CSY/reowolf Changeset - de4b7b2f3037 · Centrum Wiskunde & Informatica (CWI)

Changeset - de4b7b2f3037

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MH - 4 years ago 2021-03-24 20:51:46
contact@maxhenger.nl

little progress on struct literal validation

2 files changed with 144 insertions and 59 deletions:

src/protocol/parser/type_table.rs

src/protocol/parser/visitor_linker.rs

134

0 comments (0 inline, 0 general)

src/protocol/parser/type_table.rs

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 /**
 TypeTable
 Contains the type table: a datastructure that, when compilation succeeds,
 contains a concrete type definition for each AST type definition. In general
 terms the type table will go through the following phases during the compilation
 process:
 . The base type definitions are resolved after the parser phase has
     finished. This implies that the AST is fully constructed, but not yet
     annotated.
 . With the base type definitions resolved, the validation/linker phase will
     use the type table (together with the symbol table) to disambiguate
     terms (e.g. does an expression refer to a variable, an enum, a constant,
     etc.)
 . During the type checking/inference phase the type table is used to ensure
     that the AST contains valid use of types in expressions and statements.
     At the same time type inference will find concrete instantiations of
     polymorphic types, these will be stored in the type table as monomorphed
     instantiations of a generic type.
 . After type checking and inference (and possibly when constructing byte
     code) the type table will construct a type graph and solidify each
     non-polymorphic type and monomorphed instantiations of polymorphic types
     into concrete types.
 So a base type is defined by its (optionally polymorphic) representation in the
 AST. A concrete type has concrete types for each of the polymorphic arguments. A
 struct, enum or union may have polymorphic arguments but not actually be a
 polymorphic type. This happens when the polymorphic arguments are not used in
 the type definition itself. Similarly for functions/components: but here we just
 check the arguments/return type of the signature.
 Apart from base types and concrete types, we also use the term "embedded type"
 for types that are embedded within another type, such as a type of a struct
 struct field or of a union variant. Embedded types may themselves have
 polymorphic arguments and therefore form an embedded type tree.
 NOTE: for now a polymorphic definition of a function/component is illegal if the
     polymorphic arguments are not used in the arguments/return type. It should
     be legal, but we disallow it for now.
 TODO: Allow potentially cyclic datatypes and reject truly cyclic datatypes.
 TODO: Allow for the full potential of polymorphism
 TODO: Detect "true" polymorphism: for datatypes like structs/enum/unions this
     is simple. For functions we need to check the entire body. Do it here? Or
     do it somewhere else?
 TODO: Do we want to check fn argument collision here, or in validation phase?
 TODO: Make type table an on-demand thing instead of constructing all base types.
 TODO: Cleanup everything, feels like a lot can be written cleaner and with less
     assumptions on each function call.
 // TODO: Review all comments
 */
 use std::fmt::{Formatter, Result as FmtResult};
 use std::collections::{HashMap, VecDeque};
 use crate::protocol::ast::*;
 use crate::protocol::parser::symbol_table::{SymbolTable, Symbol};
 use crate::protocol::inputsource::*;
 use crate::protocol::parser::*;
 //------------------------------------------------------------------------------
 // Defined Types
 //------------------------------------------------------------------------------
 #[derive(Copy, Clone, PartialEq, Eq)]
 pub enum TypeClass {
     Enum,
     Union,
     Struct,
     Function,
     Component
+}
 impl TypeClass {
     pub(crate) fn display_name(&self) -> &'static str {
         match self {
             TypeClass::Enum => "enum",
             TypeClass::Union => "enum",
             TypeClass::Struct => "struct",
             TypeClass::Function => "function",
             TypeClass::Component => "component",
+        }
+    }
     pub(crate) fn is_data_type(&self) -> bool {
         *self == TypeClass::Enum || *self == TypeClass::Union || *self == TypeClass::Struct
+    }
     pub(crate) fn is_proc_type(&self) -> bool {
         *self == TypeClass::Function || *self == TypeClass::Component
+    }
+}
 impl std::fmt::Display for TypeClass {
     fn fmt(&self, f: &mut Formatter<'_>) -> FmtResult {
         write!(f, "{}", self.display_name())
+    }
+}
 /// Struct wrapping around a potentially polymorphic type. If the type does not
 /// have any polymorphic arguments then it will not have any monomorphs and
 /// `is_polymorph` will be set to `false`. A type with polymorphic arguments
 /// only has `is_polymorph` set to `true` if the polymorphic arguments actually
 /// appear in the types associated types (function return argument, struct
 /// field, enum variant, etc.). Otherwise the polymorphic argument is just a
 /// marker and does not influence the bytesize of the type.
 pub struct DefinedType {
     pub(crate) ast_root: RootId,
     pub(crate) ast_definition: DefinitionId,
     pub(crate) definition: DefinedTypeVariant,
     pub(crate) poly_args: Vec<PolyArg>,
     pub(crate) is_polymorph: bool,
     pub(crate) is_pointerlike: bool,
     // TODO: @optimize
     pub(crate) monomorphs: Vec<Vec<ConcreteType>>,
+}
 impl DefinedType {
     fn add_monomorph(&mut self, types: Vec<ConcreteType>) {
         debug_assert!(!self.has_monomorph(&types), "monomorph already exists");
         self.monomorphs.push(types);
+    }
     fn has_monomorph(&self, types: &Vec<ConcreteType>) -> bool {
         debug_assert_eq!(self.poly_args.len(), types.len(), "mismatch in number of polymorphic types");
         for monomorph in &self.monomorphs {
             if monomorph == types { return true; }
+        }
         return false;
+    }
+}
 pub enum DefinedTypeVariant {
     Enum(EnumType),
     Union(UnionType),
     Struct(StructType),
     Function(FunctionType),
     Component(ComponentType)
+}
 pub struct PolyArg {
     identifier: Identifier,
     /// Whether the polymorphic argument is used directly in the definition of
     /// the type (not including bodies of function/component types)
     is_in_use: bool,
+}
 impl DefinedTypeVariant {
     pub(crate) fn type_class(&self) -> TypeClass {
         match self {
             DefinedTypeVariant::Enum(_) => TypeClass::Enum,
             DefinedTypeVariant::Union(_) => TypeClass::Union,
             DefinedTypeVariant::Struct(_) => TypeClass::Struct,
             DefinedTypeVariant::Function(_) => TypeClass::Function,
             DefinedTypeVariant::Component(_) => TypeClass::Component
+        }
+    }
     pub(crate) fn as_struct(&self) -> &StructType {
         match self {
             DefinedTypeVariant::Struct(v) => v,
             _ => unreachable!("Cannot convert {} to struct variant", self.type_class())
+        }
+    }
+}
 /// `EnumType` is the classical C/C++ enum type. It has various variants with
 /// an assigned integer value. The integer values may be user-defined,
 /// compiler-defined, or a mix of the two. If a user assigns the same enum
 /// value multiple times, we assume the user is an expert and we consider both
 /// variants to be equal to one another.
 pub struct EnumType {
     variants: Vec<EnumVariant>,
     representation: PrimitiveType,
+}
 // TODO: Also support maximum u64 value
 pub struct EnumVariant {
     identifier: Identifier,
     value: i64,
+}
 /// `UnionType` is the algebraic datatype (or sum type, or discriminated union).
 /// A value is an element of the union, identified by its tag, and may contain
 /// a single subtype.
 pub struct UnionType {
     variants: Vec<UnionVariant>,
     tag_representation: PrimitiveType
+}
 pub struct UnionVariant {
     identifier: Identifier,
     parser_type: Option<ParserTypeId>,
     tag_value: i64,
+}
 pub struct StructType {
     fields: Vec<StructField>,
+    pub(crate) fields: Vec<StructField>,
+}
 pub struct StructField {
     identifier: Identifier,
     parser_type: ParserTypeId,
     pub(crate) identifier: Identifier,
     pub(crate) parser_type: ParserTypeId,
+}
 pub struct FunctionType {
     pub return_type: ParserTypeId,
     pub arguments: Vec<FunctionArgument>
+}
 pub struct ComponentType {
     pub variant: ComponentVariant,
     pub arguments: Vec<FunctionArgument>
+}
 pub struct FunctionArgument {
     identifier: Identifier,
     parser_type: ParserTypeId,
+}
 //------------------------------------------------------------------------------
 // Type table
 //------------------------------------------------------------------------------
 // TODO: @cleanup Do I really need this, doesn't make the code that much cleaner
 struct TypeIterator {
     breadcrumbs: Vec<(RootId, DefinitionId)>
+}
 impl TypeIterator {
     fn new() -> Self {
         Self{ breadcrumbs: Vec::with_capacity(32) }
+    }
     fn reset(&mut self, root_id: RootId, definition_id: DefinitionId) {
         self.breadcrumbs.clear();
         self.breadcrumbs.push((root_id, definition_id))
+    }
     fn push(&mut self, root_id: RootId, definition_id: DefinitionId) {
         self.breadcrumbs.push((root_id, definition_id));
+    }
     fn contains(&self, root_id: RootId, definition_id: DefinitionId) -> bool {
         for (stored_root_id, stored_definition_id) in self.breadcrumbs.iter() {
             if *stored_root_id == root_id && *stored_definition_id == definition_id { return true; }
+        }
         return false
+    }
     fn top(&self) -> Option<(RootId, DefinitionId)> {
         self.breadcrumbs.last().map(|(r, d)| (*r, *d))
+    }
     fn pop(&mut self) {
         debug_assert!(!self.breadcrumbs.is_empty());
         self.breadcrumbs.pop();
+    }
+}
 /// Result from attempting to resolve a `ParserType` using the symbol table and
 /// the type table.
 enum ResolveResult {
     /// ParserType is a builtin type
     BuiltIn,
     /// ParserType points to a polymorphic argument, contains the index of the
     /// polymorphic argument in the outermost definition (e.g. we may have
     /// structs nested three levels deep, but in the innermost struct we can
     /// only use the polyargs that are specified in the type definition of the
     /// outermost struct).
     PolyArg(usize),
     /// ParserType points to a user-defined type that is already resolved in the
     /// type table.
     Resolved((RootId, DefinitionId)),
     /// ParserType points to a user-defined type that is not yet resolved into
     /// the type table.
     Unresolved((RootId, DefinitionId))
+}
 pub(crate) struct TypeTable {
     /// Lookup from AST DefinitionId to a defined type. Considering possible
     /// polymorphs is done inside the `DefinedType` struct.
     lookup: HashMap<DefinitionId, DefinedType>,
     /// Iterator over `(module, definition)` tuples used as workspace to make sure
     /// that each base definition of all a type's subtypes are resolved.
     iter: TypeIterator,
     /// Iterator over `parser type`s during the process where `parser types` are
     /// resolved into a `(module, definition)` tuple.
     parser_type_iter: VecDeque<ParserTypeId>,
+}
 pub(crate) struct TypeCtx<'a> {
     symbols: &'a SymbolTable,
     heap: &'a mut Heap,
     modules: &'a [LexedModule]
+}
 impl<'a> TypeCtx<'a> {
     pub(crate) fn new(symbols: &'a SymbolTable, heap: &'a mut Heap, modules: &'a [LexedModule]) -> Self {
         Self{ symbols, heap, modules }
+    }
+}
 impl TypeTable {
     /// Construct a new type table without any resolved types. Types will be
     /// resolved on-demand.
     pub(crate) fn new(ctx: &mut TypeCtx) -> Result<Self, ParseError2> {
         // Make sure we're allowed to cast root_id to index into ctx.modules
         if cfg!(debug_assertions) {
             for (index, module) in ctx.modules.iter().enumerate() {
                 debug_assert_eq!(index, module.root_id.index as usize);
+            }
+        }
         // Use context to guess hashmap size
         let reserve_size = ctx.heap.definitions.len();
         let mut table = Self{
             lookup: HashMap::with_capacity(reserve_size),
             iter: TypeIterator::new(),
             parser_type_iter: VecDeque::with_capacity(64),
         };
         // TODO: @cleanup Rework this hack
         for root_idx in 0..ctx.modules.len() {
             let last_definition_idx = ctx.heap[ctx.modules[root_idx].root_id].definitions.len();
             for definition_idx in 0..last_definition_idx {
                 let definition_id = ctx.heap[ctx.modules[root_idx].root_id].definitions[definition_idx];
                 table.resolve_base_definition(ctx, definition_id)?;
+            }
+        }
         debug_assert_eq!(table.lookup.len(), reserve_size, "mismatch in reserved size of type table");
         Ok(table)
+    }
     /// Retrieves base definition from type table. We must be able to retrieve
     /// it as we resolve all base types upon type table construction (for now).
     /// However, in the future we might do on-demand type resolving, so return
     /// an option anyway
     pub(crate) fn get_base_definition(&self, definition_id: &DefinitionId) -> Option<&DefinedType> {
         self.lookup.get(&definition_id)
+    }
     /// Instantiates a monomorph for a given base definition.
     pub(crate) fn add_monomorph(&mut self, definition_id: &DefinitionId, types: Vec<ConcreteType>) {
         debug_assert!(
             self.lookup.contains_key(definition_id),
             "attempting to instantiate monomorph of definition unknown to type table"
         );
         let definition = self.lookup.get_mut(definition_id).unwrap();
         definition.add_monomorph(types);
+    }
     /// Checks if a given definition already has a specific monomorph
     pub(crate) fn has_monomorph(&mut self, definition_id: &DefinitionId, types: &Vec<ConcreteType>) -> bool {
         debug_assert!(
             self.lookup.contains_key(definition_id),
             "attempting to check monomorph existence of definition unknown to type table"
         );
         let definition = self.lookup.get(definition_id).unwrap();
         definition.has_monomorph(types)
+    }
     /// This function will resolve just the basic definition of the type, it
     /// will not handle any of the monomorphized instances of the type.
     fn resolve_base_definition<'a>(&'a mut self, ctx: &mut TypeCtx, definition_id: DefinitionId) -> Result<(), ParseError2> {
         // Check if we have already resolved the base definition
         if self.lookup.contains_key(&definition_id) { return Ok(()); }
         let root_id = Self::find_root_id(ctx, definition_id);
         self.iter.reset(root_id, definition_id);
         while let Some((root_id, definition_id)) = self.iter.top() {
             // We have a type to resolve
             let definition = &ctx.heap[definition_id];
             let can_pop_breadcrumb = match definition {
                 // TODO: @cleanup Borrow rules hax
                 Definition::Enum(_) => self.resolve_base_enum_definition(ctx, root_id, definition_id),
                 Definition::Struct(_) => self.resolve_base_struct_definition(ctx, root_id, definition_id),
                 Definition::Component(_) => self.resolve_base_component_definition(ctx, root_id, definition_id),
                 Definition::Function(_) => self.resolve_base_function_definition(ctx, root_id, definition_id),
             }?;
             // Otherwise: `ingest_resolve_result` has pushed a new breadcrumb
             // that we must follow before we can resolve the current type
             if can_pop_breadcrumb {
                 self.iter.pop();
+            }
+        }

src/protocol/parser/visitor_linker.rs

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Show inline comments

 use crate::protocol::ast::*;
 use crate::protocol::inputsource::*;
 use crate::protocol::parser::{
     symbol_table::*,
     type_table::*,
     utils::*,
 };
 use super::visitor::{
     STMT_BUFFER_INIT_CAPACITY,
     EXPR_BUFFER_INIT_CAPACITY,
     TYPE_BUFFER_INIT_CAPACITY,
     Ctx,
     Visitor2,
     VisitorResult
 };
 use std::hint::unreachable_unchecked;
 #[derive(PartialEq, Eq)]
 enum DefinitionType {
     None,
     Primitive(ComponentId),
     Composite(ComponentId),
     Function(FunctionId)
+}
 impl DefinitionType {
     fn is_primitive(&self) -> bool { if let Self::Primitive(_) = self { true } else { false } }
     fn is_composite(&self) -> bool { if let Self::Composite(_) = self { true } else { false } }
     fn is_function(&self) -> bool { if let Self::Function(_) = self { true } else { false } }
+}
 /// This particular visitor will go through the entire AST in a recursive manner
 /// and check if all statements and expressions are legal (e.g. no "return"
 /// statements in component definitions), and will link certain AST nodes to
 /// their appropriate targets (e.g. goto statements, or function calls).
 ///
 /// This visitor will not perform control-flow analysis (e.g. making sure that
 /// each function actually returns) and will also not perform type checking. So
 /// the linking of function calls and component instantiations will be checked
 /// and linked to the appropriate definitions, but the return types and/or
 /// arguments will not be checked for validity.
 ///
 /// The visitor visits each statement in a block in a breadth-first manner
 /// first. We are thereby sure that we have found all variables/labels in a
 /// particular block. In this phase nodes may queue statements for insertion
 /// (e.g. the insertion of an `EndIf` statement for a particular `If`
 /// statement). These will be inserted after visiting every node, after which
 /// the visitor recurses into each statement in a block.
 ///
 /// Because of this scheme expressions will not be visited in the breadth-first
 /// pass.
 pub(crate) struct ValidityAndLinkerVisitor {
     /// `in_sync` is `Some(id)` if the visitor is visiting the children of a
     /// synchronous statement. A single value is sufficient as nested
     /// synchronous statements are not allowed
     in_sync: Option<SynchronousStatementId>,
     /// `in_while` contains the last encountered `While` statement. This is used
     /// to resolve unlabeled `Continue`/`Break` statements.
     in_while: Option<WhileStatementId>,
     // Traversal state: current scope (which can be used to find the parent
     // scope), the definition variant we are considering, and whether the
     // visitor is performing breadthwise block statement traversal.
     cur_scope: Option<Scope>,
     def_type: DefinitionType,
     performing_breadth_pass: bool,
     // Parent expression (the previous stmt/expression we visited that could be
     // used as an expression parent)
     expr_parent: ExpressionParent,
     // Keeping track of relative position in block in the breadth-first pass.
     // May not correspond to block.statement[index] if any statements are
     // inserted after the breadth-pass
     relative_pos_in_block: u32,
     // Single buffer of statement IDs that we want to traverse in a block.
     // Required to work around Rust borrowing rules and to prevent constant
     // cloning of vectors.
     statement_buffer: Vec<StatementId>,
     // Another buffer, now with expression IDs, to prevent constant cloning of
     // vectors while working around rust's borrowing rules
     expression_buffer: Vec<ExpressionId>,
     // Yet another buffer, now with parser type IDs, similar to above
     parser_type_buffer: Vec<ParserTypeId>,
     // Statements to insert after the breadth pass in a single block
     insert_buffer: Vec<(u32, StatementId)>,
+}
 impl ValidityAndLinkerVisitor {
     pub(crate) fn new() -> Self {
         Self{
             in_sync: None,
             in_while: None,
             cur_scope: None,
             expr_parent: ExpressionParent::None,
             def_type: DefinitionType::None,
             performing_breadth_pass: false,
             relative_pos_in_block: 0,
             statement_buffer: Vec::with_capacity(STMT_BUFFER_INIT_CAPACITY),
             expression_buffer: Vec::with_capacity(EXPR_BUFFER_INIT_CAPACITY),
             parser_type_buffer: Vec::with_capacity(TYPE_BUFFER_INIT_CAPACITY),
             insert_buffer: Vec::with_capacity(32),
+        }
+    }
     fn reset_state(&mut self) {
         self.in_sync = None;
         self.in_while = None;
         self.cur_scope = None;
         self.expr_parent = ExpressionParent::None;
         self.def_type = DefinitionType::None;
         self.relative_pos_in_block = 0;
         self.performing_breadth_pass = false;
         self.statement_buffer.clear();
         self.expression_buffer.clear();
         self.parser_type_buffer.clear();
         self.insert_buffer.clear();
+    }
     /// Debug call to ensure that we didn't make any mistakes in any of the
     /// employed buffers
     fn check_post_definition_state(&self) {
         debug_assert!(self.statement_buffer.is_empty());
         debug_assert!(self.expression_buffer.is_empty());
         debug_assert!(self.parser_type_buffer.is_empty());
         debug_assert!(self.insert_buffer.is_empty());
+    }
+}
 impl Visitor2 for ValidityAndLinkerVisitor {
     //--------------------------------------------------------------------------
     // Definition visitors
     //--------------------------------------------------------------------------
     fn visit_component_definition(&mut self, ctx: &mut Ctx, id: ComponentId) -> VisitorResult {
         self.reset_state();
         self.def_type = match &ctx.heap[id].variant {
             ComponentVariant::Primitive => DefinitionType::Primitive(id),
             ComponentVariant::Composite => DefinitionType::Composite(id),
         };
         self.cur_scope = Some(Scope::Definition(id.upcast()));
         self.expr_parent = ExpressionParent::None;
         // Visit types of parameters
         debug_assert!(self.parser_type_buffer.is_empty());
         let comp_def = &ctx.heap[id];
         self.parser_type_buffer.extend(
             comp_def.parameters
                 .iter()
                 .map(|id| ctx.heap[*id].parser_type)
         );
         let num_types = self.parser_type_buffer.len();
         for idx in 0..num_types {
             self.visit_parser_type(ctx, self.parser_type_buffer[idx])?;
+        }
         self.parser_type_buffer.clear();
         // Visit statements in component body
         let body_id = ctx.heap[id].body;
         self.performing_breadth_pass = true;
         self.visit_stmt(ctx, body_id)?;
         self.performing_breadth_pass = false;
         self.visit_stmt(ctx, body_id)?;
         self.check_post_definition_state();
         Ok(())
+    }
     fn visit_function_definition(&mut self, ctx: &mut Ctx, id: FunctionId) -> VisitorResult {
         self.reset_state();
         // Set internal statement indices
         self.def_type = DefinitionType::Function(id);
         self.cur_scope = Some(Scope::Definition(id.upcast()));
         self.expr_parent = ExpressionParent::None;
         // Visit types of parameters
         debug_assert!(self.parser_type_buffer.is_empty());
         let func_def = &ctx.heap[id];
         self.parser_type_buffer.extend(
             func_def.parameters
                 .iter()
                 .map(|id| ctx.heap[*id].parser_type)
         );
         self.parser_type_buffer.push(func_def.return_type);
         let num_types = self.parser_type_buffer.len();
         for idx in 0..num_types {
             self.visit_parser_type(ctx, self.parser_type_buffer[idx])?;
+        }
         self.parser_type_buffer.clear();
         // Visit statements in function body
         let body_id = ctx.heap[id].body;
         self.performing_breadth_pass = true;
         self.visit_stmt(ctx, body_id)?;
         self.performing_breadth_pass = false;
         self.visit_stmt(ctx, body_id)?;
         self.check_post_definition_state();
         Ok(())
+    }
     //--------------------------------------------------------------------------
     // Statement visitors
     //--------------------------------------------------------------------------
@@ @@ -509,592 +510,637 @@ impl Visitor2 for ValidityAndLinkerVisitor { @@
             debug_assert_eq!(self.expr_parent, ExpressionParent::None);
             self.expr_parent = ExpressionParent::New(id);
             self.visit_call_expr(ctx, call_expr_id)?;
             self.expr_parent = ExpressionParent::None;
+        }
         Ok(())
+    }
     fn visit_expr_stmt(&mut self, ctx: &mut Ctx, id: ExpressionStatementId) -> VisitorResult {
         if !self.performing_breadth_pass {
             let expr_id = ctx.heap[id].expression;
             debug_assert_eq!(self.expr_parent, ExpressionParent::None);
             self.expr_parent = ExpressionParent::ExpressionStmt(id);
             self.visit_expr(ctx, expr_id)?;
             self.expr_parent = ExpressionParent::None;
+        }
         Ok(())
+    }
     //--------------------------------------------------------------------------
     // Expression visitors
     //--------------------------------------------------------------------------
     fn visit_assignment_expr(&mut self, ctx: &mut Ctx, id: AssignmentExpressionId) -> VisitorResult {
         debug_assert!(!self.performing_breadth_pass);
         let upcast_id = id.upcast();
         let assignment_expr = &mut ctx.heap[id];
         let left_expr_id = assignment_expr.left;
         let right_expr_id = assignment_expr.right;
         let old_expr_parent = self.expr_parent;
         assignment_expr.parent = old_expr_parent;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
         self.visit_expr(ctx, left_expr_id)?;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
         self.visit_expr(ctx, right_expr_id)?;
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_conditional_expr(&mut self, ctx: &mut Ctx, id: ConditionalExpressionId) -> VisitorResult {
         debug_assert!(!self.performing_breadth_pass);
         let upcast_id = id.upcast();
         let conditional_expr = &mut ctx.heap[id];
         let test_expr_id = conditional_expr.test;
         let true_expr_id = conditional_expr.true_expression;
         let false_expr_id = conditional_expr.false_expression;
         let old_expr_parent = self.expr_parent;
         conditional_expr.parent = old_expr_parent;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
         self.visit_expr(ctx, test_expr_id)?;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
         self.visit_expr(ctx, true_expr_id)?;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 2);
         self.visit_expr(ctx, false_expr_id)?;
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_binary_expr(&mut self, ctx: &mut Ctx, id: BinaryExpressionId) -> VisitorResult {
         debug_assert!(!self.performing_breadth_pass);
         let upcast_id = id.upcast();
         let binary_expr = &mut ctx.heap[id];
         let left_expr_id = binary_expr.left;
         let right_expr_id = binary_expr.right;
         let old_expr_parent = self.expr_parent;
         binary_expr.parent = old_expr_parent;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
         self.visit_expr(ctx, left_expr_id)?;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
         self.visit_expr(ctx, right_expr_id)?;
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_unary_expr(&mut self, ctx: &mut Ctx, id: UnaryExpressionId) -> VisitorResult {
         debug_assert!(!self.performing_breadth_pass);
         let unary_expr = &mut ctx.heap[id];
         let expr_id = unary_expr.expression;
         let old_expr_parent = self.expr_parent;
         unary_expr.parent = old_expr_parent;
         self.expr_parent = ExpressionParent::Expression(id.upcast(), 0);
         self.visit_expr(ctx, expr_id)?;
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_indexing_expr(&mut self, ctx: &mut Ctx, id: IndexingExpressionId) -> VisitorResult {
         debug_assert!(!self.performing_breadth_pass);
         let upcast_id = id.upcast();
         let indexing_expr = &mut ctx.heap[id];
         let subject_expr_id = indexing_expr.subject;
         let index_expr_id = indexing_expr.index;
         let old_expr_parent = self.expr_parent;
         indexing_expr.parent = old_expr_parent;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
         self.visit_expr(ctx, subject_expr_id)?;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
         self.visit_expr(ctx, index_expr_id)?;
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_slicing_expr(&mut self, ctx: &mut Ctx, id: SlicingExpressionId) -> VisitorResult {
         debug_assert!(!self.performing_breadth_pass);
         let upcast_id = id.upcast();
         let slicing_expr = &mut ctx.heap[id];
         let subject_expr_id = slicing_expr.subject;
         let from_expr_id = slicing_expr.from_index;
         let to_expr_id = slicing_expr.to_index;
         let old_expr_parent = self.expr_parent;
         slicing_expr.parent = old_expr_parent;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
         self.visit_expr(ctx, subject_expr_id)?;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
         self.visit_expr(ctx, from_expr_id)?;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 2);
         self.visit_expr(ctx, to_expr_id)?;
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_select_expr(&mut self, ctx: &mut Ctx, id: SelectExpressionId) -> VisitorResult {
         debug_assert!(!self.performing_breadth_pass);
         let select_expr = &mut ctx.heap[id];
         let expr_id = select_expr.subject;
         let old_expr_parent = self.expr_parent;
         select_expr.parent = old_expr_parent;
         self.expr_parent = ExpressionParent::Expression(id.upcast(), 0);
         self.visit_expr(ctx, expr_id)?;
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_array_expr(&mut self, ctx: &mut Ctx, id: ArrayExpressionId) -> VisitorResult {
         debug_assert!(!self.performing_breadth_pass);
         let upcast_id = id.upcast();
         let array_expr = &mut ctx.heap[id];
         let old_num_exprs = self.expression_buffer.len();
         self.expression_buffer.extend(&array_expr.elements);
         let new_num_exprs = self.expression_buffer.len();
         let old_expr_parent = self.expr_parent;
         array_expr.parent = old_expr_parent;
         for field_expr_idx in old_num_exprs..new_num_exprs {
             let field_expr_id = self.expression_buffer[field_expr_idx];
             self.expr_parent = ExpressionParent::Expression(upcast_id, field_expr_idx as u32);
             self.visit_expr(ctx, field_expr_id)?;
+        }
         self.expression_buffer.truncate(old_num_exprs);
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_literal_expr(&mut self, ctx: &mut Ctx, id: LiteralExpressionId) -> VisitorResult {
         debug_assert!(!self.performing_breadth_pass);
         const FIELD_NOT_FOUND_SENTINEL: usize = usize::max_value();
         let constant_expr = &mut ctx.heap[id];
         let old_expr_parent = self.expr_parent;
         constant_expr.parent = old_expr_parent;
         match &mut constant_expr.value {
             Literal::Null | Literal::True | Literal::False |
             Literal::Character(_) | Literal::Integer(_) => {
                 // Just the parent has to be set, done above
             },
             Literal::Struct(literal) => {
                 // Retrieve and set the literals definition
                 let definition =
                 let upcast_id = id.upcast();
                 // Retrieve and set the literal's definition
                 let definition = self.find_symbol_of_type(
                     &ctx.module.source, ctx.module.root_id, &ctx.symbols, &ctx.types,
                     &literal.identifier, TypeClass::Struct
                 )?;
                 literal.definition = Some(definition.ast_definition);
                 let definition = definition.definition.as_struct();
                 // Make sure all fields are specified, none are specified twice
                 // and all fields exist on the struct definition
                 let mut specified = Vec::new(); // TODO: @performance
                 specified.resize(definition.fields.len(), false);
                 for field in &mut literal.fields {
                     // Find field in the struct definition
                     field.field_idx = FIELD_NOT_FOUND_SENTINEL;
                     for (def_field_idx, def_field) in definition.fields.iter().enumerate() {
                         if field.identifier == def_field.identifier {
                             field.field_idx = def_field_idx;
                             num_found += 1;
                             break;
+                        }
+                    }
                     // Check if not found
                     if field.field_idx == FIELD_NOT_FOUND_SENTINEL {
                         return Err(ParseError2::new_error(
                             &ctx.module.source, field.identifier.position(),
                             &format!(
                                 "This field does not exist on the struct '{}'",
                                 &String::from_utf8_lossy(&literal.identifier.value),
+                            )
                         ));
+                    }
                     // Check if specified more than once
                     if specified[field.field_idx] {
                         return Err(ParseError2::new_error(
                             &ctx.module.source, field.identifier.position(),
                             "This field is specified more than once"
                         ));
+                    }
                     specified[field.field_idx] = true;
+                }
                 if !specified.iter().all(|v| *v) {
                     // Some fields were not specified
                     let mut not_specified = String::new();
                     for (def_field_idx, is_specified) in specified.iter().enumerate() {
                         if !is_specified {
                             if !not_specified.is_empty() { not_specified.push_str(", ") }
                             let field_ident = &definition.fields[def_field_idx].identifier;
                             not_specified.push_str(&String::from_utf8_lossy(&field_ident.value));
+                        }
+                    }
                     return Err(ParseError2::new_error(
                         &ctx.module.source, literal.identifier.position,
                         &format!("Not all fields are specified, [{}] are missing", not_specified)
                     ));
+                }
                 // Need to traverse fields expressions in struct
                 let old_num_exprs = self.expression_buffer.len();
                 self.expression_buffer.extend(literal.fields.iter().map(|v| v.value));
                 let new_num_exprs = self.expression_buffer.len();
                 for expr_idx in old_num_exprs..new_num_exprs {
                     let expr_id = self.expression_buffer[expr_idx];
                     self.expr_parent = ExpressionParent::Expression(upcast_id, expr_idx as u32);
                     self.visit_expr(ctx, expr_id)
+                }
                 self.expression_buffer.truncate(old_num_exprs);
+            }
+        }
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_call_expr(&mut self, ctx: &mut Ctx, id: CallExpressionId) -> VisitorResult {
         debug_assert!(!self.performing_breadth_pass);
         let call_expr = &mut ctx.heap[id];
         let num_expr_args = call_expr.arguments.len();
         // Resolve the method to the appropriate definition and check the
         // legality of the particular method call.
         // TODO: @cleanup Unify in some kind of signature call, see similar
         //  cleanup comments with this `match` format.
         let num_definition_args;
         match &mut call_expr.method {
             Method::Create => {
                 num_definition_args = 1;
             },
             Method::Fires => {
                 if !self.def_type.is_primitive() {
                     return Err(ParseError2::new_error(
                         &ctx.module.source, call_expr.position,
                         "A call to 'fires' may only occur in primitive component definitions"
                     ));
+                }
                 if self.in_sync.is_none() {
                     return Err(ParseError2::new_error(
                         &ctx.module.source, call_expr.position,
                         "A call to 'fires' may only occur inside synchronous blocks"
                     ));
+                }
                 num_definition_args = 1;
             },
             Method::Get => {
                 if !self.def_type.is_primitive() {
                     return Err(ParseError2::new_error(
                         &ctx.module.source, call_expr.position,
                         "A call to 'get' may only occur in primitive component definitions"
                     ));
+                }
                 if self.in_sync.is_none() {
                     return Err(ParseError2::new_error(
                         &ctx.module.source, call_expr.position,
                         "A call to 'get' may only occur inside synchronous blocks"
                     ));
+                }
                 num_definition_args = 1;
             },
             Method::Put => {
                 if !self.def_type.is_primitive() {
                     return Err(ParseError2::new_error(
                         &ctx.module.source, call_expr.position,
                         "A call to 'put' may only occur in primitive component definitions"
                     ));
+                }
                 if self.in_sync.is_none() {
                     return Err(ParseError2::new_error(
                         &ctx.module.source, call_expr.position,
                         "A call to 'put' may only occur inside synchronous blocks"
                     ));
+                }
                 num_definition_args = 2;
+            }
             Method::Symbolic(symbolic) => {
                 // Find symbolic method
                 let (verb, expected_type) = if let ExpressionParent::New(_) = self.expr_parent {
                     // Expect to find a component
                     ("instantiated", TypeClass::Component)
                 } else {
                     // Expect to find a function
                     ("called", TypeClass::Function)
                 };
                 let found_symbol = self.find_symbol_of_type(
                     ctx.module.root_id, &ctx.symbols, &ctx.types,
                 let definition = self.find_symbol_of_type(
                     &ctx.module.source, ctx.module.root_id, &ctx.symbols, &ctx.types,
                     &symbolic.identifier, expected_type
                 );
                 let definition_id = match found_symbol {
                     FindOfTypeResult::Found(definition_id) => definition_id,
                     FindOfTypeResult::TypeMismatch(got_type_class) => {
                         return Err(ParseError2::new_error(
                             &ctx.module.source, symbolic.identifier.position,
                             &format!(
                                 "Only {}s can be {}, this identifier points to a {}",
                                 expected_type, verb, got_type_class
+                            )
                         ))
                     },
                     FindOfTypeResult::NotFound => {
                         return Err(ParseError2::new_error(
                             &ctx.module.source, symbolic.identifier.position,
                             &format!("Could not find a {} with this name", expected_type)
                         ))
+                    }
                 };
                 )?;
                 symbolic.definition = Some(definition_id);
                 match &ctx.types.get_base_definition(&definition_id).unwrap().definition {
                 symbolic.definition = Some(definition.ast_definition);
                 match definition {
                     DefinedTypeVariant::Function(definition) => {
                         num_definition_args = definition.arguments.len();
                     },
                     DefinedTypeVariant::Component(definition) => {
                         num_definition_args = definition.arguments.len();
+                    }
                     _ => unreachable!(),
+                }
+            }
+        }
         // Check the poly args and the number of variables in the call
         // expression
         self.visit_call_poly_args(ctx, id)?;
         let call_expr = &mut ctx.heap[id];
         if num_expr_args != num_definition_args {
             return Err(ParseError2::new_error(
                 &ctx.module.source, call_expr.position,
                 &format!(
                     "This call expects {} arguments, but {} were provided",
                     num_definition_args, num_expr_args
+                )
             ));
+        }
         // Recurse into all of the arguments and set the expression's parent
         let upcast_id = id.upcast();
         let old_num_exprs = self.expression_buffer.len();
         self.expression_buffer.extend(&call_expr.arguments);
         let new_num_exprs = self.expression_buffer.len();
         let old_expr_parent = self.expr_parent;
         call_expr.parent = old_expr_parent;
         for arg_expr_idx in old_num_exprs..new_num_exprs {
             let arg_expr_id = self.expression_buffer[arg_expr_idx];
             self.expr_parent = ExpressionParent::Expression(upcast_id, arg_expr_idx as u32);
             self.visit_expr(ctx, arg_expr_id)?;
+        }
         self.expression_buffer.truncate(old_num_exprs);
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_variable_expr(&mut self, ctx: &mut Ctx, id: VariableExpressionId) -> VisitorResult {
         debug_assert!(!self.performing_breadth_pass);
         let var_expr = &ctx.heap[id];
         let variable_id = self.find_variable(ctx, self.relative_pos_in_block, &var_expr.identifier)?;
         let var_expr = &mut ctx.heap[id];
         var_expr.declaration = Some(variable_id);
         var_expr.parent = self.expr_parent;
         Ok(())
+    }
     //--------------------------------------------------------------------------
     // ParserType visitors
     //--------------------------------------------------------------------------
     fn visit_parser_type(&mut self, ctx: &mut Ctx, id: ParserTypeId) -> VisitorResult {
         let old_num_types = self.parser_type_buffer.len();
         match self.visit_parser_type_without_buffer_cleanup(ctx, id) {
             Ok(_) => {
                 debug_assert_eq!(self.parser_type_buffer.len(), old_num_types);
                 Ok(())
             },
             Err(err) => {
                 self.parser_type_buffer.truncate(old_num_types);
                 Err(err)
+            }
+        }
+    }
+}
 enum FindOfTypeResult {
     // Identifier was exactly matched, type matched as well
     Found(DefinitionId),
     // Identifier was matched, but the type differs from the expected one
     TypeMismatch(&'static str),
     // Identifier could not be found
     NotFound,
+}
 impl ValidityAndLinkerVisitor {
     //--------------------------------------------------------------------------
     // Special traversal
     //--------------------------------------------------------------------------
     /// Will visit a statement with a hint about its wrapping statement. This is
     /// used to distinguish block statements with a wrapping synchronous
     /// statement from normal block statements.
     fn visit_stmt_with_hint(&mut self, ctx: &mut Ctx, id: StatementId, hint: Option<SynchronousStatementId>) -> VisitorResult {
         if let Statement::Block(block_stmt) = &ctx.heap[id] {
             let block_id = block_stmt.this;
             self.visit_block_stmt_with_hint(ctx, block_id, hint)
         } else {
             self.visit_stmt(ctx, id)
+        }
+    }
     fn visit_block_stmt_with_hint(&mut self, ctx: &mut Ctx, id: BlockStatementId, hint: Option<SynchronousStatementId>) -> VisitorResult {
         if self.performing_breadth_pass {
             // Performing a breadth pass, so don't traverse into the statements
             // of the block.
             return Ok(())
+        }
         // Set parent scope and relative position in the parent scope. Remember
         // these values to set them back to the old values when we're done with
         // the traversal of the block's statements.
         let body = &mut ctx.heap[id];
         body.parent_scope = self.cur_scope.clone();
         body.relative_pos_in_parent = self.relative_pos_in_block;
         let old_scope = self.cur_scope.replace(match hint {
             Some(sync_id) => Scope::Synchronous((sync_id, id)),
             None => Scope::Regular(id),
         });
         let old_relative_pos = self.relative_pos_in_block;
         // Copy statement IDs into buffer
         let old_num_stmts = self.statement_buffer.len();
+        {
             let body = &ctx.heap[id];
             self.statement_buffer.extend_from_slice(&body.statements);
+        }
         let new_num_stmts = self.statement_buffer.len();
         // Perform the breadth-first pass. Its main purpose is to find labeled
         // statements such that we can find the `goto`-targets immediately when
         // performing the depth pass
         self.performing_breadth_pass = true;
         for stmt_idx in old_num_stmts..new_num_stmts {
             self.relative_pos_in_block = (stmt_idx - old_num_stmts) as u32;
             self.visit_stmt(ctx, self.statement_buffer[stmt_idx])?;
+        }
         if !self.insert_buffer.is_empty() {
             let body = &mut ctx.heap[id];
             for (insert_idx, (pos, stmt)) in self.insert_buffer.drain(..).enumerate() {
                 body.statements.insert(pos as usize + insert_idx, stmt);
+            }
+        }
         // And the depth pass. Because we're not actually visiting any inserted
         // nodes because we're using the statement buffer, we may safely use the
         // relative_pos_in_block counter.
         self.performing_breadth_pass = false;
         for stmt_idx in old_num_stmts..new_num_stmts {
             self.relative_pos_in_block = (stmt_idx - old_num_stmts) as u32;
             self.visit_stmt(ctx, self.statement_buffer[stmt_idx])?;
+        }
         self.cur_scope = old_scope;
         self.relative_pos_in_block = old_relative_pos;
         // Pop statement buffer
         debug_assert!(self.insert_buffer.is_empty(), "insert buffer not empty after depth pass");
         self.statement_buffer.truncate(old_num_stmts);
         Ok(())
+    }
     /// Visits a particular ParserType in the AST and resolves temporary and
     /// implicitly inferred types into the appropriate tree. Note that a
     /// ParserType node is a tree. Only call this function on the root node of
     /// that tree to prevent doing work more than once.
     fn visit_parser_type_without_buffer_cleanup(&mut self, ctx: &mut Ctx, id: ParserTypeId) -> VisitorResult {
         use ParserTypeVariant as PTV;
         debug_assert!(!self.performing_breadth_pass);
         let init_num_types = self.parser_type_buffer.len();
         self.parser_type_buffer.push(id);
         'resolve_loop: while self.parser_type_buffer.len() > init_num_types {
             let parser_type_id = self.parser_type_buffer.pop().unwrap();
             let parser_type = &ctx.heap[parser_type_id];
             let (symbolic_pos, symbolic_variant, num_inferred_to_allocate) = match &parser_type.variant {
                 PTV::Message | PTV::Bool |
                 PTV::Byte | PTV::Short | PTV::Int | PTV::Long |
                 PTV::String |
                 PTV::IntegerLiteral | PTV::Inferred => {
                     // Builtin types or types that do not require recursion
                     continue 'resolve_loop;
                 },
                 PTV::Array(subtype_id) |
                 PTV::Input(subtype_id) |
                 PTV::Output(subtype_id) => {
                     // Requires recursing
                     self.parser_type_buffer.push(*subtype_id);
                     continue 'resolve_loop;
                 },
                 PTV::Symbolic(symbolic) => {
                     // Retrieve poly_vars from function/component definition to
                     // match against.
                     let (definition_id, poly_vars) = match self.def_type {
                         DefinitionType::None => unreachable!(),
                         DefinitionType::Primitive(id) => (id.upcast(), &ctx.heap[id].poly_vars),
                         DefinitionType::Composite(id) => (id.upcast(), &ctx.heap[id].poly_vars),
                         DefinitionType::Function(id) => (id.upcast(), &ctx.heap[id].poly_vars),
                     };
                     let mut symbolic_variant = None;
                     for (poly_var_idx, poly_var) in poly_vars.iter().enumerate() {
                         if symbolic.identifier.value == poly_var.value {
                             // Type refers to a polymorphic variable.
                             // TODO: @hkt Maybe allow higher-kinded types?
                             if !symbolic.poly_args.is_empty() {
                                 return Err(ParseError2::new_error(
                                     &ctx.module.source, symbolic.identifier.position,
                                     "Polymorphic arguments to a polymorphic variable (higher-kinded types) are not allowed (yet)"
                                 ));
+                            }
                             symbolic_variant = Some(SymbolicParserTypeVariant::PolyArg(definition_id, poly_var_idx));
+                        }
+                    }
                     if let Some(symbolic_variant) = symbolic_variant {
                         // Identifier points to a symbolic type
                         (symbolic.identifier.position, symbolic_variant, 0)
                     } else {
                         // Must be a user-defined type, otherwise an error
                         let found_type = find_type_definition(
                             &ctx.symbols, &ctx.types, ctx.module.root_id, &symbolic.identifier
                         ).as_parse_error(&ctx.module.source)?;
                         symbolic_variant = Some(SymbolicParserTypeVariant::Definition(found_type.ast_definition));
                         // TODO: @function_ptrs: Allow function pointers at some
                         //  point in the future
                         if found_type.definition.type_class().is_proc_type() {
                             return Err(ParseError2::new_error(
                                 &ctx.module.source, symbolic.identifier.position,
                                 &format!(
                                     "This identifier points to a {} type, expected a datatype",
                                     found_type.definition.type_class()
+                                )
                             ));
+                        }
                         // If the type is polymorphic then we have two cases: if
                         // the programmer did not specify the polyargs then we
                         // assume we're going to infer all of them. Otherwise we
                         // make sure that they match in count.
                         if !found_type.poly_args.is_empty() && symbolic.poly_args.is_empty() {
                             // All inferred
+                            (
                                 symbolic.identifier.position,
                                 SymbolicParserTypeVariant::Definition(found_type.ast_definition),
                                 found_type.poly_args.len()
+                            )
                         } else if symbolic.poly_args.len() != found_type.poly_args.len() {
                             return Err(ParseError2::new_error(
                                 &ctx.module.source, symbolic.identifier.position,
                                 &format!(
                                     "Expected {} polymorphic arguments (or none, to infer them), but {} were specified",
                                     found_type.poly_args.len(), symbolic.poly_args.len()
+                                )
                             ))
                         } else {
                             // If here then the type is not polymorphic, or all
                             // types are properly specified by the user.
                             for specified_poly_arg in &symbolic.poly_args {
                                 self.parser_type_buffer.push(*specified_poly_arg);
+                            }
+                            (
                                 symbolic.identifier.position,
                                 SymbolicParserTypeVariant::Definition(found_type.ast_definition),
+                            )
+                        }
+                    }
+                }
             };
@@ @@ -1154,378 +1200,410 @@ impl ValidityAndLinkerVisitor { @@
         // that variables in parent scopes may be declared later
         let local = &ctx.heap[id];
         let mut scope = self.cur_scope.as_ref().unwrap();
         let mut local_relative_pos = self.relative_pos_in_block;
         loop {
             debug_assert!(scope.is_block(), "scope is not a block");
             let block = &ctx.heap[scope.to_block()];
             for other_local_id in &block.locals {
                 let other_local = &ctx.heap[*other_local_id];
                 // Position check in case another variable with the same name
                 // is defined in a higher-level scope, but later than the scope
                 // in which the current variable resides.
                 if local.this != *other_local_id &&
                     local_relative_pos >= other_local.relative_pos_in_block &&
                     local.identifier.value == other_local.identifier.value {
                     // Collision within this scope
                     return Err(
                         ParseError2::new_error(&ctx.module.source, local.position, "Local variable name conflicts with another variable")
                             .with_postfixed_info(&ctx.module.source, other_local.position, "Previous variable is found here")
                     );
+                }
+            }
             // Current scope is fine, move to parent scope if any
             debug_assert!(block.parent_scope.is_some(), "block scope does not have a parent");
             scope = block.parent_scope.as_ref().unwrap();
             if let Scope::Definition(definition_id) = scope {
                 // At outer scope, check parameters of function/component
                 for parameter_id in ctx.heap[*definition_id].parameters() {
                     let parameter = &ctx.heap[*parameter_id];
                     if local.identifier.value == parameter.identifier.value {
                         return Err(
                             ParseError2::new_error(&ctx.module.source, local.position, "Local variable name conflicts with parameter")
                                 .with_postfixed_info(&ctx.module.source, parameter.position, "Parameter definition is found here")
                         );
+                    }
+                }
                 break;
+            }
             // If here, then we are dealing with a block-like parent block
             local_relative_pos = ctx.heap[scope.to_block()].relative_pos_in_parent;
+        }
         // No collisions at all
         let block = &mut ctx.heap[self.cur_scope.as_ref().unwrap().to_block()];
         block.locals.push(id);
         Ok(())
+    }
     /// Finds a variable in the visitor's scope that must appear before the
     /// specified relative position within that block.
     fn find_variable(&self, ctx: &Ctx, mut relative_pos: u32, identifier: &NamespacedIdentifier) -> Result<VariableId, ParseError2> {
         debug_assert!(self.cur_scope.is_some());
         debug_assert!(identifier.num_namespaces > 0);
         // TODO: Update once globals are possible as well
         if identifier.num_namespaces > 1 {
             todo!("Implement namespaced constant seeking")
+        }
         // TODO: May still refer to an alias of a global symbol using a single
         //  identifier in the namespace.
         // No need to use iterator over namespaces if here
         let mut scope = self.cur_scope.as_ref().unwrap();
         loop {
             debug_assert!(scope.is_block());
             let block = &ctx.heap[scope.to_block()];
             for local_id in &block.locals {
                 let local = &ctx.heap[*local_id];
                 if local.relative_pos_in_block < relative_pos && local.identifier.value == identifier.value {
                     return Ok(local_id.upcast());
+                }
+            }
             debug_assert!(block.parent_scope.is_some());
             scope = block.parent_scope.as_ref().unwrap();
             if !scope.is_block() {
                 // Definition scope, need to check arguments to definition
                 match scope {
                     Scope::Definition(definition_id) => {
                         let definition = &ctx.heap[*definition_id];
                         for parameter_id in definition.parameters() {
                             let parameter = &ctx.heap[*parameter_id];
                             if parameter.identifier.value == identifier.value {
                                 return Ok(parameter_id.upcast());
+                            }
+                        }
                     },
                     _ => unreachable!(),
+                }
                 // Variable could not be found
                 return Err(ParseError2::new_error(
                     &ctx.module.source, identifier.position, "This variable is not declared"
                 ));
             } else {
                 relative_pos = block.relative_pos_in_parent;
+            }
+        }
+    }
     /// Adds a particular label to the current scope. Will return an error if
     /// there is another label with the same name visible in the current scope.
     fn checked_label_add(&mut self, ctx: &mut Ctx, id: LabeledStatementId) -> Result<(), ParseError2> {
         debug_assert!(self.cur_scope.is_some());
         // Make sure label is not defined within the current scope or any of the
         // parent scope.
         let label = &ctx.heap[id];
         let mut scope = self.cur_scope.as_ref().unwrap();
         loop {
             debug_assert!(scope.is_block(), "scope is not a block");
             let block = &ctx.heap[scope.to_block()];
             for other_label_id in &block.labels {
                 let other_label = &ctx.heap[*other_label_id];
                 if other_label.label.value == label.label.value {
                     // Collision
                     return Err(
                         ParseError2::new_error(&ctx.module.source, label.position, "Label name conflicts with another label")
                             .with_postfixed_info(&ctx.module.source, other_label.position, "Other label is found here")
                     );
+                }
+            }
             debug_assert!(block.parent_scope.is_some(), "block scope does not have a parent");
             scope = block.parent_scope.as_ref().unwrap();
             if !scope.is_block() {
                 break;
+            }
+        }
         // No collisions
         let block = &mut ctx.heap[self.cur_scope.as_ref().unwrap().to_block()];
         block.labels.push(id);
         Ok(())
+    }
     /// Finds a particular labeled statement by its identifier. Once found it
     /// will make sure that the target label does not skip over any variable
     /// declarations within the scope in which the label was found.
     fn find_label(&self, ctx: &Ctx, identifier: &Identifier) -> Result<LabeledStatementId, ParseError2> {
         debug_assert!(self.cur_scope.is_some());
         let mut scope = self.cur_scope.as_ref().unwrap();
         loop {
             debug_assert!(scope.is_block(), "scope is not a block");
             let relative_scope_pos = ctx.heap[scope.to_block()].relative_pos_in_parent;
             let block = &ctx.heap[scope.to_block()];
             for label_id in &block.labels {
                 let label = &ctx.heap[*label_id];
                 if label.label.value == identifier.value {
                     for local_id in &block.locals {
                         // TODO: Better to do this in control flow analysis, it
                         //  is legal to skip over a variable declaration if it
                         //  is not actually being used. I might be missing
                         //  something here when laying out the bytecode...
                         let local = &ctx.heap[*local_id];
                         if local.relative_pos_in_block > relative_scope_pos && local.relative_pos_in_block < label.relative_pos_in_block {
                             return Err(
                                 ParseError2::new_error(&ctx.module.source, identifier.position, "This target label skips over a variable declaration")
                                     .with_postfixed_info(&ctx.module.source, label.position, "Because it jumps to this label")
                                     .with_postfixed_info(&ctx.module.source, local.position, "Which skips over this variable")
                             );
+                        }
+                    }
                     return Ok(*label_id);
+                }
+            }
             debug_assert!(block.parent_scope.is_some(), "block scope does not have a parent");
             scope = block.parent_scope.as_ref().unwrap();
             if !scope.is_block() {
                 return Err(ParseError2::new_error(&ctx.module.source, identifier.position, "Could not find this label"));
+            }
+        }
+    }
     /// Finds a particular symbol in the symbol table which must correspond to
     /// a definition of a particular type.
     // Note: root_id, symbols and types passed in explicitly to prevent
     //  borrowing errors
     fn find_symbol_of_type(
         &self, root_id: RootId, symbols: &SymbolTable, types: &TypeTable,
     fn find_symbol_of_type<'a>(
         &self, source: &InputSource, root_id: RootId, symbols: &SymbolTable, types: &'a TypeTable,
         identifier: &NamespacedIdentifier, expected_type_class: TypeClass
-    ) -> FindOfTypeResult {
+    ) -> Result<&'a DefinedType, ParseError2> {
         // Find symbol associated with identifier
         let symbol = symbols.resolve_namespaced_symbol(root_id, &identifier);
         if symbol.is_none() { return FindOfTypeResult::NotFound; }
         let (symbol, iter) = symbol.unwrap();
         if iter.num_remaining() != 0 { return FindOfTypeResult::NotFound; }
         match &symbol.symbol {
             Symbol::Definition((_, definition_id)) => {
                 // Make sure definition is of the expected type
                 let definition_type = types.get_base_definition(&definition_id);
                 debug_assert!(definition_type.is_some(), "Found symbol '{}' in symbol table, but not in type table", String::from_utf8_lossy(&identifier.value));
                 let definition_type_class = definition_type.unwrap().definition.type_class();
         let find_result = find_type_definition(symbols, types, root_id, identifier)
             .as_parse_error(source)?;
                 if definition_type_class != expected_type_class {
                     FindOfTypeResult::TypeMismatch(definition_type_class.display_name())
                 } else {
                     FindOfTypeResult::Found(*definition_id)
+                }
             },
             Symbol::Namespace(_) => FindOfTypeResult::TypeMismatch("namespace"),
         let definition_type_class = find_result.definition.type_class();
         if expected_type_class != definition_type_class {
             return Err(ParseError2::new_error(
                 source, identifier.position,
                 &format!(
                     "Expected to find a {}, this symbol points to a {}",
                     expected_type_class, definition_type_class
+                )
             ))
+        }
         Ok(find_result)
+    }
     /// This function will check if the provided while statement ID has a block
     /// statement that is one of our current parents.
     fn has_parent_while_scope(&self, ctx: &Ctx, id: WhileStatementId) -> bool {
         debug_assert!(self.cur_scope.is_some());
         let mut scope = self.cur_scope.as_ref().unwrap();
         let while_stmt = &ctx.heap[id];
         loop {
             debug_assert!(scope.is_block());
             let block = scope.to_block();
             if while_stmt.body == block.upcast() {
                 return true;
+            }
             let block = &ctx.heap[block];
             debug_assert!(block.parent_scope.is_some(), "block scope does not have a parent");
             scope = block.parent_scope.as_ref().unwrap();
             if !scope.is_block() {
                 return false;
+            }
+        }
+    }
     /// This function should be called while dealing with break/continue
     /// statements. It will try to find the targeted while statement, using the
     /// target label if provided. If a valid target is found then the loop's
     /// ID will be returned, otherwise a parsing error is constructed.
     /// The provided input position should be the position of the break/continue
     /// statement.
     fn resolve_break_or_continue_target(&self, ctx: &Ctx, position: InputPosition, label: &Option<Identifier>) -> Result<WhileStatementId, ParseError2> {
         let target = match label {
             Some(label) => {
                 let target_id = self.find_label(ctx, label)?;
                 // Make sure break target is a while statement
                 let target = &ctx.heap[target_id];
                 if let Statement::While(target_stmt) = &ctx.heap[target.body] {
                     // Even though we have a target while statement, the break might not be
                     // present underneath this particular labeled while statement
                     if !self.has_parent_while_scope(ctx, target_stmt.this) {
                         ParseError2::new_error(&ctx.module.source, label.position, "Break statement is not nested under the target label's while statement")
                             .with_postfixed_info(&ctx.module.source, target.position, "The targeted label is found here");
+                    }
                     target_stmt.this
                 } else {
                     return Err(
                         ParseError2::new_error(&ctx.module.source, label.position, "Incorrect break target label, it must target a while loop")
                             .with_postfixed_info(&ctx.module.source, target.position, "The targeted label is found here")
                     );
+                }
             },
             None => {
                 // Use the enclosing while statement, the break must be
                 // nested within that while statement
                 if self.in_while.is_none() {
                     return Err(
                         ParseError2::new_error(&ctx.module.source, position, "Break statement is not nested under a while loop")
                     );
+                }
                 self.in_while.unwrap()
+            }
         };
         // We have a valid target for the break statement. But we need to
         // make sure we will not break out of a synchronous block
+        {
             let target_while = &ctx.heap[target];
             if target_while.in_sync != self.in_sync {
                 // Break is nested under while statement, so can only escape a
                 // sync block if the sync is nested inside the while statement.
                 debug_assert!(self.in_sync.is_some());
                 let sync_stmt = &ctx.heap[self.in_sync.unwrap()];
                 return Err(
                     ParseError2::new_error(&ctx.module.source, position, "Break may not escape the surrounding synchronous block")
                         .with_postfixed_info(&ctx.module.source, target_while.position, "The break escapes out of this loop")
                         .with_postfixed_info(&ctx.module.source, sync_stmt.position, "And would therefore escape this synchronous block")
                 );
+            }
+        }
         Ok(target)
+    }
     fn visit_call_poly_args(&mut self, ctx: &mut Ctx, call_id: CallExpressionId) -> VisitorResult {
         let call_expr = &ctx.heap[call_id];
         // Determine the polyarg signature
         let num_expected_poly_args = match &call_expr.method {
             Method::Create => {
             },
             Method::Fires => {
             },
             Method::Get => {
             },
             Method::Put => {
+            }
             Method::Symbolic(symbolic) => {
                 let definition = &ctx.heap[symbolic.definition.unwrap()];
                 match definition {
                     Definition::Function(definition) => definition.poly_vars.len(),
                     Definition::Component(definition) => definition.poly_vars.len(),
                     _ => {
                         debug_assert!(false, "expected function or component definition while visiting call poly args");
                         unreachable!();
+                    }
+                }
+            }
         };
         // We allow zero polyargs to imply all args are inferred. Otherwise the
         // number of arguments must be equal
         if call_expr.poly_args.is_empty() {
             if num_expected_poly_args != 0 {
                 // Infer all polyargs
                 // TODO: @cleanup Not nice to use method position as implicitly
                 //  inferred parser type pos.
                 let pos = call_expr.position();
                 for _ in 0..num_expected_poly_args {
                     self.parser_type_buffer.push(ctx.heap.alloc_parser_type(|this| ParserType {
                         this,
                         pos,
                         variant: ParserTypeVariant::Inferred,
                     }));
+                }
                 let call_expr = &mut ctx.heap[call_id];
                 call_expr.poly_args.reserve(num_expected_poly_args);
                 for _ in 0..num_expected_poly_args {
                     call_expr.poly_args.push(self.parser_type_buffer.pop().unwrap());
+                }
+            }
             Ok(())
         } else if call_expr.poly_args.len() == num_expected_poly_args {
             // Number of args is not 0, so parse all the specified ParserTypes
             let old_num_types = self.parser_type_buffer.len();
             self.parser_type_buffer.extend(&call_expr.poly_args);
             while self.parser_type_buffer.len() > old_num_types {
                 let parser_type_id = self.parser_type_buffer.pop().unwrap();
                 self.visit_parser_type(ctx, parser_type_id)?;
+            }
             self.parser_type_buffer.truncate(old_num_types);
             Ok(())
         } else {
             return Err(ParseError2::new_error(
                 &ctx.module.source, call_expr.position,
                 &format!(
                     "Expected {} polymorphic arguments (or none, to infer them), but {} were specified",
                     num_expected_poly_args, call_expr.poly_args.len()
+                )
             ));
+        }
+    }
     fn visit_literal_poly_args(&mut self, ctx: &mut Ctx, lit_id: LiteralExpressionId) -> VisitorResult {
         let literal_expr = &ctx.heap[lit_id];
         let (num_specified_poly_ags, num_expected_poly_args) = match &literal_expr.value {
             Literal::Null | Literal::False | Literal::True |
             Literal::Character(_) | Literal::Integer(_) => {
                 // Not really an error, but a programmer error as we're likely
                 // doing work twice
                 debug_assert!(false, "called visit_literal_poly_args on a non-polymorphic literal");
                 unreachable!();
             },
             Literal::Struct(literal) => {
                 let definition = &ctx.heap[literal.definition.unwrap()];
                 let num_expected = match definition {
                     Definition::Struct(definition) => definition.poly_vars.len(),
                     _ => {
                         debug_assert!(false, "expected struct literal while visiting literal poly args");
                         unreachable!();
+                    }
                 };
                 (literal.poly_args.len(), num_expected)
+            }
         };
         if num_specified_poly_ags == 0 {
             if num_expected_poly_args != 0 {
                 let pos = literal_expr.position;
                 for _ in 0..num_expected_poly_args {
                     self.parser_type_buffer.push(ctx.heap.alloc_parser_type(|this| ParserType{
                         this, pos, variant: ParserTypeVariant::Inferred
                     }));
+                }
                 let literal_expr = match &mut
+            }
+        }
+    }
+}
@@ \ No newline at end of file @@

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