
         .unwrap();
         let mut symbol_table = SymbolTable::new();
-        compilation_unit
-            .gather_declared_names(&mut symbol_table)
-            .unwrap();
-        compilation_unit.check_name_usages(&symbol_table).unwrap();
-        match compilation_unit.type_check(&symbol_table) {
-            Ok(_) => {
-                panic!("Type check missed diagnostic.");
-            }
-            Err(diagnostics) => {
-                assert_eq!(diagnostics.len(), 1);
-                assert_eq!(
-                    diagnostics[0].error_code().unwrap(),
-                    ASSIGN_MISMATCHED_TYPES
-                );
-            }
-        }
+        let mut types_table = TypesTable::new();
+        compile_up_to_type_check(&mut compilation_unit, &mut symbol_table, &mut types_table)?;
+        let diagnostics = compilation_unit
+            .type_check(&symbol_table, &mut types_table)
+            .unwrap_err();
+        assert_eq!(diagnostics.len(), 1);
+        assert_eq!(
+            diagnostics[0].error_code().unwrap(),
+            ASSIGN_MISMATCHED_TYPES
+        );
+        Ok(())
     }
 
     #[test]
-    fn finds_no_l_value() {
+    fn finds_no_l_value() -> Result<(), Vec<Diagnostic>> {
         let mut compilation_unit = parse_compilation_unit(
             "
             fn main()
                 42 = 42
             end
             ",
-        )
-        .unwrap();
+        )?;
         let mut symbol_table = SymbolTable::new();
-        compilation_unit
-            .gather_declared_names(&mut symbol_table)
-            .unwrap();
-        compilation_unit.check_name_usages(&symbol_table).unwrap();
-        match compilation_unit.type_check(&symbol_table) {
-            Ok(_) => {
-                panic!("Type check missed diagnostic.");
-            }
-            Err(diagnostics) => {
-                assert_eq!(diagnostics.len(), 1);
-                assert_eq!(diagnostics[0].error_code().unwrap(), ASSIGN_NO_L_VALUE);
-            }
-        }
+        let mut types_table = TypesTable::new();
+        compile_up_to_type_check(&mut compilation_unit, &mut symbol_table, &mut types_table)?;
+        let diagnostics = compilation_unit
+            .type_check(&symbol_table, &mut types_table)
+            .unwrap_err();
+        assert_eq!(diagnostics.len(), 1);
+        assert_eq!(diagnostics[0].error_code().unwrap(), ASSIGN_NO_L_VALUE);
+        Ok(())
     }
 
     #[test]
-    fn finds_immutable_destination() {
+    fn finds_immutable_destination() -> Result<(), Vec<Diagnostic>> {
         let mut compilation_unit = parse_compilation_unit(
             "
             fn main()
@@ -272,21 +324,15 @@ mod tests {
                 x = 43
             end
             ",
-        )
-        .unwrap();
+        )?;
         let mut symbol_table = SymbolTable::new();
-        compilation_unit
-            .gather_declared_names(&mut symbol_table)
-            .unwrap();
-        compilation_unit.check_name_usages(&symbol_table).unwrap();
-        match compilation_unit.type_check(&symbol_table) {
-            Ok(_) => {
-                panic!("Type check missed diagnostic.");
-            }
-            Err(diagnostics) => {
-                assert_eq!(diagnostics.len(), 1);
-                assert_eq!(diagnostics[0].error_code().unwrap(), ASSIGN_LHS_IMMUTABLE);
-            }
-        }
+        let mut types_table = TypesTable::new();
+        compile_up_to_type_check(&mut compilation_unit, &mut symbol_table, &mut types_table)?;
+        let diagnostics = compilation_unit
+            .type_check(&symbol_table, &mut types_table)
+            .unwrap_err();
+        assert_eq!(diagnostics.len(), 1);
+        assert_eq!(diagnostics[0].error_code().unwrap(), ASSIGN_LHS_IMMUTABLE);
+        Ok(())
     }
 }

dmc-lib/src/ast/binary_expression.rs

@@ -9,8 +9,10 @@ use crate::ir::ir_operation::IrOperation;
 use crate::ir::ir_statement::IrStatement;
 use crate::ir::ir_variable::IrVariable;
 use crate::source_range::SourceRange;
+use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol_table::SymbolTable;
 use crate::type_info::TypeInfo;
+use crate::types_table::TypesTable;
 use crate::{diagnostics_result, handle_diagnostic, handle_diagnostics, maybe_return_diagnostics};
 use std::cell::RefCell;
 use std::rc::Rc;
@@ -72,45 +74,79 @@ impl BinaryExpression {
         self.type_info.as_ref().unwrap()
     }
 
-    pub fn gather_declared_names(
-        &mut self,
-        symbol_table: &mut SymbolTable,
-    ) -> Result<(), Vec<Diagnostic>> {
-        let diagnostics = [&mut self.lhs, &mut self.rhs]
-            .iter_mut()
-            .map(|expression| expression.gather_declared_names(symbol_table))
-            .filter_map(|result| result.err())
-            .flatten()
-            .collect::<Vec<Diagnostic>>();
-        if diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(diagnostics)
-        }
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable, container_scope: usize) {
+        self.lhs.init_scopes(symbol_table, container_scope);
+        self.rhs.init_scopes(symbol_table, container_scope);
     }
 
-    pub fn check_name_usages(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        let diagnostics: Vec<Diagnostic> = [&mut self.lhs, &mut self.rhs]
-            .iter_mut()
-            .map(|expression| expression.check_name_usages(symbol_table))
-            .filter_map(Result::err)
-            .flatten()
-            .collect();
-        if diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(diagnostics)
-        }
+    pub fn check_field_initializer_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        [
+            self.lhs
+                .check_field_initializer_names(symbol_table, class_symbol),
+            self.rhs
+                .check_field_initializer_names(symbol_table, class_symbol),
+        ]
+        .into_iter()
+        .flatten()
+        .collect()
+    }
+
+    pub fn check_constructor_local_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        [
+            self.lhs
+                .check_constructor_local_names(symbol_table, class_symbol),
+            self.rhs
+                .check_constructor_local_names(symbol_table, class_symbol),
+        ]
+        .into_iter()
+        .flatten()
+        .collect()
+    }
+
+    pub fn check_method_local_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        [
+            self.lhs
+                .check_method_local_names(symbol_table, class_symbol),
+            self.rhs
+                .check_method_local_names(symbol_table, class_symbol),
+        ]
+        .into_iter()
+        .flatten()
+        .collect()
+    }
+
+    pub fn check_static_fn_local_names(&self, symbol_table: &SymbolTable) -> Vec<Diagnostic> {
+        [
+            self.lhs.check_static_fn_local_names(symbol_table),
+            self.rhs.check_static_fn_local_names(symbol_table),
+        ]
+        .into_iter()
+        .flatten()
+        .collect()
     }
 
     fn check_op(
         &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
         check: impl Fn(&TypeInfo, &TypeInfo) -> bool,
         op_result: impl Fn(&TypeInfo, &TypeInfo) -> TypeInfo,
         lazy_diagnostic_message: impl Fn(&TypeInfo, &TypeInfo) -> String,
     ) -> Result<(), Diagnostic> {
-        let lhs_type_info = self.lhs.type_info();
-        let rhs_type_info = self.rhs.type_info();
+        let lhs_type_info = self.lhs.type_info(symbol_table, types_table);
+        let rhs_type_info = self.rhs.type_info(symbol_table, types_table);
 
         if check(lhs_type_info, rhs_type_info) {
             self.type_info = Some(op_result(lhs_type_info, rhs_type_info));
@@ -128,11 +164,15 @@ impl BinaryExpression {
         }
     }
 
-    pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
+    pub fn type_check(
+        &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
         let mut diagnostics: Vec<Diagnostic> = vec![];
 
-        handle_diagnostics!(self.lhs.type_check(symbol_table), diagnostics);
-        handle_diagnostics!(self.rhs.type_check(symbol_table), diagnostics);
+        handle_diagnostics!(self.lhs.type_check(symbol_table, types_table), diagnostics);
+        handle_diagnostics!(self.rhs.type_check(symbol_table, types_table), diagnostics);
 
         maybe_return_diagnostics!(diagnostics);
 
@@ -140,6 +180,8 @@ impl BinaryExpression {
             BinaryOperation::Multiply => {
                 handle_diagnostic!(
                     self.check_op(
+                        symbol_table,
+                        types_table,
                         |lhs, rhs| lhs.can_multiply(rhs),
                         |lhs, rhs| lhs.multiply_result(rhs),
                         |lhs, rhs| format!(
@@ -153,6 +195,8 @@ impl BinaryExpression {
             BinaryOperation::Divide => {
                 handle_diagnostic!(
                     self.check_op(
+                        symbol_table,
+                        types_table,
                         |lhs, rhs| lhs.can_divide(rhs),
                         |lhs, rhs| lhs.divide_result(rhs),
                         |lhs, rhs| format!("Incompatible types: cannot divide {} by {}", lhs, rhs)
@@ -163,6 +207,8 @@ impl BinaryExpression {
             BinaryOperation::Modulo => {
                 handle_diagnostic!(
                     self.check_op(
+                        symbol_table,
+                        types_table,
                         |lhs, rhs| lhs.can_modulo(rhs),
                         |lhs, rhs| lhs.modulo_result(rhs),
                         |lhs, rhs| format!("Incompatible types: cannot modulo {} by {}", lhs, rhs)
@@ -173,6 +219,8 @@ impl BinaryExpression {
             BinaryOperation::Add => {
                 handle_diagnostic!(
                     self.check_op(
+                        symbol_table,
+                        types_table,
                         |lhs, rhs| lhs.can_add(rhs),
                         |lhs, rhs| lhs.add_result(&rhs),
                         |lhs, rhs| format!("Incompatible types: cannot add {} to {}.", rhs, lhs)
@@ -183,6 +231,8 @@ impl BinaryExpression {
             BinaryOperation::Subtract => {
                 handle_diagnostic!(
                     self.check_op(
+                        symbol_table,
+                        types_table,
                         |lhs, rhs| lhs.can_subtract(rhs),
                         |lhs, rhs| lhs.subtract_result(rhs),
                         |lhs, rhs| format!(
@@ -196,6 +246,8 @@ impl BinaryExpression {
             BinaryOperation::LeftShift => {
                 handle_diagnostic!(
                     self.check_op(
+                        symbol_table,
+                        types_table,
                         |lhs, rhs| lhs.can_left_shift(rhs),
                         |lhs, rhs| lhs.left_shift_result(rhs),
                         |lhs, rhs| format!(
@@ -209,6 +261,8 @@ impl BinaryExpression {
             BinaryOperation::RightShift => {
                 handle_diagnostic!(
                     self.check_op(
+                        symbol_table,
+                        types_table,
                         |lhs, rhs| lhs.can_right_shift(rhs),
                         |lhs, rhs| lhs.right_shift_result(rhs),
                         |lhs, rhs| format!(
@@ -222,6 +276,8 @@ impl BinaryExpression {
             BinaryOperation::BitwiseAnd => {
                 handle_diagnostic!(
                     self.check_op(
+                        symbol_table,
+                        types_table,
                         |lhs, rhs| lhs.can_bitwise_and(rhs),
                         |lhs, rhs| lhs.bitwise_and_result(rhs),
                         |lhs, rhs| format!(
@@ -234,6 +290,8 @@ impl BinaryExpression {
             }
             BinaryOperation::BitwiseXor => handle_diagnostic!(
                 self.check_op(
+                    symbol_table,
+                    types_table,
                     |lhs, rhs| lhs.can_bitwise_xor(rhs),
                     |lhs, rhs| lhs.bitwise_xor_result(rhs),
                     |lhs, rhs| format!("Incompatible types: cannot bitwise xor {} by {}", lhs, rhs)
@@ -243,6 +301,8 @@ impl BinaryExpression {
             BinaryOperation::BitwiseOr => {
                 handle_diagnostic!(
                     self.check_op(
+                        symbol_table,
+                        types_table,
                         |lhs, rhs| lhs.can_bitwise_or(rhs),
                         |lhs, rhs| lhs.bitwise_or_result(rhs),
                         |lhs, rhs| format!(
@@ -262,14 +322,15 @@ impl BinaryExpression {
         &self,
         builder: &mut IrBuilder,
         symbol_table: &SymbolTable,
+        types_table: &TypesTable,
     ) -> IrOperation {
         let lhs = self
             .lhs
-            .to_ir_expression(builder, symbol_table)
+            .to_ir_expression(builder, symbol_table, types_table)
             .expect("Attempt to use a non-value expression in binary expression.");
         let rhs = self
             .rhs
-            .to_ir_expression(builder, symbol_table)
+            .to_ir_expression(builder, symbol_table, types_table)
             .expect("Attempt to use a non-value expression in binary expression.");
         let ir_binary_operation = match self.op {
             BinaryOperation::Multiply => {
@@ -304,8 +365,9 @@ impl BinaryExpression {
         &self,
         builder: &mut IrBuilder,
         symbol_table: &SymbolTable,
+        types_table: &TypesTable,
     ) -> IrExpression {
-        let ir_operation = self.to_ir_operation(builder, symbol_table);
+        let ir_operation = self.to_ir_operation(builder, symbol_table, types_table);
         let t_var = IrVariable::new_vr(
             builder.new_t_var().into(),
             builder.current_block().id(),

dmc-lib/src/ast/call.rs

@@ -1,3 +1,4 @@
+use crate::ast::diagnostic_factories::class_has_no_constructor;
 use crate::ast::expression::Expression;
 use crate::ast::fqn_util::fqn_parts_to_string;
 use crate::ast::ir_builder::IrBuilder;
@@ -6,15 +7,16 @@ use crate::ir::ir_call::IrCall;
 use crate::ir::ir_expression::IrExpression;
 use crate::source_range::SourceRange;
 use crate::symbol::callable_symbol::CallableSymbol;
+use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol::expressible_symbol::ExpressibleSymbol;
 use crate::symbol_table::SymbolTable;
 use crate::type_info::TypeInfo;
+use crate::types_table::TypesTable;
 
 pub struct Call {
     callee: Box<Expression>,
     arguments: Vec<Expression>,
     source_range: SourceRange,
-    return_type_info: Option<TypeInfo>,
 }
 
 impl Call {
@@ -23,7 +25,6 @@ impl Call {
             callee: callee.into(),
             arguments,
             source_range,
-            return_type_info: None,
         }
     }
 
@@ -35,66 +36,110 @@ impl Call {
         self.arguments.iter().collect()
     }
 
-    pub fn gather_declared_names(
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable, container_scope: usize) {
+        self.callee.init_scopes(symbol_table, container_scope);
+        for argument in &mut self.arguments {
+            argument.init_scopes(symbol_table, container_scope);
+        }
+    }
+
+    pub fn check_field_initializer_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        let mut diagnostics: Vec<Diagnostic> = Vec::new();
+        diagnostics.append(
+            &mut self
+                .callee
+                .check_field_initializer_names(symbol_table, class_symbol),
+        );
+        for argument in &self.arguments {
+            diagnostics
+                .append(&mut argument.check_field_initializer_names(symbol_table, class_symbol))
+        }
+        diagnostics
+    }
+
+    pub fn check_constructor_local_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        let mut diagnostics = Vec::new();
+        for argument in &self.arguments {
+            diagnostics
+                .append(&mut argument.check_constructor_local_names(symbol_table, class_symbol))
+        }
+        diagnostics.append(
+            &mut self
+                .callee
+                .check_constructor_local_names(symbol_table, class_symbol),
+        );
+        diagnostics
+    }
+
+    pub fn check_method_local_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        let mut diagnostics = Vec::new();
+        for argument in &self.arguments {
+            diagnostics.append(&mut argument.check_method_local_names(symbol_table, class_symbol));
+        }
+        diagnostics.append(
+            &mut self
+                .callee
+                .check_method_local_names(symbol_table, class_symbol),
+        );
+        diagnostics
+    }
+
+    pub fn check_static_fn_local_names(&self, symbol_table: &SymbolTable) -> Vec<Diagnostic> {
+        let mut diagnostics: Vec<Diagnostic> = Vec::new();
+        for argument in &self.arguments {
+            diagnostics.append(&mut argument.check_static_fn_local_names(symbol_table));
+        }
+        diagnostics.append(&mut self.callee.check_static_fn_local_names(symbol_table));
+        diagnostics
+    }
+
+    pub fn type_check(
         &mut self,
-        symbol_table: &mut SymbolTable,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
     ) -> Result<(), Vec<Diagnostic>> {
-        let mut to_gather = vec![];
-        to_gather.push(self.callee.as_mut());
-        to_gather.extend(&mut self.arguments);
-
-        let diagnostics: Vec<Diagnostic> = to_gather
-            .iter_mut()
-            .map(|expression| expression.gather_declared_names(symbol_table))
-            .filter_map(Result::err)
-            .flatten()
-            .collect();
-        if diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(diagnostics)
-        }
-    }
-
-    pub fn check_name_usages(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        let mut to_check = vec![];
-        to_check.push(self.callee.as_mut());
-        to_check.extend(&mut self.arguments);
-        let diagnostics: Vec<Diagnostic> = to_check
-            .iter_mut()
-            .map(|expression| expression.check_name_usages(symbol_table))
-            .filter_map(Result::err)
-            .flatten()
-            .collect();
-        if diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(diagnostics)
-        }
-    }
-
-    pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        self.callee.as_mut().type_check(symbol_table)?;
+        self.callee.as_mut().type_check(symbol_table, types_table)?;
 
         let mut diagnostics: Vec<Diagnostic> = self
             .arguments
             .iter_mut()
-            .map(|argument| argument.type_check(symbol_table))
+            .map(|argument| argument.type_check(symbol_table, types_table))
             .filter_map(Result::err)
             .flatten()
             .collect();
 
         // check that callee is callable
-        let callable_symbol = match self.callee.type_info() {
+        let callable_symbol = match self.callee.type_info(symbol_table, types_table) {
             TypeInfo::Function(function_symbol) => {
                 CallableSymbol::Function(function_symbol.clone())
             }
-            TypeInfo::ClassInstance(class_symbol) => CallableSymbol::Class(class_symbol.clone()),
+            TypeInfo::Class(class_symbol) => match class_symbol.constructor_symbol_owned() {
+                None => {
+                    diagnostics.push(class_has_no_constructor(
+                        class_symbol.declared_name(),
+                        self.callee.source_range(),
+                    ));
+                    return Err(diagnostics);
+                }
+                Some(constructor_symbol) => CallableSymbol::Constructor(constructor_symbol),
+            },
             _ => {
                 diagnostics.push(Diagnostic::new(
                     &format!(
                         "Receiver of type {} is not callable.",
-                        self.callee.type_info()
+                        self.callee.type_info(symbol_table, types_table)
                     ),
                     self.callee.source_range().start(),
                     self.callee.source_range().end(),
@@ -103,9 +148,6 @@ impl Call {
             }
         };
 
-        // set return type
-        self.return_type_info = Some(callable_symbol.return_type_info());
-
         // check arguments length
         let parameters = callable_symbol.parameters();
         if parameters.len() != self.arguments.len() {
@@ -126,10 +168,10 @@ impl Call {
 
         // check argument types
         for i in 0..parameters.len() {
-            let parameter = &parameters[i].borrow();
+            let parameter = &parameters[i];
             let argument = &self.arguments[i];
-            let parameter_type_info = parameter.type_info();
-            let argument_type_info = argument.type_info();
+            let parameter_type_info = types_table.parameter_types().get(parameter).unwrap();
+            let argument_type_info = argument.type_info(symbol_table, types_table);
             if !parameter_type_info.is_assignable_from(argument_type_info) {
                 diagnostics.push(Diagnostic::new(
                     &format!(
@@ -149,20 +191,25 @@ impl Call {
         }
     }
 
-    pub fn return_type_info(&self) -> &TypeInfo {
-        self.return_type_info.as_ref().unwrap()
-    }
-
-    fn get_callee_symbol(&self) -> CallableSymbol {
+    fn get_callee_symbol(&self, symbol_table: &SymbolTable) -> CallableSymbol {
         match self.callee() {
             Expression::Identifier(identifier) => {
-                let expressible_symbol = identifier.expressible_symbol();
+                let expressible_symbol = symbol_table
+                    .find_expressible_symbol(identifier.scope_id(), identifier.name())
+                    .unwrap();
                 match expressible_symbol {
                     ExpressibleSymbol::Function(function_symbol) => {
                         CallableSymbol::Function(function_symbol.clone())
                     }
                     ExpressibleSymbol::Class(class_symbol) => {
-                        CallableSymbol::Class(class_symbol.clone())
+                        match class_symbol.constructor_symbol_owned() {
+                            None => {
+                                panic!("Attempt to get non-existent constructor symbol")
+                            }
+                            Some(constructor_symbol) => {
+                                CallableSymbol::Constructor(constructor_symbol)
+                            }
+                        }
                     }
                     _ => panic!("Calling things other than functions not yet supported."),
                 }
@@ -171,11 +218,33 @@ impl Call {
         }
     }
 
-    pub fn to_ir(&self, builder: &mut IrBuilder, symbol_table: &SymbolTable) -> IrCall {
+    pub fn return_type_info<'a>(
+        &self,
+        symbol_table: &SymbolTable,
+        types_table: &'a TypesTable,
+    ) -> &'a TypeInfo {
+        match self.get_callee_symbol(symbol_table) {
+            CallableSymbol::Function(function_symbol) => types_table
+                .function_return_types()
+                .get(&function_symbol)
+                .unwrap(),
+            CallableSymbol::Constructor(constructor_symbol) => types_table
+                .constructor_return_types()
+                .get(&constructor_symbol)
+                .unwrap(),
+        }
+    }
+
+    pub fn to_ir(
+        &self,
+        builder: &mut IrBuilder,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+    ) -> IrCall {
         let arguments: Vec<IrExpression> = self
             .arguments
             .iter()
-            .map(|argument| argument.to_ir_expression(builder, symbol_table))
+            .map(|argument| argument.to_ir_expression(builder, symbol_table, types_table))
             .inspect(|expression| {
                 if expression.is_none() {
                     panic!("Attempt to pass non-expression")
@@ -183,25 +252,18 @@ impl Call {
             })
             .map(Option::unwrap)
             .collect();
-        let callable_symbol = self.get_callee_symbol();
+        let callable_symbol = self.get_callee_symbol(symbol_table);
         match callable_symbol {
             CallableSymbol::Function(function_symbol) => IrCall::new(
-                fqn_parts_to_string(function_symbol.borrow().fqn_parts()),
+                fqn_parts_to_string(function_symbol.fqn_parts()),
                 arguments,
-                function_symbol.borrow().is_extern(),
+                function_symbol.is_extern(),
+            ),
+            CallableSymbol::Constructor(constructor_symbol) => IrCall::new(
+                fqn_parts_to_string(constructor_symbol.fqn_parts()),
+                arguments,
+                false,
             ),
-            CallableSymbol::Class(class_symbol) => {
-                let constructor_symbol = class_symbol
-                    .borrow()
-                    .constructor_symbol()
-                    .cloned()
-                    .expect("Default constructors not supported yet.");
-                IrCall::new(
-                    fqn_parts_to_string(constructor_symbol.borrow().fqn_parts()),
-                    arguments,
-                    false,
-                )
-            }
         }
     }
 

dmc-lib/src/ast/class.rs

@@ -1,3 +1,4 @@
+use crate::ast::assign_statement::AssignStatement;
 use crate::ast::constructor::Constructor;
 use crate::ast::expression::Expression;
 use crate::ast::field::Field;
@@ -5,20 +6,22 @@ use crate::ast::fqn_context::FqnContext;
 use crate::ast::fqn_util::fqn_parts_to_string;
 use crate::ast::function::Function;
 use crate::ast::generic_parameter::GenericParameter;
+use crate::ast::helpers::{collect_diagnostics_mut, collect_diagnostics_single, resolve_ctor_name};
 use crate::ast::statement::Statement;
-use crate::diagnostic::{Diagnostic, SecondaryLabel};
+use crate::diagnostic::Diagnostic;
+use crate::error_codes::{FIELD_MULTIPLE_INIT, FIELD_UNINIT};
 use crate::ir::ir_class::{IrClass, IrField};
 use crate::ir::ir_function::IrFunction;
-use crate::maybe_return_diagnostics;
 use crate::source_range::SourceRange;
 use crate::symbol::Symbol;
 use crate::symbol::class_symbol::ClassSymbol;
-use crate::symbol::field_symbol::FieldSymbol;
-use crate::symbol::generic_parameter_symbol::GenericParameterSymbol;
-use crate::symbol_table::{SymbolInsertError, SymbolTable};
-use std::cell::RefCell;
+use crate::symbol::constructor_symbol::ConstructorSymbol;
+use crate::symbol::variable_symbol::VariableSymbol;
+use crate::symbol_table::SymbolTable;
+use crate::type_info::TypeInfo;
+use crate::types_table::TypesTable;
+use crate::{diagnostics_result, handle_diagnostics, ok_or_err_diagnostics};
 use std::collections::{HashMap, HashSet};
-use std::process::id;
 use std::rc::Rc;
 
 pub struct Class {
@@ -28,7 +31,9 @@ pub struct Class {
     constructor: Option<Constructor>,
     fields: Vec<Field>,
     functions: Vec<Function>,
-    class_symbol: Option<Rc<RefCell<ClassSymbol>>>,
+    scope_id: Option<usize>,
+    self_class_scope_id: Option<usize>,
+    self_class_body_scope_id: Option<usize>,
 }
 
 impl Class {
@@ -40,326 +45,437 @@ impl Class {
         fields: Vec<Field>,
         functions: Vec<Function>,
     ) -> Self {
-        Class {
+        Self {
             declared_name: declared_name.into(),
             declared_name_source_range,
             generic_parameters,
             constructor,
             fields,
             functions,
-            class_symbol: None,
+            scope_id: None,
+            self_class_scope_id: None,
+            self_class_body_scope_id: None,
         }
     }
 
-    pub fn gather_declared_names(
-        &mut self,
-        symbol_table: &mut SymbolTable,
-        fqn_context: &mut FqnContext,
-    ) -> Result<(), Vec<Diagnostic>> {
-        // 1. insert class symbol
-        let to_insert = ClassSymbol::new(
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable, container_scope: usize) {
+        self.scope_id = Some(container_scope);
+
+        let class_scope_id =
+            symbol_table.push_class_scope(&format!("class_scope({})", self.declared_name));
+        self.self_class_scope_id = Some(class_scope_id);
+
+        for generic_parameter in &mut self.generic_parameters {
+            generic_parameter.init_scopes(symbol_table, class_scope_id);
+        }
+
+        let class_body_scope_id = symbol_table
+            .push_class_body_scope(&format!("class_body_scope({})", self.declared_name));
+        self.self_class_body_scope_id = Some(class_body_scope_id);
+
+        for field in &mut self.fields {
+            field.init_scopes(symbol_table, class_body_scope_id);
+        }
+
+        if let Some(constructor) = &mut self.constructor {
+            constructor.init_scopes(symbol_table, class_body_scope_id);
+        }
+        for function in &mut self.functions {
+            function.init_scopes(symbol_table, class_body_scope_id);
+        }
+
+        symbol_table.pop_scope();
+        symbol_table.pop_scope();
+    }
+
+    pub fn make_symbols(&self, fqn_context: &mut FqnContext) -> Vec<Symbol> {
+        let mut all_symbols: Vec<Symbol> = Vec::new();
+
+        let mut generic_parameter_symbols = Vec::new();
+        for generic_parameter in &self.generic_parameters {
+            let symbol = Rc::new(generic_parameter.make_symbol());
+            all_symbols.push(Symbol::GenericParameter(symbol.clone()));
+            generic_parameter_symbols.push(symbol);
+        }
+
+        let mut field_symbols = Vec::new();
+        for (field_index, field) in self.fields.iter().enumerate() {
+            let symbol = Rc::new(field.make_symbol(field_index));
+            all_symbols.push(Symbol::Field(symbol.clone()));
+            field_symbols.push(symbol);
+        }
+
+        fqn_context.push(self.declared_name.clone()); // namespace this class' members
+
+        let constructor_symbol = if let Some(constructor) = &self.constructor {
+            let (constructor_symbol, mut symbols) = constructor.make_symbols(fqn_context);
+            all_symbols.append(&mut symbols);
+            constructor_symbol
+        } else {
+            Rc::new(ConstructorSymbol::new(
+                &self.declared_name_source_range,
+                resolve_ctor_name(fqn_context),
+                false,
+                true,
+                self.self_class_body_scope_id.unwrap(),
+                vec![],
+            ))
+        };
+        all_symbols.push(Symbol::Constructor(constructor_symbol.clone()));
+
+        let mut function_symbols = Vec::new();
+        for function in &self.functions {
+            let (function_symbol, mut symbols) = function.make_symbols(fqn_context, true);
+            all_symbols.append(&mut symbols);
+            function_symbols.push(function_symbol);
+        }
+
+        fqn_context.pop(); // un-namespace
+
+        let class_symbol = Rc::new(ClassSymbol::new(
             &self.declared_name,
-            self.declared_name_source_range.clone(),
+            Some(self.declared_name_source_range.clone()),
             fqn_context.resolve(&self.declared_name),
             false,
-        );
+            self.scope_id.unwrap(),
+            generic_parameter_symbols,
+            Some(constructor_symbol),
+            field_symbols,
+            function_symbols,
+        ));
+        all_symbols.push(Symbol::Class(class_symbol.clone()));
 
-        // 1a. Push class name on fqn
-        fqn_context.push(self.declared_name.clone());
+        all_symbols
+    }
 
-        let class_symbol = symbol_table
-            .insert_class_symbol(to_insert)
-            .map_err(|e| match e {
-                SymbolInsertError::AlreadyDeclared(already_declared) => {
-                    let symbol = already_declared.symbol().borrow();
-                    vec![
-                        Diagnostic::new(
-                            &format!(
-                                "Symbol {} already declared in current scope.",
-                                already_declared.symbol().borrow().declared_name(),
-                            ),
-                            self.declared_name_source_range.start(),
-                            self.declared_name_source_range.end(),
-                        )
-                        .with_secondary_labels(&[SecondaryLabel::new(
-                            symbol.declared_name_source_range().start(),
-                            symbol.declared_name_source_range().end(),
-                            Some("Symbol declared here.".to_string()),
-                        )])
-                        .with_reporter(file!(), line!()),
-                    ]
-                }
-            })?;
+    pub fn check_names(&self, symbol_table: &mut SymbolTable) -> Vec<Diagnostic> {
+        let mut diagnostics: Vec<Diagnostic> = Vec::new();
 
-        // save symbol for later
-        self.class_symbol = Some(class_symbol);
-
-        // 2. push scope
-        symbol_table.push_class_scope(&format!("class_scope({})", self.declared_name));
-
-        // 3a. gather generic parameters
-        let mut generic_parameter_symbols: Vec<Rc<RefCell<GenericParameterSymbol>>> = vec![];
-        let mut generic_parameter_diagnostics: Vec<Diagnostic> = vec![];
-        for generic_parameter in &mut self.generic_parameters {
-            match generic_parameter.gather_declared_names(symbol_table) {
-                Ok(generic_parameter_symbol) => {
-                    generic_parameter_symbols.push(generic_parameter_symbol);
-                }
-                Err(mut d) => {
-                    generic_parameter_diagnostics.append(&mut d);
-                }
-            }
+        for generic_parameter in &self.generic_parameters {
+            diagnostics.append(&mut generic_parameter.check_names(symbol_table));
         }
 
-        maybe_return_diagnostics!(generic_parameter_diagnostics);
-        // save generics to class symbol
-        self.class_symbol
-            .as_mut()
+        for field in &self.fields {
+            diagnostics.append(&mut field.check_names(symbol_table));
+        }
+
+        if let Some(constructor) = &self.constructor {
+            diagnostics.append(&mut constructor.check_names(symbol_table));
+        }
+
+        for function in &self.functions {
+            diagnostics.append(&mut function.check_names(symbol_table));
+        }
+
+        diagnostics
+    }
+
+    fn get_class_symbol_owned(&self, symbol_table: &SymbolTable) -> Rc<ClassSymbol> {
+        symbol_table
+            .get_class_symbol(self.scope_id.unwrap(), &self.declared_name)
+            .cloned()
             .unwrap()
-            .borrow_mut()
-            .set_generic_parameters(generic_parameter_symbols);
+    }
 
-        // 3b. gather fields
-        let mut field_symbols: HashMap<Rc<str>, Rc<RefCell<FieldSymbol>>> = HashMap::new();
-        let mut fields_diagnostics: Vec<Diagnostic> = vec![];
+    pub fn check_field_initializer_names(&self, symbol_table: &SymbolTable) -> Vec<Diagnostic> {
+        let class_symbol = self.get_class_symbol_owned(symbol_table);
+        self.fields
+            .iter()
+            .flat_map(|field| field.check_field_initializer_names(symbol_table, &class_symbol))
+            .collect()
+    }
 
-        for (index, field) in self.fields.iter_mut().enumerate() {
-            match field.gather_declared_names(symbol_table, index) {
-                Ok(field_symbol) => {
-                    field_symbols.insert(field.declared_name_owned(), field_symbol);
-                }
-                Err(mut d) => {
-                    fields_diagnostics.append(&mut d);
-                }
-            };
+    pub fn analyze_local_names(&self, symbol_table: &mut SymbolTable) -> Vec<Diagnostic> {
+        let class_symbol = self.get_class_symbol_owned(symbol_table);
+        let mut diagnostics: Vec<Diagnostic> = Vec::new();
+        if let Some(constructor) = &self.constructor {
+            diagnostics.append(&mut constructor.analyze_local_names(symbol_table, &class_symbol));
+        }
+        for function in &self.functions {
+            diagnostics
+                .append(&mut function.analyze_method_local_names(symbol_table, &class_symbol));
+        }
+        diagnostics
+    }
+
+    pub fn gather_types(
+        &self,
+        symbol_table: &SymbolTable,
+        types_table: &mut TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
+        // class type
+        let class_symbol = self.get_class_symbol_owned(symbol_table);
+        types_table
+            .class_types_mut()
+            .insert(class_symbol.clone(), TypeInfo::Class(class_symbol.clone()));
+
+        // constructor return type
+        // this works for both declared and default constructors
+        let constructor_symbol = symbol_table
+            .get_constructor_symbol_owned(self.self_class_body_scope_id.unwrap())
+            .unwrap();
+        types_table
+            .constructor_return_types_mut()
+            .insert(constructor_symbol, TypeInfo::Class(class_symbol));
+
+        let mut diagnostics = Vec::new();
+
+        // generic params
+        for generic_parameter in &self.generic_parameters {
+            handle_diagnostics!(
+                generic_parameter.gather_types(symbol_table, types_table),
+                diagnostics
+            );
         }
 
-        if !fields_diagnostics.is_empty() {
-            return Err(fields_diagnostics);
-        } else {
-            self.class_symbol
-                .as_mut()
-                .unwrap()
-                .borrow_mut()
-                .set_fields(field_symbols);
+        // field types
+        for field in &self.fields {
+            handle_diagnostics!(field.gather_types(symbol_table, types_table), diagnostics);
         }
 
-        // 4. gather constructor
+        // now the constructor (parameters, etc.)
+        if let Some(constructor) = &self.constructor {
+            constructor.gather_types_into(symbol_table, types_table);
+        }
+
+        // function return types
+        for function in &self.functions {
+            function.gather_types(symbol_table, types_table);
+        }
+
+        diagnostics_result!(diagnostics)
+    }
+
+    fn type_check_generics(
+        &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
+        collect_diagnostics_mut(&mut self.generic_parameters, |gp| {
+            gp.type_check(symbol_table, types_table)
+        })
+    }
+
+    fn type_check_fields(
+        &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
+        collect_diagnostics_mut(&mut self.fields, |f| {
+            f.type_check(symbol_table, types_table)
+        })
+    }
+
+    fn type_check_constructor(
+        &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &mut TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
         if let Some(constructor) = &mut self.constructor {
-            let constructor_symbol =
-                constructor.gather_declared_names(symbol_table, fqn_context)?;
-            self.class_symbol
-                .as_mut()
-                .unwrap()
-                .borrow_mut()
-                .set_constructor_symbol(Some(constructor_symbol));
+            constructor.type_check(symbol_table, types_table)?;
         }
-
-        // 5. gather functions
-        //    note: for each function, insert at index 0 a self parameter
-        let functions_diagnostics: Vec<Diagnostic> = self
-            .functions
-            .iter_mut()
-            .map(|function| {
-                function.gather_declared_names(
-                    symbol_table,
-                    fqn_context,
-                    self.class_symbol.as_ref(),
-                )
-            })
-            .filter_map(Result::err)
-            .flatten()
-            .collect();
-
-        if !functions_diagnostics.is_empty() {
-            return Err(functions_diagnostics);
-        }
-
-        // 6. pop scope
-        symbol_table.pop_scope();
-
-        // 7. pop fqn part
-        fqn_context.pop();
-
         Ok(())
     }
 
-    pub fn check_name_usages(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        let generics_diagnostics: Vec<Diagnostic> = self
-            .generic_parameters
-            .iter_mut()
-            .map(|generic_parameter| {
-                generic_parameter.check_name_usages(symbol_table, self.class_symbol.as_ref())
-            })
-            .filter_map(Result::err)
-            .flatten()
-            .collect();
-        maybe_return_diagnostics!(generics_diagnostics);
+    fn type_check_functions(
+        &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &mut TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
+        collect_diagnostics_mut(&mut self.functions, |f| {
+            f.type_check(symbol_table, types_table)
+        })
+    }
 
-        self.constructor
-            .as_mut()
-            .map(|constructor| {
-                constructor.check_name_usages(symbol_table, self.class_symbol.as_ref())
-            })
-            .transpose()?;
-
-        let fields_diagnostics: Vec<Diagnostic> = self
-            .fields
-            .iter_mut()
-            .map(|field| field.check_name_usages(symbol_table, self.class_symbol.as_ref()))
-            .filter_map(Result::err)
-            .flatten()
-            .collect();
-        if !fields_diagnostics.is_empty() {
-            return Err(fields_diagnostics);
+    /// Returns all field names with declared initializers.
+    fn field_names_with_initializers(&self) -> HashSet<&str> {
+        let mut set: HashSet<&str> = HashSet::new();
+        for field in &self.fields {
+            if field.initializer().is_some() {
+                set.insert(field.declared_name());
+            }
         }
+        set
+    }
 
-        if let Some(constructor) = &mut self.constructor {
-            constructor.check_name_usages(symbol_table, self.class_symbol.as_ref())?;
-        }
-
-        let functions_diagnostics: Vec<Diagnostic> = self
-            .functions
-            .iter_mut()
-            .map(|function| function.check_name_usages(symbol_table, self.class_symbol.as_ref()))
-            .filter_map(Result::err)
-            .flatten()
-            .collect();
-
-        if functions_diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(functions_diagnostics)
+    /// If the destination of the given [AssignStatement] matches a field, returns an
+    /// `Ok(Some(field_name))` only if the field is not already in the `fields_already_init` set,
+    /// AND, if the field is immutable, the field is not initialized more than once in the
+    /// constructor. Otherwise, returns an `Err(Diagnostic)`.
+    fn check_ctor_assign_statement<'a>(
+        &self,
+        assign_statement: &'a AssignStatement,
+        fields_already_init: &HashSet<&&str>,
+        class_symbol: &ClassSymbol,
+    ) -> Result<Option<&'a str>, Diagnostic> {
+        match assign_statement.destination() {
+            Expression::Identifier(identifier) => {
+                // find matching field symbol, if there is one
+                if let Some(field_symbol) = class_symbol.fields().get(identifier.name()) {
+                    // check that we don't init more than once IF field is immutable
+                    if fields_already_init.contains(&identifier.name()) && !field_symbol.is_mut() {
+                        let diagnostic = Diagnostic::new(
+                            &format!("Immutable field {} cannot be initialized more than once in constructor.", identifier.name()),
+                            identifier.source_range().start(),
+                            identifier.source_range().end(),
+                        ).with_reporter(file!(), line!())
+                            .with_error_code(FIELD_MULTIPLE_INIT);
+                        Err(diagnostic)
+                    } else {
+                        Ok(Some(identifier.name()))
+                    }
+                } else {
+                    Ok(None)
+                }
+            }
+            _ => panic!("Found a non-L Value destination"),
         }
     }
 
-    pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
+    /// Returns an `Ok(HashSet<&str>)` containing the names of all fields initialized in the
+    /// constructor, provided that the following are true:
+    ///
+    /// - The field is not initialized more than once in the constructor
+    /// - The field is not also initialized with a declared initializer.
+    ///
+    /// If the above are not met, returns `Err(diagnostics)`.
+    fn get_fields_init_in_ctor<'a>(
+        &self,
+        fields_with_declared_initializers: &HashSet<&str>,
+        symbol_table: &SymbolTable,
+    ) -> Result<HashSet<&str>, Vec<Diagnostic>> {
+        let mut constructor_inits: HashSet<&str> = HashSet::new();
         let mut diagnostics: Vec<Diagnostic> = vec![];
-
-        self.fields
-            .iter_mut()
-            .map(|field| field.type_check(symbol_table))
-            .filter_map(Result::err)
-            .flatten()
-            .for_each(|diagnostic| diagnostics.push(diagnostic));
-
-        if !diagnostics.is_empty() {
-            return Err(diagnostics);
-        }
-
-        if let Some(constructor) = &mut self.constructor {
-            match constructor.type_check(symbol_table) {
-                Ok(_) => {}
-                Err(mut constructor_diagnostics) => {
-                    diagnostics.append(&mut constructor_diagnostics);
-                }
-            }
-        }
-
-        if !diagnostics.is_empty() {
-            return Err(diagnostics);
-        }
-
-        self.functions
-            .iter_mut()
-            .map(|function| function.type_check(symbol_table))
-            .filter_map(Result::err)
-            .flatten()
-            .for_each(|diagnostic| diagnostics.push(diagnostic));
-
-        if !diagnostics.is_empty() {
-            return Err(diagnostics);
-        }
-
-        // We need to determine if fields are initialized or not (the latter is an error).
-        // First phase: check all fields, then check constructor, leaving pending those things that
-        // are fields <- initialized by constructor. Then circle back to fields and check all are
-        // initialized
-        let mut initialized_field_names: HashSet<&str> = HashSet::new();
-
-        for field in &self.fields {
-            if field.initializer().is_some() {
-                initialized_field_names.insert(field.declared_name());
-            }
-        }
-
-        // check constructor
         if let Some(constructor) = &self.constructor {
+            let class_symbol = symbol_table
+                .get_class_symbol(self.scope_id.unwrap(), &self.declared_name)
+                .unwrap();
             for statement in constructor.statements() {
                 match statement {
-                    Statement::Assign(assign_statement) => match assign_statement.destination() {
-                        Expression::Identifier(identifier) => {
-                            if self
-                                .class_symbol
-                                .as_ref()
-                                .unwrap()
-                                .borrow()
-                                .fields()
-                                .contains_key(identifier.name())
-                            {
-                                initialized_field_names.insert(identifier.name());
+                    Statement::Assign(assign_statement) => {
+                        let fields_init_so_far = constructor_inits
+                            .union(fields_with_declared_initializers)
+                            .collect::<HashSet<_>>();
+                        match self.check_ctor_assign_statement(
+                            assign_statement,
+                            &fields_init_so_far,
+                            &class_symbol,
+                        ) {
+                            Ok(maybe_init_field) => match maybe_init_field {
+                                None => {}
+                                Some(init_field) => {
+                                    constructor_inits.insert(init_field);
+                                }
+                            },
+                            Err(diagnostic) => {
+                                diagnostics.push(diagnostic);
                             }
                         }
-                        _ => panic!("Found a non L Value assign lhs"),
-                    },
+                    }
                     _ => {}
                 }
             }
         }
-
-        // check that all fields are present in the hash set
-        for field in &self.fields {
-            if !initialized_field_names.contains(field.declared_name()) {
-                diagnostics.push(
-                    Diagnostic::new(
-                        &format!("Field {} is not initialized.", field.declared_name()),
-                        field.declared_name_source_range().start(),
-                        field.declared_name_source_range().end(),
-                    )
-                    .with_primary_label_message(
-                        "Must be initialized in declaration or constructor.",
-                    )
-                    .with_reporter(file!(), line!()),
-                )
-            }
-        }
-
-        if diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(diagnostics)
-        }
+        ok_or_err_diagnostics!(constructor_inits, diagnostics)
     }
 
-    pub fn to_ir(&self, symbol_table: &SymbolTable) -> (IrClass, Vec<IrFunction>) {
+    /// Checks that all declared fields in this `Class` are present in the `all_inits` set. If so,
+    /// returns `Ok`, else `Err`.
+    fn check_all_fields_in_init_set(
+        &self,
+        all_inits: &HashSet<&&str>,
+    ) -> Result<(), Vec<Diagnostic>> {
+        collect_diagnostics_single(&self.fields, |field| {
+            if all_inits.contains(&field.declared_name()) {
+                Ok(())
+            } else {
+                Err(Diagnostic::new(
+                    &format!("Field {} is not initialized.", field.declared_name()),
+                    field.declared_name_source_range().start(),
+                    field.declared_name_source_range().end(),
+                )
+                .with_primary_label_message("Must be initialized in declaration or constructor.")
+                .with_reporter(file!(), line!())
+                .with_error_code(FIELD_UNINIT))
+            }
+        })
+    }
+
+    /// Checks that all fields are initialized, either at their declaration or in the constructor.
+    /// Immutable fields may be only initialized once, either at their declaration or once in the
+    /// constructor. Mutable fields may be initialized either at their declaration, or at least once
+    /// in the constructor.
+    fn check_field_initialization(
+        &self,
+        symbol_table: &SymbolTable,
+    ) -> Result<(), Vec<Diagnostic>> {
+        // We need to determine if fields are initialized or not (the latter is an error).
+        // First phase: check all fields, then check constructor, leaving pending those things that
+        // are fields <- initialized by constructor. Then circle back to fields and check all are
+        // initialized
+        let field_names_with_initializers = self.field_names_with_initializers();
+        let field_names_init_in_constructor =
+            self.get_fields_init_in_ctor(&field_names_with_initializers, symbol_table)?;
+        let combined = field_names_with_initializers
+            .union(&field_names_init_in_constructor)
+            .collect::<HashSet<_>>();
+
+        // check that all fields are present in the hash set
+        self.check_all_fields_in_init_set(&combined)?;
+
+        Ok(())
+    }
+
+    pub fn type_check(
+        &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &mut TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
+        self.type_check_generics(symbol_table, types_table)?;
+        self.type_check_fields(symbol_table, types_table)?;
+        self.type_check_constructor(symbol_table, types_table)?;
+        self.type_check_functions(symbol_table, types_table)?;
+        self.check_field_initialization(symbol_table)?;
+        Ok(())
+    }
+
+    pub fn to_ir(
+        &self,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+    ) -> (IrClass, Vec<IrFunction>) {
+        let self_class_symbol = symbol_table
+            .get_class_symbol(self.scope_id.unwrap(), &self.declared_name)
+            .unwrap();
+
         let mut ir_functions: Vec<IrFunction> = vec![];
         if let Some(constructor) = &self.constructor {
             ir_functions.push(constructor.to_ir(
-                self.class_symbol.as_ref().unwrap(),
+                self_class_symbol,
                 &self.fields,
                 symbol_table,
+                types_table,
             ))
         }
 
         for function in &self.functions {
-            ir_functions.push(function.to_ir(
-                symbol_table,
-                Some(self.class_symbol.as_ref().unwrap().clone()),
-            ));
+            ir_functions.push(function.to_ir(symbol_table, types_table, Some(self_class_symbol)));
         }
 
-        let class_symbol = self.class_symbol.as_ref().unwrap().borrow();
-
         let ir_class = IrClass::new(
-            class_symbol.declared_name_owned(),
-            fqn_parts_to_string(class_symbol.fqn_parts()).into(),
+            self_class_symbol.declared_name_owned(),
+            fqn_parts_to_string(self_class_symbol.fqn_parts()).into(),
             self.fields
                 .iter()
                 .map(|field| {
+                    let field_symbol = symbol_table
+                        .get_field_symbol_owned(field.scope_id(), field.declared_name())
+                        .unwrap();
+                    let field_type = types_table.field_types().get(&field_symbol).unwrap();
                     IrField::new(
                         field.declared_name().into(),
-                        field.field_symbol().borrow().field_index(),
-                        field.field_symbol().borrow().type_info().clone(),
+                        field_symbol.field_index(),
+                        field_type.clone(),
                     )
                 })
                 .collect(),

dmc-lib/src/ast/compilation_unit.rs

@@ -2,10 +2,13 @@ use crate::ast::class::Class;
 use crate::ast::extern_function::ExternFunction;
 use crate::ast::fqn_context::FqnContext;
 use crate::ast::function::Function;
+use crate::ast::helpers::{collect_diagnostics_into_mut, try_insert_symbols_into};
 use crate::diagnostic::Diagnostic;
 use crate::ir::ir_class::IrClass;
 use crate::ir::ir_function::IrFunction;
 use crate::symbol_table::SymbolTable;
+use crate::types_table::TypesTable;
+use crate::{diagnostics_result, handle_diagnostics, ok_or_err_diagnostics};
 
 pub struct CompilationUnit {
     functions: Vec<Function>,
@@ -38,118 +41,125 @@ impl CompilationUnit {
         &self.classes
     }
 
-    pub fn gather_declared_names(
-        &mut self,
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable) {
+        let compilation_unit_scope = symbol_table.push_module_scope("compilation_unit_scope");
+        for class in &mut self.classes {
+            class.init_scopes(symbol_table, compilation_unit_scope);
+        }
+        for function in &mut self.functions {
+            function.init_scopes(symbol_table, compilation_unit_scope);
+        }
+        for extern_function in &mut self.extern_functions {
+            extern_function.init_scopes(symbol_table, compilation_unit_scope);
+        }
+        symbol_table.pop_scope();
+    }
+
+    pub fn gather_symbols_into(
+        &self,
         symbol_table: &mut SymbolTable,
     ) -> Result<(), Vec<Diagnostic>> {
-        symbol_table.push_module_scope("compilation_unit_scope");
-
-        let mut fqn_context = FqnContext::new(); // in the future, we'll push the pkg/ns on here
-        let mut diagnostics: Vec<Diagnostic> = vec![];
-
-        self.functions
-            .iter_mut()
-            .map(|f| f.gather_declared_names(symbol_table, &fqn_context, None))
-            .filter_map(Result::err)
-            .flatten()
-            .for_each(|diagnostic| diagnostics.push(diagnostic));
-
-        self.extern_functions
-            .iter_mut()
-            .map(|f| f.gather_declared_names(symbol_table, &fqn_context))
-            .filter_map(Result::err)
-            .flatten()
-            .for_each(|diagnostic| diagnostics.push(diagnostic));
-
-        self.classes
-            .iter_mut()
-            .map(|c| c.gather_declared_names(symbol_table, &mut fqn_context))
-            .filter_map(Result::err)
-            .flatten()
-            .for_each(|diagnostic| diagnostics.push(diagnostic));
-
-        symbol_table.pop_scope();
-
-        if diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(diagnostics)
+        let mut diagnostics = vec![];
+        let mut fqn_context = FqnContext::new();
+        for class in &self.classes {
+            handle_diagnostics!(
+                try_insert_symbols_into(class.make_symbols(&mut fqn_context), symbol_table),
+                diagnostics
+            );
         }
+        for function in &self.functions {
+            let (_, symbols) = function.make_symbols(&mut fqn_context, false);
+            handle_diagnostics!(try_insert_symbols_into(symbols, symbol_table), diagnostics);
+        }
+        for extern_function in &self.extern_functions {
+            let (_, symbols) = extern_function.make_symbols(&mut fqn_context);
+            handle_diagnostics!(try_insert_symbols_into(symbols, symbol_table), diagnostics);
+        }
+        diagnostics_result!(diagnostics)
     }
 
-    pub fn check_name_usages(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        let mut diagnostics: Vec<Diagnostic> = vec![];
-
-        self.functions
-            .iter_mut()
-            .map(|f| f.check_name_usages(symbol_table, None))
-            .filter_map(Result::err)
-            .flatten()
-            .for_each(|diagnostic| diagnostics.push(diagnostic));
-
-        self.extern_functions
-            .iter_mut()
-            .map(|f| f.check_name_usages(symbol_table, None))
-            .filter_map(Result::err)
-            .flatten()
-            .for_each(|diagnostic| diagnostics.push(diagnostic));
-
-        self.classes
-            .iter_mut()
-            .map(|c| c.check_name_usages(symbol_table))
-            .filter_map(Result::err)
-            .flatten()
-            .for_each(|diagnostic| diagnostics.push(diagnostic));
-
-        if diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(diagnostics)
+    pub fn check_names(&self, symbol_table: &mut SymbolTable) -> Result<(), Vec<Diagnostic>> {
+        let mut diagnostics = vec![];
+        for class in &self.classes {
+            diagnostics.append(&mut class.check_names(symbol_table));
+            diagnostics.append(&mut class.check_field_initializer_names(symbol_table));
+            diagnostics.append(&mut class.analyze_local_names(symbol_table));
         }
+        for function in &self.functions {
+            diagnostics.append(&mut function.check_names(symbol_table));
+            diagnostics.append(&mut function.analyze_static_fn_local_names(symbol_table));
+        }
+        for extern_function in &self.extern_functions {
+            diagnostics.append(&mut extern_function.check_names(symbol_table));
+        }
+        diagnostics_result!(diagnostics)
     }
 
-    pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        let mut diagnostics: Vec<Diagnostic> = vec![];
+    pub fn gather_types_into(
+        &self,
+        symbol_table: &SymbolTable,
+        types_table: &mut TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
+        let mut diagnostics = Vec::new();
 
-        self.functions
-            .iter_mut()
-            .map(|f| f.type_check(symbol_table))
-            .filter_map(Result::err)
-            .flatten()
-            .for_each(|diagnostic| diagnostics.push(diagnostic));
-
-        self.extern_functions
-            .iter_mut()
-            .map(|f| f.type_check(symbol_table))
-            .filter_map(Result::err)
-            .flatten()
-            .for_each(|diagnostic| diagnostics.push(diagnostic));
-
-        self.classes
-            .iter_mut()
-            .map(|c| c.type_check(symbol_table))
-            .filter_map(Result::err)
-            .flatten()
-            .for_each(|diagnostic| diagnostics.push(diagnostic));
-
-        if diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(diagnostics)
+        for class in &self.classes {
+            handle_diagnostics!(class.gather_types(symbol_table, types_table), diagnostics);
         }
+
+        for function in &self.functions {
+            function.gather_types(symbol_table, types_table);
+        }
+
+        for extern_function in &self.extern_functions {
+            extern_function.gather_types(symbol_table, types_table);
+        }
+
+        diagnostics_result!(diagnostics)
     }
 
-    pub fn to_ir(&self, symbol_table: &SymbolTable) -> (Vec<IrClass>, Vec<IrFunction>) {
+    pub fn type_check(
+        &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &mut TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
+        let mut diagnostics: Vec<Diagnostic> = vec![];
+
+        collect_diagnostics_into_mut(
+            &mut self.functions,
+            |f| f.type_check(symbol_table, types_table),
+            &mut diagnostics,
+        );
+
+        collect_diagnostics_into_mut(
+            &mut self.extern_functions,
+            |ef| ef.type_check(symbol_table, types_table),
+            &mut diagnostics,
+        );
+
+        collect_diagnostics_into_mut(
+            &mut self.classes,
+            |c| c.type_check(symbol_table, types_table),
+            &mut diagnostics,
+        );
+
+        diagnostics_result!(diagnostics)
+    }
+
+    pub fn to_ir(
+        &self,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+    ) -> (Vec<IrClass>, Vec<IrFunction>) {
         let mut functions: Vec<IrFunction> = vec![];
         let mut classes: Vec<IrClass> = vec![];
 
         self.functions
             .iter()
-            .map(|f| f.to_ir(symbol_table, None))
+            .map(|f| f.to_ir(symbol_table, types_table, None))
             .for_each(|f| functions.push(f));
 
         for class in &self.classes {
-            let (class, mut class_functions) = class.to_ir(symbol_table);
+            let (class, mut class_functions) = class.to_ir(symbol_table, types_table);
             functions.append(&mut class_functions);
             classes.push(class);
         }

dmc-lib/src/ast/constructor.rs

@@ -1,6 +1,7 @@
 use crate::ast::field::Field;
 use crate::ast::fqn_context::FqnContext;
 use crate::ast::fqn_util::fqn_parts_to_string;
+use crate::ast::helpers::{collect_parameter_symbols_into, resolve_ctor_name};
 use crate::ast::ir_builder::IrBuilder;
 use crate::ast::parameter::Parameter;
 use crate::ast::statement::Statement;
@@ -21,9 +22,9 @@ use crate::source_range::SourceRange;
 use crate::symbol::Symbol;
 use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol::constructor_symbol::ConstructorSymbol;
-use crate::symbol::parameter_symbol::ParameterSymbol;
-use crate::symbol_table::{SymbolInsertError, SymbolTable};
+use crate::symbol_table::SymbolTable;
 use crate::type_info::TypeInfo;
+use crate::types_table::TypesTable;
 use std::cell::RefCell;
 use std::ops::Neg;
 use std::rc::Rc;
@@ -33,6 +34,7 @@ pub struct Constructor {
     ctor_keyword_source_range: SourceRange,
     parameters: Vec<Parameter>,
     statements: Vec<Statement>,
+    scope_id: Option<usize>,
 }
 
 impl Constructor {
@@ -47,6 +49,7 @@ impl Constructor {
             ctor_keyword_source_range,
             parameters,
             statements,
+            scope_id: None,
         }
     }
 
@@ -54,87 +57,77 @@ impl Constructor {
         &self.statements
     }
 
-    pub fn gather_declared_names(
-        &mut self,
-        symbol_table: &mut SymbolTable,
-        fqn_context: &FqnContext,
-    ) -> Result<Rc<RefCell<ConstructorSymbol>>, Vec<Diagnostic>> {
-        // insert constructor symbol
-        let to_insert = ConstructorSymbol::new(
-            self.ctor_keyword_source_range.clone(),
-            fqn_context.resolve("ctor"), // ctor is a keyword at the language level, should not be callable via normal means
-            false,
-        );
-        let constructor_symbol =
-            symbol_table
-                .insert_constructor_symbol(to_insert)
-                .map_err(|symbol_insert_error| match symbol_insert_error {
-                    SymbolInsertError::AlreadyDeclared(_) => {
-                        vec![
-                            Diagnostic::new(
-                                "Cannot declare more than one constructor.",
-                                self.ctor_keyword_source_range.start(),
-                                self.ctor_keyword_source_range.end(),
-                            )
-                            .with_reporter(file!(), line!()),
-                        ]
-                    }
-                })?;
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable, container_scope: usize) {
+        self.scope_id = Some(container_scope);
 
-        symbol_table.push_function_scope("ctor_scope");
-
-        let mut parameter_symbols: Vec<Rc<RefCell<ParameterSymbol>>> = vec![];
-        let mut parameters_diagnostics = vec![];
+        let function_scope = symbol_table.push_function_scope("constructor_scope");
 
         for parameter in &mut self.parameters {
-            match parameter.gather_declared_names(symbol_table) {
-                Ok(parameter_symbol) => {
-                    parameter_symbols.push(parameter_symbol);
-                }
-                Err(mut ds) => {
-                    parameters_diagnostics.append(&mut ds);
-                }
-            }
+            parameter.init_scopes(symbol_table, function_scope);
         }
 
-        if !parameters_diagnostics.is_empty() {
-            symbol_table.pop_scope();
-            return Err(parameters_diagnostics);
-        } else {
-            constructor_symbol
-                .borrow_mut()
-                .set_parameters(parameter_symbols);
+        let body_scope = symbol_table.push_block_scope("body_scope");
+        for statement in &mut self.statements {
+            statement.init_scopes(symbol_table, body_scope);
         }
 
-        symbol_table.push_block_scope("ctor_main_block");
+        symbol_table.pop_scope();
+        symbol_table.pop_scope();
+    }
 
-        let statements_diagnostics = self
-            .statements
-            .iter_mut()
-            .map(|stmt| stmt.gather_declared_names(symbol_table))
-            .filter_map(Result::err)
-            .flatten()
-            .collect::<Vec<_>>();
+    pub fn make_symbols(&self, fqn_context: &FqnContext) -> (Rc<ConstructorSymbol>, Vec<Symbol>) {
+        let mut all_symbols: Vec<Symbol> = Vec::new();
 
-        symbol_table.pop_scope(); // block
-        symbol_table.pop_scope(); // function
+        let mut parameter_symbols = Vec::new();
+        collect_parameter_symbols_into(&self.parameters, &mut all_symbols, &mut parameter_symbols);
 
-        if statements_diagnostics.is_empty() {
-            Ok(constructor_symbol)
-        } else {
-            Err(statements_diagnostics)
+        let constructor_symbol = Rc::new(ConstructorSymbol::new(
+            &self.ctor_keyword_source_range,
+            resolve_ctor_name(fqn_context),
+            false,
+            false,
+            self.scope_id.unwrap(),
+            parameter_symbols,
+        ));
+        all_symbols.push(Symbol::Constructor(constructor_symbol.clone()));
+
+        (constructor_symbol, all_symbols)
+    }
+
+    pub fn check_names(&self, symbol_table: &SymbolTable) -> Vec<Diagnostic> {
+        let mut diagnostics: Vec<Diagnostic> = Vec::new();
+        for parameter in &self.parameters {
+            diagnostics.append(&mut parameter.check_names(symbol_table));
+        }
+        diagnostics
+    }
+
+    pub fn analyze_local_names(
+        &self,
+        symbol_table: &mut SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        self.statements
+            .iter()
+            .flat_map(|s| s.analyze_constructor_local_names(symbol_table, class_symbol))
+            .collect()
+    }
+
+    pub fn gather_types_into(&self, symbol_table: &SymbolTable, types_table: &mut TypesTable) {
+        for parameter in &self.parameters {
+            parameter.gather_types_into(symbol_table, types_table);
         }
     }
 
-    pub fn check_name_usages(
+    pub fn type_check(
         &mut self,
         symbol_table: &SymbolTable,
-        class_context: Option<&Rc<RefCell<ClassSymbol>>>,
+        types_table: &mut TypesTable,
     ) -> Result<(), Vec<Diagnostic>> {
         let parameters_diagnostics: Vec<Diagnostic> = self
             .parameters
             .iter_mut()
-            .map(|param| param.check_name_usages(symbol_table, class_context))
+            .map(|param| param.type_check(symbol_table, types_table))
             .filter_map(Result::err)
             .flatten()
             .collect();
@@ -146,35 +139,7 @@ impl Constructor {
         let statements_diagnostics: Vec<Diagnostic> = self
             .statements
             .iter_mut()
-            .map(|statement| statement.check_name_usages(symbol_table))
-            .filter_map(Result::err)
-            .flatten()
-            .collect();
-
-        if statements_diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(statements_diagnostics)
-        }
-    }
-
-    pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        let parameters_diagnostics: Vec<Diagnostic> = self
-            .parameters
-            .iter_mut()
-            .map(|param| param.type_check(symbol_table))
-            .filter_map(Result::err)
-            .flatten()
-            .collect();
-
-        if !parameters_diagnostics.is_empty() {
-            return Err(parameters_diagnostics);
-        }
-
-        let statements_diagnostics: Vec<Diagnostic> = self
-            .statements
-            .iter_mut()
-            .map(|statement| statement.type_check(symbol_table, None))
+            .map(|statement| statement.type_check(symbol_table, types_table, None))
             .filter_map(Result::err)
             .flatten()
             .collect();
@@ -188,9 +153,10 @@ impl Constructor {
 
     pub fn to_ir(
         &self,
-        class_symbol: &Rc<RefCell<ClassSymbol>>,
+        class_symbol: &Rc<ClassSymbol>,
         fields: &[Field],
         symbol_table: &SymbolTable,
+        types_table: &TypesTable,
     ) -> IrFunction {
         let mut ir_builder = IrBuilder::new();
 
@@ -200,17 +166,22 @@ impl Constructor {
             .iter()
             .enumerate()
             .map(|(i, parameter)| {
-                let mut parameter_symbol = parameter.parameter_symbol().borrow_mut();
+                let parameter_symbol = symbol_table
+                    .get_parameter_symbol_owned(parameter.scope_id(), parameter.declared_name())
+                    .unwrap();
+                let parameter_type = types_table
+                    .parameter_types()
+                    .get(&parameter_symbol)
+                    .unwrap();
                 let offset = (parameters_count as isize).neg() + i as isize;
                 let ir_parameter = Rc::new(IrParameter::new(
                     parameter_symbol.declared_name(),
-                    parameter_symbol.type_info().clone(),
+                    parameter_type.clone(),
                     offset,
                 ));
 
                 // make sure to save ir_parameter to symbol so others can access it
-                let to_save = ir_parameter.clone();
-                parameter_symbol.set_ir_parameter(to_save);
+                ir_builder.push_parameter(&parameter_symbol, ir_parameter.clone());
 
                 ir_parameter
             })
@@ -222,7 +193,7 @@ impl Constructor {
         let alloc_assign_destination = IrVariable::new_vr(
             ir_builder.new_t_var().into(),
             ir_builder.current_block().id(),
-            &TypeInfo::ClassInstance(class_symbol.clone()),
+            &TypeInfo::Class(class_symbol.clone()),
         );
         let self_variable = Rc::new(RefCell::new(alloc_assign_destination));
 
@@ -232,7 +203,7 @@ impl Constructor {
 
         let alloc_assign = IrAssign::new(
             self_variable.clone(),
-            IrOperation::Allocate(IrAllocate::new(class_symbol.borrow().declared_name_owned())),
+            IrOperation::Allocate(IrAllocate::new(class_symbol.declared_name_owned())),
         );
         ir_builder
             .current_block_mut()
@@ -241,16 +212,20 @@ impl Constructor {
         // next, initialize fields that have an initializer in their declaration
         for field in fields {
             if let Some(initializer) = field.initializer() {
+                let field_symbol = symbol_table
+                    .get_field_symbol_owned(field.scope_id(), field.declared_name())
+                    .unwrap();
+                let field_type = types_table.field_types().get(&field_symbol).unwrap();
                 // get a mut ref to the field
                 let ir_get_field_ref_mut = IrGetFieldRefMut::new(
                     IrParameterOrVariable::Variable(self_variable.clone()),
-                    field.field_symbol().borrow().field_index(),
+                    field_symbol.field_index(),
                 );
                 let field_mut_ref_variable_name: Rc<str> = ir_builder.new_t_var().into();
                 let field_mut_ref_variable = Rc::new(RefCell::new(IrVariable::new_vr(
                     field_mut_ref_variable_name.clone(),
                     ir_builder.current_block().id(),
-                    field.field_symbol().borrow().type_info(),
+                    field_type,
                 )));
                 let field_mut_ref_assign = IrAssign::new(
                     field_mut_ref_variable.clone(),
@@ -273,7 +248,7 @@ impl Constructor {
                     .clone();
 
                 let ir_expression = initializer
-                    .to_ir_expression(&mut ir_builder, symbol_table)
+                    .to_ir_expression(&mut ir_builder, symbol_table, types_table)
                     .unwrap();
                 let ir_set_field = IrSetField::new(
                     &field_mut_ref_variable, // dumb that we clone it and then ref it
@@ -287,7 +262,7 @@ impl Constructor {
 
         // do "declared" statements of constructor
         for statement in &self.statements {
-            statement.to_ir(&mut ir_builder, symbol_table, false);
+            statement.to_ir(&mut ir_builder, symbol_table, types_table, false);
         }
 
         // return complete self object
@@ -301,17 +276,13 @@ impl Constructor {
         ir_builder.finish_block();
         let entry_block = ir_builder.get_block(entry_block_id);
 
+        let constructor_symbol = symbol_table
+            .get_constructor_symbol(self.scope_id.unwrap())
+            .unwrap();
         IrFunction::new(
-            fqn_parts_to_string(
-                class_symbol
-                    .borrow()
-                    .constructor_symbol()
-                    .unwrap()
-                    .borrow()
-                    .fqn_parts(),
-            ), // fake function symbol
-            &ir_parameters, // make params
-            &TypeInfo::ClassInstance(class_symbol.clone()),
+            fqn_parts_to_string(constructor_symbol.fqn_parts()),
+            ir_parameters,
+            &TypeInfo::Class(class_symbol.clone()),
             entry_block.clone(),
         )
     }

dmc-lib/src/ast/diagnostic_factories.rs

@@ -0,0 +1,119 @@
+use crate::diagnostic::{Diagnostic, SecondaryLabel};
+use crate::error_codes::{
+    CLASS_NO_CONSTRUCTOR, FIELD_NO_TYPE_OR_INIT, OUTER_CLASS_FIELD_USED_IN_INIT,
+    OUTER_CLASS_METHOD_USED_IN_INIT, SELF_CONSTRUCTOR_USED_IN_INIT, SELF_FIELD_USED_IN_INIT,
+    SELF_METHOD_USED_IN_INIT, SYMBOL_ALREADY_DECLARED, SYMBOL_NOT_FOUND,
+};
+use crate::source_range::SourceRange;
+use crate::symbol::Symbol;
+
+pub fn symbol_not_found(name: &str, source_range: &SourceRange) -> Diagnostic {
+    Diagnostic::new(
+        &format!("Symbol {} not found in scope.", name),
+        source_range.start(),
+        source_range.end(),
+    )
+    .with_error_code(SYMBOL_NOT_FOUND)
+}
+
+pub fn field_has_no_type_or_init(name: &str, source_range: &SourceRange) -> Diagnostic {
+    Diagnostic::new(
+        &format!("Field {} has no declared type nor initializer.", name),
+        source_range.start(),
+        source_range.end(),
+    )
+    .with_error_code(FIELD_NO_TYPE_OR_INIT)
+    .with_primary_label_message("Declare a type and/or an initializer.")
+}
+
+pub fn cannot_reference_field_in_init(name: &str, source_range: &SourceRange) -> Diagnostic {
+    Diagnostic::new(
+        &format!("Cannot reference field {} during initialization.", name),
+        source_range.start(),
+        source_range.end(),
+    )
+    .with_error_code(SELF_FIELD_USED_IN_INIT)
+}
+
+pub fn symbol_already_declared(already_inserted: &Symbol, would_insert: &Symbol) -> Diagnostic {
+    let secondary_label = if let Some(source_range) = already_inserted.declared_name_source_range()
+    {
+        Some(SecondaryLabel::new(
+            source_range.start(),
+            source_range.end(),
+            Some("Symbol already declared here.".to_string()),
+        ))
+    } else {
+        None
+    };
+
+    let diagnostic = Diagnostic::new(
+        &format!(
+            "Symbol {} already declared in current scope.",
+            would_insert.declared_name()
+        ),
+        would_insert.declared_name_source_range().unwrap().start(), // unwrap should be okay, since this is user code
+        would_insert.declared_name_source_range().unwrap().end(),
+    )
+    .with_error_code(SYMBOL_ALREADY_DECLARED);
+
+    if let Some(secondary_label) = secondary_label {
+        diagnostic.with_secondary_labels(&[secondary_label])
+    } else {
+        diagnostic
+    }
+}
+
+pub fn self_constructor_used_in_init(source_range: &SourceRange) -> Diagnostic {
+    Diagnostic::new(
+        "Cannot call Self constructor during initialization.",
+        source_range.start(),
+        source_range.end(),
+    )
+    .with_error_code(SELF_CONSTRUCTOR_USED_IN_INIT)
+}
+
+pub fn self_field_used_in_init(source_range: &SourceRange) -> Diagnostic {
+    Diagnostic::new(
+        "Cannot reference Self field during initialization.",
+        source_range.start(),
+        source_range.end(),
+    )
+    .with_error_code(SELF_FIELD_USED_IN_INIT)
+}
+
+pub fn self_method_used_in_init(source_range: &SourceRange) -> Diagnostic {
+    Diagnostic::new(
+        "Cannot call Self method during initialization.",
+        source_range.start(),
+        source_range.end(),
+    )
+    .with_error_code(SELF_METHOD_USED_IN_INIT)
+}
+
+pub fn outer_class_field_usage(source_range: &SourceRange) -> Diagnostic {
+    Diagnostic::new(
+        "Cannot reference an outer class member.",
+        source_range.start(),
+        source_range.end(),
+    )
+    .with_error_code(OUTER_CLASS_FIELD_USED_IN_INIT)
+}
+
+pub fn outer_class_method_usage(source_range: &SourceRange) -> Diagnostic {
+    Diagnostic::new(
+        "Cannot call an outer class method.",
+        source_range.start(),
+        source_range.end(),
+    )
+    .with_error_code(OUTER_CLASS_METHOD_USED_IN_INIT)
+}
+
+pub fn class_has_no_constructor(name: &str, source_range: &SourceRange) -> Diagnostic {
+    Diagnostic::new(
+        &format!("Class {} has no constructor.", name),
+        source_range.start(),
+        source_range.end(),
+    )
+    .with_error_code(CLASS_NO_CONSTRUCTOR)
+}

dmc-lib/src/ast/expression.rs

@@ -13,8 +13,10 @@ use crate::ir::ir_operation::IrOperation;
 use crate::ir::ir_statement::IrStatement;
 use crate::ir::ir_variable::IrVariable;
 use crate::source_range::SourceRange;
+use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol_table::SymbolTable;
 use crate::type_info::TypeInfo;
+use crate::types_table::TypesTable;
 use std::cell::RefCell;
 use std::rc::Rc;
 
@@ -29,61 +31,192 @@ pub enum Expression {
 }
 
 impl Expression {
-    pub fn gather_declared_names(
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable, container_scope: usize) {
+        match self {
+            Expression::Binary(binary_expression) => {
+                binary_expression.init_scopes(symbol_table, container_scope);
+            }
+            Expression::Negative(negative_expression) => {
+                negative_expression.init_scopes(symbol_table, container_scope);
+            }
+            Expression::Call(call) => {
+                call.init_scopes(symbol_table, container_scope);
+            }
+            Expression::Identifier(identifier) => {
+                identifier.init_scope_id(container_scope);
+            }
+            _ => {}
+        }
+    }
+
+    pub fn check_field_initializer_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        match self {
+            Expression::Binary(binary_expression) => {
+                binary_expression.check_field_initializer_names(symbol_table, class_symbol)
+            }
+            Expression::Negative(negative_expression) => {
+                negative_expression.check_field_initializer_names(symbol_table, class_symbol)
+            }
+            Expression::Call(call) => {
+                call.check_field_initializer_names(symbol_table, class_symbol)
+            }
+            Expression::Identifier(identifier) => {
+                if let Some(diagnostic) =
+                    identifier.check_name_as_field_initializer(symbol_table, class_symbol)
+                {
+                    vec![diagnostic]
+                } else {
+                    vec![]
+                }
+            }
+            _ => vec![],
+        }
+    }
+
+    pub fn check_constructor_destination_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        match self {
+            Expression::Binary(_) => {
+                panic!()
+            }
+            Expression::Negative(_) => {
+                panic!()
+            }
+            Expression::Call(_) => {
+                panic!()
+            }
+            Expression::Identifier(identifier) => {
+                if let Some(diagnostic) =
+                    identifier.check_constructor_destination_name(symbol_table, class_symbol)
+                {
+                    vec![diagnostic]
+                } else {
+                    vec![]
+                }
+            }
+            _ => vec![],
+        }
+    }
+
+    pub fn check_constructor_local_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        match self {
+            Expression::Binary(binary_expression) => {
+                binary_expression.check_constructor_local_names(symbol_table, class_symbol)
+            }
+            Expression::Negative(negative_expression) => {
+                negative_expression.check_constructor_local_names(symbol_table, class_symbol)
+            }
+            Expression::Call(call) => {
+                call.check_constructor_local_names(symbol_table, class_symbol)
+            }
+            Expression::Identifier(identifier) => {
+                if let Some(diagnostic) =
+                    identifier.check_constructor_local_name(symbol_table, class_symbol)
+                {
+                    vec![diagnostic]
+                } else {
+                    vec![]
+                }
+            }
+            _ => vec![],
+        }
+    }
+
+    pub fn check_method_local_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        match self {
+            Expression::Binary(binary_expression) => {
+                binary_expression.check_method_local_names(symbol_table, class_symbol)
+            }
+            Expression::Negative(negative_expression) => {
+                negative_expression.check_method_local_names(symbol_table, class_symbol)
+            }
+            Expression::Call(call) => call.check_method_local_names(symbol_table, class_symbol),
+            Expression::Identifier(identifier) => {
+                if let Some(diagnostic) =
+                    identifier.check_method_local_name(symbol_table, class_symbol)
+                {
+                    vec![diagnostic]
+                } else {
+                    vec![]
+                }
+            }
+            _ => vec![],
+        }
+    }
+
+    pub fn check_static_fn_local_names(&self, symbol_table: &SymbolTable) -> Vec<Diagnostic> {
+        match self {
+            Expression::Binary(binary_expression) => {
+                binary_expression.check_static_fn_local_names(symbol_table)
+            }
+            Expression::Negative(negative_expression) => {
+                negative_expression.check_static_fn_local_names(symbol_table)
+            }
+            Expression::Call(call) => call.check_static_fn_local_names(symbol_table),
+            Expression::Identifier(identifier) => {
+                if let Some(diagnostic) = identifier.check_static_fn_local_name(symbol_table) {
+                    vec![diagnostic]
+                } else {
+                    vec![]
+                }
+            }
+            Expression::Integer(_) => {
+                vec![]
+            }
+            Expression::Double(_) => {
+                vec![]
+            }
+            Expression::String(_) => {
+                vec![]
+            }
+        }
+    }
+
+    pub fn type_check(
         &mut self,
-        symbol_table: &mut SymbolTable,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
     ) -> Result<(), Vec<Diagnostic>> {
         match self {
             Expression::Binary(binary_expression) => {
-                binary_expression.gather_declared_names(symbol_table)
+                binary_expression.type_check(symbol_table, types_table)
             }
             Expression::Negative(negative_expression) => {
-                negative_expression.gather_declared_names(symbol_table)
+                negative_expression.type_check(symbol_table, types_table)
             }
-            Expression::Call(call) => call.gather_declared_names(symbol_table),
-            Expression::Identifier(identifier) => identifier.gather_declared_names(symbol_table),
+            Expression::Call(call) => call.type_check(symbol_table, types_table),
+            Expression::Identifier(_) => Ok(()),
             Expression::Integer(_) => Ok(()),
             Expression::Double(_) => Ok(()),
             Expression::String(_) => Ok(()),
         }
     }
 
-    pub fn check_name_usages(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        match self {
-            Expression::Binary(binary_expression) => {
-                binary_expression.check_name_usages(symbol_table)
-            }
-            Expression::Negative(negative_expression) => {
-                negative_expression.check_name_usages(symbol_table)
-            }
-            Expression::Call(call) => call.check_name_usages(symbol_table),
-            Expression::Identifier(identifier) => identifier.check_name_usages(symbol_table),
-            Expression::Integer(_) => Ok(()),
-            Expression::Double(_) => Ok(()),
-            Expression::String(_) => Ok(()),
-        }
-    }
-
-    pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        match self {
-            Expression::Binary(binary_expression) => binary_expression.type_check(symbol_table),
-            Expression::Negative(negative_expression) => {
-                negative_expression.type_check(symbol_table)
-            }
-            Expression::Call(call) => call.type_check(symbol_table),
-            Expression::Identifier(identifier) => identifier.type_check(symbol_table),
-            Expression::Integer(_) => Ok(()),
-            Expression::Double(_) => Ok(()),
-            Expression::String(_) => Ok(()),
-        }
-    }
-
-    pub fn type_info(&self) -> &TypeInfo {
+    pub fn type_info<'a>(
+        &'a self,
+        symbol_table: &SymbolTable,
+        types_table: &'a TypesTable,
+    ) -> &'a TypeInfo {
         match self {
             Expression::Binary(binary_expression) => binary_expression.type_info(),
             Expression::Negative(negative_expression) => negative_expression.type_info(),
-            Expression::Call(call) => call.return_type_info(),
-            Expression::Identifier(identifier) => identifier.type_info(),
+            Expression::Call(call) => call.return_type_info(symbol_table, types_table),
+            Expression::Identifier(identifier) => identifier.type_info(symbol_table, types_table),
             Expression::Integer(integer_literal) => integer_literal.type_info(),
             Expression::Double(double_literal) => double_literal.type_info(),
             Expression::String(string_literal) => string_literal.type_info(),
@@ -106,12 +239,15 @@ impl Expression {
         &self,
         builder: &mut IrBuilder,
         symbol_table: &SymbolTable,
+        types_table: &TypesTable,
     ) -> IrOperation {
         match self {
             Expression::Binary(binary_expression) => {
-                binary_expression.to_ir_operation(builder, symbol_table)
+                binary_expression.to_ir_operation(builder, symbol_table, types_table)
+            }
+            Expression::Call(call) => {
+                IrOperation::Call(call.to_ir(builder, symbol_table, types_table))
             }
-            Expression::Call(call) => IrOperation::Call(call.to_ir(builder, symbol_table)),
             Expression::Integer(integer_literal) => {
                 IrOperation::Load(IrExpression::Int(integer_literal.value()))
             }
@@ -122,10 +258,10 @@ impl Expression {
                 IrOperation::Load(IrExpression::String(string_literal.content().into()))
             }
             Expression::Identifier(identifier) => {
-                IrOperation::Load(identifier.expressible_symbol().ir_expression(builder))
+                IrOperation::Load(identifier.ir_expression(builder, symbol_table, types_table))
             }
             Expression::Negative(negative_expression) => {
-                IrOperation::Load(negative_expression.to_ir(builder, symbol_table))
+                IrOperation::Load(negative_expression.to_ir(builder, symbol_table, types_table))
             }
         }
     }
@@ -134,14 +270,21 @@ impl Expression {
         &self,
         builder: &mut IrBuilder,
         symbol_table: &SymbolTable,
+        types_table: &TypesTable,
     ) -> Option<IrExpression> {
         match self {
             Expression::Binary(binary_expression) => {
-                Some(binary_expression.to_ir_expression(builder, symbol_table))
+                Some(binary_expression.to_ir_expression(builder, symbol_table, types_table))
+            }
+            Expression::Negative(negative_expression) => {
+                Some(negative_expression.to_ir(builder, symbol_table, types_table))
             }
             Expression::Call(call) => {
-                let ir_call = call.to_ir(builder, symbol_table);
-                if matches!(call.return_type_info(), TypeInfo::Void) {
+                let ir_call = call.to_ir(builder, symbol_table, types_table);
+                if matches!(
+                    call.return_type_info(symbol_table, types_table),
+                    TypeInfo::Void
+                ) {
                     builder
                         .current_block_mut()
                         .add_statement(IrStatement::Call(ir_call));
@@ -150,7 +293,7 @@ impl Expression {
                     let t_var = IrVariable::new_vr(
                         builder.new_t_var().into(),
                         builder.current_block().id(),
-                        call.return_type_info(),
+                        call.return_type_info(symbol_table, types_table),
                     );
                     let as_rc = Rc::new(RefCell::new(t_var));
                     let assign = IrAssign::new(as_rc.clone(), IrOperation::Call(ir_call));
@@ -160,6 +303,9 @@ impl Expression {
                     Some(IrExpression::Variable(as_rc))
                 }
             }
+            Expression::Identifier(identifier) => {
+                Some(identifier.ir_expression(builder, symbol_table, types_table))
+            }
             Expression::Integer(integer_literal) => {
                 Some(IrExpression::Int(integer_literal.value()))
             }
@@ -169,13 +315,6 @@ impl Expression {
             Expression::String(string_literal) => {
                 Some(IrExpression::String(string_literal.content().into()))
             }
-            Expression::Identifier(identifier) => {
-                let expressible_symbol = identifier.expressible_symbol();
-                Some(expressible_symbol.ir_expression(builder))
-            }
-            Expression::Negative(negative_expression) => {
-                Some(negative_expression.to_ir(builder, symbol_table))
-            }
         }
     }
 }

dmc-lib/src/ast/expression_statement.rs

@@ -3,8 +3,10 @@ use crate::ast::ir_builder::IrBuilder;
 use crate::diagnostic::Diagnostic;
 use crate::ir::ir_return::IrReturn;
 use crate::ir::ir_statement::IrStatement;
+use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol_table::SymbolTable;
 use crate::type_info::TypeInfo;
+use crate::types_table::TypesTable;
 
 pub struct ExpressionStatement {
     expression: Box<Expression>,
@@ -21,26 +23,42 @@ impl ExpressionStatement {
         &self.expression
     }
 
-    pub fn gather_declared_names(
-        &mut self,
-        symbol_table: &mut SymbolTable,
-    ) -> Result<(), Vec<Diagnostic>> {
-        self.expression.gather_declared_names(symbol_table)
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable, container_scope: usize) {
+        self.expression.init_scopes(symbol_table, container_scope);
     }
 
-    pub fn check_name_usages(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        self.expression.check_name_usages(symbol_table)
+    pub fn check_constructor_local_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        self.expression
+            .check_constructor_local_names(symbol_table, class_symbol)
+    }
+
+    pub fn check_method_local_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        self.expression
+            .check_method_local_names(symbol_table, class_symbol)
+    }
+
+    pub fn check_static_fn_local_names(&self, symbol_table: &SymbolTable) -> Vec<Diagnostic> {
+        self.expression.check_static_fn_local_names(symbol_table)
     }
 
     pub fn type_check(
         &mut self,
         symbol_table: &SymbolTable,
+        types_table: &TypesTable,
         must_return_type_info: Option<&TypeInfo>,
     ) -> Result<(), Vec<Diagnostic>> {
-        self.expression.type_check(symbol_table)?;
+        self.expression.type_check(symbol_table, types_table)?;
 
         if must_return_type_info.is_some() {
-            let expression_type = self.expression.type_info();
+            let expression_type = self.expression.type_info(symbol_table, types_table);
             let return_type = must_return_type_info.unwrap();
             if !return_type.is_assignable_from(expression_type) {
                 return Err(vec![Diagnostic::new(
@@ -60,9 +78,12 @@ impl ExpressionStatement {
         &self,
         builder: &mut IrBuilder,
         symbol_table: &SymbolTable,
+        types_table: &TypesTable,
         should_return_value: bool,
     ) {
-        let ir_expression = self.expression.to_ir_expression(builder, symbol_table);
+        let ir_expression = self
+            .expression
+            .to_ir_expression(builder, symbol_table, types_table);
         if ir_expression.is_some() && should_return_value {
             builder
                 .current_block_mut()

dmc-lib/src/ast/extern_function.rs

@@ -1,20 +1,23 @@
 use crate::ast::fqn_context::FqnContext;
+use crate::ast::helpers::{collect_diagnostics_into_mut, collect_parameter_symbols_into};
 use crate::ast::parameter::Parameter;
 use crate::ast::type_use::TypeUse;
 use crate::diagnostic::Diagnostic;
 use crate::source_range::SourceRange;
-use crate::symbol::class_symbol::ClassSymbol;
+use crate::symbol::Symbol;
 use crate::symbol::function_symbol::FunctionSymbol;
-use crate::symbol_table::{SymbolInsertError, SymbolTable};
-use std::cell::RefCell;
+use crate::symbol_table::SymbolTable;
+use crate::type_info::TypeInfo;
+use crate::types_table::TypesTable;
+use crate::{diagnostics_result, handle_diagnostics};
 use std::rc::Rc;
 
 pub struct ExternFunction {
-    declared_name: String,
+    declared_name: Rc<str>,
     declared_name_source_range: SourceRange,
     parameters: Vec<Parameter>,
     return_type: TypeUse,
-    function_symbol: Option<Rc<RefCell<FunctionSymbol>>>,
+    scope_id: Option<usize>,
 }
 
 impl ExternFunction {
@@ -23,13 +26,13 @@ impl ExternFunction {
         declared_name_source_range: SourceRange,
         parameters: Vec<Parameter>,
         return_type: TypeUse,
-    ) -> ExternFunction {
-        ExternFunction {
+    ) -> Self {
+        Self {
             declared_name: name.into(),
             declared_name_source_range,
             parameters,
             return_type,
-            function_symbol: None,
+            scope_id: None,
         }
     }
 
@@ -37,126 +40,110 @@ impl ExternFunction {
         &self.declared_name
     }
 
-    pub fn gather_declared_names(
-        &mut self,
-        symbol_table: &mut SymbolTable,
-        fqn_context: &FqnContext,
-    ) -> Result<(), Vec<Diagnostic>> {
-        let mut diagnostics = vec![];
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable, container_scope: usize) {
+        self.scope_id = Some(container_scope);
 
-        let insert_result = symbol_table.insert_function_symbol(FunctionSymbol::new(
+        let function_scope = symbol_table
+            .push_function_scope(&format!("extern_function_scope({})", self.declared_name));
+
+        for parameter in &mut self.parameters {
+            parameter.init_scopes(symbol_table, function_scope);
+        }
+        self.return_type.init_scopes(symbol_table, function_scope);
+
+        symbol_table.pop_scope();
+    }
+
+    pub fn make_symbols(&self, fqn_context: &FqnContext) -> (Rc<FunctionSymbol>, Vec<Symbol>) {
+        let mut all_symbols: Vec<Symbol> = Vec::new();
+
+        let mut parameter_symbols = Vec::new();
+        collect_parameter_symbols_into(&self.parameters, &mut all_symbols, &mut parameter_symbols);
+
+        let function_symbol = Rc::new(FunctionSymbol::new(
             &self.declared_name,
             self.declared_name_source_range.clone(),
             fqn_context.resolve(self.declared_name()),
             true,
+            false,
+            self.scope_id.unwrap(),
+            parameter_symbols,
         ));
+        all_symbols.push(Symbol::Function(function_symbol.clone()));
 
-        let function_symbol = match insert_result {
-            Ok(function_symbol) => function_symbol,
-            Err(symbol_insert_error) => {
-                return match symbol_insert_error {
-                    SymbolInsertError::AlreadyDeclared(already_declared) => {
-                        diagnostics.push(Diagnostic::new(
-                            &format!(
-                                "Function {} already declared in current scope.",
-                                already_declared.symbol().borrow().declared_name()
-                            ),
-                            self.declared_name_source_range.start(),
-                            self.declared_name_source_range.end(),
-                        ));
-                        Err(diagnostics)
-                    }
-                };
-            }
-        };
+        (function_symbol, all_symbols)
+    }
 
-        symbol_table
-            .push_function_scope(&format!("extern_function_scope({})", &self.declared_name));
-
-        let mut parameter_symbols = vec![];
-        for parameter in &mut self.parameters {
-            let parameter_result = parameter.gather_declared_names(symbol_table);
-            match parameter_result {
-                Ok(parameter_symbol) => {
-                    parameter_symbols.push(parameter_symbol);
-                }
-                Err(mut parameter_diagnostics) => {
-                    diagnostics.append(&mut parameter_diagnostics);
-                }
-            }
+    pub fn check_names(&self, symbol_table: &SymbolTable) -> Vec<Diagnostic> {
+        let mut diagnostics: Vec<Diagnostic> = Vec::new();
+        for parameter in &self.parameters {
+            diagnostics.append(&mut parameter.check_names(symbol_table));
         }
-        function_symbol
-            .borrow_mut()
-            .set_parameters(parameter_symbols);
+        diagnostics.append(&mut self.return_type.check_names(symbol_table));
+        diagnostics
+    }
 
-        self.function_symbol = Some(function_symbol);
+    pub fn gather_types(&self, symbol_table: &SymbolTable, types_table: &mut TypesTable) {
+        let function_symbol = symbol_table
+            .get_function_symbol_owned(self.scope_id.unwrap(), self.declared_name())
+            .unwrap();
 
-        // handle return type
-        match self.return_type.gather_declared_names(symbol_table) {
-            Ok(_) => {}
-            Err(mut type_use_diagnostics) => {
-                diagnostics.append(&mut type_use_diagnostics);
-            }
-        }
+        // self function type
+        types_table.function_types_mut().insert(
+            function_symbol.clone(),
+            TypeInfo::Function(function_symbol.clone()),
+        );
 
-        symbol_table.pop_scope(); // function scope
+        // return type (temporary)
+        let resolved_return_type = self
+            .return_type
+            .type_info(symbol_table, types_table)
+            .clone();
+        types_table
+            .function_return_types_mut()
+            .insert(function_symbol, resolved_return_type);
 
-        if diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(diagnostics)
+        // parameters
+        for parameter in &self.parameters {
+            parameter.gather_types_into(symbol_table, types_table);
         }
     }
 
-    pub fn check_name_usages(
+    fn type_check_parameters(
         &mut self,
         symbol_table: &SymbolTable,
-        class_context: Option<&Rc<RefCell<ClassSymbol>>>,
-    ) -> Result<(), Vec<Diagnostic>> {
-        let mut diagnostics: Vec<Diagnostic> = self
-            .parameters
-            .iter_mut()
-            .map(|parameter| parameter.check_name_usages(symbol_table, class_context))
-            .filter_map(Result::err)
-            .flatten()
-            .collect();
-
-        match self
-            .return_type
-            .check_name_usages(symbol_table, class_context)
-        {
-            Ok(_) => {}
-            Err(mut return_type_diagnostics) => {
-                diagnostics.append(&mut return_type_diagnostics);
-            }
-        }
-
-        if diagnostics.is_empty() {
-            // set return type info on symbol now that its available
-            self.function_symbol
-                .as_mut()
-                .unwrap()
-                .borrow_mut()
-                .set_return_type_info(self.return_type.type_info().clone());
-
-            Ok(())
-        } else {
-            Err(diagnostics)
-        }
+        types_table: &TypesTable,
+        diagnostics: &mut Vec<Diagnostic>,
+    ) {
+        collect_diagnostics_into_mut(
+            &mut self.parameters,
+            |p| p.type_check(symbol_table, types_table),
+            diagnostics,
+        );
     }
 
-    pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        let diagnostics: Vec<Diagnostic> = self
-            .parameters
-            .iter_mut()
-            .map(|parameter| parameter.type_check(symbol_table))
-            .filter_map(Result::err)
-            .flatten()
-            .collect();
-        if diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(diagnostics)
-        }
+    fn type_check_return_type(
+        &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+        diagnostics: &mut Vec<Diagnostic>,
+    ) {
+        handle_diagnostics!(
+            self.return_type.type_check(symbol_table, types_table),
+            diagnostics
+        );
+    }
+
+    pub fn type_check(
+        &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
+        let mut diagnostics: Vec<Diagnostic> = vec![];
+
+        self.type_check_parameters(symbol_table, types_table, &mut diagnostics);
+        self.type_check_return_type(symbol_table, types_table, &mut diagnostics);
+
+        diagnostics_result!(diagnostics)
     }
 }

dmc-lib/src/ast/field.rs

@@ -1,11 +1,12 @@
+use crate::ast::diagnostic_factories::field_has_no_type_or_init;
 use crate::ast::expression::Expression;
 use crate::ast::type_use::TypeUse;
 use crate::diagnostic::Diagnostic;
 use crate::source_range::SourceRange;
 use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol::field_symbol::FieldSymbol;
-use crate::symbol_table::{SymbolInsertError, SymbolTable};
-use std::cell::RefCell;
+use crate::symbol_table::SymbolTable;
+use crate::types_table::TypesTable;
 use std::rc::Rc;
 
 pub struct Field {
@@ -15,7 +16,7 @@ pub struct Field {
     is_mut: bool,
     declared_type: Option<Box<TypeUse>>,
     initializer: Option<Box<Expression>>,
-    field_symbol: Option<Rc<RefCell<FieldSymbol>>>,
+    scope_id: Option<usize>,
 }
 
 impl Field {
@@ -34,7 +35,7 @@ impl Field {
             is_mut,
             declared_type: declared_type.map(Box::new),
             initializer: initializer.map(Box::new),
-            field_symbol: None,
+            scope_id: None,
         }
     }
 
@@ -54,87 +55,104 @@ impl Field {
         self.initializer.as_ref().map(Box::as_ref)
     }
 
-    pub fn gather_declared_names(
-        &mut self,
-        symbol_table: &mut SymbolTable,
-        field_index: usize,
-    ) -> Result<Rc<RefCell<FieldSymbol>>, Vec<Diagnostic>> {
-        // 1. insert field symbol
-        let to_insert = FieldSymbol::new(
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable, container_scope: usize) {
+        self.scope_id = Some(container_scope);
+        if let Some(type_use) = &mut self.declared_type {
+            type_use.init_scopes(symbol_table, container_scope);
+        }
+        if let Some(expression) = &mut self.initializer {
+            expression.init_scopes(symbol_table, container_scope);
+        }
+    }
+
+    pub fn scope_id(&self) -> usize {
+        self.scope_id.unwrap()
+    }
+
+    pub fn make_symbol(&self, field_index: usize) -> FieldSymbol {
+        FieldSymbol::new(
             &self.declared_name,
             self.declared_name_source_range.clone(),
             self.is_mut,
-        );
-
-        let field_symbol = symbol_table
-            .insert_field_symbol(to_insert)
-            .map_err(|e| match e {
-                SymbolInsertError::AlreadyDeclared(already_declared) => {
-                    vec![Diagnostic::new(
-                        &format!(
-                            "Symbol {} already declared in current scope.",
-                            already_declared.symbol().borrow().declared_name()
-                        ),
-                        self.declared_name_source_range.start(),
-                        self.declared_name_source_range.end(),
-                    )]
-                }
-            })?;
-
-        // save for later
-        let to_return = field_symbol.clone();
-        self.field_symbol = Some(field_symbol);
-
-        // set field index on symbol
-        self.field_symbol
-            .as_ref()
-            .unwrap()
-            .borrow_mut()
-            .set_field_index(field_index);
-
-        // 2. gather type_use and initializer, if present
-        if let Some(type_use) = &mut self.declared_type {
-            type_use.gather_declared_names(symbol_table)?;
-        }
-
-        if let Some(initializer) = &mut self.initializer {
-            initializer.gather_declared_names(symbol_table)?;
-        }
-
-        Ok(to_return)
+            self.scope_id.unwrap(),
+            field_index,
+        )
     }
 
-    pub fn check_name_usages(
-        &mut self,
-        symbol_table: &SymbolTable,
-        class_context: Option<&Rc<RefCell<ClassSymbol>>>,
-    ) -> Result<(), Vec<Diagnostic>> {
-        if let Some(type_use) = &mut self.declared_type {
-            type_use.check_name_usages(symbol_table, class_context)?;
+    pub fn check_names(&self, symbol_table: &SymbolTable) -> Vec<Diagnostic> {
+        let mut diagnostics: Vec<Diagnostic> = Vec::new();
+        if let Some(type_use) = &self.declared_type {
+            diagnostics.append(&mut type_use.check_names(symbol_table));
         }
+        diagnostics
+    }
 
-        // This is going to get hairy, because users might attempt to use a field in an initializer
-        // (for either this field, or another one) before it's actually initialized. As such, we
-        // need a way to prevent lookup of current class' fields in the initializer.
-        // For now, the following is okay so long as we don't start referencing things in the
-        // initializers.
-        if let Some(initializer) = self.initializer.as_mut() {
-            initializer.check_name_usages(symbol_table)?;
+    pub fn check_field_initializer_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        if let Some(initializer) = &self.initializer {
+            initializer.check_field_initializer_names(symbol_table, class_symbol)
+        } else {
+            vec![]
+        }
+    }
+
+    pub fn gather_types(
+        &self,
+        symbol_table: &SymbolTable,
+        types_table: &mut TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
+        // self field
+        let field_symbol = symbol_table
+            .get_field_symbol_owned(self.scope_id.unwrap(), &self.declared_name)
+            .unwrap();
+        match &self.declared_type {
+            Some(declared_type) => {
+                let resolved_type = declared_type.type_info(symbol_table, types_table).clone();
+                types_table
+                    .field_types_mut()
+                    .insert(field_symbol, resolved_type);
+            }
+            None => match &self.initializer {
+                Some(initializer) => {
+                    let initializer_type = initializer.type_info(symbol_table, types_table).clone();
+                    types_table
+                        .field_types_mut()
+                        .insert(field_symbol, initializer_type);
+                }
+                None => {
+                    // this is an error
+                    return Err(vec![field_has_no_type_or_init(
+                        self.declared_name(),
+                        self.declared_name_source_range(),
+                    )]);
+                }
+            },
         }
         Ok(())
     }
 
-    pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
+    pub fn type_check(
+        &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
         let mut diagnostics: Vec<Diagnostic> = vec![];
 
         if let Some(type_use) = &mut self.declared_type {
-            if let Some(mut type_use_diagnostics) = type_use.type_check(symbol_table).err() {
+            if let Some(mut type_use_diagnostics) =
+                type_use.type_check(symbol_table, types_table).err()
+            {
                 diagnostics.append(&mut type_use_diagnostics);
             }
         }
 
         if let Some(initializer) = &mut self.initializer {
-            if let Some(mut initializer_diagnostics) = initializer.type_check(symbol_table).err() {
+            if let Some(mut initializer_diagnostics) =
+                initializer.type_check(symbol_table, types_table).err()
+            {
                 diagnostics.append(&mut initializer_diagnostics);
             }
         }
@@ -143,67 +161,31 @@ impl Field {
             return Err(diagnostics);
         }
 
-        // Now check that types are assignable, and update field symbol's type info
-        let field_type_info =
-            match self.declared_type.as_ref() {
-                Some(type_use) => {
-                    match self.initializer.as_ref() {
-                        Some(initializer) => {
-                            let initializer_type_info = initializer.type_info();
-                            let declared_type_info = type_use.type_info();
-                            if declared_type_info.is_assignable_from(initializer_type_info) {
-                                declared_type_info
-                            } else {
-                                return Err(vec![
-                                    Diagnostic::new(
-                                        &format!(
-                                            "Mismatched types: {} is not assignable to {}",
-                                            initializer_type_info, declared_type_info
-                                        ),
-                                        initializer.source_range().start(),
-                                        initializer.source_range().end(),
-                                    )
-                                    .with_reporter(file!(), line!()),
-                                ]);
-                            }
-                        }
-                        None => {
-                            // easy: the declared type
-                            type_use.type_info()
-                        }
+        // Now check that types are assignable
+        match self.declared_type.as_ref() {
+            Some(type_use) => match self.initializer.as_ref() {
+                Some(initializer) => {
+                    let initializer_type_info = initializer.type_info(symbol_table, types_table);
+                    let declared_type_info = type_use.type_info(symbol_table, types_table);
+                    if declared_type_info.is_assignable_from(initializer_type_info) {
+                        Ok(())
+                    } else {
+                        Err(vec![
+                            Diagnostic::new(
+                                &format!(
+                                    "Mismatched types: {} is not assignable to {}",
+                                    initializer_type_info, declared_type_info
+                                ),
+                                initializer.source_range().start(),
+                                initializer.source_range().end(),
+                            )
+                            .with_reporter(file!(), line!()),
+                        ])
                     }
                 }
-                None => {
-                    // type is the initializer
-                    match self.initializer.as_ref() {
-                        Some(initializer) => initializer.type_info(),
-                        None => {
-                            // this is an error
-                            return Err(vec![Diagnostic::new(
-                            "Field must have either a declared type or initializer, or both.",
-                            self.declared_name_source_range.start(),
-                            self.declared_name_source_range.end(),
-                        ).with_reporter(file!(), line!())]);
-                        }
-                    }
-                }
-            };
-
-        // update field symbol's type info
-        self.field_symbol
-            .as_mut()
-            .unwrap()
-            .borrow_mut()
-            .set_type_info(field_type_info.clone());
-
-        if diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(diagnostics)
+                None => Ok(()),
+            },
+            None => Ok(()),
         }
     }
-
-    pub fn field_symbol(&self) -> &Rc<RefCell<FieldSymbol>> {
-        self.field_symbol.as_ref().unwrap()
-    }
 }

dmc-lib/src/ast/function.rs

@@ -1,11 +1,14 @@
 use crate::ast::fqn_context::FqnContext;
 use crate::ast::fqn_util::fqn_parts_to_string;
+use crate::ast::helpers::{
+    collect_diagnostics_into_enumerated_mut, collect_diagnostics_into_mut,
+    collect_parameter_symbols_into,
+};
 use crate::ast::ir_builder::IrBuilder;
 use crate::ast::parameter::Parameter;
 use crate::ast::statement::Statement;
 use crate::ast::type_use::TypeUse;
 use crate::diagnostic::Diagnostic;
-use crate::handle_diagnostics;
 use crate::ir::ir_function::IrFunction;
 use crate::ir::ir_parameter::IrParameter;
 use crate::ir::ir_parameter_or_variable::IrParameterOrVariable;
@@ -13,20 +16,21 @@ use crate::source_range::SourceRange;
 use crate::symbol::Symbol;
 use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol::function_symbol::FunctionSymbol;
-use crate::symbol_table::{SymbolInsertError, SymbolTable};
+use crate::symbol_table::SymbolTable;
 use crate::type_info::TypeInfo;
-use std::cell::RefCell;
+use crate::types_table::TypesTable;
+use crate::{diagnostics_result, handle_diagnostics};
 use std::ops::Neg;
 use std::rc::Rc;
 
 pub struct Function {
-    declared_name: String,
+    declared_name: Rc<str>,
     declared_name_source_range: SourceRange,
     is_public: bool,
     parameters: Vec<Parameter>,
     return_type: Option<TypeUse>,
     statements: Vec<Statement>,
-    function_symbol: Option<Rc<RefCell<FunctionSymbol>>>,
+    scope_id: Option<usize>,
 }
 
 impl Function {
@@ -39,13 +43,13 @@ impl Function {
         statements: Vec<Statement>,
     ) -> Self {
         Self {
-            declared_name: declared_name.to_string(),
+            declared_name: declared_name.into(),
             declared_name_source_range,
             is_public,
             parameters,
             return_type,
             statements,
-            function_symbol: None,
+            scope_id: None,
         }
     }
 
@@ -57,266 +61,281 @@ impl Function {
         self.statements.iter().collect()
     }
 
-    pub fn gather_declared_names(
-        &mut self,
-        symbol_table: &mut SymbolTable,
-        fqn_context: &FqnContext,
-        class_context: Option<&Rc<RefCell<ClassSymbol>>>,
-    ) -> Result<(), Vec<Diagnostic>> {
-        let mut diagnostics = vec![];
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable, container_scope: usize) {
+        self.scope_id = Some(container_scope);
+        let function_scope =
+            symbol_table.push_function_scope(&format!("function_scope({})", self.declared_name));
 
-        if !diagnostics.is_empty() {
-            return Err(diagnostics);
+        for parameter in &mut self.parameters {
+            parameter.init_scopes(symbol_table, function_scope);
+        }
+        if let Some(type_use) = &mut self.return_type {
+            type_use.init_scopes(symbol_table, function_scope);
         }
 
-        // insert function symbol
-        let insert_result = symbol_table.insert_function_symbol(FunctionSymbol::new(
-            self.declared_name(),
+        let body_scope =
+            symbol_table.push_block_scope(&format!("body_scope({})", self.declared_name));
+
+        for statement in &mut self.statements {
+            statement.init_scopes(symbol_table, body_scope);
+        }
+
+        symbol_table.pop_scope(); // body
+        symbol_table.pop_scope(); // function
+    }
+
+    pub fn make_symbols(
+        &self,
+        fqn_context: &FqnContext,
+        is_method: bool,
+    ) -> (Rc<FunctionSymbol>, Vec<Symbol>) {
+        let mut all_symbols: Vec<Symbol> = vec![];
+
+        let mut parameter_symbols = Vec::new();
+        collect_parameter_symbols_into(&self.parameters, &mut all_symbols, &mut parameter_symbols);
+
+        let function_symbol = Rc::new(FunctionSymbol::new(
+            &self.declared_name,
             self.declared_name_source_range.clone(),
             fqn_context.resolve(self.declared_name()),
             false,
+            is_method,
+            self.scope_id.unwrap(),
+            parameter_symbols,
         ));
+        all_symbols.push(Symbol::Function(function_symbol.clone()));
 
-        // get function symbol if successful
-        let function_symbol = match insert_result {
-            Ok(function_symbol) => function_symbol,
-            Err(symbol_insert_error) => {
-                return match symbol_insert_error {
-                    SymbolInsertError::AlreadyDeclared(already_declared) => {
-                        diagnostics.push(Diagnostic::new(
-                            &format!(
-                                "Function {} already declared in current scope",
-                                already_declared.symbol().borrow().declared_name()
-                            ),
-                            self.declared_name_source_range.start(),
-                            self.declared_name_source_range.end(),
-                        ));
-                        Err(diagnostics)
-                    }
-                };
-            }
-        };
+        (function_symbol, all_symbols)
+    }
 
-        // save function symbol for later
-        self.function_symbol = Some(function_symbol.clone());
-
-        // handle parameters
-        symbol_table.push_function_scope(&format!("function_scope({})", self.declared_name));
-
-        // first, if we are in a class context, insert a "fake" self parameter
-        if let Some(class_symbol) = class_context {
-            self.parameters.insert(
-                0,
-                Parameter::new(
-                    "self",
-                    SourceRange::new(0, 0),
-                    TypeUse::new("Self", SourceRange::new(0, 0), vec![]),
-                ),
-            );
+    pub fn check_names(&self, symbol_table: &SymbolTable) -> Vec<Diagnostic> {
+        let mut diagnostics = Vec::new();
+        for parameter in &self.parameters {
+            diagnostics.append(&mut parameter.check_names(symbol_table));
         }
-
-        // now gather all names for the params
-        let mut parameter_symbols = vec![];
-        for parameter in &mut self.parameters {
-            match parameter.gather_declared_names(symbol_table) {
-                Ok(parameter_symbol) => {
-                    parameter_symbols.push(parameter_symbol);
-                }
-                Err(mut parameter_diagnostics) => {
-                    diagnostics.append(&mut parameter_diagnostics);
-                }
-            }
+        if let Some(type_use) = &self.return_type {
+            diagnostics.append(&mut type_use.check_names(symbol_table));
         }
+        diagnostics
+    }
 
-        // set params on function symbol
-        function_symbol
-            .borrow_mut()
-            .set_parameters(parameter_symbols);
+    pub fn analyze_method_local_names(
+        &self,
+        symbol_table: &mut SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        self.statements
+            .iter()
+            .flat_map(|statement| statement.analyze_method_local_names(symbol_table, class_symbol))
+            .collect()
+    }
 
-        // return type
-        if let Some(type_use) = &mut self.return_type {
-            match type_use.gather_declared_names(symbol_table) {
-                Ok(_) => {}
-                Err(mut type_use_diagnostics) => {
-                    diagnostics.append(&mut type_use_diagnostics);
-                }
-            }
-        }
+    pub fn analyze_static_fn_local_names(&self, symbol_table: &mut SymbolTable) -> Vec<Diagnostic> {
+        self.statements
+            .iter()
+            .flat_map(|statement| statement.analyze_static_fn_local_names(symbol_table))
+            .collect()
+    }
 
-        symbol_table.push_block_scope(&format!("main_block_scope({})", self.declared_name));
-        for statement in &mut self.statements {
-            match statement.gather_declared_names(symbol_table) {
-                Ok(_) => {}
-                Err(mut statement_diagnostics) => {
-                    diagnostics.append(&mut statement_diagnostics);
-                }
-            }
-        }
-        symbol_table.pop_scope(); // main block scope
-        symbol_table.pop_scope(); // function scope
+    pub fn gather_types(&self, symbol_table: &SymbolTable, types_table: &mut TypesTable) {
+        let function_symbol = symbol_table
+            .get_function_symbol_owned(self.scope_id.unwrap(), self.declared_name())
+            .unwrap();
 
-        if diagnostics.is_empty() {
-            Ok(())
+        // self type (the signature)
+        types_table.function_types_mut().insert(
+            function_symbol.clone(),
+            TypeInfo::Function(function_symbol.clone()),
+        );
+
+        // put return type (temporary, this is deprecated)
+        if let Some(type_use) = &self.return_type {
+            let resolved_return_type = type_use.type_info(symbol_table, types_table).clone();
+            types_table
+                .function_return_types_mut()
+                .insert(function_symbol, resolved_return_type);
         } else {
-            Err(diagnostics)
+            types_table
+                .function_return_types_mut()
+                .insert(function_symbol, TypeInfo::Void);
+        }
+
+        // parameters
+        for parameter in &self.parameters {
+            parameter.gather_types_into(symbol_table, types_table);
         }
     }
 
-    pub fn check_name_usages(
+    fn get_return_type_info(
+        types_table: &TypesTable,
+        function_symbol: &FunctionSymbol,
+    ) -> TypeInfo {
+        types_table
+            .function_return_types()
+            .get(function_symbol)
+            .cloned()
+            .unwrap()
+    }
+
+    /// Type checks parameters.
+    fn type_check_parameters(
         &mut self,
         symbol_table: &SymbolTable,
-        class_context: Option<&Rc<RefCell<ClassSymbol>>>,
-    ) -> Result<(), Vec<Diagnostic>> {
-        let mut diagnostics = vec![];
+        types_table: &TypesTable,
+        diagnostics: &mut Vec<Diagnostic>,
+    ) {
+        collect_diagnostics_into_mut(
+            &mut self.parameters,
+            |p| p.type_check(symbol_table, types_table),
+            diagnostics,
+        )
+    }
 
-        // parameters
-        diagnostics.append(
-            &mut self
-                .parameters
-                .iter_mut()
-                .map(|parameter| parameter.check_name_usages(symbol_table, class_context))
-                .filter_map(|result| result.err())
-                .flatten()
-                .collect(),
-        );
-
-        // return type
+    /// Type checks return type.
+    fn type_check_return_type(
+        &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+        diagnostics: &mut Vec<Diagnostic>,
+    ) {
         if let Some(type_use) = &mut self.return_type {
-            match type_use.check_name_usages(symbol_table, class_context) {
-                Ok(_) => {
-                    // set return type info on function symbol
-                    self.function_symbol
-                        .as_mut()
-                        .unwrap()
-                        .borrow_mut()
-                        .set_return_type_info(type_use.type_info().clone());
-                }
-                Err(mut type_use_diagnostics) => {
-                    diagnostics.append(&mut type_use_diagnostics);
-                }
-            }
-        } else {
-            // we don't have a given return type, so it's void
-            self.function_symbol
-                .as_mut()
-                .unwrap()
-                .borrow_mut()
-                .set_return_type_info(TypeInfo::Void);
-        }
-
-        // statements
-        for statement in &mut self.statements {
-            match statement.check_name_usages(symbol_table) {
-                Ok(_) => {}
-                Err(mut statement_diagnostics) => {
-                    diagnostics.append(&mut statement_diagnostics);
-                }
-            }
-        }
-
-        if diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(diagnostics)
+            handle_diagnostics!(type_use.type_check(symbol_table, types_table), diagnostics);
         }
     }
 
-    pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        let mut diagnostics = vec![];
-
-        // parameters
-        diagnostics.append(
-            &mut self
-                .parameters
-                .iter_mut()
-                .map(|parameter| parameter.type_check(symbol_table))
-                .filter_map(Result::err)
-                .flatten()
-                .collect(),
-        );
-
-        let function_symbol = self.function_symbol.as_ref().unwrap();
-        let return_type_info = function_symbol.borrow().return_type_info().clone();
+    /// Type checks statements, making sure the last statement matches return type, if necessary.
+    fn type_check_statements(
+        &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &mut TypesTable,
+        diagnostics: &mut Vec<Diagnostic>,
+        function_symbol: &FunctionSymbol,
+    ) {
+        let return_type_info = Self::get_return_type_info(types_table, function_symbol);
         let statements_len = self.statements.len();
 
+        collect_diagnostics_into_enumerated_mut(
+            &mut self.statements,
+            |i, s| {
+                let is_last = i == statements_len - 1;
+                if is_last {
+                    s.type_check(symbol_table, types_table, Some(&return_type_info))
+                } else {
+                    s.type_check(symbol_table, types_table, None)
+                }
+            },
+            diagnostics,
+        );
+    }
+
+    pub fn type_check(
+        &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &mut TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
+        let mut diagnostics = vec![];
+        let function_symbol = symbol_table
+            .get_function_symbol(self.scope_id.unwrap(), self.declared_name())
+            .unwrap();
+
+        // parameters
+        self.type_check_parameters(symbol_table, types_table, &mut diagnostics);
+
         // return type
-        if let Some(type_use) = &mut self.return_type {
-            handle_diagnostics!(type_use.type_check(symbol_table), diagnostics);
-        }
+        self.type_check_return_type(symbol_table, types_table, &mut diagnostics);
 
         // statements
-        diagnostics.append(
-            &mut self
-                .statements
-                .iter_mut()
-                .enumerate()
-                .map(|(i, statement)| {
-                    let is_last = i == statements_len - 1;
-                    if is_last {
-                        statement.type_check(symbol_table, Some(&return_type_info))
-                    } else {
-                        statement.type_check(symbol_table, None)
-                    }
-                })
-                .filter_map(Result::err)
-                .flatten()
-                .collect(),
-        );
+        self.type_check_statements(symbol_table, types_table, &mut diagnostics, function_symbol);
 
-        if diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(diagnostics)
+        diagnostics_result!(diagnostics)
+    }
+
+    /// Converts all parameters to ir. Saves the IrParameter to the associated parameter symbol.
+    fn parameters_to_ir(
+        &self,
+        builder: &mut IrBuilder,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+    ) {
+        for (i, parameter) in self.parameters.iter().enumerate() {
+            let parameter_symbol = symbol_table
+                .get_parameter_symbol_owned(parameter.scope_id(), parameter.declared_name())
+                .unwrap();
+            let parameter_type_info = types_table
+                .parameter_types()
+                .get(&parameter_symbol)
+                .unwrap();
+            let stack_offset = (self.parameters.len() as isize).neg() + (i as isize);
+            let ir_parameter = IrParameter::new(
+                parameter_symbol.declared_name(),
+                parameter_type_info.clone(),
+                stack_offset,
+            );
+            let as_rc = Rc::new(ir_parameter);
+            builder.push_parameter(&parameter_symbol, as_rc.clone());
+        }
+    }
+
+    /// If `class_context.is_some()`, set parameter 0 to the self parameter/variable on the builder.
+    fn handle_method_case(&self, builder: &mut IrBuilder, class_context: Option<&ClassSymbol>) {
+        // if we are a method, we need to set the self parameter on the builder
+        if class_context.is_some() {
+            let parameter_0 = builder.parameters()[0].clone();
+            // put it in the self parameter
+            builder.set_self_parameter_or_variable(IrParameterOrVariable::IrParameter(parameter_0));
+        }
+    }
+
+    /// Convert all statements to ir.
+    fn statements_to_ir(
+        &self,
+        builder: &mut IrBuilder,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+        function_symbol: &FunctionSymbol,
+    ) {
+        let return_type_info = Self::get_return_type_info(types_table, function_symbol);
+        let should_return_value = !matches!(return_type_info, TypeInfo::Void);
+        for (i, statement) in self.statements.iter().enumerate() {
+            let is_last = i == self.statements.len() - 1;
+            statement.to_ir(
+                builder,
+                symbol_table,
+                types_table,
+                should_return_value && is_last,
+            );
         }
     }
 
     pub fn to_ir(
         &self,
         symbol_table: &SymbolTable,
-        class_context: Option<Rc<RefCell<ClassSymbol>>>,
+        types_table: &TypesTable,
+        class_context: Option<&ClassSymbol>,
     ) -> IrFunction {
         let mut builder = IrBuilder::new();
+        let function_symbol = symbol_table
+            .get_function_symbol(self.scope_id.unwrap(), self.declared_name())
+            .unwrap();
 
         // parameters
-        for (i, parameter) in self.parameters.iter().enumerate() {
-            let parameter_symbol = parameter.parameter_symbol();
-            let stack_offset = (self.parameters.len() as isize).neg() + (i as isize);
-            let ir_parameter = IrParameter::new(
-                parameter_symbol.borrow().declared_name(),
-                parameter_symbol.borrow().type_info().clone(),
-                stack_offset,
-            );
-            let as_rc = Rc::new(ir_parameter);
-            builder.parameters_mut().push(as_rc.clone());
-            parameter_symbol.borrow_mut().set_ir_parameter(as_rc);
-        }
+        self.parameters_to_ir(&mut builder, symbol_table, types_table);
 
         let entry_block_id = builder.new_block();
 
         // preamble
-        // if we are a method, we need to set the self parameter on the builder
-        if let Some(_) = class_context {
-            let parameter_0 = builder.parameters()[0].clone();
-            // put it in the self parameter
-            builder.set_self_parameter_or_variable(IrParameterOrVariable::IrParameter(parameter_0));
-        }
+        self.handle_method_case(&mut builder, class_context);
 
-        let function_symbol = self.function_symbol.as_ref().unwrap().borrow();
-        let return_type_info = function_symbol.return_type_info();
+        // body
+        self.statements_to_ir(&mut builder, symbol_table, types_table, function_symbol);
 
-        let should_return_value = !matches!(return_type_info, TypeInfo::Void);
-
-        for (i, statement) in self.statements.iter().enumerate() {
-            let is_last = i == self.statements.len() - 1;
-            statement.to_ir(&mut builder, symbol_table, should_return_value && is_last);
-        }
         builder.finish_block();
 
         let entry_block = builder.get_block(entry_block_id).clone();
         IrFunction::new(
-            fqn_parts_to_string(self.function_symbol.as_ref().unwrap().borrow().fqn_parts()),
-            builder.parameters(),
-            return_type_info,
+            fqn_parts_to_string(function_symbol.fqn_parts()),
+            builder.parameters().iter().map(|p| (*p).clone()).collect(),
+            &Self::get_return_type_info(types_table, function_symbol),
             entry_block,
         )
     }

dmc-lib/src/ast/generic_parameter.rs

@@ -1,11 +1,11 @@
 use crate::ast::type_use::TypeUse;
-use crate::diagnostic::{Diagnostic, SecondaryLabel};
-use crate::error_codes::SYMBOL_ALREADY_DECLARED;
+use crate::diagnostic::Diagnostic;
 use crate::source_range::SourceRange;
-use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol::generic_parameter_symbol::GenericParameterSymbol;
-use crate::symbol_table::{SymbolInsertError, SymbolTable};
-use crate::{diagnostics_result, handle_diagnostics, maybe_return_diagnostics};
+use crate::symbol_table::SymbolTable;
+use crate::type_info::TypeInfo;
+use crate::types_table::TypesTable;
+use crate::{diagnostics_result, handle_diagnostics};
 use std::cell::RefCell;
 use std::rc::Rc;
 
@@ -13,6 +13,7 @@ pub struct GenericParameter {
     declared_name: Rc<str>,
     declared_name_source_range: SourceRange,
     extends: Vec<TypeUse>,
+    scope_id: Option<usize>,
     generic_parameter_symbol: Option<Rc<RefCell<GenericParameterSymbol>>>,
 }
 
@@ -26,94 +27,68 @@ impl GenericParameter {
             declared_name: declared_name.into(),
             declared_name_source_range,
             extends,
+            scope_id: None,
             generic_parameter_symbol: None,
         }
     }
 
-    pub fn gather_declared_names(
-        &mut self,
-        symbol_table: &mut SymbolTable,
-    ) -> Result<Rc<RefCell<GenericParameterSymbol>>, Vec<Diagnostic>> {
-        // insert symbol
-        let to_insert =
-            GenericParameterSymbol::new(&self.declared_name, &self.declared_name_source_range);
-        let to_return = match symbol_table.insert_generic_parameter_symbol(to_insert) {
-            Ok(generic_parameter_symbol) => generic_parameter_symbol,
-            Err(symbol_insert_error) => {
-                return match symbol_insert_error {
-                    SymbolInsertError::AlreadyDeclared(already_declared) => {
-                        let already_declared_symbol = already_declared.symbol().borrow();
-                        let already_declared_source_range =
-                            already_declared_symbol.declared_name_source_range();
-                        let diagnostic = Diagnostic::new(
-                            &format!("Symbol {} already declared in scope.", self.declared_name),
-                            self.declared_name_source_range.start(),
-                            self.declared_name_source_range.end(),
-                        )
-                        .with_reporter(file!(), line!())
-                        .with_error_code(SYMBOL_ALREADY_DECLARED)
-                        .with_secondary_labels(&[SecondaryLabel::new(
-                            already_declared_source_range.start(),
-                            already_declared_source_range.end(),
-                            Some("Symbol already declared here.".to_string()),
-                        )]);
-                        Err(vec![diagnostic])
-                    }
-                };
-            }
-        };
-
-        // save param symbol
-        self.generic_parameter_symbol = Some(to_return.clone());
-
-        let mut diagnostics: Vec<Diagnostic> = vec![];
-
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable, container_scope: usize) {
+        self.scope_id = Some(container_scope);
         for type_use in &mut self.extends {
-            handle_diagnostics!(type_use.gather_declared_names(symbol_table), diagnostics);
-        }
-
-        if diagnostics.is_empty() {
-            Ok(to_return)
-        } else {
-            Err(diagnostics)
+            type_use.init_scopes(symbol_table, container_scope);
         }
     }
 
-    pub fn check_name_usages(
-        &mut self,
+    pub fn make_symbol(&self) -> GenericParameterSymbol {
+        GenericParameterSymbol::new(
+            &self.declared_name,
+            &self.declared_name_source_range,
+            self.scope_id.unwrap(),
+        )
+    }
+
+    pub fn check_names(&self, symbol_table: &SymbolTable) -> Vec<Diagnostic> {
+        self.extends
+            .iter()
+            .flat_map(|type_use| type_use.check_names(symbol_table))
+            .collect()
+    }
+
+    pub fn gather_types(
+        &self,
         symbol_table: &SymbolTable,
-        class_context: Option<&Rc<RefCell<ClassSymbol>>>,
+        types_table: &mut TypesTable,
     ) -> Result<(), Vec<Diagnostic>> {
-        let mut diagnostics: Vec<Diagnostic> = vec![];
-        // check the extends type uses
-        for type_use in &mut self.extends {
+        // self param
+        let generic_parameter_symbol = symbol_table
+            .get_generic_parameter_symbol_owned(self.scope_id.unwrap(), &self.declared_name)
+            .unwrap();
+        types_table.generic_parameter_types_mut().insert(
+            generic_parameter_symbol.clone(),
+            TypeInfo::GenericType(generic_parameter_symbol),
+        );
+
+        let mut diagnostics = Vec::new();
+
+        for type_use in &self.extends {
             handle_diagnostics!(
-                type_use.check_name_usages(symbol_table, class_context),
+                type_use.gather_types(symbol_table, types_table),
                 diagnostics
             );
         }
-        maybe_return_diagnostics!(diagnostics);
 
-        // now that each extends type use has type info, set the type infos on the generic parameter
-        let extends_type_infos = self
-            .extends
-            .iter()
-            .map(|type_use| type_use.type_info().clone())
-            .collect::<Vec<_>>();
-        self.generic_parameter_symbol
-            .as_mut()
-            .unwrap()
-            .borrow_mut()
-            .set_extends(extends_type_infos);
-
-        Ok(())
+        diagnostics_result!(diagnostics)
     }
 
-    pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
+    pub fn type_check(
+        &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
         let mut diagnostics: Vec<Diagnostic> = vec![];
         // check extends type uses
         for type_use in &mut self.extends {
-            handle_diagnostics!(type_use.type_check(symbol_table), diagnostics);
+            handle_diagnostics!(type_use.type_check(symbol_table, types_table), diagnostics);
         }
         diagnostics_result!(diagnostics)
     }

dmc-lib/src/ast/helpers.rs

@@ -0,0 +1,133 @@
+use crate::ast::diagnostic_factories::symbol_already_declared;
+use crate::ast::fqn_context::FqnContext;
+use crate::ast::parameter::Parameter;
+use crate::diagnostic::Diagnostic;
+use crate::diagnostics_result;
+use crate::symbol::Symbol;
+use crate::symbol::parameter_symbol::ParameterSymbol;
+use crate::symbol_table::SymbolTable;
+use std::rc::Rc;
+
+/// Iterates through all `ts`, running the `f` function, and pushing returned `Diagnostic`s
+/// into `diagnostics`.
+pub fn collect_diagnostics_into_mut<T>(
+    ts: &mut [T],
+    mut f: impl FnMut(&mut T) -> Result<(), Vec<Diagnostic>>,
+    diagnostics: &mut Vec<Diagnostic>,
+) {
+    ts.iter_mut()
+        .map(|t| f(t))
+        .filter_map(Result::err)
+        .flatten()
+        .for_each(|d| diagnostics.push(d));
+}
+
+/// Like `collect_diagnostics_into` but enumerated.
+pub fn collect_diagnostics_into_enumerated_mut<T>(
+    ts: &mut [T],
+    mut f: impl FnMut(usize, &mut T) -> Result<(), Vec<Diagnostic>>,
+    diagnostics: &mut Vec<Diagnostic>,
+) {
+    ts.iter_mut()
+        .enumerate()
+        .map(|(i, t)| f(i, t))
+        .filter_map(Result::err)
+        .flatten()
+        .for_each(|d| diagnostics.push(d));
+}
+
+pub fn collect_diagnostics_mut<T>(
+    ts: &mut [T],
+    mut f: impl FnMut(&mut T) -> Result<(), Vec<Diagnostic>>,
+) -> Result<(), Vec<Diagnostic>> {
+    let diagnostics = ts
+        .iter_mut()
+        .map(|t| f(t))
+        .filter_map(Result::err)
+        .flatten()
+        .collect::<Vec<_>>();
+    diagnostics_result!(diagnostics)
+}
+
+pub fn collect_diagnostics<T>(
+    ts: &[T],
+    f: impl Fn(&T) -> Result<(), Vec<Diagnostic>>,
+) -> Result<(), Vec<Diagnostic>> {
+    let diagnostics = ts
+        .iter()
+        .map(|t| f(t))
+        .filter_map(Result::err)
+        .flatten()
+        .collect::<Vec<_>>();
+    diagnostics_result!(diagnostics)
+}
+
+pub fn collect_diagnostics_single<T>(
+    ts: &[T],
+    f: impl Fn(&T) -> Result<(), Diagnostic>,
+) -> Result<(), Vec<Diagnostic>> {
+    let diagnostics = ts
+        .iter()
+        .map(|t| f(t))
+        .filter_map(Result::err)
+        .collect::<Vec<_>>();
+    diagnostics_result!(diagnostics)
+}
+
+pub fn gather_oks<T, R>(
+    ts: &mut [T],
+    mut f: impl FnMut(&mut T) -> Result<R, Vec<Diagnostic>>,
+    diagnostics: &mut Vec<Diagnostic>,
+) -> Vec<R> {
+    let mut rs: Vec<R> = vec![];
+    for t in &mut ts[..] {
+        match f(t) {
+            Ok(r) => rs.push(r),
+            Err(mut t_diagnostics) => {
+                diagnostics.append(&mut t_diagnostics);
+            }
+        }
+    }
+    rs
+}
+
+pub fn resolve_ctor_name(fqn_context: &FqnContext) -> Vec<Rc<str>> {
+    fqn_context.resolve("ctor") // ctor is a keyword at the language level, should not be callable via normal means
+}
+
+pub fn try_insert_symbol_into(
+    symbol: Symbol,
+    symbol_table: &mut SymbolTable,
+) -> Result<(), Diagnostic> {
+    let maybe_already_inserted = symbol_table.get_symbol(symbol.scope_id(), symbol.declared_name());
+    if let Some(already_inserted) = maybe_already_inserted {
+        Err(symbol_already_declared(&already_inserted, &symbol))
+    } else {
+        symbol_table.insert_symbol(symbol);
+        Ok(())
+    }
+}
+
+pub fn try_insert_symbols_into(
+    symbols: Vec<Symbol>,
+    symbol_table: &mut SymbolTable,
+) -> Result<(), Vec<Diagnostic>> {
+    let diagnostics: Vec<Diagnostic> = symbols
+        .into_iter()
+        .map(|symbol| try_insert_symbol_into(symbol, symbol_table))
+        .filter_map(Result::err)
+        .collect();
+    diagnostics_result!(diagnostics)
+}
+
+pub fn collect_parameter_symbols_into(
+    parameters: &[Parameter],
+    all_symbols: &mut Vec<Symbol>,
+    parameter_symbols: &mut Vec<Rc<ParameterSymbol>>,
+) {
+    for parameter in parameters {
+        let symbol = Rc::new(parameter.make_symbol());
+        all_symbols.push(Symbol::Parameter(symbol.clone()));
+        parameter_symbols.push(symbol);
+    }
+}

dmc-lib/src/ast/identifier.rs

@@ -1,25 +1,39 @@
+use crate::ast::diagnostic_factories::{
+    outer_class_field_usage, outer_class_method_usage, self_constructor_used_in_init,
+    self_field_used_in_init, self_method_used_in_init, symbol_not_found,
+};
+use crate::ast::ir_builder::IrBuilder;
+use crate::ast::ir_util::get_or_init_field_pointer_variable;
 use crate::diagnostic::Diagnostic;
+use crate::ir::ir_assign::IrAssign;
+use crate::ir::ir_expression::IrExpression;
+use crate::ir::ir_operation::IrOperation;
+use crate::ir::ir_read_field::IrReadField;
+use crate::ir::ir_statement::IrStatement;
+use crate::ir::ir_variable::IrVariable;
 use crate::source_range::SourceRange;
+use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol::expressible_symbol::ExpressibleSymbol;
+use crate::symbol::field_symbol::FieldSymbol;
+use crate::symbol::function_symbol::FunctionSymbol;
 use crate::symbol_table::SymbolTable;
 use crate::type_info::TypeInfo;
+use crate::types_table::TypesTable;
+use std::cell::RefCell;
+use std::rc::Rc;
 
 pub struct Identifier {
     name: String,
-    scope_id: Option<usize>,
-    expressible_symbol: Option<ExpressibleSymbol>,
-    type_info: Option<TypeInfo>,
     source_range: SourceRange,
+    scope_id: Option<usize>,
 }
 
 impl Identifier {
     pub fn new(name: &str, source_range: SourceRange) -> Self {
         Self {
             name: name.into(),
-            scope_id: None,
-            expressible_symbol: None,
-            type_info: None,
             source_range,
+            scope_id: None,
         }
     }
 
@@ -27,45 +41,294 @@ impl Identifier {
         &self.name
     }
 
-    pub fn gather_declared_names(
-        &mut self,
-        symbol_table: &SymbolTable,
-    ) -> Result<(), Vec<Diagnostic>> {
-        self.scope_id = Some(symbol_table.current_scope_id());
-        Ok(())
+    pub fn init_scope_id(&mut self, container_scope: usize) {
+        self.scope_id = Some(container_scope);
     }
 
-    pub fn check_name_usages(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        let maybe_expressible_symbol =
-            symbol_table.find_expressible_symbol(self.scope_id.unwrap(), &self.name);
-        match maybe_expressible_symbol {
-            None => Err(vec![Diagnostic::new(
-                &format!("Unable to resolve symbol {}", self.name),
-                self.source_range.start(),
-                self.source_range.end(),
-            )]),
-            Some(expressible_symbol) => {
-                self.expressible_symbol = Some(expressible_symbol);
-                Ok(())
-            }
+    pub fn scope_id(&self) -> usize {
+        self.scope_id.unwrap()
+    }
+
+    /// Check against recursively constructing this class.
+    fn check_self_constructor_use(
+        &self,
+        context_class_symbol: &ClassSymbol,
+        class_symbol: &ClassSymbol,
+    ) -> Option<Diagnostic> {
+        // this is not future-proof, as we will eventually allow reference to the self class, which
+        // would (theoretically) be assigned to an instance field
+        if context_class_symbol == class_symbol {
+            Some(self_constructor_used_in_init(&self.source_range))
+        } else {
+            None
         }
     }
 
-    pub fn type_check(&mut self, _symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        let type_info = self.expressible_symbol.as_ref().unwrap().type_info();
-        self.type_info = Some(type_info);
-        Ok(())
+    /// Check against using this or outer class' bare fields.
+    fn check_self_or_outer_field_use(
+        &self,
+        context_class_symbol: &ClassSymbol,
+        field_symbol: &FieldSymbol,
+    ) -> Option<Diagnostic> {
+        // Usage of a bare field will always be an error, whether in this class or an outer class
+        if context_class_symbol
+            .fields()
+            .contains_key(field_symbol.declared_name())
+        {
+            Some(self_field_used_in_init(&self.source_range))
+        } else {
+            Some(outer_class_field_usage(&self.source_range))
+        }
     }
 
-    pub fn type_info(&self) -> &TypeInfo {
-        self.type_info.as_ref().unwrap()
+    /// Check against using self or outer class methods.
+    fn check_self_or_outer_method_use(
+        &self,
+        context_class_symbol: &ClassSymbol,
+        function_symbol: &FunctionSymbol,
+    ) -> Option<Diagnostic> {
+        if context_class_symbol
+            .functions()
+            .contains_key(function_symbol.declared_name())
+        {
+            // Can only use Self static functions, which we don't have yet
+            Some(self_method_used_in_init(&self.source_range))
+        } else if function_symbol.is_method() {
+            // Can only use outer class static functions, which we don't have yet
+            Some(outer_class_method_usage(&self.source_range))
+        } else {
+            None
+        }
     }
 
-    pub fn expressible_symbol(&self) -> &ExpressibleSymbol {
-        self.expressible_symbol.as_ref().unwrap()
+    pub fn check_name_as_field_initializer(
+        &self,
+        symbol_table: &SymbolTable,
+        context_class_symbol: &ClassSymbol,
+    ) -> Option<Diagnostic> {
+        let symbol = symbol_table.find_expressible_symbol(self.scope_id.unwrap(), &self.name);
+        if let Some(symbol) = symbol {
+            match symbol {
+                ExpressibleSymbol::Class(class_symbol) => {
+                    self.check_self_constructor_use(context_class_symbol, &class_symbol)
+                }
+                ExpressibleSymbol::Field(field_symbol) => {
+                    self.check_self_or_outer_field_use(context_class_symbol, &field_symbol)
+                }
+                ExpressibleSymbol::Function(function_symbol) => {
+                    self.check_self_or_outer_method_use(context_class_symbol, &function_symbol)
+                }
+                ExpressibleSymbol::Parameter(_) => {
+                    // Cannot get here, because classes cannot currently be declared in functions
+                    unreachable!()
+                }
+                ExpressibleSymbol::Variable(_) => {
+                    // Cannot get here, as classes cannot currently be declared in functions
+                    unreachable!()
+                }
+            }
+        } else {
+            Some(symbol_not_found(&self.name, &self.source_range))
+        }
+    }
+
+    pub fn check_constructor_destination_name(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Option<Diagnostic> {
+        let expressible_symbol =
+            symbol_table.find_expressible_symbol(self.scope_id.unwrap(), &self.name);
+        if let Some(expressible_symbol) = expressible_symbol {
+            match expressible_symbol {
+                ExpressibleSymbol::Class(_) => {
+                    panic!("Class is not an L value")
+                }
+                ExpressibleSymbol::Field(field_symbol) => {
+                    // This is just a stop-gap for now. We need to decide if we are going to do
+                    // field assignment analysis (whether it's initialized already, if it's mut,
+                    // etc.) during name checking or during type checking.
+                    None
+                }
+                ExpressibleSymbol::Function(_) => {
+                    panic!("Function is not an L value")
+                }
+                ExpressibleSymbol::Parameter(_) => {
+                    panic!("Parameter is not an L value")
+                }
+                ExpressibleSymbol::Variable(variable_symbol) => {
+                    // Again, a stop-gap.
+                    None
+                }
+            }
+        } else {
+            Some(symbol_not_found(&self.name, &self.source_range))
+        }
+    }
+
+    pub fn check_constructor_local_name(
+        &self,
+        symbol_table: &SymbolTable,
+        context_class_symbol: &ClassSymbol,
+    ) -> Option<Diagnostic> {
+        let symbol = symbol_table.find_expressible_symbol(self.scope_id.unwrap(), &self.name);
+        if let Some(symbol) = symbol {
+            match symbol {
+                ExpressibleSymbol::Class(class_symbol) => {
+                    self.check_self_constructor_use(context_class_symbol, &class_symbol)
+                }
+                ExpressibleSymbol::Field(field_symbol) => {
+                    self.check_self_or_outer_field_use(context_class_symbol, &field_symbol)
+                }
+                ExpressibleSymbol::Function(function_symbol) => {
+                    self.check_self_or_outer_method_use(context_class_symbol, &function_symbol)
+                }
+                ExpressibleSymbol::Parameter(_) => None,
+                ExpressibleSymbol::Variable(_) => None,
+            }
+        } else {
+            Some(symbol_not_found(&self.name, &self.source_range))
+        }
+    }
+
+    pub fn check_method_local_name(
+        &self,
+        symbol_table: &SymbolTable,
+        context_class_symbol: &ClassSymbol,
+    ) -> Option<Diagnostic> {
+        let symbol = symbol_table.find_expressible_symbol(self.scope_id.unwrap(), &self.name);
+        if let Some(symbol) = symbol {
+            match symbol {
+                ExpressibleSymbol::Class(_) => {
+                    None // all class usages should be ok
+                }
+                ExpressibleSymbol::Field(field_symbol) => {
+                    // Must be a reference to a field in this class
+                    if context_class_symbol
+                        .fields()
+                        .contains_key(field_symbol.declared_name())
+                    {
+                        None
+                    } else {
+                        Some(outer_class_field_usage(&self.source_range))
+                    }
+                }
+                ExpressibleSymbol::Function(function_symbol) => {
+                    // Must be a method in this class
+                    if function_symbol.is_method()
+                        && !context_class_symbol
+                            .functions()
+                            .contains_key(function_symbol.declared_name())
+                    {
+                        Some(outer_class_method_usage(&self.source_range))
+                    } else {
+                        None
+                    }
+                }
+                ExpressibleSymbol::Parameter(_) => {
+                    None // ok
+                }
+                ExpressibleSymbol::Variable(_) => {
+                    None // ok
+                }
+            }
+        } else {
+            Some(symbol_not_found(&self.name, &self.source_range))
+        }
+    }
+
+    /// WARNING: this is not appropriate (yet) for class static functions.
+    pub fn check_static_fn_local_name(&self, symbol_table: &SymbolTable) -> Option<Diagnostic> {
+        if symbol_table
+            .find_expressible_symbol(self.scope_id.unwrap(), &self.name)
+            .is_some()
+        {
+            None
+        } else {
+            Some(symbol_not_found(&self.name, &self.source_range))
+        }
     }
 
     pub fn source_range(&self) -> &SourceRange {
         &self.source_range
     }
+
+    pub fn type_info<'a>(
+        &self,
+        symbol_table: &SymbolTable,
+        types_table: &'a TypesTable,
+    ) -> &'a TypeInfo {
+        let expressible_symbol = symbol_table
+            .find_expressible_symbol(self.scope_id.unwrap(), &self.name)
+            .unwrap();
+        match expressible_symbol {
+            ExpressibleSymbol::Class(class_symbol) => {
+                types_table.class_types().get(&class_symbol).unwrap()
+            }
+            ExpressibleSymbol::Field(field_symbol) => {
+                types_table.field_types().get(&field_symbol).unwrap()
+            }
+            ExpressibleSymbol::Function(function_symbol) => types_table
+                .function_types()
+                .get(&function_symbol)
+                .expect(&format!(
+                    "Unable to get function type for {:?}",
+                    function_symbol
+                )),
+            ExpressibleSymbol::Parameter(parameter_symbol) => types_table
+                .parameter_types()
+                .get(&parameter_symbol)
+                .unwrap(),
+            ExpressibleSymbol::Variable(variable_symbol) => {
+                types_table.variable_types().get(&variable_symbol).unwrap()
+            }
+        }
+    }
+
+    pub fn ir_expression(
+        &self,
+        builder: &mut IrBuilder,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+    ) -> IrExpression {
+        let expressible_symbol = symbol_table
+            .find_expressible_symbol(self.scope_id.unwrap(), &self.name)
+            .unwrap();
+        match expressible_symbol {
+            ExpressibleSymbol::Class(class_symbol) => {
+                todo!()
+            }
+            ExpressibleSymbol::Field(field_symbol) => {
+                let field_type = types_table.field_types().get(&field_symbol).unwrap();
+                let read_destination = IrVariable::new_vr(
+                    builder.new_t_var().into(),
+                    builder.current_block().id(),
+                    field_type,
+                );
+                let read_destination_as_rc = Rc::new(RefCell::new(read_destination));
+                let ir_read_field = IrReadField::new(
+                    get_or_init_field_pointer_variable(builder, &field_symbol, field_type).clone(),
+                );
+                builder
+                    .current_block_mut()
+                    .add_statement(IrStatement::Assign(IrAssign::new(
+                        read_destination_as_rc.clone(),
+                        IrOperation::ReadField(ir_read_field),
+                    )));
+                IrExpression::Variable(read_destination_as_rc)
+            }
+            ExpressibleSymbol::Function(_) => {
+                panic!("Cannot yet get ir-variable for FunctionSymbol")
+            }
+            ExpressibleSymbol::Parameter(parameter_symbol) => {
+                let parameters_map = builder.parameters_map();
+                let ir_parameter = parameters_map.get(&parameter_symbol).unwrap();
+                IrExpression::Parameter(ir_parameter.clone())
+            }
+            ExpressibleSymbol::Variable(variable_symbol) => {
+                let ir_variable = builder.local_variables().get(&variable_symbol).unwrap();
+                IrExpression::Variable(ir_variable.clone())
+            }
+        }
+    }
 }

dmc-lib/src/ast/ir_builder.rs

@@ -3,12 +3,15 @@ use crate::ir::ir_parameter::IrParameter;
 use crate::ir::ir_parameter_or_variable::IrParameterOrVariable;
 use crate::ir::ir_statement::IrStatement;
 use crate::ir::ir_variable::IrVariable;
+use crate::symbol::parameter_symbol::ParameterSymbol;
+use crate::symbol::variable_symbol::VariableSymbol;
 use std::cell::RefCell;
 use std::collections::HashMap;
 use std::rc::Rc;
 
 pub struct IrBuilder {
-    parameters: Vec<Rc<IrParameter>>,
+    parameters: Vec<(Rc<ParameterSymbol>, Rc<IrParameter>)>,
+    local_variables: HashMap<Rc<VariableSymbol>, Rc<RefCell<IrVariable>>>,
     block_counter: usize,
     t_var_counter: usize,
     blocks: HashMap<usize, Rc<RefCell<IrBlock>>>,
@@ -22,6 +25,7 @@ impl IrBuilder {
     pub fn new() -> Self {
         Self {
             parameters: vec![],
+            local_variables: HashMap::new(),
             block_counter: 0,
             t_var_counter: 0,
             blocks: HashMap::new(),
@@ -32,12 +36,37 @@ impl IrBuilder {
         }
     }
 
-    pub fn parameters(&self) -> &[Rc<IrParameter>] {
-        &self.parameters
+    pub fn local_variables(&self) -> &HashMap<Rc<VariableSymbol>, Rc<RefCell<IrVariable>>> {
+        &self.local_variables
     }
 
-    pub fn parameters_mut(&mut self) -> &mut Vec<Rc<IrParameter>> {
-        &mut self.parameters
+    pub fn local_variables_mut(
+        &mut self,
+    ) -> &mut HashMap<Rc<VariableSymbol>, Rc<RefCell<IrVariable>>> {
+        &mut self.local_variables
+    }
+
+    pub fn parameters(&self) -> Vec<&Rc<IrParameter>> {
+        self.parameters
+            .iter()
+            .map(|(_, ir_parameter)| ir_parameter)
+            .collect()
+    }
+
+    pub fn parameters_map(&self) -> HashMap<Rc<ParameterSymbol>, Rc<IrParameter>> {
+        let mut map = HashMap::new();
+        for (name, ir_parameter) in &self.parameters {
+            map.insert(name.clone(), ir_parameter.clone());
+        }
+        map
+    }
+
+    pub fn push_parameter(
+        &mut self,
+        parameter_symbol: &Rc<ParameterSymbol>,
+        parameter: Rc<IrParameter>,
+    ) {
+        self.parameters.push((parameter_symbol.clone(), parameter));
     }
 
     pub fn new_block(&mut self) -> usize {

dmc-lib/src/ast/ir_util.rs

@@ -5,25 +5,26 @@ use crate::ir::ir_get_field_ref_mut::IrGetFieldRefMut;
 use crate::ir::ir_operation::IrOperation;
 use crate::ir::ir_statement::IrStatement;
 use crate::ir::ir_variable::IrVariable;
-use crate::symbol::Symbol;
 use crate::symbol::field_symbol::FieldSymbol;
+use crate::type_info::TypeInfo;
 use std::cell::RefCell;
 use std::rc::Rc;
 
 pub fn get_or_init_field_pointer_variable<'a>(
     builder: &'a mut IrBuilder,
-    field_symbol: &Rc<RefCell<FieldSymbol>>,
+    field_symbol: &Rc<FieldSymbol>,
+    field_type: &TypeInfo,
 ) -> &'a Rc<RefCell<IrVariable>> {
     // This following should work because blocks are flat in the ir; if a variable is defined in the
     // ir block from this point forward, it's available to all subsequent blocks.
     if !builder
         .field_pointer_variables()
-        .contains_key(field_symbol.borrow().declared_name())
+        .contains_key(field_symbol.declared_name())
     {
         let field_ref_variable = IrVariable::new_vr(
             builder.new_t_var().into(),
             builder.current_block().id(),
-            field_symbol.borrow().type_info(),
+            field_type,
         );
         let as_rc = Rc::new(RefCell::new(field_ref_variable));
         let to_insert = as_rc.clone();
@@ -34,31 +35,32 @@ pub fn get_or_init_field_pointer_variable<'a>(
                 as_rc,
                 IrOperation::GetFieldRef(IrGetFieldRef::new(
                     self_parameter_or_variable.clone(),
-                    field_symbol.borrow().field_index(),
+                    field_symbol.field_index(),
                 )),
             )));
         builder
             .field_pointer_variables_mut()
-            .insert(field_symbol.borrow().declared_name_owned(), to_insert);
+            .insert(field_symbol.declared_name_owned(), to_insert);
     }
     builder
         .field_pointer_variables()
-        .get(field_symbol.borrow().declared_name())
+        .get(field_symbol.declared_name())
         .unwrap()
 }
 
 pub fn get_or_init_mut_field_pointer_variable<'a>(
     builder: &'a mut IrBuilder,
-    field_symbol: &Rc<RefCell<FieldSymbol>>,
+    field_symbol: &Rc<FieldSymbol>,
+    field_type: &TypeInfo,
 ) -> &'a Rc<RefCell<IrVariable>> {
     if !builder
         .field_mut_pointer_variables()
-        .contains_key(field_symbol.borrow().declared_name())
+        .contains_key(field_symbol.declared_name())
     {
         let mut_field_pointer_variable = IrVariable::new_vr(
             builder.new_t_var().into(),
             builder.current_block().id(),
-            field_symbol.borrow().type_info(),
+            field_type,
         );
         let as_rc = Rc::new(RefCell::new(mut_field_pointer_variable));
         let to_insert = as_rc.clone();
@@ -69,15 +71,15 @@ pub fn get_or_init_mut_field_pointer_variable<'a>(
                 as_rc,
                 IrOperation::GetFieldRefMut(IrGetFieldRefMut::new(
                     self_parameter_or_variable.clone(),
-                    field_symbol.borrow().field_index(),
+                    field_symbol.field_index(),
                 )),
             )));
         builder
             .field_mut_pointer_variables_mut()
-            .insert(field_symbol.borrow().declared_name_owned(), to_insert);
+            .insert(field_symbol.declared_name_owned(), to_insert);
     }
     builder
         .field_mut_pointer_variables()
-        .get(field_symbol.borrow().declared_name())
+        .get(field_symbol.declared_name())
         .unwrap()
 }

dmc-lib/src/ast/let_statement.rs

@@ -1,12 +1,16 @@
 use crate::ast::expression::Expression;
+use crate::ast::helpers::try_insert_symbol_into;
 use crate::ast::ir_builder::IrBuilder;
 use crate::diagnostic::Diagnostic;
 use crate::ir::ir_assign::IrAssign;
 use crate::ir::ir_statement::IrStatement;
 use crate::ir::ir_variable::IrVariable;
 use crate::source_range::SourceRange;
+use crate::symbol::Symbol;
+use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol::variable_symbol::VariableSymbol;
-use crate::symbol_table::{SymbolInsertError, SymbolTable};
+use crate::symbol_table::SymbolTable;
+use crate::types_table::TypesTable;
 use std::cell::RefCell;
 use std::rc::Rc;
 
@@ -46,76 +50,131 @@ impl LetStatement {
         &mut self.initializer
     }
 
-    pub fn gather_declared_names(
-        &mut self,
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable, container_scope: usize) {
+        self.scope_id = Some(container_scope);
+        self.initializer.init_scopes(symbol_table, container_scope);
+    }
+
+    fn make_and_insert_variable_symbol(
+        &self,
         symbol_table: &mut SymbolTable,
-    ) -> Result<(), Vec<Diagnostic>> {
-        let mut diagnostics = vec![];
-
-        match self.initializer_mut().gather_declared_names(symbol_table) {
-            Ok(_) => {}
-            Err(mut initializer_diagnostics) => {
-                diagnostics.append(&mut initializer_diagnostics);
-            }
-        }
-
-        let insert_result = symbol_table.insert_variable_symbol(VariableSymbol::new(
+    ) -> Option<Diagnostic> {
+        let variable_symbol = Rc::new(VariableSymbol::new(
             &self.declared_name,
-            self.declared_name_source_range.clone(),
+            &self.declared_name_source_range,
             self.is_mut,
+            self.scope_id.unwrap(),
         ));
-        if let Err(symbol_insert_error) = insert_result {
-            match symbol_insert_error {
-                SymbolInsertError::AlreadyDeclared(already_declared) => {
-                    diagnostics.push(Diagnostic::new(
-                        &format!(
-                            "Symbol {} already declared in current scope",
-                            already_declared.symbol().borrow().declared_name()
-                        ),
-                        self.declared_name_source_range.start(),
-                        self.declared_name_source_range.end(),
-                    ))
-                }
-            }
-        }
-
-        self.scope_id = Some(symbol_table.current_scope_id());
-
-        if diagnostics.is_empty() {
-            Ok(())
-        } else {
-            Err(diagnostics)
-        }
+        try_insert_symbol_into(Symbol::Variable(variable_symbol), symbol_table).err()
     }
 
-    pub fn check_name_usages(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        self.initializer.check_name_usages(symbol_table)
+    pub fn analyze_constructor_local_names(
+        &self,
+        symbol_table: &mut SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        let mut diagnostics = Vec::new();
+        diagnostics.append(
+            &mut self
+                .initializer
+                .check_constructor_local_names(symbol_table, class_symbol),
+        );
+        if let Some(diagnostic) = self.make_and_insert_variable_symbol(symbol_table) {
+            diagnostics.push(diagnostic);
+        }
+
+        diagnostics
     }
 
-    pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        self.initializer.type_check(symbol_table)?;
-        let initializer_type_info = self.initializer.type_info();
-        let variable_symbol =
-            symbol_table.get_variable_symbol(self.scope_id.unwrap(), &self.declared_name);
-        variable_symbol
-            .borrow_mut()
-            .set_type_info(initializer_type_info.clone());
+    pub fn analyze_method_local_names(
+        &self,
+        symbol_table: &mut SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        let mut diagnostics = Vec::new();
+        diagnostics.append(
+            &mut self
+                .initializer
+                .check_method_local_names(symbol_table, class_symbol),
+        );
+        if let Some(diagnostic) = self.make_and_insert_variable_symbol(symbol_table) {
+            diagnostics.push(diagnostic);
+        }
+        diagnostics
+    }
+
+    pub fn analyze_static_fn_local_names(&self, symbol_table: &mut SymbolTable) -> Vec<Diagnostic> {
+        let mut diagnostics = Vec::new();
+        diagnostics.append(&mut self.initializer.check_static_fn_local_names(symbol_table));
+        if let Some(diagnostic) = self.make_and_insert_variable_symbol(symbol_table) {
+            diagnostics.push(diagnostic);
+        }
+        diagnostics
+    }
+
+    pub fn gather_local_type(&self, symbol_table: &SymbolTable, types_table: &mut TypesTable) {
+        let initializer_type_info = self
+            .initializer
+            .type_info(symbol_table, types_table)
+            .clone();
+        let variable_symbol = symbol_table
+            .get_variable_symbol_owned(self.scope_id.unwrap(), &self.declared_name)
+            .unwrap();
+        types_table
+            .variable_types_mut()
+            .insert(variable_symbol, initializer_type_info);
+    }
+
+    pub fn type_check(
+        &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &mut TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
+        self.initializer.type_check(symbol_table, types_table)?;
+        let initializer_type_info = self
+            .initializer
+            .type_info(symbol_table, types_table)
+            .clone();
+        let variable_symbol = symbol_table
+            .get_variable_symbol_owned(self.scope_id.unwrap(), &self.declared_name)
+            .unwrap();
+        types_table
+            .variable_types_mut()
+            .insert(variable_symbol, initializer_type_info);
         Ok(())
     }
 
-    pub fn to_ir(&self, builder: &mut IrBuilder, symbol_table: &SymbolTable) {
-        let init_operation = self.initializer.to_ir_operation(builder, symbol_table);
+    pub fn to_ir(
+        &self,
+        builder: &mut IrBuilder,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+    ) {
+        let init_operation = self
+            .initializer
+            .to_ir_operation(builder, symbol_table, types_table);
+
+        let destination_symbol = symbol_table
+            .get_variable_symbol_owned(self.scope_id.unwrap(), &self.declared_name)
+            .unwrap();
+
+        let destination_type = types_table
+            .variable_types()
+            .get(&destination_symbol)
+            .unwrap();
 
-        let destination_symbol =
-            symbol_table.get_variable_symbol(self.scope_id.unwrap(), &self.declared_name);
         let destination_vr_variable = IrVariable::new_vr(
             self.declared_name().into(),
             builder.current_block().id(),
-            self.initializer.type_info(),
+            destination_type,
         );
+
         let as_rc = Rc::new(RefCell::new(destination_vr_variable));
         let ir_assign = IrAssign::new(as_rc.clone(), init_operation);
-        destination_symbol.borrow_mut().set_vr_variable(as_rc);
+
+        builder
+            .local_variables_mut()
+            .insert(destination_symbol, as_rc.clone());
 
         builder
             .current_block_mut()

dmc-lib/src/ast/mod.rs

@@ -4,6 +4,7 @@ pub mod call;
 pub mod class;
 pub mod compilation_unit;
 pub mod constructor;
+mod diagnostic_factories;
 pub mod double_literal;
 pub mod expression;
 pub mod expression_statement;
@@ -14,6 +15,7 @@ pub mod fqn_context;
 pub mod fqn_util;
 pub mod function;
 pub mod generic_parameter;
+mod helpers;
 pub mod identifier;
 pub mod integer_literal;
 pub mod ir_builder;

dmc-lib/src/ast/negative_expression.rs

@@ -8,8 +8,10 @@ use crate::ir::ir_operation::IrOperation;
 use crate::ir::ir_statement::IrStatement;
 use crate::ir::ir_variable::IrVariable;
 use crate::source_range::SourceRange;
+use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol_table::SymbolTable;
 use crate::type_info::TypeInfo;
+use crate::types_table::TypesTable;
 use std::cell::RefCell;
 use std::rc::Rc;
 
@@ -40,21 +42,49 @@ impl NegativeExpression {
         &mut self.operand
     }
 
-    pub fn gather_declared_names(
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable, container_scope: usize) {
+        self.operand.init_scopes(symbol_table, container_scope);
+    }
+
+    pub fn check_field_initializer_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        self.operand
+            .check_field_initializer_names(symbol_table, class_symbol)
+    }
+
+    pub fn check_constructor_local_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        self.operand
+            .check_constructor_local_names(symbol_table, class_symbol)
+    }
+
+    pub fn check_method_local_names(
+        &self,
+        symbol_table: &SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        self.operand
+            .check_method_local_names(symbol_table, class_symbol)
+    }
+
+    pub fn check_static_fn_local_names(&self, symbol_table: &SymbolTable) -> Vec<Diagnostic> {
+        self.operand.check_static_fn_local_names(symbol_table)
+    }
+
+    pub fn type_check(
         &mut self,
-        symbol_table: &mut SymbolTable,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
     ) -> Result<(), Vec<Diagnostic>> {
-        self.operand.gather_declared_names(symbol_table)
-    }
+        self.operand.type_check(symbol_table, types_table)?;
 
-    pub fn check_name_usages(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        self.operand.check_name_usages(symbol_table)
-    }
-
-    pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        self.operand.type_check(symbol_table)?;
-
-        let type_info = self.operand.type_info();
+        let type_info = self.operand.type_info(symbol_table, types_table);
         if type_info.can_negate() {
             self.type_info = Some(type_info.negate_result());
             Ok(())
@@ -67,10 +97,15 @@ impl NegativeExpression {
         }
     }
 
-    pub fn to_ir(&self, builder: &mut IrBuilder, symbol_table: &SymbolTable) -> IrExpression {
+    pub fn to_ir(
+        &self,
+        builder: &mut IrBuilder,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+    ) -> IrExpression {
         let operand_as_ir = self
             .operand
-            .to_ir_expression(builder, symbol_table)
+            .to_ir_expression(builder, symbol_table, types_table)
             .expect("Attempt to negate non-value expression");
 
         match operand_as_ir {

dmc-lib/src/ast/parameter.rs

@@ -1,17 +1,16 @@
 use crate::ast::type_use::TypeUse;
 use crate::diagnostic::Diagnostic;
 use crate::source_range::SourceRange;
-use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol::parameter_symbol::ParameterSymbol;
-use crate::symbol_table::{SymbolInsertError, SymbolTable};
-use std::cell::RefCell;
+use crate::symbol_table::SymbolTable;
+use crate::types_table::TypesTable;
 use std::rc::Rc;
 
 pub struct Parameter {
     declared_name: Rc<str>,
     declared_name_source_range: SourceRange,
     type_use: TypeUse,
-    parameter_symbol: Option<Rc<RefCell<ParameterSymbol>>>,
+    scope_id: Option<usize>,
 }
 
 impl Parameter {
@@ -24,71 +23,51 @@ impl Parameter {
             declared_name: declared_name.into(),
             declared_name_source_range,
             type_use,
-            parameter_symbol: None,
+            scope_id: None,
         }
     }
 
-    pub fn gather_declared_names(
-        &mut self,
-        symbol_table: &mut SymbolTable,
-    ) -> Result<Rc<RefCell<ParameterSymbol>>, Vec<Diagnostic>> {
-        // insert parameter symbol
-        let insert_result = symbol_table.insert_parameter_symbol(ParameterSymbol::new(
+    pub fn declared_name(&self) -> &str {
+        &self.declared_name
+    }
+
+    pub fn scope_id(&self) -> usize {
+        self.scope_id.unwrap()
+    }
+
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable, container_scope: usize) {
+        self.scope_id = Some(container_scope);
+        self.type_use.init_scopes(symbol_table, container_scope);
+    }
+
+    pub fn make_symbol(&self) -> ParameterSymbol {
+        ParameterSymbol::new(
             &self.declared_name,
             self.declared_name_source_range.clone(),
-        ));
-        match insert_result {
-            Ok(parameter_symbol) => {
-                self.parameter_symbol = Some(parameter_symbol.clone());
-            }
-            Err(symbol_insert_error) => {
-                return match symbol_insert_error {
-                    SymbolInsertError::AlreadyDeclared(already_declared) => {
-                        Err(vec![Diagnostic::new(
-                            &format!(
-                                "Parameter {} already declared.",
-                                already_declared.symbol().borrow().declared_name()
-                            ),
-                            self.declared_name_source_range.start(),
-                            self.declared_name_source_range.end(),
-                        )])
-                    }
-                };
-            }
-        }
-
-        // type use
-        self.type_use.gather_declared_names(symbol_table)?;
-
-        Ok(self.parameter_symbol.clone().unwrap())
+            self.scope_id.unwrap(),
+        )
     }
 
-    pub fn check_name_usages(
+    pub fn check_names(&self, symbol_table: &SymbolTable) -> Vec<Diagnostic> {
+        self.type_use.check_names(symbol_table)
+    }
+
+    pub fn gather_types_into(&self, symbol_table: &SymbolTable, types_table: &mut TypesTable) {
+        let type_info = self.type_use.type_info(symbol_table, types_table).clone();
+        let parameter_symbol = symbol_table
+            .get_parameter_symbol_owned(self.scope_id.unwrap(), &self.declared_name)
+            .unwrap();
+        types_table
+            .parameter_types_mut()
+            .insert(parameter_symbol, type_info);
+    }
+
+    pub fn type_check(
         &mut self,
         symbol_table: &SymbolTable,
-        class_context: Option<&Rc<RefCell<ClassSymbol>>>,
+        types_table: &TypesTable,
     ) -> Result<(), Vec<Diagnostic>> {
-        // check the type use
-        self.type_use
-            .check_name_usages(symbol_table, class_context)?;
-
-        // set type on parameter symbol
-        self.parameter_symbol
-            .as_mut()
-            .unwrap()
-            .borrow_mut()
-            .set_type_info(self.type_use.type_info().clone());
+        self.type_use.type_check(symbol_table, types_table)?;
         Ok(())
     }
-
-    pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
-        self.type_use.type_check(symbol_table)?;
-        Ok(())
-    }
-
-    pub fn parameter_symbol(&self) -> &Rc<RefCell<ParameterSymbol>> {
-        self.parameter_symbol
-            .as_ref()
-            .expect("parameter symbol not initialized")
-    }
 }

dmc-lib/src/ast/statement.rs

@@ -3,8 +3,10 @@ use crate::ast::expression_statement::ExpressionStatement;
 use crate::ast::ir_builder::IrBuilder;
 use crate::ast::let_statement::LetStatement;
 use crate::diagnostic::Diagnostic;
+use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol_table::SymbolTable;
 use crate::type_info::TypeInfo;
+use crate::types_table::TypesTable;
 
 pub enum Statement {
     Let(LetStatement),
@@ -13,42 +15,84 @@ pub enum Statement {
 }
 
 impl Statement {
-    pub fn gather_declared_names(
-        &mut self,
-        symbol_table: &mut SymbolTable,
-    ) -> Result<(), Vec<Diagnostic>> {
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable, container_scope: usize) {
         match self {
-            Statement::Let(let_statement) => let_statement.gather_declared_names(symbol_table),
+            Statement::Let(let_statement) => {
+                let_statement.init_scopes(symbol_table, container_scope);
+            }
             Statement::Expression(expression_statement) => {
-                expression_statement.gather_declared_names(symbol_table)
+                expression_statement.init_scopes(symbol_table, container_scope);
             }
             Statement::Assign(assign_statement) => {
-                assign_statement.gather_declared_names(symbol_table)
+                assign_statement.init_scopes(symbol_table, container_scope);
             }
         }
     }
 
-    pub fn check_name_usages(&mut self, symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
+    pub fn analyze_constructor_local_names(
+        &self,
+        symbol_table: &mut SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
         match self {
-            Statement::Let(let_statement) => let_statement.check_name_usages(symbol_table),
-            Statement::Expression(expression_statement) => {
-                expression_statement.check_name_usages(symbol_table)
+            Statement::Let(let_statement) => {
+                let_statement.analyze_constructor_local_names(symbol_table, class_symbol)
+            }
+            Statement::Expression(expression_statement) => {
+                expression_statement.check_constructor_local_names(symbol_table, class_symbol)
+            }
+            Statement::Assign(assign_statement) => {
+                assign_statement.check_constructor_local_names(symbol_table, class_symbol)
+            }
+        }
+    }
+
+    pub fn analyze_method_local_names(
+        &self,
+        symbol_table: &mut SymbolTable,
+        class_symbol: &ClassSymbol,
+    ) -> Vec<Diagnostic> {
+        match self {
+            Statement::Let(let_statement) => {
+                let_statement.analyze_method_local_names(symbol_table, class_symbol)
+            }
+            Statement::Expression(expression_statement) => {
+                expression_statement.check_method_local_names(symbol_table, class_symbol)
+            }
+            Statement::Assign(assign_statement) => {
+                assign_statement.check_method_local_names(symbol_table, class_symbol)
+            }
+        }
+    }
+
+    pub fn analyze_static_fn_local_names(&self, symbol_table: &mut SymbolTable) -> Vec<Diagnostic> {
+        match self {
+            Statement::Let(let_statement) => {
+                let_statement.analyze_static_fn_local_names(symbol_table)
+            }
+            Statement::Expression(expression_statement) => {
+                expression_statement.check_static_fn_local_names(symbol_table)
+            }
+            Statement::Assign(assign_statement) => {
+                assign_statement.check_static_fn_local_names(symbol_table)
             }
-            Statement::Assign(assign_statement) => assign_statement.check_name_usages(symbol_table),
         }
     }
 
     pub fn type_check(
         &mut self,
         symbol_table: &SymbolTable,
+        types_table: &mut TypesTable,
         must_return_type_info: Option<&TypeInfo>,
     ) -> Result<(), Vec<Diagnostic>> {
         match self {
-            Statement::Let(let_statement) => let_statement.type_check(symbol_table),
+            Statement::Let(let_statement) => let_statement.type_check(symbol_table, types_table),
             Statement::Expression(expression_statement) => {
-                expression_statement.type_check(symbol_table, must_return_type_info)
+                expression_statement.type_check(symbol_table, types_table, must_return_type_info)
+            }
+            Statement::Assign(assign_statement) => {
+                assign_statement.type_check(symbol_table, types_table)
             }
-            Statement::Assign(assign_statement) => assign_statement.type_check(symbol_table),
         }
     }
 
@@ -56,17 +100,18 @@ impl Statement {
         &self,
         builder: &mut IrBuilder,
         symbol_table: &SymbolTable,
+        types_table: &TypesTable,
         should_return_value: bool,
     ) {
         match self {
             Statement::Let(let_statement) => {
-                let_statement.to_ir(builder, symbol_table);
+                let_statement.to_ir(builder, symbol_table, types_table);
             }
             Statement::Expression(expression_statement) => {
-                expression_statement.to_ir(builder, symbol_table, should_return_value);
+                expression_statement.to_ir(builder, symbol_table, types_table, should_return_value);
             }
             Statement::Assign(assign_statement) => {
-                assign_statement.to_ir(builder, symbol_table);
+                assign_statement.to_ir(builder, symbol_table, types_table);
             }
         }
     }

dmc-lib/src/ast/type_use.rs

@@ -1,19 +1,19 @@
+use crate::ast::diagnostic_factories::symbol_not_found;
 use crate::diagnostic::Diagnostic;
 use crate::error_codes::INCORRECT_GENERIC_ARGUMENTS;
 use crate::source_range::SourceRange;
-use crate::symbol::class_symbol::ClassSymbol;
+use crate::symbol::type_symbol::TypeSymbol;
 use crate::symbol_table::SymbolTable;
 use crate::type_info::TypeInfo;
+use crate::types_table::TypesTable;
 use crate::{diagnostics_result, handle_diagnostics, maybe_return_diagnostics};
-use std::cell::RefCell;
 use std::rc::Rc;
 
 pub struct TypeUse {
-    declared_name: String,
+    declared_name: Rc<str>,
     declared_name_source_range: SourceRange,
     generic_arguments: Vec<TypeUse>,
     scope_id: Option<usize>,
-    type_info: Option<TypeInfo>,
 }
 
 impl TypeUse {
@@ -27,7 +27,6 @@ impl TypeUse {
             declared_name_source_range,
             generic_arguments,
             scope_id: None,
-            type_info: None,
         }
     }
 
@@ -35,63 +34,88 @@ impl TypeUse {
         &self.declared_name
     }
 
-    pub fn gather_declared_names(
-        &mut self,
-        symbol_table: &mut SymbolTable,
-    ) -> Result<(), Vec<Diagnostic>> {
-        self.scope_id = Some(symbol_table.current_scope_id());
-        let mut inner_diagnostics: Vec<Diagnostic> = vec![];
-        for generic_argument in &mut self.generic_arguments {
-            handle_diagnostics!(
-                generic_argument.gather_declared_names(symbol_table),
-                inner_diagnostics
-            );
+    pub fn init_scopes(&mut self, symbol_table: &mut SymbolTable, container_scope: usize) {
+        self.scope_id = Some(container_scope);
+        for type_use in &mut self.generic_arguments {
+            type_use.init_scopes(symbol_table, container_scope);
         }
-        diagnostics_result!(inner_diagnostics)
     }
 
-    pub fn check_name_usages(
-        &mut self,
-        symbol_table: &SymbolTable,
-        class_context: Option<&Rc<RefCell<ClassSymbol>>>,
-    ) -> Result<(), Vec<Diagnostic>> {
-        let mut diagnostics: Vec<Diagnostic> = vec![];
+    pub fn check_names(&self, symbol_table: &SymbolTable) -> Vec<Diagnostic> {
+        let mut diagnostics: Vec<Diagnostic> = Vec::new();
 
-        if let Some(type_info) = TypeInfo::from_declared_name(
-            &self.declared_name,
-            self.scope_id.unwrap(),
-            symbol_table,
-            class_context,
-        ) {
-            self.type_info = Some(type_info);
-        } else {
-            let diagnostic = Diagnostic::new(
-                &format!("Unable to resolve symbol {}", self.declared_name),
-                self.declared_name_source_range.start(),
-                self.declared_name_source_range.end(),
-            )
-            .with_reporter(file!(), line!());
-            diagnostics.push(diagnostic);
+        // find this name
+        let maybe_type_symbol =
+            symbol_table.find_type_symbol(self.scope_id.unwrap(), &self.declared_name);
+        if maybe_type_symbol.is_none() {
+            diagnostics.push(symbol_not_found(
+                self.declared_name(),
+                &self.declared_name_source_range,
+            ));
         }
 
-        for generic_argument in &mut self.generic_arguments {
+        // check generic args
+        for type_use in &self.generic_arguments {
+            diagnostics.append(&mut type_use.check_names(symbol_table));
+        }
+
+        diagnostics
+    }
+
+    pub fn gather_types(
+        &self,
+        symbol_table: &SymbolTable,
+        types_table: &mut TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
+        let mut diagnostics = Vec::new();
+        for type_use in &self.generic_arguments {
             handle_diagnostics!(
-                generic_argument.check_name_usages(symbol_table, class_context),
+                type_use.gather_types(symbol_table, types_table),
                 diagnostics
             );
         }
-
         diagnostics_result!(diagnostics)
     }
 
-    pub fn type_check(&mut self, _symbol_table: &SymbolTable) -> Result<(), Vec<Diagnostic>> {
+    pub fn type_info<'a>(
+        &self,
+        symbol_table: &SymbolTable,
+        types_table: &'a TypesTable,
+    ) -> &'a TypeInfo {
+        let type_symbol = symbol_table
+            .find_type_symbol(self.scope_id.unwrap(), self.declared_name())
+            .unwrap();
+        match type_symbol {
+            TypeSymbol::Class(class_symbol) => {
+                types_table
+                    .class_types()
+                    .get(&class_symbol)
+                    .expect(&format!(
+                        "Could not get TypeInfo for {}",
+                        self.declared_name
+                    ))
+            }
+            TypeSymbol::GenericParameter(generic_parameter_symbol) => types_table
+                .generic_parameter_types()
+                .get(&generic_parameter_symbol)
+                .expect(&format!(
+                    "Could not get TypeInfo for {}",
+                    self.declared_name
+                )),
+        }
+    }
+
+    pub fn type_check(
+        &mut self,
+        symbol_table: &SymbolTable,
+        types_table: &TypesTable,
+    ) -> Result<(), Vec<Diagnostic>> {
         let mut diagnostics: Vec<Diagnostic> = vec![];
 
-        match self.type_info() {
-            TypeInfo::ClassInstance(class_symbol) => {
+        match self.type_info(symbol_table, types_table) {
+            TypeInfo::Class(class_symbol) => {
                 // check number of params/args match
-                let borrowed_class_symbol = class_symbol.borrow();
-                let generic_parameters = borrowed_class_symbol.generic_parameters();
+                let generic_parameters = class_symbol.generic_parameters();
                 if generic_parameters.len() != self.generic_arguments.len() {
                     let diagnostic = Diagnostic::new(
                         &format!(
@@ -110,12 +134,12 @@ impl TypeUse {
                 maybe_return_diagnostics!(diagnostics);
 
                 // check that each arg is assignable to the param's extends
-                for i in 0..self.generic_arguments.len() {
-                    let generic_parameter_symbol = generic_parameters[i].borrow();
-                    if generic_parameter_symbol.extends().len() > 0 {
-                        unimplemented!("Generic extends not implemented yet.")
-                    }
-                }
+                // for i in 0..self.generic_arguments.len() {
+                //     let generic_parameter_symbol = &generic_parameters[i];
+                //     if generic_parameter_symbol.extends().len() > 0 {
+                //         unimplemented!("Generic extends not implemented yet.")
+                //     }
+                // }
             }
             _ => {
                 // cannot extend a non-class type (except for Any)
@@ -123,7 +147,7 @@ impl TypeUse {
                     let diagnostic = Diagnostic::new(
                         &format!(
                             "Type {} does not accept generic arguments.",
-                            self.type_info()
+                            self.type_info(symbol_table, types_table)
                         ),
                         self.declared_name_source_range.start(),
                         self.declared_name_source_range.end(),
@@ -137,15 +161,14 @@ impl TypeUse {
 
         // recurse on generic arguments
         for generic_argument in &mut self.generic_arguments {
-            handle_diagnostics!(generic_argument.type_check(_symbol_table), diagnostics);
+            handle_diagnostics!(
+                generic_argument.type_check(symbol_table, types_table),
+                diagnostics
+            );
         }
 
         diagnostics_result!(diagnostics)
     }
-
-    pub fn type_info(&self) -> &TypeInfo {
-        self.type_info.as_ref().unwrap()
-    }
 }
 
 #[cfg(test)]
@@ -153,11 +176,14 @@ mod tests {
     use crate::diagnostic::Diagnostic;
     use crate::parser::parse_compilation_unit;
     use crate::symbol_table::SymbolTable;
+    use crate::types_table::TypesTable;
 
     #[test]
     fn type_check_generics() -> Result<(), Vec<Diagnostic>> {
         let mut compilation_unit = parse_compilation_unit(
             "
+            class String end
+
             class Foo<T>
                 ctor(t: T) end
             end
@@ -167,10 +193,13 @@ mod tests {
         )?;
 
         let mut symbol_table = SymbolTable::new();
+        let mut types_table = TypesTable::new();
 
-        compilation_unit.gather_declared_names(&mut symbol_table)?;
-        compilation_unit.check_name_usages(&mut symbol_table)?;
-        compilation_unit.type_check(&mut symbol_table)?;
+        compilation_unit.init_scopes(&mut symbol_table);
+        compilation_unit.gather_symbols_into(&mut symbol_table)?;
+        compilation_unit.check_names(&mut symbol_table)?;
+        compilation_unit.gather_types_into(&symbol_table, &mut types_table)?;
+        compilation_unit.type_check(&mut symbol_table, &mut types_table)?;
 
         Ok(())
     }

dmc-lib/src/ast/util.rs

@@ -22,6 +22,27 @@ macro_rules! handle_diagnostics {
     };
 }
 
+#[macro_export]
+macro_rules! ok_or_return {
+    ( $result: expr, $diagnostics: expr ) => {
+        match $result {
+            Ok(inner) => inner,
+            Err(mut diagnostics) => {
+                $diagnostics.append(&mut diagnostics);
+                return Err($diagnostics);
+            }
+        }
+    };
+    ( $result: expr ) => {
+        match $result {
+            Ok(inner) => inner,
+            Err(diagnostics) => {
+                return Err(diagnostics);
+            }
+        }
+    };
+}
+
 #[macro_export]
 macro_rules! maybe_return_diagnostics {
     ( $diagnostics: expr ) => {
@@ -41,3 +62,24 @@ macro_rules! diagnostics_result {
         }
     };
 }
+
+#[macro_export]
+macro_rules! ok_or_err_diagnostics {
+    ( $to_return: expr, $diagnostics: expr ) => {
+        if $diagnostics.is_empty() {
+            Ok($to_return)
+        } else {
+            Err($diagnostics)
+        }
+    };
+}
+
+#[macro_export]
+macro_rules! push_ok_or_push_errs {
+    ( $result: expr, $oks: expr, $errs: expr ) => {
+        match $result {
+            Ok(inner) => $oks.push(inner),
+            Err(mut errs) => $errs.append(&mut errs),
+        }
+    };
+}

dmc-lib/src/error_codes.rs

@@ -1,5 +1,6 @@
 pub type ErrorCode = usize;
 
+pub const SYMBOL_NOT_FOUND: ErrorCode = 13;
 pub const SYMBOL_ALREADY_DECLARED: ErrorCode = 14;
 pub const BINARY_INCOMPATIBLE_TYPES: ErrorCode = 15;
 pub const ASSIGN_MISMATCHED_TYPES: ErrorCode = 16;
@@ -7,3 +8,12 @@ pub const ASSIGN_NO_L_VALUE: ErrorCode = 17;
 pub const ASSIGN_LHS_IMMUTABLE: ErrorCode = 18;
 pub const INCORRECT_GENERIC_ARGUMENTS: ErrorCode = 19;
 pub const GENERIC_ARGUMENT_TYPE_MISMATCH: ErrorCode = 20;
+pub const FIELD_MULTIPLE_INIT: ErrorCode = 21;
+pub const FIELD_UNINIT: ErrorCode = 22;
+pub const SELF_FIELD_USED_IN_INIT: ErrorCode = 23;
+pub const SELF_METHOD_USED_IN_INIT: ErrorCode = 24;
+pub const SELF_CONSTRUCTOR_USED_IN_INIT: ErrorCode = 25;
+pub const OUTER_CLASS_FIELD_USED_IN_INIT: ErrorCode = 26;
+pub const OUTER_CLASS_METHOD_USED_IN_INIT: ErrorCode = 27;
+pub const FIELD_NO_TYPE_OR_INIT: ErrorCode = 28;
+pub const CLASS_NO_CONSTRUCTOR: ErrorCode = 29;

dmc-lib/src/intrinsics/mod.rs

@@ -0,0 +1,48 @@
+use crate::symbol::class_symbol::ClassSymbol;
+use crate::symbol_table::SymbolTable;
+use crate::type_info::TypeInfo;
+use crate::types_table::TypesTable;
+use std::rc::Rc;
+
+fn create_simple_primitive(name: &str) -> ClassSymbol {
+    ClassSymbol::new(
+        &Rc::from(name),
+        None,
+        vec![Rc::from(name)],
+        true,
+        0, // global
+        vec![],
+        None,
+        vec![],
+        vec![],
+    )
+}
+
+pub fn insert_intrinsic_symbols(symbol_table: &mut SymbolTable) {
+    let primitives = [
+        create_simple_primitive("Int"),
+        create_simple_primitive("Double"),
+        create_simple_primitive("String"),
+        create_simple_primitive("Void"),
+        create_simple_primitive("Any"),
+    ];
+    for primitive in primitives {
+        symbol_table.insert_class_symbol(Rc::new(primitive));
+    }
+}
+
+pub fn insert_intrinsic_types(symbol_table: &SymbolTable, types_table: &mut TypesTable) {
+    let primitives = ["Int", "Double", "String", "Void", "Any"];
+    for primitive in primitives {
+        let symbol = symbol_table.get_class_symbol(0, primitive).unwrap().clone();
+        let type_info = match primitive {
+            "Int" => TypeInfo::Integer,
+            "Double" => TypeInfo::Double,
+            "String" => TypeInfo::String,
+            "Void" => TypeInfo::Void,
+            "Any" => TypeInfo::Any,
+            _ => unreachable!(),
+        };
+        types_table.class_types_mut().insert(symbol, type_info);
+    }
+}

dmc-lib/src/ir/ir_block.rs

@@ -121,11 +121,13 @@ impl Display for IrBlock {
 
 #[cfg(test)]
 mod tests {
+    use crate::diagnostic::Diagnostic;
     use crate::parser::parse_compilation_unit;
     use crate::symbol_table::SymbolTable;
+    use crate::types_table::TypesTable;
 
     #[test]
-    fn overlapping_assignments_bug_when_k_2() {
+    fn overlapping_assignments_bug_when_k_2() -> Result<(), Vec<Diagnostic>> {
         let mut compilation_unit = parse_compilation_unit(
             "
             fn main()
@@ -135,18 +137,16 @@ mod tests {
                 let x = a + b + c
             end
         ",
-        )
-        .unwrap();
+        )?;
+
         let mut symbol_table = SymbolTable::new();
-        compilation_unit
-            .gather_declared_names(&mut symbol_table)
-            .expect("gather failed");
-        compilation_unit
-            .check_name_usages(&mut symbol_table)
-            .expect("name check failed");
-        compilation_unit
-            .type_check(&mut symbol_table)
-            .expect("type check failed");
+        let mut types_table = TypesTable::new();
+
+        compilation_unit.init_scopes(&mut symbol_table);
+        compilation_unit.gather_symbols_into(&mut symbol_table)?;
+        compilation_unit.check_names(&mut symbol_table)?;
+        compilation_unit.gather_types_into(&symbol_table, &mut types_table)?;
+        compilation_unit.type_check(&symbol_table, &mut types_table)?;
 
         let main = compilation_unit
             .functions()
@@ -154,8 +154,10 @@ mod tests {
             .find(|f| f.declared_name() == "main")
             .unwrap();
 
-        let mut main_ir = main.to_ir(&symbol_table, None);
+        let mut main_ir = main.to_ir(&symbol_table, &types_table, None);
         let (register_assignments, _) = main_ir.assign_registers(2);
         assert_eq!(register_assignments.len(), 4);
+
+        Ok(())
     }
 }

dmc-lib/src/ir/ir_class.rs

@@ -51,9 +51,9 @@ impl IrField {
                 TypeInfo::Integer => VmTypeInfo::Int,
                 TypeInfo::Double => VmTypeInfo::Double,
                 TypeInfo::String => VmTypeInfo::String,
-                TypeInfo::ClassInstance(class_symbol) => VmTypeInfo::ClassInstance(
-                    fqn_parts_to_string(class_symbol.borrow().fqn_parts()).into(),
-                ),
+                TypeInfo::Class(class_symbol) => {
+                    VmTypeInfo::ClassInstance(fqn_parts_to_string(class_symbol.fqn_parts()).into())
+                }
                 TypeInfo::GenericType(_) => VmTypeInfo::Any,
                 _ => panic!(),
             },

dmc-lib/src/ir/ir_function.rs

@@ -21,7 +21,7 @@ pub struct IrFunction {
 impl IrFunction {
     pub fn new(
         fqn: Rc<str>,
-        parameters: &[Rc<IrParameter>],
+        parameters: Vec<Rc<IrParameter>>,
         return_type_info: &TypeInfo,
         entry: Rc<RefCell<IrBlock>>,
     ) -> Self {

dmc-lib/src/lib.rs

@@ -2,12 +2,14 @@ pub mod ast;
 pub mod constants_table;
 pub mod diagnostic;
 pub mod error_codes;
+pub mod intrinsics;
 pub mod ir;
 pub mod lexer;
 pub mod parser;
-mod scope;
+pub mod scope;
 pub mod source_range;
 pub mod symbol;
 pub mod symbol_table;
 pub mod token;
 pub mod type_info;
+pub mod types_table;

dmc-lib/src/scope/block_scope.rs

@@ -1,12 +1,12 @@
 use crate::symbol::variable_symbol::VariableSymbol;
-use std::cell::RefCell;
 use std::collections::HashMap;
+use std::fmt::{Debug, Formatter};
 use std::rc::Rc;
 
 pub struct BlockScope {
     debug_name: String,
     parent_id: usize,
-    variable_symbols: HashMap<Rc<str>, Rc<RefCell<VariableSymbol>>>,
+    variable_symbols: HashMap<Rc<str>, Rc<VariableSymbol>>,
 }
 
 impl BlockScope {
@@ -18,11 +18,11 @@ impl BlockScope {
         }
     }
 
-    pub fn variable_symbols(&self) -> &HashMap<Rc<str>, Rc<RefCell<VariableSymbol>>> {
+    pub fn variable_symbols(&self) -> &HashMap<Rc<str>, Rc<VariableSymbol>> {
         &self.variable_symbols
     }
 
-    pub fn variable_symbols_mut(&mut self) -> &mut HashMap<Rc<str>, Rc<RefCell<VariableSymbol>>> {
+    pub fn variable_symbols_mut(&mut self) -> &mut HashMap<Rc<str>, Rc<VariableSymbol>> {
         &mut self.variable_symbols
     }
 
@@ -30,3 +30,9 @@ impl BlockScope {
         self.parent_id
     }
 }
+
+impl Debug for BlockScope {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "BlockScope({}, {})", self.debug_name, self.parent_id)
+    }
+}

dmc-lib/src/scope/class_body_scope.rs

@@ -0,0 +1,71 @@
+use crate::symbol::class_symbol::ClassSymbol;
+use crate::symbol::constructor_symbol::ConstructorSymbol;
+use crate::symbol::field_symbol::FieldSymbol;
+use crate::symbol::function_symbol::FunctionSymbol;
+use std::collections::HashMap;
+use std::fmt::{Debug, Formatter};
+use std::rc::Rc;
+
+pub struct ClassBodyScope {
+    debug_name: String,
+    parent_id: usize,
+    class_symbols: HashMap<Rc<str>, Rc<ClassSymbol>>,
+    field_symbols: HashMap<Rc<str>, Rc<FieldSymbol>>,
+    function_symbols: HashMap<Rc<str>, Rc<FunctionSymbol>>,
+    constructor_symbol: Option<Rc<ConstructorSymbol>>,
+}
+
+impl ClassBodyScope {
+    pub fn new(debug_name: &str, parent_id: usize) -> Self {
+        Self {
+            debug_name: debug_name.into(),
+            parent_id,
+            class_symbols: HashMap::new(),
+            field_symbols: HashMap::new(),
+            function_symbols: HashMap::new(),
+            constructor_symbol: None,
+        }
+    }
+
+    pub fn class_symbols(&self) -> &HashMap<Rc<str>, Rc<ClassSymbol>> {
+        &self.class_symbols
+    }
+
+    pub fn class_symbols_mut(&mut self) -> &mut HashMap<Rc<str>, Rc<ClassSymbol>> {
+        &mut self.class_symbols
+    }
+
+    pub fn field_symbols(&self) -> &HashMap<Rc<str>, Rc<FieldSymbol>> {
+        &self.field_symbols
+    }
+
+    pub fn field_symbols_mut(&mut self) -> &mut HashMap<Rc<str>, Rc<FieldSymbol>> {
+        &mut self.field_symbols
+    }
+
+    pub fn function_symbols(&self) -> &HashMap<Rc<str>, Rc<FunctionSymbol>> {
+        &self.function_symbols
+    }
+
+    pub fn function_symbols_mut(&mut self) -> &mut HashMap<Rc<str>, Rc<FunctionSymbol>> {
+        &mut self.function_symbols
+    }
+
+    pub fn constructor_symbol(&self) -> Option<&Rc<ConstructorSymbol>> {
+        self.constructor_symbol.as_ref()
+    }
+
+    pub fn constructor_symbol_mut(&mut self) -> &mut Option<Rc<ConstructorSymbol>> {
+        &mut self.constructor_symbol
+    }
+
+    pub fn parent_id(&self) -> usize {
+        self.parent_id
+    }
+}
+
+impl Debug for ClassBodyScope {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "ClassBodyScope({}, {})", self.debug_name, self.parent_id)
+    }
+}

dmc-lib/src/scope/class_scope.rs

@@ -1,20 +1,12 @@
-use crate::symbol::class_symbol::ClassSymbol;
-use crate::symbol::constructor_symbol::ConstructorSymbol;
-use crate::symbol::field_symbol::FieldSymbol;
-use crate::symbol::function_symbol::FunctionSymbol;
 use crate::symbol::generic_parameter_symbol::GenericParameterSymbol;
-use std::cell::RefCell;
 use std::collections::HashMap;
+use std::fmt::{Debug, Formatter};
 use std::rc::Rc;
 
 pub struct ClassScope {
     debug_name: String,
     parent_id: usize,
-    generic_parameter_symbols: HashMap<Rc<str>, Rc<RefCell<GenericParameterSymbol>>>,
-    class_symbols: HashMap<Rc<str>, Rc<RefCell<ClassSymbol>>>,
-    field_symbols: HashMap<Rc<str>, Rc<RefCell<FieldSymbol>>>,
-    function_symbols: HashMap<Rc<str>, Rc<RefCell<FunctionSymbol>>>,
-    constructor_symbol: Option<Rc<RefCell<ConstructorSymbol>>>,
+    generic_parameter_symbols: HashMap<Rc<str>, Rc<GenericParameterSymbol>>,
 }
 
 impl ClassScope {
@@ -23,58 +15,26 @@ impl ClassScope {
             debug_name: debug_name.into(),
             parent_id,
             generic_parameter_symbols: HashMap::new(),
-            class_symbols: HashMap::new(),
-            field_symbols: HashMap::new(),
-            function_symbols: HashMap::new(),
-            constructor_symbol: None,
         }
     }
 
-    pub fn generic_parameter_symbols(
-        &self,
-    ) -> &HashMap<Rc<str>, Rc<RefCell<GenericParameterSymbol>>> {
-        &self.generic_parameter_symbols
-    }
-
-    pub fn generic_parameter_symbols_mut(
-        &mut self,
-    ) -> &mut HashMap<Rc<str>, Rc<RefCell<GenericParameterSymbol>>> {
-        &mut self.generic_parameter_symbols
-    }
-
-    pub fn class_symbols(&self) -> &HashMap<Rc<str>, Rc<RefCell<ClassSymbol>>> {
-        &self.class_symbols
-    }
-
-    pub fn class_symbols_mut(&mut self) -> &mut HashMap<Rc<str>, Rc<RefCell<ClassSymbol>>> {
-        &mut self.class_symbols
-    }
-
-    pub fn field_symbols(&self) -> &HashMap<Rc<str>, Rc<RefCell<FieldSymbol>>> {
-        &self.field_symbols
-    }
-
-    pub fn field_symbols_mut(&mut self) -> &mut HashMap<Rc<str>, Rc<RefCell<FieldSymbol>>> {
-        &mut self.field_symbols
-    }
-
-    pub fn function_symbols(&self) -> &HashMap<Rc<str>, Rc<RefCell<FunctionSymbol>>> {
-        &self.function_symbols
-    }
-
-    pub fn function_symbols_mut(&mut self) -> &mut HashMap<Rc<str>, Rc<RefCell<FunctionSymbol>>> {
-        &mut self.function_symbols
-    }
-
-    pub fn constructor_symbol(&self) -> Option<&Rc<RefCell<ConstructorSymbol>>> {
-        self.constructor_symbol.as_ref()
-    }
-
-    pub fn constructor_symbol_mut(&mut self) -> &mut Option<Rc<RefCell<ConstructorSymbol>>> {
-        &mut self.constructor_symbol
-    }
-
     pub fn parent_id(&self) -> usize {
         self.parent_id
     }
+
+    pub fn generic_parameter_symbols(&self) -> &HashMap<Rc<str>, Rc<GenericParameterSymbol>> {
+        &self.generic_parameter_symbols
+    }
+
+    pub fn generic_parameter_symbols_mut(
+        &mut self,
+    ) -> &mut HashMap<Rc<str>, Rc<GenericParameterSymbol>> {
+        &mut self.generic_parameter_symbols
+    }
+}
+
+impl Debug for ClassScope {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "ClassScope({}, {})", self.debug_name, self.parent_id)
+    }
 }

dmc-lib/src/scope/function_scope.rs

@@ -1,12 +1,12 @@
 use crate::symbol::parameter_symbol::ParameterSymbol;
-use std::cell::RefCell;
 use std::collections::HashMap;
+use std::fmt::{Debug, Formatter};
 use std::rc::Rc;
 
 pub struct FunctionScope {
     debug_name: String,
     parent_id: usize,
-    parameter_symbols: HashMap<Rc<str>, Rc<RefCell<ParameterSymbol>>>,
+    parameter_symbols: HashMap<Rc<str>, Rc<ParameterSymbol>>,
 }
 
 impl FunctionScope {
@@ -18,11 +18,11 @@ impl FunctionScope {
         }
     }
 
-    pub fn parameter_symbols(&self) -> &HashMap<Rc<str>, Rc<RefCell<ParameterSymbol>>> {
+    pub fn parameter_symbols(&self) -> &HashMap<Rc<str>, Rc<ParameterSymbol>> {
         &self.parameter_symbols
     }
 
-    pub fn parameter_symbols_mut(&mut self) -> &mut HashMap<Rc<str>, Rc<RefCell<ParameterSymbol>>> {
+    pub fn parameter_symbols_mut(&mut self) -> &mut HashMap<Rc<str>, Rc<ParameterSymbol>> {
         &mut self.parameter_symbols
     }
 
@@ -30,3 +30,9 @@ impl FunctionScope {
         self.parent_id
     }
 }
+
+impl Debug for FunctionScope {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "FunctionScope({}, {})", self.debug_name, self.parent_id)
+    }
+}

dmc-lib/src/scope/mod.rs

@@ -1,9 +1,12 @@
 use crate::scope::block_scope::BlockScope;
+use crate::scope::class_body_scope::ClassBodyScope;
 use crate::scope::class_scope::ClassScope;
 use crate::scope::function_scope::FunctionScope;
 use crate::scope::module_scope::ModuleScope;
+use std::fmt::{Debug, Formatter};
 
 pub mod block_scope;
+pub mod class_body_scope;
 pub mod class_scope;
 pub mod function_scope;
 pub mod module_scope;
@@ -11,6 +14,7 @@ pub mod module_scope;
 pub enum Scope {
     Module(ModuleScope),
     Class(ClassScope),
+    ClassBody(ClassBodyScope),
     Function(FunctionScope),
     Block(BlockScope),
 }
@@ -20,8 +24,31 @@ impl Scope {
         match self {
             Scope::Module(module_scope) => module_scope.parent_id(),
             Scope::Class(class_scope) => Some(class_scope.parent_id()),
+            Scope::ClassBody(class_body_scope) => Some(class_body_scope.parent_id()),
             Scope::Function(function_scope) => Some(function_scope.parent_id()),
             Scope::Block(block_scope) => Some(block_scope.parent_id()),
         }
     }
 }
+
+impl Debug for Scope {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Scope::Module(module_scope) => {
+                write!(f, "{:?}", module_scope)
+            }
+            Scope::Class(class_scope) => {
+                write!(f, "{:?}", class_scope)
+            }
+            Scope::ClassBody(class_body_scope) => {
+                write!(f, "{:?}", class_body_scope)
+            }
+            Scope::Function(function_scope) => {
+                write!(f, "{:?}", function_scope)
+            }
+            Scope::Block(block_scope) => {
+                write!(f, "{:?}", block_scope)
+            }
+        }
+    }
+}

dmc-lib/src/scope/module_scope.rs

@@ -1,14 +1,14 @@
 use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol::function_symbol::FunctionSymbol;
-use std::cell::RefCell;
 use std::collections::HashMap;
+use std::fmt::{Debug, Formatter};
 use std::rc::Rc;
 
 pub struct ModuleScope {
     debug_name: String,
     parent_id: Option<usize>,
-    class_symbols: HashMap<Rc<str>, Rc<RefCell<ClassSymbol>>>,
-    function_symbols: HashMap<Rc<str>, Rc<RefCell<FunctionSymbol>>>,
+    class_symbols: HashMap<Rc<str>, Rc<ClassSymbol>>,
+    function_symbols: HashMap<Rc<str>, Rc<FunctionSymbol>>,
 }
 
 impl ModuleScope {
@@ -21,19 +21,19 @@ impl ModuleScope {
         }
     }
 
-    pub fn class_symbols(&self) -> &HashMap<Rc<str>, Rc<RefCell<ClassSymbol>>> {
+    pub fn class_symbols(&self) -> &HashMap<Rc<str>, Rc<ClassSymbol>> {
         &self.class_symbols
     }
 
-    pub fn class_symbols_mut(&mut self) -> &mut HashMap<Rc<str>, Rc<RefCell<ClassSymbol>>> {
+    pub fn class_symbols_mut(&mut self) -> &mut HashMap<Rc<str>, Rc<ClassSymbol>> {
         &mut self.class_symbols
     }
 
-    pub fn function_symbols(&self) -> &HashMap<Rc<str>, Rc<RefCell<FunctionSymbol>>> {
+    pub fn function_symbols(&self) -> &HashMap<Rc<str>, Rc<FunctionSymbol>> {
         &self.function_symbols
     }
 
-    pub fn function_symbols_mut(&mut self) -> &mut HashMap<Rc<str>, Rc<RefCell<FunctionSymbol>>> {
+    pub fn function_symbols_mut(&mut self) -> &mut HashMap<Rc<str>, Rc<FunctionSymbol>> {
         &mut self.function_symbols
     }
 
@@ -41,3 +41,9 @@ impl ModuleScope {
         self.parent_id
     }
 }
+
+impl Debug for ModuleScope {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "ModuleScope({}, {:?})", self.debug_name, self.parent_id)
+    }
+}

dmc-lib/src/symbol/callable_symbol.rs

@@ -1,34 +1,19 @@
-use crate::symbol::class_symbol::ClassSymbol;
+use crate::symbol::constructor_symbol::ConstructorSymbol;
 use crate::symbol::function_symbol::FunctionSymbol;
 use crate::symbol::parameter_symbol::ParameterSymbol;
-use crate::type_info::TypeInfo;
-use std::cell::RefCell;
 use std::rc::Rc;
 
 pub enum CallableSymbol {
-    Function(Rc<RefCell<FunctionSymbol>>),
-    Class(Rc<RefCell<ClassSymbol>>),
+    Function(Rc<FunctionSymbol>),
+    Constructor(Rc<ConstructorSymbol>),
 }
 
 impl CallableSymbol {
-    pub fn return_type_info(&self) -> TypeInfo {
+    pub fn parameters(&self) -> Vec<Rc<ParameterSymbol>> {
         match self {
-            CallableSymbol::Function(function) => function.borrow().return_type_info().clone(),
-            CallableSymbol::Class(class_symbol) => TypeInfo::ClassInstance(class_symbol.clone()),
-        }
-    }
-
-    pub fn parameters(&self) -> Vec<Rc<RefCell<ParameterSymbol>>> {
-        match self {
-            CallableSymbol::Function(function_symbol) => {
-                function_symbol.borrow().parameters().to_vec()
-            }
-            CallableSymbol::Class(class_symbol) => {
-                if let Some(constructor_symbol) = class_symbol.borrow().constructor_symbol() {
-                    constructor_symbol.borrow().parameters().to_vec()
-                } else {
-                    vec![]
-                }
+            CallableSymbol::Function(function_symbol) => function_symbol.parameters().to_vec(),
+            CallableSymbol::Constructor(constructor_symbol) => {
+                constructor_symbol.parameters().to_vec()
             }
         }
     }

dmc-lib/src/symbol/class_symbol.rs

@@ -1,89 +1,115 @@
+use crate::ast::fqn_util::fqn_parts_to_string;
 use crate::source_range::SourceRange;
-use crate::symbol::Symbol;
 use crate::symbol::constructor_symbol::ConstructorSymbol;
 use crate::symbol::field_symbol::FieldSymbol;
 use crate::symbol::function_symbol::FunctionSymbol;
 use crate::symbol::generic_parameter_symbol::GenericParameterSymbol;
-use std::cell::RefCell;
 use std::collections::HashMap;
+use std::fmt::{Debug, Formatter};
+use std::hash::{Hash, Hasher};
 use std::rc::Rc;
 
 pub struct ClassSymbol {
     declared_name: Rc<str>,
-    declared_name_source_range: SourceRange,
+    declared_name_source_range: Option<SourceRange>,
     fqn_parts: Vec<Rc<str>>,
     is_extern: bool,
-    generic_parameters: Vec<Rc<RefCell<GenericParameterSymbol>>>,
-    constructor_symbol: Option<Rc<RefCell<ConstructorSymbol>>>,
-    fields: HashMap<Rc<str>, Rc<RefCell<FieldSymbol>>>,
-    functions: HashMap<Rc<str>, Rc<RefCell<FunctionSymbol>>>,
+    scope_id: usize,
+    generic_parameters: Vec<Rc<GenericParameterSymbol>>,
+    constructor_symbol: Option<Rc<ConstructorSymbol>>,
+    fields: HashMap<Rc<str>, Rc<FieldSymbol>>,
+    functions: HashMap<Rc<str>, Rc<FunctionSymbol>>,
 }
 
 impl ClassSymbol {
     pub fn new(
         declared_name: &Rc<str>,
-        declared_name_source_range: SourceRange,
+        declared_name_source_range: Option<SourceRange>,
         fqn_parts: Vec<Rc<str>>,
         is_extern: bool,
+        scope_id: usize,
+        generic_parameters: Vec<Rc<GenericParameterSymbol>>,
+        constructor_symbol: Option<Rc<ConstructorSymbol>>,
+        fields: Vec<Rc<FieldSymbol>>,
+        functions: Vec<Rc<FunctionSymbol>>,
     ) -> Self {
         Self {
             declared_name: declared_name.clone(),
             declared_name_source_range,
             fqn_parts,
             is_extern,
-            generic_parameters: vec![],
-            constructor_symbol: None,
-            fields: HashMap::new(),
-            functions: HashMap::new(),
+            scope_id,
+            generic_parameters,
+            constructor_symbol,
+            fields: fields
+                .into_iter()
+                .map(|fs| (fs.declared_name_owned(), fs))
+                .collect(),
+            functions: functions
+                .into_iter()
+                .map(|fs| (fs.declared_name_owned(), fs))
+                .collect(),
         }
     }
 
+    pub fn declared_name(&self) -> &str {
+        &self.declared_name
+    }
+
+    pub fn declared_name_owned(&self) -> Rc<str> {
+        self.declared_name.clone()
+    }
+
+    pub fn declared_name_source_range(&self) -> Option<&SourceRange> {
+        self.declared_name_source_range.as_ref()
+    }
+
     pub fn fqn_parts(&self) -> &[Rc<str>] {
         &self.fqn_parts
     }
 
-    pub fn set_generic_parameters(
-        &mut self,
-        generic_parameters: Vec<Rc<RefCell<GenericParameterSymbol>>>,
-    ) {
-        self.generic_parameters = generic_parameters;
+    pub fn scope_id(&self) -> usize {
+        self.scope_id
     }
 
-    pub fn generic_parameters(&self) -> &[Rc<RefCell<GenericParameterSymbol>>] {
+    pub fn generic_parameters(&self) -> &[Rc<GenericParameterSymbol>] {
         &self.generic_parameters
     }
 
-    pub fn set_constructor_symbol(
-        &mut self,
-        constructor_symbol: Option<Rc<RefCell<ConstructorSymbol>>>,
-    ) {
-        self.constructor_symbol = constructor_symbol;
+    pub fn constructor_symbol(&self) -> Option<&ConstructorSymbol> {
+        self.constructor_symbol.as_ref().map(|s| s.as_ref())
     }
 
-    pub fn set_fields(&mut self, fields: HashMap<Rc<str>, Rc<RefCell<FieldSymbol>>>) {
-        self.fields = fields;
+    pub fn constructor_symbol_owned(&self) -> Option<Rc<ConstructorSymbol>> {
+        self.constructor_symbol.as_ref().cloned()
     }
 
-    pub fn fields(&self) -> &HashMap<Rc<str>, Rc<RefCell<FieldSymbol>>> {
+    pub fn fields(&self) -> &HashMap<Rc<str>, Rc<FieldSymbol>> {
         &self.fields
     }
 
-    /// A value of `None` indicates that there is no declared constructor for this class.
-    pub fn constructor_symbol(&self) -> Option<&Rc<RefCell<ConstructorSymbol>>> {
-        self.constructor_symbol.as_ref()
+    pub fn functions(&self) -> &HashMap<Rc<str>, Rc<FunctionSymbol>> {
+        &self.functions
     }
 }
 
-impl Symbol for ClassSymbol {
-    fn declared_name(&self) -> &str {
-        &self.declared_name
-    }
+impl Eq for ClassSymbol {}
 
-    fn declared_name_owned(&self) -> Rc<str> {
-        self.declared_name.clone()
-    }
-
-    fn declared_name_source_range(&self) -> &SourceRange {
-        &self.declared_name_source_range
+impl PartialEq for ClassSymbol {
+    fn eq(&self, other: &Self) -> bool {
+        self.declared_name == other.declared_name && self.scope_id == other.scope_id
+    }
+}
+
+impl Hash for ClassSymbol {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.declared_name.hash(state);
+        self.scope_id.hash(state);
+    }
+}
+
+impl Debug for ClassSymbol {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "ClassSymbol({})", fqn_parts_to_string(&self.fqn_parts))
     }
 }

dmc-lib/src/symbol/constructor_symbol.rs

@@ -1,40 +1,58 @@
 use crate::source_range::SourceRange;
-use crate::symbol::Symbol;
 use crate::symbol::parameter_symbol::ParameterSymbol;
-use std::cell::RefCell;
+use std::hash::{Hash, Hasher};
 use std::rc::Rc;
 
 pub struct ConstructorSymbol {
-    ctor_keyword_source_range: SourceRange,
+    keyword_source_range: SourceRange,
     fqn_parts: Vec<Rc<str>>,
     is_extern: bool,
-    parameters: Option<Vec<Rc<RefCell<ParameterSymbol>>>>,
+    is_default: bool,
+    scope_id: usize,
+    parameters: Vec<Rc<ParameterSymbol>>,
 }
 
 impl ConstructorSymbol {
     pub fn new(
-        ctor_keyword_source_range: SourceRange,
+        keyword_source_range: &SourceRange,
         fqn_parts: Vec<Rc<str>>,
         is_extern: bool,
+        is_default: bool,
+        scope_id: usize,
+        parameters: Vec<Rc<ParameterSymbol>>,
     ) -> Self {
         Self {
-            ctor_keyword_source_range,
+            keyword_source_range: keyword_source_range.clone(),
             fqn_parts,
             is_extern,
-            parameters: None,
+            is_default,
+            scope_id,
+            parameters,
         }
     }
 
+    pub fn declared_name(&self) -> &str {
+        "ctor"
+    }
+
+    pub fn declared_name_owned(&self) -> Rc<str> {
+        Rc::from(self.declared_name())
+    }
+
+    pub fn declared_name_source_range(&self) -> &SourceRange {
+        &self.keyword_source_range
+    }
+
     pub fn fqn_parts(&self) -> &[Rc<str>] {
         &self.fqn_parts
     }
 
-    pub fn set_parameters(&mut self, parameters: Vec<Rc<RefCell<ParameterSymbol>>>) {
-        self.parameters = Some(parameters);
+    pub fn scope_id(&self) -> usize {
+        self.scope_id
     }
 
-    pub fn parameters(&self) -> &[Rc<RefCell<ParameterSymbol>>] {
-        self.parameters.as_ref().unwrap()
+    pub fn parameters(&self) -> &[Rc<ParameterSymbol>] {
+        &self.parameters
     }
 
     pub fn is_extern(&self) -> bool {
@@ -42,16 +60,16 @@ impl ConstructorSymbol {
     }
 }
 
-impl Symbol for ConstructorSymbol {
-    fn declared_name(&self) -> &str {
-        "ctor"
-    }
+impl Eq for ConstructorSymbol {}
 
-    fn declared_name_owned(&self) -> Rc<str> {
-        Rc::from(self.declared_name())
-    }
-
-    fn declared_name_source_range(&self) -> &SourceRange {
-        &self.ctor_keyword_source_range
+impl PartialEq for ConstructorSymbol {
+    fn eq(&self, other: &Self) -> bool {
+        self.scope_id == other.scope_id
+    }
+}
+
+impl Hash for ConstructorSymbol {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.scope_id.hash(state);
     }
 }

dmc-lib/src/symbol/expressible_symbol.rs

@@ -1,111 +1,34 @@
-use crate::ast::ir_builder::IrBuilder;
-use crate::ast::ir_util::get_or_init_field_pointer_variable;
-use crate::ir::ir_assign::IrAssign;
-use crate::ir::ir_expression::IrExpression;
-use crate::ir::ir_operation::IrOperation;
-use crate::ir::ir_read_field::IrReadField;
-use crate::ir::ir_statement::IrStatement;
-use crate::ir::ir_variable::IrVariable;
 use crate::source_range::SourceRange;
-use crate::symbol::Symbol;
 use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol::field_symbol::FieldSymbol;
 use crate::symbol::function_symbol::FunctionSymbol;
 use crate::symbol::parameter_symbol::ParameterSymbol;
 use crate::symbol::variable_symbol::VariableSymbol;
-use crate::type_info::TypeInfo;
-use std::cell::RefCell;
 use std::rc::Rc;
 
 pub enum ExpressibleSymbol {
-    Class(Rc<RefCell<ClassSymbol>>),
-    Field(Rc<RefCell<FieldSymbol>>),
-    Function(Rc<RefCell<FunctionSymbol>>),
-    Parameter(Rc<RefCell<ParameterSymbol>>),
-    Variable(Rc<RefCell<VariableSymbol>>),
+    Class(Rc<ClassSymbol>),
+    Field(Rc<FieldSymbol>),
+    Function(Rc<FunctionSymbol>),
+    Parameter(Rc<ParameterSymbol>),
+    Variable(Rc<VariableSymbol>),
 }
 
 impl ExpressibleSymbol {
-    pub fn type_info(&self) -> TypeInfo {
+    pub fn source_range(&self) -> Option<&SourceRange> {
         match self {
-            ExpressibleSymbol::Class(class_symbol) => TypeInfo::ClassInstance(class_symbol.clone()),
-            ExpressibleSymbol::Field(field_symbol) => field_symbol.borrow().type_info().clone(),
+            ExpressibleSymbol::Class(class_symbol) => class_symbol.declared_name_source_range(),
+            ExpressibleSymbol::Field(field_symbol) => {
+                Some(field_symbol.declared_name_source_range())
+            }
             ExpressibleSymbol::Function(function_symbol) => {
-                TypeInfo::Function(function_symbol.clone()) // n.b. not the return type!
+                Some(function_symbol.declared_name_source_range())
             }
             ExpressibleSymbol::Parameter(parameter_symbol) => {
-                parameter_symbol.borrow().type_info().clone()
+                Some(parameter_symbol.declared_name_source_range())
             }
             ExpressibleSymbol::Variable(variable_symbol) => {
-                variable_symbol.borrow().type_info().clone()
-            }
-        }
-    }
-
-    pub fn is_mut(&self) -> bool {
-        match self {
-            ExpressibleSymbol::Field(field_symbol) => field_symbol.borrow().is_mut(),
-            ExpressibleSymbol::Variable(variable_symbol) => variable_symbol.borrow().is_mut(),
-            _ => false,
-        }
-    }
-
-    pub fn source_range(&self) -> SourceRange {
-        match self {
-            ExpressibleSymbol::Class(class_symbol) => {
-                class_symbol.borrow().declared_name_source_range().clone()
-            }
-            ExpressibleSymbol::Field(field_symbol) => {
-                field_symbol.borrow().declared_name_source_range().clone()
-            }
-            ExpressibleSymbol::Function(function_symbol) => function_symbol
-                .borrow()
-                .declared_name_source_range()
-                .clone(),
-            ExpressibleSymbol::Parameter(parameter_symbol) => parameter_symbol
-                .borrow()
-                .declared_name_source_range()
-                .clone(),
-            ExpressibleSymbol::Variable(variable_symbol) => variable_symbol
-                .borrow()
-                .declared_name_source_range()
-                .clone(),
-        }
-    }
-
-    pub fn ir_expression(&self, builder: &mut IrBuilder) -> IrExpression {
-        match self {
-            ExpressibleSymbol::Class(class_symbol) => {
-                todo!()
-            }
-            ExpressibleSymbol::Field(field_symbol) => {
-                // now we need to read the field into a variable and return an expression pointing
-                // to that variable
-                let read_destination = IrVariable::new_vr(
-                    builder.new_t_var().into(),
-                    builder.current_block().id(),
-                    field_symbol.borrow().type_info(),
-                );
-                let read_destination_as_rc = Rc::new(RefCell::new(read_destination));
-                let ir_read_field = IrReadField::new(
-                    get_or_init_field_pointer_variable(builder, field_symbol).clone(),
-                );
-                builder
-                    .current_block_mut()
-                    .add_statement(IrStatement::Assign(IrAssign::new(
-                        read_destination_as_rc.clone(),
-                        IrOperation::ReadField(ir_read_field),
-                    )));
-                IrExpression::Variable(read_destination_as_rc)
-            }
-            ExpressibleSymbol::Function(_) => {
-                panic!("Cannot get ir_variable for FunctionSymbol");
-            }
-            ExpressibleSymbol::Parameter(parameter_symbol) => {
-                IrExpression::Parameter(parameter_symbol.borrow().ir_parameter().clone())
-            }
-            ExpressibleSymbol::Variable(variable_symbol) => {
-                IrExpression::Variable(variable_symbol.borrow().vr_variable().clone())
+                Some(variable_symbol.declared_name_source_range())
             }
         }
     }

dmc-lib/src/symbol/field_symbol.rs

@@ -1,14 +1,13 @@
 use crate::source_range::SourceRange;
-use crate::symbol::Symbol;
-use crate::type_info::TypeInfo;
+use std::hash::{Hash, Hasher};
 use std::rc::Rc;
 
 pub struct FieldSymbol {
     declared_name: Rc<str>,
     declared_name_source_range: SourceRange,
     is_mut: bool,
-    type_info: Option<TypeInfo>,
-    field_index: Option<usize>,
+    scope_id: usize,
+    field_index: usize,
 }
 
 impl FieldSymbol {
@@ -16,47 +15,54 @@ impl FieldSymbol {
         declared_name: &Rc<str>,
         declared_name_source_range: SourceRange,
         is_mut: bool,
+        scope_id: usize,
+        field_index: usize,
     ) -> Self {
         Self {
             declared_name: declared_name.clone(),
             declared_name_source_range,
             is_mut,
-            type_info: None,
-            field_index: None,
+            scope_id,
+            field_index,
         }
     }
 
+    pub fn declared_name(&self) -> &str {
+        &self.declared_name
+    }
+
+    pub fn declared_name_owned(&self) -> Rc<str> {
+        self.declared_name.clone()
+    }
+
+    pub fn declared_name_source_range(&self) -> &SourceRange {
+        &self.declared_name_source_range
+    }
+
+    pub fn scope_id(&self) -> usize {
+        self.scope_id
+    }
+
     pub fn is_mut(&self) -> bool {
         self.is_mut
     }
 
-    pub fn set_type_info(&mut self, type_info: TypeInfo) {
-        self.type_info = Some(type_info);
-    }
-
-    pub fn type_info(&self) -> &TypeInfo {
-        self.type_info.as_ref().unwrap()
-    }
-
-    pub fn set_field_index(&mut self, field_index: usize) {
-        self.field_index = Some(field_index);
-    }
-
     pub fn field_index(&self) -> usize {
-        self.field_index.unwrap()
+        self.field_index
     }
 }
 
-impl Symbol for FieldSymbol {
-    fn declared_name(&self) -> &str {
-        &self.declared_name
-    }
+impl Eq for FieldSymbol {}
 
-    fn declared_name_owned(&self) -> Rc<str> {
-        self.declared_name.clone()
-    }
-
-    fn declared_name_source_range(&self) -> &SourceRange {
-        &self.declared_name_source_range
+impl PartialEq for FieldSymbol {
+    fn eq(&self, other: &Self) -> bool {
+        self.declared_name == other.declared_name && self.scope_id == other.scope_id
+    }
+}
+
+impl Hash for FieldSymbol {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.declared_name.hash(state);
+        self.scope_id.hash(state);
     }
 }

dmc-lib/src/symbol/function_symbol.rs

@@ -1,8 +1,8 @@
+use crate::ast::fqn_util::fqn_parts_to_string;
 use crate::source_range::SourceRange;
-use crate::symbol::Symbol;
 use crate::symbol::parameter_symbol::ParameterSymbol;
-use crate::type_info::TypeInfo;
-use std::cell::RefCell;
+use std::fmt::{Debug, Formatter};
+use std::hash::Hash;
 use std::rc::Rc;
 
 pub struct FunctionSymbol {
@@ -10,45 +10,57 @@ pub struct FunctionSymbol {
     declared_name_source_range: SourceRange,
     fqn_parts: Vec<Rc<str>>,
     is_extern: bool,
-    parameters: Option<Vec<Rc<RefCell<ParameterSymbol>>>>,
-    return_type: Option<TypeInfo>,
+    is_method: bool,
+    scope_id: usize,
+    parameters: Vec<Rc<ParameterSymbol>>,
 }
 
 impl FunctionSymbol {
     pub fn new(
-        declared_name: &str,
+        declared_name: &Rc<str>,
         declared_name_source_range: SourceRange,
         fqn_parts: Vec<Rc<str>>,
         is_extern: bool,
+        is_method: bool,
+        scope_id: usize,
+        parameters: Vec<Rc<ParameterSymbol>>,
     ) -> Self {
         Self {
-            declared_name: declared_name.into(),
+            declared_name: declared_name.clone(),
             declared_name_source_range,
             fqn_parts,
             is_extern,
-            parameters: None,
-            return_type: None,
+            is_method,
+            scope_id,
+            parameters,
         }
     }
 
+    pub fn declared_name(&self) -> &str {
+        &self.declared_name
+    }
+
+    pub fn declared_name_owned(&self) -> Rc<str> {
+        self.declared_name.clone()
+    }
+
+    pub fn declared_name_source_range(&self) -> &SourceRange {
+        &self.declared_name_source_range
+    }
+
     pub fn fqn_parts(&self) -> &[Rc<str>] {
         &self.fqn_parts
     }
 
-    pub fn set_parameters(&mut self, parameters: Vec<Rc<RefCell<ParameterSymbol>>>) {
-        self.parameters = Some(parameters);
+    pub fn is_method(&self) -> bool {
+        self.is_method
     }
 
-    pub fn parameters(&self) -> &[Rc<RefCell<ParameterSymbol>>] {
-        self.parameters.as_ref().unwrap()
+    pub fn scope_id(&self) -> usize {
+        self.scope_id
     }
-
-    pub fn set_return_type_info(&mut self, return_type: TypeInfo) {
-        self.return_type = Some(return_type);
-    }
-
-    pub fn return_type_info(&self) -> &TypeInfo {
-        self.return_type.as_ref().unwrap()
+    pub fn parameters(&self) -> &[Rc<ParameterSymbol>] {
+        &self.parameters
     }
 
     pub fn is_extern(&self) -> bool {
@@ -56,16 +68,27 @@ impl FunctionSymbol {
     }
 }
 
-impl Symbol for FunctionSymbol {
-    fn declared_name(&self) -> &str {
-        &self.declared_name
-    }
+impl Eq for FunctionSymbol {}
 
-    fn declared_name_owned(&self) -> Rc<str> {
-        self.declared_name.clone()
-    }
-
-    fn declared_name_source_range(&self) -> &SourceRange {
-        &self.declared_name_source_range
+impl PartialEq for FunctionSymbol {
+    fn eq(&self, other: &Self) -> bool {
+        self.declared_name == other.declared_name && self.scope_id == other.scope_id
+    }
+}
+
+impl Hash for FunctionSymbol {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        self.declared_name.hash(state);
+        self.scope_id.hash(state);
+    }
+}
+
+impl Debug for FunctionSymbol {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "FunctionSymbol({})",
+            fqn_parts_to_string(&self.fqn_parts)
+        )
     }
 }

dmc-lib/src/symbol/generic_parameter_symbol.rs

@@ -1,42 +1,54 @@
 use crate::source_range::SourceRange;
-use crate::symbol::Symbol;
-use crate::type_info::TypeInfo;
+use std::hash::{Hash, Hasher};
 use std::rc::Rc;
 
 pub struct GenericParameterSymbol {
     declared_name: Rc<str>,
     declared_name_source_range: SourceRange,
-    extends: Option<Vec<TypeInfo>>,
+    scope_id: usize,
 }
 
 impl GenericParameterSymbol {
-    pub fn new(declared_name: &Rc<str>, declared_name_source_range: &SourceRange) -> Self {
+    pub fn new(
+        declared_name: &Rc<str>,
+        declared_name_source_range: &SourceRange,
+        scope_id: usize,
+    ) -> Self {
         Self {
             declared_name: declared_name.clone(),
             declared_name_source_range: declared_name_source_range.clone(),
-            extends: None,
+            scope_id,
         }
     }
 
-    pub fn set_extends(&mut self, extends: Vec<TypeInfo>) {
-        self.extends = Some(extends);
-    }
-
-    pub fn extends(&self) -> &[TypeInfo] {
-        self.extends.as_ref().unwrap()
-    }
-}
-
-impl Symbol for GenericParameterSymbol {
-    fn declared_name(&self) -> &str {
+    pub fn declared_name(&self) -> &str {
         &self.declared_name
     }
 
-    fn declared_name_owned(&self) -> Rc<str> {
+    pub fn declared_name_owned(&self) -> Rc<str> {
         self.declared_name.clone()
     }
 
-    fn declared_name_source_range(&self) -> &SourceRange {
+    pub fn declared_name_source_range(&self) -> &SourceRange {
         &self.declared_name_source_range
     }
+
+    pub fn scope_id(&self) -> usize {
+        self.scope_id
+    }
+}
+
+impl Eq for GenericParameterSymbol {}
+
+impl PartialEq for GenericParameterSymbol {
+    fn eq(&self, other: &Self) -> bool {
+        self.declared_name == other.declared_name && self.scope_id == other.scope_id
+    }
+}
+
+impl Hash for GenericParameterSymbol {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.declared_name.hash(state);
+        self.scope_id.hash(state);
+    }
 }

dmc-lib/src/symbol/mod.rs

@@ -1,4 +1,11 @@
 use crate::source_range::SourceRange;
+use crate::symbol::class_symbol::ClassSymbol;
+use crate::symbol::constructor_symbol::ConstructorSymbol;
+use crate::symbol::field_symbol::FieldSymbol;
+use crate::symbol::function_symbol::FunctionSymbol;
+use crate::symbol::generic_parameter_symbol::GenericParameterSymbol;
+use crate::symbol::parameter_symbol::ParameterSymbol;
+use crate::symbol::variable_symbol::VariableSymbol;
 use std::rc::Rc;
 
 pub mod callable_symbol;
@@ -12,8 +19,61 @@ pub mod parameter_symbol;
 pub mod type_symbol;
 pub mod variable_symbol;
 
-pub trait Symbol {
-    fn declared_name(&self) -> &str;
-    fn declared_name_owned(&self) -> Rc<str>;
-    fn declared_name_source_range(&self) -> &SourceRange;
+#[derive(Eq, PartialEq, Hash)]
+pub enum Symbol {
+    Class(Rc<ClassSymbol>),
+    GenericParameter(Rc<GenericParameterSymbol>),
+    Field(Rc<FieldSymbol>),
+    Constructor(Rc<ConstructorSymbol>),
+    Function(Rc<FunctionSymbol>),
+    Parameter(Rc<ParameterSymbol>),
+    Variable(Rc<VariableSymbol>),
+}
+
+impl Symbol {
+    pub fn scope_id(&self) -> usize {
+        match self {
+            Symbol::Class(class_symbol) => class_symbol.scope_id(),
+            Symbol::GenericParameter(generic_parameter_symbol) => {
+                generic_parameter_symbol.scope_id()
+            }
+            Symbol::Field(field_symbol) => field_symbol.scope_id(),
+            Symbol::Constructor(constructor_symbol) => constructor_symbol.scope_id(),
+            Symbol::Function(function_symbol) => function_symbol.scope_id(),
+            Symbol::Parameter(parameter_symbol) => parameter_symbol.scope_id(),
+            Symbol::Variable(variable_symbol) => variable_symbol.scope_id(),
+        }
+    }
+
+    pub fn declared_name(&self) -> &str {
+        match self {
+            Symbol::Class(class_symbol) => class_symbol.declared_name(),
+            Symbol::GenericParameter(generic_parameter_symbol) => {
+                generic_parameter_symbol.declared_name()
+            }
+            Symbol::Field(field_symbol) => field_symbol.declared_name(),
+            Symbol::Constructor(constructor_symbol) => constructor_symbol.declared_name(),
+            Symbol::Function(function_symbol) => function_symbol.declared_name(),
+            Symbol::Parameter(parameter_symbol) => parameter_symbol.declared_name(),
+            Symbol::Variable(variable_symbol) => variable_symbol.declared_name(),
+        }
+    }
+
+    pub fn declared_name_source_range(&self) -> Option<&SourceRange> {
+        match self {
+            Symbol::Class(class_symbol) => class_symbol.declared_name_source_range(),
+            Symbol::GenericParameter(generic_parameter_symbol) => {
+                Some(generic_parameter_symbol.declared_name_source_range())
+            }
+            Symbol::Field(field_symbol) => Some(field_symbol.declared_name_source_range()),
+            Symbol::Constructor(constructor_symbol) => {
+                Some(constructor_symbol.declared_name_source_range())
+            }
+            Symbol::Function(function_symbol) => Some(function_symbol.declared_name_source_range()),
+            Symbol::Parameter(parameter_symbol) => {
+                Some(parameter_symbol.declared_name_source_range())
+            }
+            Symbol::Variable(variable_symbol) => Some(variable_symbol.declared_name_source_range()),
+        }
+    }
 }

dmc-lib/src/symbol/parameter_symbol.rs

@@ -1,53 +1,54 @@
-use crate::ir::ir_parameter::IrParameter;
 use crate::source_range::SourceRange;
-use crate::symbol::Symbol;
-use crate::type_info::TypeInfo;
+use std::hash::{Hash, Hasher};
 use std::rc::Rc;
 
 pub struct ParameterSymbol {
     declared_name: Rc<str>,
     declared_name_source_range: SourceRange,
-    type_info: Option<TypeInfo>,
-    ir_parameter: Option<Rc<IrParameter>>,
+    scope_id: usize,
 }
 
 impl ParameterSymbol {
-    pub fn new(declared_name: &Rc<str>, declared_name_source_range: SourceRange) -> Self {
+    pub fn new(
+        declared_name: &Rc<str>,
+        declared_name_source_range: SourceRange,
+        scope_id: usize,
+    ) -> Self {
         Self {
             declared_name: declared_name.clone(),
             declared_name_source_range,
-            type_info: None,
-            ir_parameter: None,
+            scope_id,
         }
     }
 
-    pub fn set_type_info(&mut self, type_info: TypeInfo) {
-        self.type_info = Some(type_info);
-    }
-
-    pub fn type_info(&self) -> &TypeInfo {
-        self.type_info.as_ref().unwrap()
-    }
-
-    pub fn set_ir_parameter(&mut self, ir_parameter: Rc<IrParameter>) {
-        self.ir_parameter = Some(ir_parameter);
-    }
-
-    pub fn ir_parameter(&self) -> &Rc<IrParameter> {
-        self.ir_parameter.as_ref().unwrap()
-    }
-}
-
-impl Symbol for ParameterSymbol {
-    fn declared_name(&self) -> &str {
+    pub fn declared_name(&self) -> &str {
         &self.declared_name
     }
 
-    fn declared_name_owned(&self) -> Rc<str> {
+    pub fn declared_name_owned(&self) -> Rc<str> {
         self.declared_name.clone()
     }
 
-    fn declared_name_source_range(&self) -> &SourceRange {
+    pub fn declared_name_source_range(&self) -> &SourceRange {
         &self.declared_name_source_range
     }
+
+    pub fn scope_id(&self) -> usize {
+        self.scope_id
+    }
+}
+
+impl Eq for ParameterSymbol {}
+
+impl PartialEq for ParameterSymbol {
+    fn eq(&self, other: &Self) -> bool {
+        self.declared_name == other.declared_name && self.scope_id == other.scope_id
+    }
+}
+
+impl Hash for ParameterSymbol {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.declared_name.hash(state);
+        self.scope_id.hash(state);
+    }
 }

dmc-lib/src/symbol/type_symbol.rs

@@ -1,9 +1,8 @@
 use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol::generic_parameter_symbol::GenericParameterSymbol;
-use std::cell::RefCell;
 use std::rc::Rc;
 
 pub enum TypeSymbol {
-    Class(Rc<RefCell<ClassSymbol>>),
-    GenericParameter(Rc<RefCell<GenericParameterSymbol>>),
+    Class(Rc<ClassSymbol>),
+    GenericParameter(Rc<GenericParameterSymbol>),
 }

dmc-lib/src/symbol/variable_symbol.rs

@@ -1,64 +1,61 @@
-use crate::ir::ir_variable::IrVariable;
 use crate::source_range::SourceRange;
-use crate::symbol::Symbol;
-use crate::type_info::TypeInfo;
-use std::cell::RefCell;
+use std::hash::{Hash, Hasher};
 use std::rc::Rc;
 
 pub struct VariableSymbol {
     declared_name: Rc<str>,
     declared_name_source_range: SourceRange,
     is_mut: bool,
-    type_info: Option<TypeInfo>,
-    vr_variable: Option<Rc<RefCell<IrVariable>>>,
+    scope_id: usize,
 }
 
 impl VariableSymbol {
-    pub fn new(name: &Rc<str>, declared_name_source_range: SourceRange, is_mut: bool) -> Self {
+    pub fn new(
+        name: &Rc<str>,
+        declared_name_source_range: &SourceRange,
+        is_mut: bool,
+        scope_id: usize,
+    ) -> Self {
         Self {
             declared_name: name.clone(),
-            declared_name_source_range,
+            declared_name_source_range: declared_name_source_range.clone(),
             is_mut,
-            type_info: None,
-            vr_variable: None,
+            scope_id,
         }
     }
 
+    pub fn declared_name(&self) -> &str {
+        &self.declared_name
+    }
+
+    pub fn declared_name_owned(&self) -> Rc<str> {
+        self.declared_name.clone()
+    }
+
+    pub fn declared_name_source_range(&self) -> &SourceRange {
+        &self.declared_name_source_range
+    }
+
     pub fn is_mut(&self) -> bool {
         self.is_mut
     }
 
-    pub fn set_type_info(&mut self, type_info: TypeInfo) {
-        self.type_info = Some(type_info);
-    }
-
-    pub fn type_info(&self) -> &TypeInfo {
-        self.type_info
-            .as_ref()
-            .expect("TypeInfo not initialized. Did you type check?")
-    }
-
-    pub fn set_vr_variable(&mut self, ir_variable: Rc<RefCell<IrVariable>>) {
-        self.vr_variable = Some(ir_variable);
-    }
-
-    pub fn vr_variable(&self) -> &Rc<RefCell<IrVariable>> {
-        self.vr_variable
-            .as_ref()
-            .expect("ir_variable not yet initialized")
+    pub fn scope_id(&self) -> usize {
+        self.scope_id
     }
 }
 
-impl Symbol for VariableSymbol {
-    fn declared_name(&self) -> &str {
-        &self.declared_name
-    }
+impl Eq for VariableSymbol {}
 
-    fn declared_name_owned(&self) -> Rc<str> {
-        self.declared_name.clone()
-    }
-
-    fn declared_name_source_range(&self) -> &SourceRange {
-        &self.declared_name_source_range
+impl PartialEq for VariableSymbol {
+    fn eq(&self, other: &Self) -> bool {
+        self.declared_name == other.declared_name && self.scope_id == other.scope_id
+    }
+}
+
+impl Hash for VariableSymbol {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.declared_name.hash(state);
+        self.scope_id.hash(state);
     }
 }

dmc-lib/src/symbol_table/helpers.rs

@@ -1,134 +1,210 @@
 use crate::scope::Scope;
 use crate::scope::block_scope::BlockScope;
+use crate::scope::class_body_scope::ClassBodyScope;
 use crate::scope::class_scope::ClassScope;
 use crate::scope::function_scope::FunctionScope;
 use crate::scope::module_scope::ModuleScope;
 use crate::symbol::Symbol;
+use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol::expressible_symbol::ExpressibleSymbol;
+use crate::symbol::field_symbol::FieldSymbol;
+use crate::symbol::function_symbol::FunctionSymbol;
+use crate::symbol::generic_parameter_symbol::GenericParameterSymbol;
+use crate::symbol::parameter_symbol::ParameterSymbol;
 use crate::symbol::type_symbol::TypeSymbol;
-use std::cell::RefCell;
+use crate::symbol::variable_symbol::VariableSymbol;
+use std::collections::HashMap;
 use std::rc::Rc;
 
-pub fn find_in_module_by_name(
-    module_scope: &ModuleScope,
+fn find_class_symbol_ref(
+    symbols: &HashMap<Rc<str>, Rc<ClassSymbol>>,
     name: &str,
-) -> Option<Rc<RefCell<dyn Symbol>>> {
-    module_scope
-        .function_symbols()
+) -> Option<Symbol> {
+    symbols
         .get(name)
-        .map(|symbol| symbol.clone() as Rc<RefCell<dyn Symbol>>)
-        .or_else(|| {
-            module_scope
-                .class_symbols()
-                .get(name)
-                .map(|symbol| symbol.clone() as Rc<RefCell<dyn Symbol>>)
-        })
+        .map(|symbol| Symbol::Class(symbol.clone()))
 }
 
-pub fn find_in_class_by_name(
-    class_scope: &ClassScope,
+fn find_generic_parameter_symbol_ref(
+    symbols: &HashMap<Rc<str>, Rc<GenericParameterSymbol>>,
     name: &str,
-) -> Option<Rc<RefCell<dyn Symbol>>> {
-    class_scope
-        .class_symbols()
+) -> Option<Symbol> {
+    symbols
         .get(name)
-        .map(|symbol| symbol.clone() as Rc<RefCell<dyn Symbol>>)
-        .or_else(|| {
-            class_scope
-                .function_symbols()
-                .get(name)
-                .map(|symbol| symbol.clone() as Rc<RefCell<dyn Symbol>>)
-        })
-        .or_else(|| {
-            class_scope
-                .field_symbols()
-                .get(name)
-                .map(|symbol| symbol.clone() as Rc<RefCell<dyn Symbol>>)
-        })
+        .map(|symbol| Symbol::GenericParameter(symbol.clone()))
 }
 
-pub fn find_in_function_by_name(
-    function_scope: &FunctionScope,
+fn find_field_symbol_ref(
+    symbols: &HashMap<Rc<str>, Rc<FieldSymbol>>,
     name: &str,
-) -> Option<Rc<RefCell<dyn Symbol>>> {
-    function_scope
-        .parameter_symbols()
+) -> Option<Symbol> {
+    symbols
         .get(name)
-        .map(|symbol| symbol.clone() as Rc<RefCell<dyn Symbol>>)
+        .map(|symbol| Symbol::Field(symbol.clone()))
 }
 
-pub fn find_in_block_by_name(
-    block_scope: &BlockScope,
+fn find_function_symbol_ref(
+    symbols: &HashMap<Rc<str>, Rc<FunctionSymbol>>,
     name: &str,
-) -> Option<Rc<RefCell<dyn Symbol>>> {
-    block_scope
-        .variable_symbols()
+) -> Option<Symbol> {
+    symbols
         .get(name)
-        .map(|symbol| symbol.clone() as Rc<RefCell<dyn Symbol>>)
+        .map(|symbol| Symbol::Function(symbol.clone()))
 }
 
+fn find_parameter_symbol_ref(
+    symbols: &HashMap<Rc<str>, Rc<ParameterSymbol>>,
+    name: &str,
+) -> Option<Symbol> {
+    symbols
+        .get(name)
+        .map(|symbol| Symbol::Parameter(symbol.clone()))
+}
+
+fn find_variable_symbol_ref(
+    symbols: &HashMap<Rc<str>, Rc<VariableSymbol>>,
+    name: &str,
+) -> Option<Symbol> {
+    symbols
+        .get(name)
+        .map(|symbol| Symbol::Variable(symbol.clone()))
+}
+
+/* Expressible symbol refs */
+
+fn find_class_expressible_symbol_ref(
+    symbols: &HashMap<Rc<str>, Rc<ClassSymbol>>,
+    name: &str,
+) -> Option<ExpressibleSymbol> {
+    symbols
+        .get(name)
+        .map(|symbol| ExpressibleSymbol::Class(symbol.clone()))
+}
+
+fn find_field_expressible_symbol_ref(
+    symbols: &HashMap<Rc<str>, Rc<FieldSymbol>>,
+    name: &str,
+) -> Option<ExpressibleSymbol> {
+    symbols
+        .get(name)
+        .map(|symbol| ExpressibleSymbol::Field(symbol.clone()))
+}
+
+fn find_function_expressible_symbol_ref(
+    symbols: &HashMap<Rc<str>, Rc<FunctionSymbol>>,
+    name: &str,
+) -> Option<ExpressibleSymbol> {
+    symbols
+        .get(name)
+        .map(|symbol| ExpressibleSymbol::Function(symbol.clone()))
+}
+
+fn find_parameter_expressible_symbol_ref(
+    symbols: &HashMap<Rc<str>, Rc<ParameterSymbol>>,
+    name: &str,
+) -> Option<ExpressibleSymbol> {
+    symbols
+        .get(name)
+        .map(|symbol| ExpressibleSymbol::Parameter(symbol.clone()))
+}
+
+fn find_variable_expressible_symbol_ref(
+    symbols: &HashMap<Rc<str>, Rc<VariableSymbol>>,
+    name: &str,
+) -> Option<ExpressibleSymbol> {
+    symbols
+        .get(name)
+        .map(|symbol| ExpressibleSymbol::Variable(symbol.clone()))
+}
+
+/* Find type symbols */
+
+fn find_class_type_symbol_ref(
+    symbols: &HashMap<Rc<str>, Rc<ClassSymbol>>,
+    name: &str,
+) -> Option<TypeSymbol> {
+    symbols
+        .get(name)
+        .map(|symbol| TypeSymbol::Class(symbol.clone()))
+}
+
+fn find_generic_parameter_type_symbol_ref(
+    symbols: &HashMap<Rc<str>, Rc<GenericParameterSymbol>>,
+    name: &str,
+) -> Option<TypeSymbol> {
+    symbols
+        .get(name)
+        .map(|symbol| TypeSymbol::GenericParameter(symbol.clone()))
+}
+
+/* Public helper functions */
+/* Various find in functions */
+
+pub fn find_in_module_by_name(module_scope: &ModuleScope, name: &str) -> Option<Symbol> {
+    find_function_symbol_ref(&module_scope.function_symbols(), name)
+        .or_else(|| find_class_symbol_ref(&module_scope.class_symbols(), name))
+}
+
+pub fn find_in_class_by_name(class_scope: &ClassScope, name: &str) -> Option<Symbol> {
+    find_generic_parameter_symbol_ref(&class_scope.generic_parameter_symbols(), name)
+}
+
+pub fn find_in_class_body_by_name(class_body_scope: &ClassBodyScope, name: &str) -> Option<Symbol> {
+    find_class_symbol_ref(&class_body_scope.class_symbols(), name)
+        .or_else(|| find_function_symbol_ref(&class_body_scope.function_symbols(), name))
+        .or_else(|| find_field_symbol_ref(&class_body_scope.field_symbols(), name))
+}
+
+pub fn find_in_function_by_name(function_scope: &FunctionScope, name: &str) -> Option<Symbol> {
+    find_parameter_symbol_ref(&function_scope.parameter_symbols(), name)
+}
+
+pub fn find_in_block_by_name(block_scope: &BlockScope, name: &str) -> Option<Symbol> {
+    find_variable_symbol_ref(&block_scope.variable_symbols(), name)
+}
+
+/* Find expressible */
+
 fn find_expressible_in_module_by_name(
     module_scope: &ModuleScope,
     name: &str,
 ) -> Option<ExpressibleSymbol> {
-    module_scope
-        .class_symbols()
-        .get(name)
-        .map(|class_symbol| ExpressibleSymbol::Class(class_symbol.clone()))
-        .or_else(|| {
-            module_scope
-                .function_symbols()
-                .get(name)
-                .map(|function_symbol| ExpressibleSymbol::Function(function_symbol.clone()))
-        })
+    find_class_expressible_symbol_ref(&module_scope.class_symbols(), name)
+        .or_else(|| find_function_expressible_symbol_ref(&module_scope.function_symbols(), name))
 }
 
-fn find_expressible_in_class_by_name(
-    class_scope: &ClassScope,
+fn find_expressible_in_class_body_by_name(
+    class_body_scope: &ClassBodyScope,
     name: &str,
 ) -> Option<ExpressibleSymbol> {
-    class_scope
-        .class_symbols()
-        .get(name)
-        .map(|symbol| ExpressibleSymbol::Class(symbol.clone()))
+    find_class_expressible_symbol_ref(&class_body_scope.class_symbols(), name)
         .or_else(|| {
-            class_scope
-                .function_symbols()
-                .get(name)
-                .map(|function_symbol| ExpressibleSymbol::Function(function_symbol.clone()))
-        })
-        .or_else(|| {
-            class_scope
-                .field_symbols()
-                .get(name)
-                .map(|field_symbol| ExpressibleSymbol::Field(field_symbol.clone()))
+            find_function_expressible_symbol_ref(&class_body_scope.function_symbols(), name)
         })
+        .or_else(|| find_field_expressible_symbol_ref(&class_body_scope.field_symbols(), name))
 }
 
 fn find_expressible_in_function_by_name(
     function_scope: &FunctionScope,
     name: &str,
 ) -> Option<ExpressibleSymbol> {
-    function_scope
-        .parameter_symbols()
-        .get(name)
-        .map(|parameter_symbol| ExpressibleSymbol::Parameter(parameter_symbol.clone()))
+    find_parameter_expressible_symbol_ref(function_scope.parameter_symbols(), name)
 }
 
 fn find_expressible_in_block_by_name(
     block_scope: &BlockScope,
     name: &str,
 ) -> Option<ExpressibleSymbol> {
-    block_scope
-        .variable_symbols()
-        .get(name)
-        .map(|variable_symbol| ExpressibleSymbol::Variable(variable_symbol.clone()))
+    find_variable_expressible_symbol_ref(block_scope.variable_symbols(), name)
 }
 
 pub fn find_expressible_symbol(scope: &Scope, name: &str) -> Option<ExpressibleSymbol> {
     match scope {
         Scope::Module(module_scope) => find_expressible_in_module_by_name(module_scope, name),
-        Scope::Class(class_scope) => find_expressible_in_class_by_name(class_scope, name),
+        Scope::Class(_) => None,
+        Scope::ClassBody(class_body_scope) => {
+            find_expressible_in_class_body_by_name(class_body_scope, name)
+        }
         Scope::Function(function_scope) => {
             find_expressible_in_function_by_name(function_scope, name)
         }
@@ -136,32 +212,30 @@ pub fn find_expressible_symbol(scope: &Scope, name: &str) -> Option<ExpressibleS
     }
 }
 
+/* Find type */
+
 fn find_type_symbol_in_module(module_scope: &ModuleScope, name: &str) -> Option<TypeSymbol> {
-    module_scope
-        .class_symbols()
-        .get(name)
-        .map(|symbol| TypeSymbol::Class(symbol.clone()))
+    find_class_type_symbol_ref(&module_scope.class_symbols(), name)
 }
 
-pub fn find_type_symbol_in_class(class_scope: &ClassScope, name: &str) -> Option<TypeSymbol> {
-    class_scope
-        .class_symbols()
-        .get(name)
-        .map(|symbol| TypeSymbol::Class(symbol.clone()))
-        .or_else(|| {
-            class_scope
-                .generic_parameter_symbols()
-                .get(name)
-                .map(|generic_parameter_symbol| {
-                    TypeSymbol::GenericParameter(generic_parameter_symbol.clone())
-                })
-        })
+fn find_type_symbol_in_class_body(
+    class_body_scope: &ClassBodyScope,
+    name: &str,
+) -> Option<TypeSymbol> {
+    find_class_type_symbol_ref(&class_body_scope.class_symbols(), name)
+}
+
+fn find_type_symbol_in_class(class_scope: &ClassScope, name: &str) -> Option<TypeSymbol> {
+    find_generic_parameter_type_symbol_ref(&class_scope.generic_parameter_symbols(), name)
 }
 
 pub fn find_type_symbol(scope: &Scope, name: &str) -> Option<TypeSymbol> {
     match scope {
         Scope::Module(module_scope) => find_type_symbol_in_module(module_scope, name),
         Scope::Class(class_scope) => find_type_symbol_in_class(class_scope, name),
+        Scope::ClassBody(class_body_scope) => {
+            find_type_symbol_in_class_body(class_body_scope, name)
+        }
         _ => None,
     }
 }

dmc-lib/src/symbol_table/mod.rs

@@ -2,6 +2,7 @@ mod helpers;
 
 use crate::scope::Scope;
 use crate::scope::block_scope::BlockScope;
+use crate::scope::class_body_scope::ClassBodyScope;
 use crate::scope::class_scope::ClassScope;
 use crate::scope::function_scope::FunctionScope;
 use crate::scope::module_scope::ModuleScope;
@@ -16,10 +17,9 @@ use crate::symbol::parameter_symbol::ParameterSymbol;
 use crate::symbol::type_symbol::TypeSymbol;
 use crate::symbol::variable_symbol::VariableSymbol;
 use crate::symbol_table::helpers::{
-    find_expressible_symbol, find_in_block_by_name, find_in_class_by_name,
-    find_in_function_by_name, find_in_module_by_name, find_type_symbol, find_type_symbol_in_class,
+    find_expressible_symbol, find_in_block_by_name, find_in_class_body_by_name,
+    find_in_class_by_name, find_in_function_by_name, find_in_module_by_name, find_type_symbol,
 };
-use std::cell::RefCell;
 use std::rc::Rc;
 
 pub struct SymbolTable {
@@ -39,282 +39,213 @@ impl SymbolTable {
         self.scopes.len()
     }
 
-    fn push_scope(&mut self, scope: Scope) {
+    fn push_scope(&mut self, scope: Scope) -> usize {
         let scope_id = self.new_scope_id();
         self.scopes.push(scope);
         self.current_scope_id = Some(scope_id);
+        scope_id
     }
 
-    pub fn push_module_scope(&mut self, debug_name: &str) {
+    pub fn push_module_scope(&mut self, debug_name: &str) -> usize {
         self.push_scope(Scope::Module(ModuleScope::new(
             debug_name,
             self.current_scope_id,
-        )));
+        )))
     }
 
-    pub fn push_class_scope(&mut self, debug_name: &str) {
+    pub fn push_class_scope(&mut self, debug_name: &str) -> usize {
         self.push_scope(Scope::Class(ClassScope::new(
             debug_name,
             self.current_scope_id.unwrap(),
-        )));
+        )))
     }
 
-    pub fn push_function_scope(&mut self, debug_name: &str) {
+    pub fn push_class_body_scope(&mut self, debug_name: &str) -> usize {
+        self.push_scope(Scope::ClassBody(ClassBodyScope::new(
+            debug_name,
+            self.current_scope_id.unwrap(),
+        )))
+    }
+
+    pub fn push_function_scope(&mut self, debug_name: &str) -> usize {
         self.push_scope(Scope::Function(FunctionScope::new(
             debug_name,
             self.current_scope_id.unwrap(),
-        )));
+        )))
     }
 
-    pub fn push_block_scope(&mut self, debug_name: &str) {
+    pub fn push_block_scope(&mut self, debug_name: &str) -> usize {
         self.push_scope(Scope::Block(BlockScope::new(
             debug_name,
             self.current_scope_id.unwrap(),
-        )));
+        )))
     }
 
     pub fn pop_scope(&mut self) {
-        self.current_scope_id = self.current_scope().parent_id();
+        self.current_scope_id = self.scopes[self.current_scope_id.unwrap()].parent_id();
     }
 
     pub fn current_scope_id(&self) -> usize {
         self.current_scope_id.unwrap()
     }
 
-    fn current_scope(&self) -> &Scope {
-        &self.scopes[self.current_scope_id.unwrap()]
+    fn scope(&self, scope_id: usize) -> &Scope {
+        &self.scopes[scope_id]
     }
 
-    fn current_scope_mut(&mut self) -> &mut Scope {
-        &mut self.scopes[self.current_scope_id.unwrap()]
+    fn scope_mut(&mut self, scope_id: usize) -> &mut Scope {
+        &mut self.scopes[scope_id]
     }
 
-    pub fn insert_class_symbol(
-        &mut self,
-        class_symbol: ClassSymbol,
-    ) -> Result<Rc<RefCell<ClassSymbol>>, SymbolInsertError> {
-        let maybe_already_inserted = match self.current_scope() {
-            Scope::Module(module_scope) => {
-                find_in_module_by_name(module_scope, class_symbol.declared_name())
+    pub fn get_symbol(&self, scope_id: usize, name: &str) -> Option<Symbol> {
+        match self.scope(scope_id) {
+            Scope::Module(module_scope) => find_in_module_by_name(module_scope, name),
+            Scope::Class(class_scope) => find_in_class_by_name(class_scope, name),
+            Scope::ClassBody(class_body_scope) => {
+                find_in_class_body_by_name(class_body_scope, name)
             }
-            Scope::Class(class_scope) => {
-                find_in_class_by_name(class_scope, class_symbol.declared_name())
+            Scope::Function(function_scope) => find_in_function_by_name(function_scope, name),
+            Scope::Block(block_scope) => find_in_block_by_name(block_scope, name),
+        }
+    }
+
+    pub fn insert_symbol(&mut self, symbol: Symbol) {
+        match symbol {
+            Symbol::Class(class_symbol) => {
+                self.insert_class_symbol(class_symbol);
+            }
+            Symbol::GenericParameter(generic_parameter_symbol) => {
+                self.insert_generic_parameter_symbol(generic_parameter_symbol);
+            }
+            Symbol::Field(field_symbol) => {
+                self.insert_field_symbol(field_symbol);
+            }
+            Symbol::Constructor(constructor_symbol) => {
+                self.insert_constructor_symbol(constructor_symbol);
+            }
+            Symbol::Function(function_symbol) => {
+                self.insert_function_symbol(function_symbol);
+            }
+            Symbol::Parameter(parameter_symbol) => {
+                self.insert_parameter_symbol(parameter_symbol);
+            }
+            Symbol::Variable(variable_symbol) => {
+                self.insert_variable_symbol(variable_symbol);
+            }
+        }
+    }
+
+    pub fn insert_class_symbol(&mut self, class_symbol: Rc<ClassSymbol>) {
+        let name = class_symbol.declared_name_owned();
+        match self.scope_mut(class_symbol.scope_id()) {
+            Scope::Module(module_scope) => {
+                module_scope.class_symbols_mut().insert(name, class_symbol);
+            }
+            Scope::ClassBody(class_scope) => {
+                class_scope.class_symbols_mut().insert(name, class_symbol);
             }
             _ => panic!("Attempt to insert ClassSymbol in incompatible scope"),
-        };
-
-        if let Some(already_inserted) = maybe_already_inserted {
-            return Err(SymbolInsertError::AlreadyDeclared(AlreadyDeclared::new(
-                already_inserted,
-            )));
         }
-
-        let name = class_symbol.declared_name_owned();
-        let as_rc = Rc::new(RefCell::new(class_symbol));
-        let to_return = as_rc.clone();
-
-        match self.current_scope_mut() {
-            Scope::Module(module_scope) => {
-                module_scope.class_symbols_mut().insert(name, as_rc);
-            }
-            Scope::Class(class_scope) => {
-                class_scope.class_symbols_mut().insert(name, as_rc);
-            }
-            _ => unreachable!(),
-        }
-        Ok(to_return)
     }
 
     pub fn insert_generic_parameter_symbol(
         &mut self,
-        generic_parameter_symbol: GenericParameterSymbol,
-    ) -> Result<Rc<RefCell<GenericParameterSymbol>>, SymbolInsertError> {
-        let maybe_already_inserted = match self.current_scope() {
-            Scope::Class(class_scope) => {
-                find_type_symbol_in_class(class_scope, generic_parameter_symbol.declared_name())
-            }
-            _ => panic!("Attempt to insert GenericParameterSymbol in incompatible scope"),
-        };
-
-        if let Some(already_inserted) = maybe_already_inserted {
-            match already_inserted {
-                TypeSymbol::Class(class_symbol) => {
-                    return Err(SymbolInsertError::AlreadyDeclared(AlreadyDeclared::new(
-                        class_symbol as Rc<RefCell<dyn Symbol>>,
-                    )));
-                }
-                TypeSymbol::GenericParameter(generic_parameter_symbol) => {
-                    return Err(SymbolInsertError::AlreadyDeclared(AlreadyDeclared::new(
-                        generic_parameter_symbol as Rc<RefCell<dyn Symbol>>,
-                    )));
-                }
-            }
-        }
-
+        generic_parameter_symbol: Rc<GenericParameterSymbol>,
+    ) {
         let name = generic_parameter_symbol.declared_name_owned();
-        let as_rc = Rc::new(RefCell::new(generic_parameter_symbol));
-        let to_return = as_rc.clone();
-
-        match self.current_scope_mut() {
+        match self.scope_mut(generic_parameter_symbol.scope_id()) {
             Scope::Class(class_scope) => {
                 class_scope
                     .generic_parameter_symbols_mut()
-                    .insert(name, as_rc);
+                    .insert(name, generic_parameter_symbol);
             }
-            _ => unreachable!(),
+            _ => panic!("Attempt to insert GenericParameterSymbol in incompatible scope"),
         }
-
-        Ok(to_return)
     }
 
-    pub fn insert_constructor_symbol(
-        &mut self,
-        constructor_symbol: ConstructorSymbol,
-    ) -> Result<Rc<RefCell<ConstructorSymbol>>, SymbolInsertError> {
-        let maybe_already_inserted = match self.current_scope() {
-            Scope::Class(class_scope) => class_scope.constructor_symbol(),
-            _ => panic!("Attempt to insert ConstructorSymbol in incompatible scope"),
-        };
-        if let Some(already_inserted) = maybe_already_inserted {
-            return Err(SymbolInsertError::AlreadyDeclared(AlreadyDeclared::new(
-                already_inserted.clone() as Rc<RefCell<dyn Symbol>>,
-            )));
-        }
-
-        let as_rc = Rc::new(RefCell::new(constructor_symbol));
-        let to_return = as_rc.clone();
-
-        match self.current_scope_mut() {
-            Scope::Class(class_scope) => {
-                class_scope.constructor_symbol_mut().replace(as_rc);
+    pub fn insert_constructor_symbol(&mut self, constructor_symbol: Rc<ConstructorSymbol>) {
+        match self.scope_mut(constructor_symbol.scope_id()) {
+            Scope::ClassBody(class_body_scope) => {
+                class_body_scope
+                    .constructor_symbol_mut()
+                    .replace(constructor_symbol);
             }
-            _ => unreachable!(),
+            _ => panic!(
+                "Attempt to insert ConstructorSymbol in incompatible scope: {:?}",
+                self.scope(constructor_symbol.scope_id())
+            ),
         }
-        Ok(to_return)
     }
 
-    pub fn insert_field_symbol(
-        &mut self,
-        field_symbol: FieldSymbol,
-    ) -> Result<Rc<RefCell<FieldSymbol>>, SymbolInsertError> {
-        let maybe_already_inserted = match self.current_scope() {
-            Scope::Class(class_scope) => {
-                find_in_class_by_name(class_scope, field_symbol.declared_name())
+    pub fn insert_field_symbol(&mut self, field_symbol: Rc<FieldSymbol>) {
+        let name = field_symbol.declared_name_owned();
+        match self.scope_mut(field_symbol.scope_id()) {
+            Scope::ClassBody(class_scope) => {
+                class_scope.field_symbols_mut().insert(name, field_symbol);
             }
             _ => panic!("Attempt to insert FieldSymbol in incompatible scope"),
-        };
-
-        if let Some(already_inserted) = maybe_already_inserted {
-            return Err(SymbolInsertError::AlreadyDeclared(AlreadyDeclared::new(
-                already_inserted,
-            )));
         }
-
-        let name = field_symbol.declared_name_owned();
-        let as_rc = Rc::new(RefCell::new(field_symbol));
-        let to_return = as_rc.clone();
-
-        match self.current_scope_mut() {
-            Scope::Class(class_scope) => {
-                class_scope.field_symbols_mut().insert(name, as_rc);
-            }
-            _ => unreachable!(),
-        }
-        Ok(to_return)
     }
 
-    pub fn insert_function_symbol(
-        &mut self,
-        function_symbol: FunctionSymbol,
-    ) -> Result<Rc<RefCell<FunctionSymbol>>, SymbolInsertError> {
-        let maybe_already_inserted = match self.current_scope() {
+    pub fn insert_function_symbol(&mut self, function_symbol: Rc<FunctionSymbol>) {
+        let name = function_symbol.declared_name_owned();
+        match self.scope_mut(function_symbol.scope_id()) {
             Scope::Module(module_scope) => {
-                find_in_module_by_name(module_scope, function_symbol.declared_name())
+                module_scope
+                    .function_symbols_mut()
+                    .insert(name, function_symbol);
             }
-            Scope::Class(class_scope) => {
-                find_in_class_by_name(class_scope, function_symbol.declared_name())
+            Scope::ClassBody(class_scope) => {
+                class_scope
+                    .function_symbols_mut()
+                    .insert(name, function_symbol);
             }
             _ => panic!("Attempt to insert FunctionSymbol in incompatible scope"),
-        };
-
-        if let Some(already_inserted) = maybe_already_inserted {
-            return Err(SymbolInsertError::AlreadyDeclared(AlreadyDeclared::new(
-                already_inserted,
-            )));
         }
-
-        let name = function_symbol.declared_name_owned();
-        let as_rc = Rc::new(RefCell::new(function_symbol));
-        let to_return = as_rc.clone();
-
-        match self.current_scope_mut() {
-            Scope::Module(module_scope) => {
-                module_scope.function_symbols_mut().insert(name, as_rc);
-            }
-            Scope::Class(class_scope) => {
-                class_scope.function_symbols_mut().insert(name, as_rc);
-            }
-            _ => unreachable!(),
-        }
-        Ok(to_return)
     }
 
-    pub fn insert_parameter_symbol(
-        &mut self,
-        parameter_symbol: ParameterSymbol,
-    ) -> Result<Rc<RefCell<ParameterSymbol>>, SymbolInsertError> {
-        let maybe_already_inserted = match self.current_scope() {
-            Scope::Function(function_scope) => {
-                find_in_function_by_name(function_scope, parameter_symbol.declared_name())
-            }
-            _ => panic!("Attempt to insert ParameterSymbol in incompatible scope"),
-        };
-        if let Some(already_inserted) = maybe_already_inserted {
-            return Err(SymbolInsertError::AlreadyDeclared(AlreadyDeclared::new(
-                already_inserted,
-            )));
-        }
-
+    pub fn insert_parameter_symbol(&mut self, parameter_symbol: Rc<ParameterSymbol>) {
         let name = parameter_symbol.declared_name_owned();
-        let as_rc = Rc::new(RefCell::new(parameter_symbol));
-        let to_return = as_rc.clone();
-
-        match self.current_scope_mut() {
+        match self.scope_mut(parameter_symbol.scope_id()) {
             Scope::Function(function_scope) => {
-                function_scope.parameter_symbols_mut().insert(name, as_rc);
+                function_scope
+                    .parameter_symbols_mut()
+                    .insert(name, parameter_symbol);
             }
             _ => panic!("Attempt to insert ParameterSymbol in incompatible scope"),
         }
-
-        Ok(to_return)
     }
 
-    pub fn insert_variable_symbol(
-        &mut self,
-        variable_symbol: VariableSymbol,
-    ) -> Result<(), SymbolInsertError> {
-        let maybe_already_inserted = match self.current_scope() {
+    pub fn insert_variable_symbol(&mut self, variable_symbol: Rc<VariableSymbol>) {
+        match self.scope_mut(variable_symbol.scope_id()) {
             Scope::Block(block_scope) => {
-                find_in_block_by_name(block_scope, variable_symbol.declared_name())
+                block_scope
+                    .variable_symbols_mut()
+                    .insert(variable_symbol.declared_name_owned(), variable_symbol);
             }
             _ => panic!("Attempt to insert VariableSymbol in incompatible scope"),
-        };
-        if let Some(already_inserted) = maybe_already_inserted {
-            return Err(SymbolInsertError::AlreadyDeclared(AlreadyDeclared::new(
-                already_inserted,
-            )));
         }
+    }
 
-        match self.current_scope_mut() {
-            Scope::Block(block_scope) => {
-                block_scope.variable_symbols_mut().insert(
-                    variable_symbol.declared_name_owned(),
-                    Rc::new(RefCell::new(variable_symbol)),
-                );
-            }
-            _ => unreachable!(),
+    fn find_symbol<S>(
+        &self,
+        scope_id: usize,
+        name: &str,
+        f: impl Fn(&Scope, &str) -> Option<S>,
+    ) -> Option<S> {
+        let mut maybe_scope = self.scopes.get(scope_id);
+        if maybe_scope.is_none() {
+            panic!("Invalid scope_id: {}", scope_id);
         }
-        Ok(())
+        while let Some(scope) = maybe_scope {
+            let maybe_symbol = f(scope, name);
+            if maybe_symbol.is_some() {
+                return maybe_symbol;
+            } else {
+                maybe_scope = scope.parent_id().and_then(|id| self.scopes.get(id));
+            }
+        }
+        None
     }
 
     pub fn find_expressible_symbol(
@@ -353,28 +284,132 @@ impl SymbolTable {
         None
     }
 
-    pub fn get_variable_symbol(&self, scope_id: usize, name: &str) -> Rc<RefCell<VariableSymbol>> {
+    pub fn get_class_symbol(&self, scope_id: usize, name: &str) -> Option<&Rc<ClassSymbol>> {
+        match self.scope(scope_id) {
+            Scope::Module(module_scope) => module_scope.class_symbols().get(name),
+            Scope::ClassBody(class_body_scope) => class_body_scope.class_symbols().get(name),
+            _ => panic!("scope_id {} cannot contain classes", scope_id),
+        }
+    }
+
+    pub fn get_generic_parameter_symbol_owned(
+        &self,
+        scope_id: usize,
+        name: &str,
+    ) -> Option<Rc<GenericParameterSymbol>> {
+        match self.scope(scope_id) {
+            Scope::Class(class_scope) => class_scope.generic_parameter_symbols().get(name).cloned(),
+            _ => panic!("scope_id {} cannot contain generic types", scope_id),
+        }
+    }
+
+    pub fn get_field_symbol(&self, scope_id: usize, name: &str) -> Option<&FieldSymbol> {
+        match self.scope(scope_id) {
+            Scope::ClassBody(class_body_scope) => {
+                class_body_scope.field_symbols().get(name).map(Rc::as_ref)
+            }
+            _ => panic!("scope_id {} is not a ClassBodyScope", scope_id),
+        }
+    }
+
+    pub fn get_field_symbol_owned(&self, scope_id: usize, name: &str) -> Option<Rc<FieldSymbol>> {
+        match self.scope(scope_id) {
+            Scope::ClassBody(class_body_scope) => class_body_scope
+                .field_symbols()
+                .get(name)
+                .map(|s| Rc::clone(s)),
+            _ => panic!("scope_id {} is not a ClassBodyScope", scope_id),
+        }
+    }
+
+    pub fn get_constructor_symbol(&self, scope_id: usize) -> Option<&ConstructorSymbol> {
+        match self.scope(scope_id) {
+            Scope::ClassBody(class_body_scope) => {
+                class_body_scope.constructor_symbol().map(Rc::as_ref)
+            }
+            _ => panic!("scope_id {} is not a ClassBodyScope", scope_id),
+        }
+    }
+
+    pub fn get_constructor_symbol_owned(&self, scope_id: usize) -> Option<Rc<ConstructorSymbol>> {
+        match self.scope(scope_id) {
+            Scope::ClassBody(class_body_scope) => class_body_scope.constructor_symbol().cloned(),
+            _ => panic!(
+                "scope_id {} is not a ClassBodyScope: {:?}",
+                scope_id,
+                self.scope(scope_id)
+            ),
+        }
+    }
+
+    pub fn get_function_symbol(&self, scope_id: usize, name: &str) -> Option<&FunctionSymbol> {
+        match self.scope(scope_id) {
+            Scope::Module(module_scope) => {
+                module_scope.function_symbols().get(name).map(Rc::as_ref)
+            }
+            Scope::ClassBody(class_body_scope) => class_body_scope
+                .function_symbols()
+                .get(name)
+                .map(Rc::as_ref),
+            _ => panic!("scope_id {} cannot contain Functions", scope_id),
+        }
+    }
+
+    pub fn get_function_symbol_owned(
+        &self,
+        scope_id: usize,
+        name: &str,
+    ) -> Option<Rc<FunctionSymbol>> {
+        match self.scope(scope_id) {
+            Scope::Module(module_scope) => module_scope
+                .function_symbols()
+                .get(name)
+                .map(|s| Rc::clone(s)),
+            Scope::ClassBody(class_body_scope) => class_body_scope
+                .function_symbols()
+                .get(name)
+                .map(|s| Rc::clone(s)),
+            _ => panic!("scope_id {} cannot contain Functions", scope_id),
+        }
+    }
+
+    pub fn get_parameter_symbol(&self, scope_id: usize, name: &str) -> Option<&ParameterSymbol> {
+        match self.scope(scope_id) {
+            Scope::Function(function_scope) => {
+                function_scope.parameter_symbols().get(name).map(Rc::as_ref)
+            }
+            _ => panic!("scope_id {} cannot contain Parameters", scope_id),
+        }
+    }
+
+    pub fn get_parameter_symbol_owned(
+        &self,
+        scope_id: usize,
+        name: &str,
+    ) -> Option<Rc<ParameterSymbol>> {
+        match self.scope(scope_id) {
+            Scope::Function(function_scope) => {
+                function_scope.parameter_symbols().get(name).cloned()
+            }
+            _ => panic!("scope_id {} cannot contain Parameters", scope_id),
+        }
+    }
+
+    pub fn get_variable_symbol(&self, scope_id: usize, name: &str) -> Option<&VariableSymbol> {
         match &self.scopes[scope_id] {
-            Scope::Block(block_scope) => block_scope.variable_symbols().get(name).cloned().unwrap(),
+            Scope::Block(block_scope) => block_scope.variable_symbols().get(name).map(Rc::as_ref),
+            _ => panic!("scope_id {} is not a BlockScope", scope_id),
+        }
+    }
+
+    pub fn get_variable_symbol_owned(
+        &self,
+        scope_id: usize,
+        name: &str,
+    ) -> Option<Rc<VariableSymbol>> {
+        match self.scope(scope_id) {
+            Scope::Block(block_scope) => block_scope.variable_symbols().get(name).map(Rc::clone),
             _ => panic!("scope_id {} is not a BlockScope", scope_id),
         }
     }
 }
-
-pub enum SymbolInsertError {
-    AlreadyDeclared(AlreadyDeclared),
-}
-
-pub struct AlreadyDeclared {
-    symbol: Rc<RefCell<dyn Symbol>>,
-}
-
-impl AlreadyDeclared {
-    pub fn new(symbol: Rc<RefCell<dyn Symbol>>) -> Self {
-        Self { symbol }
-    }
-
-    pub fn symbol(&self) -> &Rc<RefCell<dyn Symbol>> {
-        &self.symbol
-    }
-}

dmc-lib/src/type_info.rs

@@ -1,10 +1,6 @@
-use crate::symbol::Symbol;
 use crate::symbol::class_symbol::ClassSymbol;
 use crate::symbol::function_symbol::FunctionSymbol;
 use crate::symbol::generic_parameter_symbol::GenericParameterSymbol;
-use crate::symbol::type_symbol::TypeSymbol;
-use crate::symbol_table::SymbolTable;
-use std::cell::RefCell;
 use std::fmt::{Display, Formatter};
 use std::rc::Rc;
 
@@ -14,9 +10,9 @@ pub enum TypeInfo {
     Integer,
     Double,
     String,
-    Function(Rc<RefCell<FunctionSymbol>>),
-    ClassInstance(Rc<RefCell<ClassSymbol>>),
-    GenericType(Rc<RefCell<GenericParameterSymbol>>),
+    Function(Rc<FunctionSymbol>),
+    Class(Rc<ClassSymbol>),
+    GenericType(Rc<GenericParameterSymbol>),
     Void,
 }
 
@@ -29,16 +25,19 @@ impl Display for TypeInfo {
             TypeInfo::String => write!(f, "String"),
             TypeInfo::Function(function_symbol) => {
                 write!(f, "fn(")?;
-                for parameter in function_symbol.borrow().parameters() {
-                    parameter.borrow().type_info().fmt(f)?;
+                for (i, parameter) in function_symbol.parameters().iter().enumerate() {
+                    parameter.declared_name().fmt(f)?;
+                    if i < function_symbol.parameters().len() - 1 {
+                        f.write_str(", ")?;
+                    }
                 }
                 write!(f, ")")
             }
-            TypeInfo::ClassInstance(class_symbol) => {
-                write!(f, "{}", class_symbol.borrow().declared_name())
+            TypeInfo::Class(class_symbol) => {
+                write!(f, "Class({:?})", class_symbol)
             }
             TypeInfo::GenericType(generic_parameter_symbol) => {
-                write!(f, "{}", generic_parameter_symbol.borrow().declared_name())
+                write!(f, "{}", generic_parameter_symbol.declared_name())
             }
             TypeInfo::Void => write!(f, "Void"),
         }
@@ -54,31 +53,6 @@ fn are_numbers(left: &TypeInfo, right: &TypeInfo) -> bool {
 }
 
 impl TypeInfo {
-    pub fn from_declared_name(
-        declared_name: &str,
-        scope_id: usize,
-        symbol_table: &SymbolTable,
-        class_context: Option<&Rc<RefCell<ClassSymbol>>>,
-    ) -> Option<Self> {
-        match declared_name {
-            "Any" => Some(TypeInfo::Any),
-            "Int" => Some(TypeInfo::Integer),
-            "Double" => Some(TypeInfo::Double),
-            "String" => Some(TypeInfo::String),
-            "Void" => Some(TypeInfo::Void),
-            "Self" => Some(TypeInfo::ClassInstance(class_context.unwrap().clone())),
-            _ => match symbol_table.find_type_symbol(scope_id, declared_name) {
-                None => None,
-                Some(type_symbol) => match type_symbol {
-                    TypeSymbol::Class(class_symbol) => Some(TypeInfo::ClassInstance(class_symbol)),
-                    TypeSymbol::GenericParameter(generic_parameter_symbol) => {
-                        Some(TypeInfo::GenericType(generic_parameter_symbol))
-                    }
-                },
-            },
-        }
-    }
-
     pub fn is_assignable_from(&self, other: &TypeInfo) -> bool {
         match self {
             TypeInfo::Any => true,
@@ -94,21 +68,16 @@ impl TypeInfo {
             TypeInfo::Function(_) => {
                 unimplemented!("Type matching on Functions not yet supported.")
             }
-            TypeInfo::ClassInstance(class_symbol) => {
-                match other {
-                    TypeInfo::ClassInstance(other_class_symbol) => {
-                        class_symbol.borrow().declared_name()
-                            == other_class_symbol.borrow().declared_name() // good enough for now
-                    }
-                    _ => false,
-                }
-            }
+            TypeInfo::Class(class_symbol) => match other {
+                TypeInfo::Class(other_class_symbol) => class_symbol == other_class_symbol,
+                _ => false,
+            },
             TypeInfo::GenericType(generic_parameter_symbol) => {
-                if generic_parameter_symbol.borrow().extends().len() > 0 {
-                    unimplemented!(
-                        "Assigning to generic parameter type with extends type uses not yet supported."
-                    );
-                }
+                // if generic_parameter_symbol.extends().len() > 0 {
+                //     unimplemented!(
+                //         "Assigning to generic parameter type with extends type uses not yet supported."
+                //     );
+                // }
                 true
             }
             TypeInfo::Void => {

dmc-lib/src/types_table.rs

@@ -0,0 +1,118 @@
+use crate::symbol::class_symbol::ClassSymbol;
+use crate::symbol::constructor_symbol::ConstructorSymbol;
+use crate::symbol::field_symbol::FieldSymbol;
+use crate::symbol::function_symbol::FunctionSymbol;
+use crate::symbol::generic_parameter_symbol::GenericParameterSymbol;
+use crate::symbol::parameter_symbol::ParameterSymbol;
+use crate::symbol::variable_symbol::VariableSymbol;
+use crate::type_info::TypeInfo;
+use std::collections::HashMap;
+use std::rc::Rc;
+
+pub struct TypesTable {
+    class_types: HashMap<Rc<ClassSymbol>, TypeInfo>,
+    class_instance_types: HashMap<Rc<ClassSymbol>, TypeInfo>,
+    generic_parameter_types: HashMap<Rc<GenericParameterSymbol>, TypeInfo>,
+    field_types: HashMap<Rc<FieldSymbol>, TypeInfo>,
+    constructor_return_types: HashMap<Rc<ConstructorSymbol>, TypeInfo>,
+    function_types: HashMap<Rc<FunctionSymbol>, TypeInfo>,
+    function_return_types: HashMap<Rc<FunctionSymbol>, TypeInfo>,
+    parameter_types: HashMap<Rc<ParameterSymbol>, TypeInfo>,
+    variable_types: HashMap<Rc<VariableSymbol>, TypeInfo>,
+}
+
+impl TypesTable {
+    pub fn new() -> Self {
+        Self {
+            class_types: HashMap::new(),
+            class_instance_types: HashMap::new(),
+            generic_parameter_types: HashMap::new(),
+            field_types: HashMap::new(),
+            parameter_types: HashMap::new(),
+            variable_types: HashMap::new(),
+            function_types: HashMap::new(),
+            function_return_types: HashMap::new(),
+            constructor_return_types: HashMap::new(),
+        }
+    }
+
+    pub fn class_types(&self) -> &HashMap<Rc<ClassSymbol>, TypeInfo> {
+        &self.class_types
+    }
+
+    pub fn class_types_mut(&mut self) -> &mut HashMap<Rc<ClassSymbol>, TypeInfo> {
+        &mut self.class_types
+    }
+
+    pub fn class_instance_types(&self) -> &HashMap<Rc<ClassSymbol>, TypeInfo> {
+        &self.class_instance_types
+    }
+
+    pub fn class_instance_types_mut(&mut self) -> &mut HashMap<Rc<ClassSymbol>, TypeInfo> {
+        &mut self.class_instance_types
+    }
+
+    pub fn generic_parameter_types(&self) -> &HashMap<Rc<GenericParameterSymbol>, TypeInfo> {
+        &self.generic_parameter_types
+    }
+
+    pub fn generic_parameter_types_mut(
+        &mut self,
+    ) -> &mut HashMap<Rc<GenericParameterSymbol>, TypeInfo> {
+        &mut self.generic_parameter_types
+    }
+
+    pub fn field_types(&self) -> &HashMap<Rc<FieldSymbol>, TypeInfo> {
+        &self.field_types
+    }
+
+    pub fn field_types_mut(&mut self) -> &mut HashMap<Rc<FieldSymbol>, TypeInfo> {
+        &mut self.field_types
+    }
+
+    pub fn parameter_types(&self) -> &HashMap<Rc<ParameterSymbol>, TypeInfo> {
+        &self.parameter_types
+    }
+
+    pub fn parameter_types_mut(&mut self) -> &mut HashMap<Rc<ParameterSymbol>, TypeInfo> {
+        &mut self.parameter_types
+    }
+
+    pub fn variable_types(&self) -> &HashMap<Rc<VariableSymbol>, TypeInfo> {
+        &self.variable_types
+    }
+
+    pub fn variable_types_mut(&mut self) -> &mut HashMap<Rc<VariableSymbol>, TypeInfo> {
+        &mut self.variable_types
+    }
+
+    pub fn function_types(&self) -> &HashMap<Rc<FunctionSymbol>, TypeInfo> {
+        &self.function_types
+    }
+
+    pub fn function_types_mut(&mut self) -> &mut HashMap<Rc<FunctionSymbol>, TypeInfo> {
+        &mut self.function_types
+    }
+
+    #[deprecated]
+    pub fn function_return_types(&self) -> &HashMap<Rc<FunctionSymbol>, TypeInfo> {
+        &self.function_return_types
+    }
+
+    #[deprecated]
+    pub fn function_return_types_mut(&mut self) -> &mut HashMap<Rc<FunctionSymbol>, TypeInfo> {
+        &mut self.function_return_types
+    }
+
+    #[deprecated]
+    pub fn constructor_return_types(&self) -> &HashMap<Rc<ConstructorSymbol>, TypeInfo> {
+        &self.constructor_return_types
+    }
+
+    #[deprecated]
+    pub fn constructor_return_types_mut(
+        &mut self,
+    ) -> &mut HashMap<Rc<ConstructorSymbol>, TypeInfo> {
+        &mut self.constructor_return_types
+    }
+}

e2e-tests/src/lib.rs

@@ -2,8 +2,10 @@
 mod e2e_tests {
     use dmc_lib::constants_table::ConstantsTable;
     use dmc_lib::diagnostic::Diagnostic;
+    use dmc_lib::intrinsics::{insert_intrinsic_symbols, insert_intrinsic_types};
     use dmc_lib::parser::parse_compilation_unit;
     use dmc_lib::symbol_table::SymbolTable;
+    use dmc_lib::types_table::TypesTable;
     use dvm_lib::vm::class::Class;
     use dvm_lib::vm::constant::{Constant, StringConstant};
     use dvm_lib::vm::function::Function;
@@ -26,7 +28,7 @@ mod e2e_tests {
         panic!("There were diagnostics.");
     }
 
-    fn prepare_context(input: &str) -> DvmContext {
+    fn prepare_context(input: &str) -> Result<DvmContext, Vec<Diagnostic>> {
         let parse_result = parse_compilation_unit(input);
         let mut compilation_unit = match parse_result {
             Ok(compilation_unit) => compilation_unit,
@@ -36,29 +38,19 @@ mod e2e_tests {
         };
 
         let mut symbol_table = SymbolTable::new();
+        symbol_table.push_module_scope("global_scope");
+        insert_intrinsic_symbols(&mut symbol_table);
 
-        match compilation_unit.gather_declared_names(&mut symbol_table) {
-            Ok(_) => {}
-            Err(diagnostics) => {
-                report_diagnostics(&diagnostics);
-            }
-        }
+        let mut types_table = TypesTable::new();
+        insert_intrinsic_types(&symbol_table, &mut types_table);
 
-        match compilation_unit.check_name_usages(&symbol_table) {
-            Ok(_) => {}
-            Err(diagnostics) => {
-                report_diagnostics(&diagnostics);
-            }
-        }
+        compilation_unit.init_scopes(&mut symbol_table);
+        compilation_unit.gather_symbols_into(&mut symbol_table)?;
+        compilation_unit.check_names(&mut symbol_table)?;
+        compilation_unit.gather_types_into(&symbol_table, &mut types_table)?;
+        compilation_unit.type_check(&symbol_table, &mut types_table)?;
 
-        match compilation_unit.type_check(&symbol_table) {
-            Ok(_) => {}
-            Err(diagnostics) => {
-                report_diagnostics(&diagnostics);
-            }
-        }
-
-        let (ir_classes, mut ir_functions) = compilation_unit.to_ir(&symbol_table);
+        let (ir_classes, mut ir_functions) = compilation_unit.to_ir(&symbol_table, &types_table);
 
         let mut functions: Vec<Function> = vec![];
         let mut constants_table = ConstantsTable::new();
@@ -95,7 +87,7 @@ mod e2e_tests {
             );
         }
 
-        dvm_context
+        Ok(dvm_context)
     }
 
     fn get_result(
@@ -116,7 +108,10 @@ mod e2e_tests {
     }
 
     fn assert_result(input: &str, function_name: &str, arguments: &[Value], expected_value: Value) {
-        let context = prepare_context(input);
+        let context = match prepare_context(input) {
+            Ok(context) => context,
+            Err(diagnostics) => report_diagnostics(&diagnostics),
+        };
         match get_result(&context, function_name, arguments) {
             None => panic!("Call returned no value"),
             Some(result_value) => {
@@ -214,41 +209,6 @@ mod e2e_tests {
         )
     }
 
-    #[test]
-    fn two_classes() {
-        let context = prepare_context(
-            "
-            class Foo
-                mut bar: Int = 42
-
-                ctor(_bar: Int)
-                end
-
-                fn baz() -> Int
-                    bar
-                end
-            end
-
-            class Qux
-                fn foo() -> Foo
-                    Foo(42)
-                end
-            end
-
-            fn foo(n: Int) -> Foo
-                Foo(n)
-            end
-            ",
-        );
-        let result = get_result(&context, "foo", &[Value::Int(42)]);
-        assert!(result.is_some());
-        let value = result.unwrap();
-        assert!(matches!(value, Value::Object(_)));
-        let o = value.unwrap_object().borrow();
-        assert_eq!(o.fields().len(), 1);
-        assert_eq!(o.fields()[0].unwrap_int(), 42);
-    }
-
     #[test]
     fn simple_assign() {
         assert_result(
@@ -266,7 +226,7 @@ mod e2e_tests {
     }
 
     #[test]
-    fn assign_field() {
+    fn assign_field() -> Result<(), Vec<Diagnostic>> {
         let context = prepare_context(
             "
             class Foo
@@ -281,7 +241,7 @@ mod e2e_tests {
                 Foo(42)
             end
             ",
-        );
+        )?;
         let result = get_result(&context, "foo", &vec![]);
         assert!(result.is_some());
         let value = result.unwrap();
@@ -289,10 +249,11 @@ mod e2e_tests {
         let o = value.unwrap_object().borrow();
         assert_eq!(o.fields().len(), 1);
         assert_eq!(o.fields()[0].unwrap_int(), 42);
+        Ok(())
     }
 
     #[test]
-    fn see_what_happens() {
+    fn generic_field_and_ctor_param() -> Result<(), Vec<Diagnostic>> {
         let context = prepare_context(
             "
             class Foo<T>
@@ -306,7 +267,7 @@ mod e2e_tests {
                 Foo(42)
             end
             ",
-        );
+        )?;
         let result = get_result(&context, "main", &vec![]);
         assert!(result.is_some());
         let value = result.unwrap();
@@ -314,49 +275,6 @@ mod e2e_tests {
         let o = value.unwrap_object().borrow();
         assert_eq!(o.fields().len(), 1);
         assert_eq!(o.fields()[0].unwrap_int(), 42);
-    }
-}
-
-#[cfg(test)]
-mod diagnostic_tests {
-    use dmc_lib::diagnostic::Diagnostic;
-    use dmc_lib::parser::parse_compilation_unit;
-    use dmc_lib::symbol_table::SymbolTable;
-
-    fn get_diagnostics(input: &str) -> Vec<Diagnostic> {
-        let parse_result = parse_compilation_unit(input);
-        let mut compilation_unit = match parse_result {
-            Ok(compilation_unit) => compilation_unit,
-            Err(diagnostics) => {
-                return diagnostics;
-            }
-        };
-
-        let mut symbol_table = SymbolTable::new();
-
-        match compilation_unit.gather_declared_names(&mut symbol_table) {
-            Ok(_) => {}
-            Err(diagnostics) => {
-                return diagnostics;
-            }
-        }
-
-        match compilation_unit.check_name_usages(&symbol_table) {
-            Ok(_) => {}
-            Err(diagnostics) => {
-                return diagnostics;
-            }
-        }
-
-        match compilation_unit.type_check(&symbol_table) {
-            Ok(_) => vec![],
-            Err(diagnostics) => diagnostics,
-        }
-    }
-
-    #[test]
-    fn wrong_return_type() {
-        let diagnostics = get_diagnostics("fn main() -> String 42 end");
-        assert_eq!(diagnostics.len(), 1);
+        Ok(())
     }
 }

sketching/march_2026/class_class.dm

@@ -0,0 +1,13 @@
+class Class
+    pub type Target
+
+    pub declaredName: String
+    pub fqn: String
+
+    pub extern fn constructor() -> Constructor<Self::Target>
+end
+
+class Constructor<T>
+    pub type Args : []
+    pub fn new(...args: Self::Args) -> T
+end

sketching/march_2026/traits_and_ints.dm

@@ -0,0 +1,47 @@
+trait Add<R = Self>
+    type Output = Self
+
+    fn add(other: R) -> Self::Output
+end
+
+intrinsic class Int end
+intrinsic class Double end
+
+impl Add for Int
+    fn add(other: Self) -> Self
+        self + other
+    end
+end
+
+impl Add<Double> for Int
+    type Output = Double
+
+    fn add(other: Double) -> Double
+        self + other
+    end
+end
+
+impl Add for Double
+    fn add(other: Self) -> Self
+        self + other
+    end
+end
+
+impl Add<Int> for Double
+    fn add(other: Int) -> Self
+        self + other
+    end
+end
+
+fn add_rough_pi(a: impl Add<Double>) -> Double = a + 3.14
+
+fn concat<T: impl Add<U>, U>(a: T, b: U) -> T::Output
+    a + b
+end
+
+fn main()
+    let x = add_rough_pi(3)
+    println(x) // 6.14
+    let y = concat(1, 2) // 3
+    let z = concat("Hello, ", "World!") // "Hello, World!"
+end