CSY/reowolf Changeset - e24c723760cb · Centrum Wiskunde & Informatica (CWI)

Changeset - e24c723760cb

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0 6 1

MH - 4 years ago 2021-03-26 17:28:33
contact@maxhenger.nl

struct field access and inference seems to be implemented

7 files changed with 574 insertions and 115 deletions:

src/protocol/ast.rs

src/protocol/ast_printer.rs

src/protocol/lexer.rs

src/protocol/parser/type_resolver.rs

279

112

src/protocol/tests/parser_inference.rs

new file

src/protocol/tests/parser_validation.rs

src/protocol/tests/utils.rs

221

0 comments (0 inline, 0 general)

src/protocol/ast.rs

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Show inline comments

@@ @@ -977,107 +977,116 @@ impl Literal { @@
+    }
     pub(crate) fn as_struct_mut(&mut self) -> &mut LiteralStruct {
         if let Literal::Struct(literal) = self{
             literal
         } else {
             unreachable!("Attempted to obtain {:?} as Literal::Struct", self)
+        }
+    }
+}
 #[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
 pub struct LiteralStructField {
     // Phase 1: parser
     pub(crate) identifier: Identifier,
     pub(crate) value: ExpressionId,
     // Phase 2: linker
     pub(crate) field_idx: usize, // in struct definition
+}
 #[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
 pub struct LiteralStruct {
     // Phase 1: parser
     pub(crate) identifier: NamespacedIdentifier,
     pub(crate) poly_args: Vec<ParserTypeId>,
     pub(crate) fields: Vec<LiteralStructField>,
     // Phase 2: linker
     pub(crate) definition: Option<DefinitionId>
+}
 #[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
 pub enum Method {
     Get,
     Put,
     Fires,
     Create,
     Symbolic(MethodSymbolic)
+}
 #[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
 pub struct MethodSymbolic {
     pub(crate) identifier: NamespacedIdentifier,
     pub(crate) definition: Option<DefinitionId>
+}
 #[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
 pub enum Field {
     Length,
-    Symbolic(Identifier),
+    Symbolic(FieldSymbolic),
+}
 impl Field {
     pub fn is_length(&self) -> bool {
         match self {
             Field::Length => true,
             _ => false,
+        }
+    }
+}
 #[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
 pub struct FieldSymbolic {
     // Phase 1: Parser
     pub(crate) identifier: Identifier,
     // Phase 3: Typing
     pub(crate) definition: Option<DefinitionId>,
     pub(crate) field_idx: usize,
+}
 #[derive(Debug, Clone, Copy, serde::Serialize, serde::Deserialize)]
 pub enum Scope {
     Definition(DefinitionId),
     Regular(BlockStatementId),
     Synchronous((SynchronousStatementId, BlockStatementId)),
+}
 impl Scope {
     pub fn is_block(&self) -> bool {
         match &self {
             Scope::Definition(_) => false,
             Scope::Regular(_) => true,
             Scope::Synchronous(_) => true,
+        }
+    }
     pub fn to_block(&self) -> BlockStatementId {
         match &self {
             Scope::Regular(id) => *id,
             Scope::Synchronous((_, id)) => *id,
             _ => panic!("unable to get BlockStatement from Scope")
+        }
+    }
+}
 pub trait VariableScope {
     fn parent_scope(&self, h: &Heap) -> Option<Scope>;
     fn get_variable(&self, h: &Heap, id: &Identifier) -> Option<VariableId>;
+}
 impl VariableScope for Scope {
     fn parent_scope(&self, h: &Heap) -> Option<Scope> {
         match self {
             Scope::Definition(def) => h[*def].parent_scope(h),
             Scope::Regular(stmt) => h[*stmt].parent_scope(h),
             Scope::Synchronous((stmt, _)) => h[*stmt].parent_scope(h),
+        }
+    }
     fn get_variable(&self, h: &Heap, id: &Identifier) -> Option<VariableId> {
         match self {
             Scope::Definition(def) => h[*def].get_variable(h, id),
             Scope::Regular(stmt) => h[*stmt].get_variable(h, id),
             Scope::Synchronous((stmt, _)) => h[*stmt].get_variable(h, id),
+        }
+    }
+}
 #[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
 pub enum Variable {

src/protocol/ast_printer.rs

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Show inline comments

@@ @@ -546,97 +546,99 @@ impl ASTWriter { @@
             Expression::Unary(expr) => {
                 self.kv(indent).with_id(PREFIX_UNARY_EXPR_ID, expr.this.0.index)
                     .with_s_key("UnaryExpr");
                 self.kv(indent2).with_s_key("Operation").with_debug_val(&expr.operation);
                 self.kv(indent2).with_s_key("Argument");
                 self.write_expr(heap, expr.expression, indent3);
                 self.kv(indent2).with_s_key("Parent")
                     .with_custom_val(|v| write_expression_parent(v, &expr.parent));
                 self.kv(indent2).with_s_key("ConcreteType")
                     .with_custom_val(|v| write_concrete_type(v, heap, def_id, &expr.concrete_type));
             },
             Expression::Indexing(expr) => {
                 self.kv(indent).with_id(PREFIX_INDEXING_EXPR_ID, expr.this.0.index)
                     .with_s_key("IndexingExpr");
                 self.kv(indent2).with_s_key("Subject");
                 self.write_expr(heap, expr.subject, indent3);
                 self.kv(indent2).with_s_key("Index");
                 self.write_expr(heap, expr.index, indent3);
                 self.kv(indent2).with_s_key("Parent")
                     .with_custom_val(|v| write_expression_parent(v, &expr.parent));
                 self.kv(indent2).with_s_key("ConcreteType")
                     .with_custom_val(|v| write_concrete_type(v, heap, def_id, &expr.concrete_type));
             },
             Expression::Slicing(expr) => {
                 self.kv(indent).with_id(PREFIX_SLICING_EXPR_ID, expr.this.0.index)
                     .with_s_key("SlicingExpr");
                 self.kv(indent2).with_s_key("Subject");
                 self.write_expr(heap, expr.subject, indent3);
                 self.kv(indent2).with_s_key("FromIndex");
                 self.write_expr(heap, expr.from_index, indent3);
                 self.kv(indent2).with_s_key("ToIndex");
                 self.write_expr(heap, expr.to_index, indent3);
                 self.kv(indent2).with_s_key("Parent")
                     .with_custom_val(|v| write_expression_parent(v, &expr.parent));
                 self.kv(indent2).with_s_key("ConcreteType")
                     .with_custom_val(|v| write_concrete_type(v, heap, def_id, &expr.concrete_type));
             },
             Expression::Select(expr) => {
                 self.kv(indent).with_id(PREFIX_SELECT_EXPR_ID, expr.this.0.index)
                     .with_s_key("SelectExpr");
                 self.kv(indent2).with_s_key("Subject");
                 self.write_expr(heap, expr.subject, indent3);
                 match &expr.field {
                     Field::Length => {
                         self.kv(indent2).with_s_key("Field").with_s_val("length");
                     },
                     Field::Symbolic(field) => {
                         self.kv(indent2).with_s_key("Field").with_ascii_val(&field.value);
                         self.kv(indent2).with_s_key("Field").with_ascii_val(&field.identifier.value);
                         self.kv(indent3).with_s_key("Definition").with_opt_disp_val(field.definition.as_ref().map(|v| &v.index));
                         self.kv(indent3).with_s_key("Index").with_disp_val(&field.field_idx);
+                    }
+                }
                 self.kv(indent2).with_s_key("Parent")
                     .with_custom_val(|v| write_expression_parent(v, &expr.parent));
                 self.kv(indent2).with_s_key("ConcreteType")
                     .with_custom_val(|v| write_concrete_type(v, heap, def_id, &expr.concrete_type));
             },
             Expression::Array(expr) => {
                 self.kv(indent).with_id(PREFIX_ARRAY_EXPR_ID, expr.this.0.index)
                     .with_s_key("ArrayExpr");
                 self.kv(indent2).with_s_key("Elements");
                 for expr_id in &expr.elements {
                     self.write_expr(heap, *expr_id, indent3);
+                }
                 self.kv(indent2).with_s_key("Parent")
                     .with_custom_val(|v| write_expression_parent(v, &expr.parent));
                 self.kv(indent2).with_s_key("ConcreteType")
                     .with_custom_val(|v| write_concrete_type(v, heap, def_id, &expr.concrete_type));
             },
             Expression::Literal(expr) => {
                 self.kv(indent).with_id(PREFIX_CONST_EXPR_ID, expr.this.0.index)
                     .with_s_key("ConstantExpr");
                 let val = self.kv(indent2).with_s_key("Value");
                 match &expr.value {
                     Literal::Null => { val.with_s_val("null"); },
                     Literal::True => { val.with_s_val("true"); },
                     Literal::False => { val.with_s_val("false"); },
                     Literal::Character(data) => { val.with_ascii_val(data); },
                     Literal::Integer(data) => { val.with_disp_val(data); },
                     Literal::Struct(data) => {
                         val.with_s_val("Struct");
                         let indent4 = indent3 + 1;
                         // Polymorphic arguments
                         if !data.poly_args.is_empty() {
                             self.kv(indent3).with_s_key("PolymorphicArguments");
                             for poly_arg in &data.poly_args {
                                 self.kv(indent4).with_s_key("Argument")
                                     .with_custom_val(|v| write_parser_type(v, heap, &heap[*poly_arg]));
+                            }
+                        }
                         for field in &data.fields {
                             self.kv(indent3).with_s_key("Field");
                             self.kv(indent4).with_s_key("Name").with_ascii_val(&field.identifier.value);
                             self.kv(indent4).with_s_key("Index").with_disp_val(&field.field_idx);

src/protocol/lexer.rs

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Show inline comments

@@ @@ -1262,97 +1262,102 @@ impl Lexer<'_> { @@
                 let subject = result;
                 let index = self.consume_expression(h)?;
                 self.consume_whitespace(false)?;
                 if self.has_string(b"..") || self.has_string(b":") {
                     position = self.source.pos();
                     if self.has_string(b"..") {
                         self.consume_string(b"..")?;
                     } else {
                         self.consume_string(b":")?;
+                    }
                     self.consume_whitespace(false)?;
                     let to_index = self.consume_expression(h)?;
                     self.consume_whitespace(false)?;
                     result = h
                         .alloc_slicing_expression(|this| SlicingExpression {
                             this,
                             position,
                             subject,
                             from_index: index,
                             to_index,
                             parent: ExpressionParent::None,
                             concrete_type: ConcreteType::default(),
                         })
                         .upcast();
                 } else {
                     result = h
                         .alloc_indexing_expression(|this| IndexingExpression {
                             this,
                             position,
                             subject,
                             index,
                             parent: ExpressionParent::None,
                             concrete_type: ConcreteType::default(),
                         })
                         .upcast();
+                }
                 self.consume_string(b"]")?;
                 self.consume_whitespace(false)?;
             } else {
                 assert!(self.has_string(b"."));
                 self.consume_string(b".")?;
                 self.consume_whitespace(false)?;
                 let subject = result;
                 let field;
                 if self.has_keyword(b"length") {
                     self.consume_keyword(b"length")?;
                     field = Field::Length;
                 } else {
                     field = Field::Symbolic(self.consume_identifier()?);
                     let identifier = self.consume_identifier()?;
                     field = Field::Symbolic(FieldSymbolic{
                         identifier,
                         definition: None,
                         field_idx: 0,
                     });
+                }
                 result = h
                     .alloc_select_expression(|this| SelectExpression {
                         this,
                         position,
                         subject,
                         field,
                         parent: ExpressionParent::None,
                         concrete_type: ConcreteType::default(),
                     })
                     .upcast();
+            }
+        }
         Ok(result)
+    }
     fn consume_primary_expression(&mut self, h: &mut Heap) -> Result<ExpressionId, ParseError2> {
         if self.has_string(b"(") {
             return self.consume_paren_expression(h);
+        }
         if self.has_string(b"{") {
             return Ok(self.consume_array_expression(h)?.upcast());
+        }
         if self.has_builtin_literal() {
             return Ok(self.consume_builtin_literal_expression(h)?.upcast());
+        }
         if self.has_struct_literal() {
             return Ok(self.consume_struct_literal_expression(h)?.upcast());
+        }
         if self.has_call_expression() {
             return Ok(self.consume_call_expression(h)?.upcast());
+        }
         Ok(self.consume_variable_expression(h)?.upcast())
+    }
     fn consume_array_expression(&mut self, h: &mut Heap) -> Result<ArrayExpressionId, ParseError2> {
         let position = self.source.pos();
         let mut elements = Vec::new();
         self.consume_string(b"{")?;
         self.consume_whitespace(false)?;
         if !self.has_string(b"}") {
             while self.source.next().is_some() {
                 elements.push(self.consume_expression(h)?);
                 self.consume_whitespace(false)?;
                 if self.has_string(b"}") {
                     break;
+                }
                 self.consume_string(b",")?;
                 self.consume_whitespace(false)?;
+            }

src/protocol/parser/type_resolver.rs

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Show inline comments

 /// type_resolver.rs
 ///
 /// Performs type inference and type checking. Type inference is implemented by
 /// applying constraints on (sub)trees of types. During this process the
 /// resolver takes the `ParserType` structs (the representation of the types
 /// written by the programmer), converts them to `InferenceType` structs (the
 /// temporary data structure used during type inference) and attempts to arrive
 /// at `ConcreteType` structs (the representation of a fully checked and
 /// validated type).
 ///
 /// The resolver will visit every statement and expression relevant to the
 /// procedure and insert and determine its initial type based on context (e.g. a
 /// return statement's expression must match the function's return type, an
 /// if statement's test expression must evaluate to a boolean). When all are
 /// visited we attempt to make progress in evaluating the types. Whenever a type
 /// is progressed we queue the related expressions for further type progression.
 /// Once no more expressions are in the queue the algorithm is finished. At this
 /// point either all types are inferred (or can be trivially implicitly
 /// determined), or we have incomplete types. In the latter casee we return an
 /// error.
 ///
 /// Inference may be applied on non-polymorphic procedures and on polymorphic
 /// procedures. When dealing with a non-polymorphic procedure we apply the type
 /// resolver and annotate the AST with the `ConcreteType`s. When dealing with
 /// polymorphic procedures we will only annotate the AST once, preserving
 /// references to polymorphic variables. Any later pass will perform just the
 /// type checking.
 ///
 /// TODO: Needs an optimization pass
 /// TODO: Needs a cleanup pass
 ///     slightly more specific: initially it seemed that expressions just need
 ///     to apply constraints between their expression types and the expression
 ///     types of the arguments. But it seems to appear more-and-more that the
 ///     expressions may need their own little datastructures. Using some kind of
 ///     scratch allocator and proper considerations for dependencies might lead
 ///     to a much more efficient algorithm
 ///     to a much more efficient algorithm.
 /// Also: Perhaps instead of this serialized tree with markers, we could
 ///     investigate writing it as a graph, where ocurrences of polymorphic
 ///     variables all point to the same type.
 /// TODO: Disallow `Void` types in various expressions (and other future types)
 /// TODO: Maybe remove msg type?
 macro_rules! enabled_debug_print {
     (false, $name:literal, $format:literal) => {};
     (false, $name:literal, $format:literal, $($args:expr),*) => {};
     (true, $name:literal, $format:literal) => {
         println!("[{}] {}", $name, $format)
     };
     (true, $name:literal, $format:literal, $($args:expr),*) => {
         println!("[{}] {}", $name, format!($format, $($args),*))
     };
+}
 macro_rules! debug_log {
     ($format:literal) => {
         enabled_debug_print!(true, "types", $format);
     };
     ($format:literal, $($args:expr),*) => {
         enabled_debug_print!(true, "types", $format, $($args),*);
     };
+}
 use std::collections::{HashMap, HashSet, VecDeque};
 use crate::protocol::ast::*;
 use crate::protocol::inputsource::*;
 use crate::protocol::parser::type_table::*;
 use super::visitor::{
     STMT_BUFFER_INIT_CAPACITY,
     EXPR_BUFFER_INIT_CAPACITY,
     Ctx,
     Visitor2,
     VisitorResult
 };
 use std::collections::hash_map::Entry;
 const MESSAGE_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::Message, InferenceTypePart::Byte ];
 const BOOL_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::Bool ];
 const NUMBERLIKE_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::NumberLike ];
 const INTEGERLIKE_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::IntegerLike ];
 const ARRAY_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::Array, InferenceTypePart::Unknown ];
 const ARRAYLIKE_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::ArrayLike, InferenceTypePart::Unknown ];
 /// TODO: @performance Turn into PartialOrd+Ord to simplify checks
 /// TODO: @types Remove the Message -> Byte hack at some point...
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub(crate) enum InferenceTypePart {
@@ @@ -229,98 +232,114 @@ impl From<ConcreteTypePart> for InferenceTypePart { @@
             CTP::Array => ITP::Array,
             CTP::Slice => ITP::Slice,
             CTP::Input => ITP::Input,
             CTP::Output => ITP::Output,
             CTP::Instance(id, num) => ITP::Instance(id, num),
+        }
+    }
+}
 #[derive(Debug)]
 struct InferenceType {
     has_body_marker: bool,
     is_done: bool,
     parts: Vec<InferenceTypePart>,
+}
 impl InferenceType {
     /// Generates a new InferenceType. The two boolean flags will be checked in
     /// debug mode.
     fn new(has_body_marker: bool, is_done: bool, parts: Vec<InferenceTypePart>) -> Self {
         if cfg!(debug_assertions) {
             debug_assert!(!parts.is_empty());
             if !has_body_marker {
                 debug_assert!(parts.iter().all(|v| {
                     if let InferenceTypePart::MarkerBody(_) = v { false } else { true }
                 }));
+            }
             if is_done {
                 debug_assert!(parts.iter().all(|v| v.is_concrete()));
+            }
+        }
         Self{ has_body_marker: has_body_marker, is_done, parts }
+    }
     /// Replaces a type subtree with the provided subtree. The caller must make
     /// sure the the replacement is a well formed type subtree.
     fn replace_subtree(&mut self, start_idx: usize, with: &[InferenceTypePart]) {
         let end_idx = Self::find_subtree_end_idx(&self.parts, start_idx);
         debug_assert_eq!(with.len(), Self::find_subtree_end_idx(with, 0));
         self.parts.splice(start_idx..end_idx, with.iter().cloned());
         self.recompute_is_done();
+    }
     // TODO: @performance, might all be done inline in the type inference methods
     fn recompute_is_done(&mut self) {
         self.is_done = self.parts.iter().all(|v| v.is_concrete());
+    }
     /// Seeks a body marker starting at the specified position. If a marker is
     /// found then its value and the index of the type subtree that follows it
     /// is returned.
     fn find_body_marker(&self, mut start_idx: usize) -> Option<(usize, usize)> {
         while start_idx < self.parts.len() {
             if let InferenceTypePart::MarkerBody(marker) = &self.parts[start_idx] {
                 return Some((*marker, start_idx + 1))
+            }
             start_idx += 1;
+        }
         None
+    }
     /// Returns an iterator over all body markers and the partial type tree that
     /// follows those markers.
     /// follows those markers. If it is a problem that `InferenceType` is
     /// borrowed by the iterator, then use `find_body_marker`.
     fn body_marker_iter(&self) -> InferenceTypeMarkerIter {
         InferenceTypeMarkerIter::new(&self.parts)
+    }
     /// Given that the `parts` are a depth-first serialized tree of types, this
     /// function finds the subtree anchored at a specific node. The returned
     /// index is exclusive.
     fn find_subtree_end_idx(parts: &[InferenceTypePart], start_idx: usize) -> usize {
         let mut depth = 1;
         let mut idx = start_idx;
         while idx < parts.len() {
             depth += parts[idx].depth_change();
             if depth == 0 {
                 return idx + 1;
+            }
             idx += 1;
+        }
         // If here, then the inference type is malformed
         unreachable!();
+    }
     /// Call that attempts to infer the part at `to_infer.parts[to_infer_idx]`
     /// using the subtree at `template.parts[template_idx]`. Will return
     /// `Some(depth_change_due_to_traversal)` if type inference has been
     /// applied. In this case the indices will also be modified to point to the
     /// next part in both templates. If type inference has not (or: could not)
     /// be applied then `None` will be returned. Note that this might mean that
     /// the types are incompatible.
     ///
     /// As this is a helper functions, some assumptions: the parts are not
     /// exactly equal, and neither of them contains a marker. Also: only the
     /// `to_infer` parts are checked for inference. It might be that this
     /// function returns `None`, but that that `template` is still compatible
     /// with `to_infer`, e.g. when `template` has an `Unknown` part.
     fn infer_part_for_single_type(
         to_infer: &mut InferenceType, to_infer_idx: &mut usize,
         template_parts: &[InferenceTypePart], template_idx: &mut usize,
     ) -> Option<i32> {
         use InferenceTypePart as ITP;
         let to_infer_part = &to_infer.parts[*to_infer_idx];
         let template_part = &template_parts[*template_idx];
         // TODO: Maybe do this differently?
         let mut template_definition_marker = None;
         if *template_idx > 0 {
@@ @@ -764,97 +783,97 @@ impl DualInferenceResult { @@
             DualInferenceResult::First | DualInferenceResult::Both => true,
             _ => false
+        }
+    }
     fn modified_rhs(&self) -> bool {
         match self {
             DualInferenceResult::Second | DualInferenceResult::Both => true,
             _ => false
+        }
+    }
+}
 #[derive(Debug, PartialEq, Eq)]
 enum SingleInferenceResult {
     Unmodified,
     Modified,
     Incompatible
+}
 enum DefinitionType{
     None,
     Component(ComponentId),
     Function(FunctionId),
+}
 pub(crate) struct ResolveQueueElement {
     pub(crate) root_id: RootId,
     pub(crate) definition_id: DefinitionId,
     pub(crate) monomorph_types: Vec<ConcreteType>,
+}
 pub(crate) type ResolveQueue = Vec<ResolveQueueElement>;
 /// This particular visitor will recurse depth-first into the AST and ensures
 /// that all expressions have the appropriate types.
 pub(crate) struct TypeResolvingVisitor {
     // Current definition we're typechecking.
     definition_type: DefinitionType,
     poly_vars: Vec<ConcreteType>,
     // Buffers for iteration over substatements and subexpressions
     stmt_buffer: Vec<StatementId>,
     expr_buffer: Vec<ExpressionId>,
     // Mapping from parser type to inferred type. We attempt to continue to
     // specify these types until we're stuck or we've fully determined the type.
     var_types: HashMap<VariableId, VarData>,      // types of variables
     expr_types: HashMap<ExpressionId, InferenceType>,   // types of expressions
-    extra_data: HashMap<ExpressionId, ExtraData>,       // data for function call inference
+    extra_data: HashMap<ExpressionId, ExtraData>,       // data for polymorph inference
     // Keeping track of which expressions need to be reinferred because the
     // expressions they're linked to made progression on an associated type
     expr_queued: HashSet<ExpressionId>,
+}
 // TODO: @rename used for calls and struct literals, maybe union literals?
 struct ExtraData {
     /// Progression of polymorphic variables (if any)
     poly_vars: Vec<InferenceType>,
     /// Progression of types of call arguments or struct members
     embedded: Vec<InferenceType>,
     returned: InferenceType,
+}
 struct VarData {
     /// Type of the variable
     var_type: InferenceType,
     /// VariableExpressions that use the variable
     used_at: Vec<ExpressionId>,
     /// For channel statements we link to the other variable such that when one
     /// channel's interior type is resolved, we can also resolve the other one.
     linked_var: Option<VariableId>,
+}
 impl VarData {
     fn new_channel(var_type: InferenceType, other_port: VariableId) -> Self {
         Self{ var_type, used_at: Vec::new(), linked_var: Some(other_port) }
+    }
     fn new_local(var_type: InferenceType) -> Self {
         Self{ var_type, used_at: Vec::new(), linked_var: None }
+    }
+}
 impl TypeResolvingVisitor {
     pub(crate) fn new() -> Self {
         TypeResolvingVisitor{
             definition_type: DefinitionType::None,
             poly_vars: Vec::new(),
             stmt_buffer: Vec::with_capacity(STMT_BUFFER_INIT_CAPACITY),
             expr_buffer: Vec::with_capacity(EXPR_BUFFER_INIT_CAPACITY),
             var_types: HashMap::new(),
             expr_types: HashMap::new(),
             extra_data: HashMap::new(),
             expr_queued: HashSet::new(),
+        }
+    }
     // TODO: @cleanup Unsure about this, maybe a pattern will arise after
@@ @@ -1255,146 +1274,162 @@ macro_rules! debug_assert_expr_ids_unique_and_known { @@
+}
 macro_rules! debug_assert_ptrs_distinct {
     // Base case
     ($ptr1:ident, $ptr2:ident) => {
         debug_assert!(!std::ptr::eq($ptr1, $ptr2));
     };
     // Generic case
     ($ptr1:ident, $ptr2:ident, $($tail:ident),+) => {
         debug_assert_ptrs_distinct!($ptr1, $ptr2);
         debug_assert_ptrs_distinct!($ptr2, $($tail),+);
     };
+}
 impl TypeResolvingVisitor {
     fn resolve_types(&mut self, ctx: &mut Ctx, queue: &mut ResolveQueue) -> Result<(), ParseError2> {
         // Keep inferring until we can no longer make any progress
         while let Some(next_expr_id) = self.expr_queued.iter().next() {
             let next_expr_id = *next_expr_id;
             self.expr_queued.remove(&next_expr_id);
             self.progress_expr(ctx, next_expr_id)?;
+        }
         // Should have inferred everything. Check for this and optionally
         // auto-infer the remaining types
         for (expr_id, expr_type) in self.expr_types.iter_mut() {
             if !expr_type.is_done {
                 // Auto-infer numberlike/integerlike types to a regular int
                 if expr_type.parts.len() == 1 && expr_type.parts[0] == InferenceTypePart::IntegerLike {
                     expr_type.parts[0] = InferenceTypePart::Int;
                 } else {
                     let expr = &ctx.heap[*expr_id];
                     return Err(ParseError2::new_error(
                         &ctx.module.source, expr.position(),
                         &format!(
                             "Could not fully infer the type of this expression (got '{}')",
                             expr_type.display_name(&ctx.heap)
+                        )
                     ))
+                }
+            }
             let concrete_type = ctx.heap[*expr_id].get_type_mut();
             expr_type.write_concrete_type(concrete_type);
+        }
         // Check all things we need to monomorphize
         // TODO: Struct/enum/union monomorphization
-        for (call_expr_id, extra_data) in self.extra_data.iter() {
+        for (expr_id, extra_data) in self.extra_data.iter() {
             if extra_data.poly_vars.is_empty() { continue; }
             // Retrieve polymorph variable specification
             let mut monomorph_types = Vec::with_capacity(extra_data.poly_vars.len());
             for (poly_idx, poly_type) in extra_data.poly_vars.iter().enumerate() {
                 if !poly_type.is_done {
                     // TODO: Single clean function for function signatures and polyvars.
                     // TODO: Better error message
                     let expr = &ctx.heap[*call_expr_id];
                     return Err(ParseError2::new_error(
                         &ctx.module.source, expr.position(),
                         &format!(
                             "Could not fully infer the type of polymorphic variable {} of this expression (got '{}')",
                             poly_idx, poly_type.display_name(&ctx.heap)
+                        )
                     ))
+                }
             // Retrieve polymorph variable specification. Those of struct
             // literals and those of procedure calls need to be fully inferred
             let needs_full_inference = match &ctx.heap[*expr_id] {
                 Expression::Call(_) => true,
                 Expression::Literal(_) => true,
                 _ => false
             };
                 let mut concrete_type = ConcreteType::default();
                 poly_type.write_concrete_type(&mut concrete_type);
                 monomorph_types.insert(poly_idx, concrete_type);
+            }
             if needs_full_inference {
                 let mut monomorph_types = Vec::with_capacity(extra_data.poly_vars.len());
                 for (poly_idx, poly_type) in extra_data.poly_vars.iter().enumerate() {
                     if !poly_type.is_done {
                         // TODO: Single clean function for function signatures and polyvars.
                         // TODO: Better error message
                         let expr = &ctx.heap[*expr_id];
                         return Err(ParseError2::new_error(
                             &ctx.module.source, expr.position(),
                             &format!(
                                 "Could not fully infer the type of polymorphic variable {} of this expression (got '{}')",
                                 poly_idx, poly_type.display_name(&ctx.heap)
+                            )
                         ))
+                    }
             // Resolve to call expression's definition
             let call_expr = if let Expression::Call(call_expr) = &ctx.heap[*call_expr_id] {
                 call_expr
             } else {
                 todo!("implement different kinds of polymorph expressions");
             };
                     let mut concrete_type = ConcreteType::default();
                     poly_type.write_concrete_type(&mut concrete_type);
                     monomorph_types.insert(poly_idx, concrete_type);
+                }
             // Add to type table if not yet typechecked
             if let Method::Symbolic(symbolic) = &call_expr.method {
                 let definition_id = symbolic.definition.unwrap();
                 if !ctx.types.has_monomorph(&definition_id, &monomorph_types) {
                     let root_id = ctx.types
                         .get_base_definition(&definition_id)
                         .unwrap()
                         .ast_root;
                     // Pre-emptively add the monomorph to the type table, but
                     // we still need to perform typechecking on it
                     ctx.types.add_monomorph(&definition_id, monomorph_types.clone());
                     queue.push(ResolveQueueElement {
                         root_id,
                         definition_id,
                         monomorph_types,
                     })
                 // Resolve to the appropriate expression and instantiate
                 // monomorphs.
                 match &ctx.heap[*expr_id] {
                     Expression::Call(call_expr) => {
                         // Add to type table if not yet typechecked
                         if let Method::Symbolic(symbolic) = &call_expr.method {
                             let definition_id = symbolic.definition.unwrap();
                             if !ctx.types.has_monomorph(&definition_id, &monomorph_types) {
                                 let root_id = ctx.types
                                     .get_base_definition(&definition_id)
                                     .unwrap()
                                     .ast_root;
                                 // Pre-emptively add the monomorph to the type table, but
                                 // we still need to perform typechecking on it
                                 ctx.types.add_monomorph(&definition_id, monomorph_types.clone());
                                 queue.push(ResolveQueueElement {
                                     root_id,
                                     definition_id,
                                     monomorph_types,
                                 })
+                            }
+                        }
                     },
                     Expression::Literal(lit_expr) => {
                         let lit_struct = lit_expr.value.as_struct();
                         let definition_id = lit_struct.definition.as_ref().unwrap();
                         if !ctx.types.has_monomorph(definition_id, &monomorph_types) {
                             ctx.types.add_monomorph(definition_id, monomorph_types);
+                        }
                     },
                     _ => unreachable!("needs fully inference, but not a struct literal or call expression")
+                }
+            }
+            } // else: was just a helper structure...
+        }
         Ok(())
+    }
     fn progress_expr(&mut self, ctx: &mut Ctx, id: ExpressionId) -> Result<(), ParseError2> {
         match &ctx.heap[id] {
             Expression::Assignment(expr) => {
                 let id = expr.this;
                 self.progress_assignment_expr(ctx, id)
             },
             Expression::Conditional(expr) => {
                 let id = expr.this;
                 self.progress_conditional_expr(ctx, id)
             },
             Expression::Binary(expr) => {
                 let id = expr.this;
                 self.progress_binary_expr(ctx, id)
             },
             Expression::Unary(expr) => {
                 let id = expr.this;
                 self.progress_unary_expr(ctx, id)
             },
             Expression::Indexing(expr) => {
                 let id = expr.this;
                 self.progress_indexing_expr(ctx, id)
             },
             Expression::Slicing(expr) => {
                 let id = expr.this;
                 self.progress_slicing_expr(ctx, id)
             },
             Expression::Select(expr) => {
                 let id = expr.this;
                 self.progress_select_expr(ctx, id)
             },
             Expression::Array(expr) => {
                 let id = expr.this;
                 self.progress_array_expr(ctx, id)
             },
             Expression::Literal(expr) => {
                 let id = expr.this;
                 self.progress_literal_expr(ctx, id)
             },
             Expression::Call(expr) => {
                 let id = expr.this;
                 self.progress_call_expr(ctx, id)
             },
             Expression::Variable(expr) => {
@@ @@ -1633,171 +1668,265 @@ impl TypeResolvingVisitor { @@
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_subject_base || progress_subject { self.queue_expr(subject_id); }
         if progress_index { self.queue_expr(index_id); }
         Ok(())
+    }
     fn progress_slicing_expr(&mut self, ctx: &mut Ctx, id: SlicingExpressionId) -> Result<(), ParseError2> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let subject_id = expr.subject;
         let from_id = expr.from_index;
         let to_id = expr.to_index;
         debug_log!("Slicing expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Subject type: {}", self.expr_types.get(&subject_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - FromIdx type: {}", self.expr_types.get(&from_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - ToIdx   type: {}", self.expr_types.get(&to_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - Expr    type: {}", self.expr_types.get(&upcast_id).unwrap().display_name(&ctx.heap));
         // Make sure subject is arraylike and indices are of equal integerlike
         let progress_subject_base = self.apply_forced_constraint(ctx, subject_id, &ARRAYLIKE_TEMPLATE)?;
         let progress_idx_base = self.apply_forced_constraint(ctx, from_id, &INTEGERLIKE_TEMPLATE)?;
         let (progress_from, progress_to) = self.apply_equal2_constraint(ctx, upcast_id, from_id, 0, to_id, 0)?;
         // Make sure if output is of T then subject is Array<T>
         let (progress_expr, progress_subject) =
             self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 0, subject_id, 1)?;
         debug_log!(" * After:");
         debug_log!("   - Subject type [{}]: {}", progress_subject_base || progress_subject, self.expr_types.get(&subject_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - FromIdx type [{}]: {}", progress_idx_base || progress_from, self.expr_types.get(&from_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - ToIdx   type [{}]: {}", progress_idx_base || progress_to, self.expr_types.get(&to_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - Expr    type [{}]: {}", progress_expr, self.expr_types.get(&upcast_id).unwrap().display_name(&ctx.heap));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_subject_base || progress_subject { self.queue_expr(subject_id); }
         if progress_idx_base || progress_from { self.queue_expr(from_id); }
         if progress_idx_base || progress_to { self.queue_expr(to_id); }
         Ok(())
+    }
     fn progress_select_expr(&mut self, ctx: &mut Ctx, id: SelectExpressionId) -> Result<(), ParseError2> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let subject_id = expr.subject;
         debug_log!("Select expr: {}", upcast_id.index);
         debug_log!(" * Before:");
-        debug_log!("   - Subject type: {}", self.expr_types.get(&subject_id).unwrap().display_name(&ctx.heap));
+        debug_log!("   - Subject type: {}", self.expr_types.get(&ctx.heap[id].subject).unwrap().display_name(&ctx.heap));
         debug_log!("   - Expr    type: {}", self.expr_types.get(&upcast_id).unwrap().display_name(&ctx.heap));
         let (progress_subject, progress_expr) = match &expr.field {
         let expr = &mut ctx.heap[id];
         let subject_id = expr.subject;
         fn determine_inference_type_instance<'a>(types: &'a TypeTable, infer_type: &InferenceType) -> Result<Option<&'a DefinedType>, ()> {
             for part in &infer_type.parts {
                 if part.is_marker() || !part.is_concrete() {
                     continue;
+                }
                 // Part is concrete, check if it is an instance of something
                 if let InferenceTypePart::Instance(definition_id, _num_sub) = part {
                     // Lookup type definition and ensure the specified field
                     // name exists on the struct
                     let definition = types.get_base_definition(definition_id);
                     debug_assert!(definition.is_some());
                     let definition = definition.unwrap();
                     return Ok(Some(definition))
                 } else {
                     // Expected an instance of something
                     return Err(())
+                }
+            }
             // Nothing is concrete yet
             Ok(None)
+        }
         let (progress_subject, progress_expr) = match &mut expr.field {
             Field::Length => {
                 let progress_subject = self.apply_forced_constraint(ctx, subject_id, &ARRAYLIKE_TEMPLATE)?;
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &INTEGERLIKE_TEMPLATE)?;
                 (progress_subject, progress_expr)
             },
             Field::Symbolic(field) => {
                 // Check if we already know the definition ID of the subject
                 let mut definition_and_field = None;
                 let subject_type = self.expr_types.get(&subject_id).unwrap();
                 'type_loop: for part in &subject_type.parts {
                     if part.is_marker() || !part.is_concrete() { continue; }
                     if let InferenceTypePart::Instance(definition_id, _) = part {
                         // Make sure we're accessing a struct of some sort
                         let definition_type = ctx.types.get_base_definition(definition_id).unwrap();
                         if let DefinedTypeVariant::Struct(definition) = &definition_type.definition {
                             // Make sure the struct has the specified field
                             let mut field_found = false;
                             for (def_field_idx, def_field) in definition.fields.iter().enumerate() {
                                 if def_field.identifier == *field {
                                     definition_and_field = Some((*definition_id, def_field_idx));
                                     break 'type_loop;
                 // Retrieve the struct definition id and field index if possible
                 // and not previously determined
                 if field.definition.is_none() {
                     // Not yet known, check if we can determine it
                     let subject_type = self.expr_types.get(&subject_id).unwrap();
                     let type_def = determine_inference_type_instance(&ctx.types, subject_type);
                     match type_def {
                         Ok(Some(type_def)) => {
                             // Subject type is known, check if it is a
                             // struct and the field exists on the struct
                             let struct_def = if let DefinedTypeVariant::Struct(struct_def) = &type_def.definition {
                                 struct_def
                             } else {
                                 return Err(ParseError2::new_error(
                                     &ctx.module.source, field.identifier.position,
                                     &format!(
                                         "Can only apply field access to structs, got a subject of type '{}'",
                                         subject_type.display_name(&ctx.heap)
+                                    )
                                 ));
                             };
                             for (field_def_idx, field_def) in struct_def.fields.iter().enumerate() {
                                 if field_def.identifier == field.identifier {
                                     // Set field definition and index
                                     field.definition = Some(type_def.ast_definition);
                                     field.field_idx = field_def_idx;
                                     break;
+                                }
+                            }
                             // If here then field was not found
                             if !field_found {
                                 let definition = &ctx.heap[*definition_id];
                             if field.definition.is_none() {
                                 let field_position = field.identifier.position;
                                 let ast_struct_def = ctx.heap[type_def.ast_definition].as_struct();
                                 return Err(ParseError2::new_error(
-                                    &ctx.module.source, field.position,
+                                    &ctx.module.source, field_position,
                                     &format!(
                                         "The field '{}' does not exist on the struct '{}'",
                                         &String::from_utf8_lossy(&field.value),
                                         &String::from_utf8_lossy(&definition.identifier().value)
                                         "This field does not exist on the struct '{}'",
                                         &String::from_utf8_lossy(&ast_struct_def.identifier.value)
+                                    )
                                 ))
+                            }
                             // Encountered definition and field index for the
                             // first time
                             self.insert_initial_select_polymorph_data(ctx, id);
                         },
                         Ok(None) => {
                             // Type of subject is not yet known, so we
                             // cannot make any progress yet
                             return Ok(())
                         },
                         Err(()) => {
                             return Err(ParseError2::new_error(
                                 &ctx.module.source, field.identifier.position,
                                 &format!(
                                     "Can only apply field access to structs, got a subject of type '{}'",
                                     subject_type.display_name(&ctx.heap)
+                                )
                             ));
+                        }
+                    }
+                }
                 // If here then field definition and index are known, and the
                 // initial type (based on the struct's definition) has been
                 // applied.
                 // Check to see if we can infer anything about the subject's and
                 // the field's polymorphic variables
                 let poly_data = self.extra_data.get_mut(&upcast_id).unwrap();
                 let mut poly_progress = HashSet::new();
                 // Apply to struct's type
                 let signature_type: *mut _ = &mut poly_data.embedded[0];
                 let subject_type: *mut _ = self.expr_types.get_mut(&subject_id).unwrap();
                 let (_, progress_subject) = Self::apply_equal2_signature_constraint(
                     ctx, upcast_id, Some(subject_id), poly_data, &mut poly_progress,
                     signature_type, 0, subject_type, 0
                 )?;
                 if progress_subject {
                     self.expr_queued.insert(subject_id);
+                }
                 // Apply to field's type
                 let signature_type: *mut _ = &mut poly_data.returned;
                 let expr_type: *mut _ = self.expr_types.get_mut(&upcast_id).unwrap();
                 let (_, progress_expr) = Self::apply_equal2_signature_constraint(
                     ctx, upcast_id, None, poly_data, &mut poly_progress,
                     signature_type, 0, expr_type, 0
                 )?;
                         // Else, fall through and complain about not being a struct
                 if progress_expr {
                     if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
                         self.expr_queued.insert(parent_id);
+                    }
                     // Concrete part that is not an instance of a struct,
                     // select expression cannot possibly be correct
                     return Err(ParseError2::new_error(
                         &ctx.module.source, ctx.heap[subject_id].position(),
                         &format!(
                             "Expected to find a struct instance to access a field from, found a '{}'",
                             subject_type.display_name(&ctx.heap)
+                        )
                     ))
+                }
                 // If here then we have our definition and field idx
                 let (definition_id, field_idx) = definition_and_field.unwrap();
                 (false, false)
                 // Reapply progress in polymorphic variables to struct's type
                 let signature_type: *mut _ = &mut poly_data.embedded[0];
                 let subject_type: *mut _ = self.expr_types.get_mut(&subject_id).unwrap();
                 let progress_subject = Self::apply_equal2_polyvar_constraint(
                     poly_data, &poly_progress, signature_type, subject_type
                 );
                 let signature_type: *mut _ = &mut poly_data.returned;
                 let expr_type: *mut _ = self.expr_types.get_mut(&upcast_id).unwrap();
                 let progress_expr = Self::apply_equal2_polyvar_constraint(
                     poly_data, &poly_progress, signature_type, expr_type
                 );
                 (progress_subject, progress_expr)
+            }
         };
         if progress_subject { self.queue_expr(subject_id); }
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         debug_log!(" * After:");
         debug_log!("   - Subject type [{}]: {}", progress_subject, self.expr_types.get(&subject_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - Expr    type [{}]: {}", progress_expr, self.expr_types.get(&upcast_id).unwrap().display_name(&ctx.heap));
         if progress_subject { self.queue_expr(subject_id); }
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         Ok(())
+    }
     fn progress_array_expr(&mut self, ctx: &mut Ctx, id: ArrayExpressionId) -> Result<(), ParseError2> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let expr_elements = expr.elements.clone(); // TODO: @performance
         debug_log!("Array expr ({} elements): {}", expr_elements.len(), upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Expr type: {}", self.expr_types.get(&upcast_id).unwrap().display_name(&ctx.heap));
         // All elements should have an equal type
         let progress = self.apply_equal_n_constraint(ctx, upcast_id, &expr_elements)?;
         for (progress_arg, arg_id) in progress.iter().zip(expr_elements.iter()) {
             if *progress_arg {
                 self.queue_expr(*arg_id);
+            }
+        }
         // And the output should be an array of the element types
         let mut expr_progress = self.apply_forced_constraint(ctx, upcast_id, &ARRAY_TEMPLATE)?;
         if !expr_elements.is_empty() {
             let first_arg_id = expr_elements[0];
             let (inner_expr_progress, arg_progress) = self.apply_equal2_constraint(
                 ctx, upcast_id, upcast_id, 1, first_arg_id, 0
             )?;
             expr_progress = expr_progress || inner_expr_progress;
             // Note that if the array type progressed the type of the arguments,
             // then we should enqueue this progression function again
             // TODO: @fix Make apply_equal_n accept a start idx as well
             if arg_progress { self.queue_expr(upcast_id); }
+        }
         debug_log!(" * After:");
         debug_log!("   - Expr type [{}]: {}", expr_progress, self.expr_types.get(&upcast_id).unwrap().display_name(&ctx.heap));
         if expr_progress { self.queue_expr_parent(ctx, upcast_id); }
         Ok(())
+    }
     fn progress_literal_expr(&mut self, ctx: &mut Ctx, id: LiteralExpressionId) -> Result<(), ParseError2> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
@@ @@ -2246,116 +2375,110 @@ impl TypeResolvingVisitor { @@
         let progress_sig = infer_res.modified_lhs();
         let progress_expr = infer_res.modified_rhs();
         if progress_sig {
             let signature_type = unsafe{&mut *signature_type};
             debug_assert!(
                 signature_type.has_body_marker,
                 "made progress on signature type, but it doesn't have a marker"
             );
             for (poly_idx, poly_section) in signature_type.body_marker_iter() {
                 let polymorph_type = &mut polymorph_data.poly_vars[poly_idx];
                 match Self::apply_forced_constraint_types(
                     polymorph_type, 0, poly_section, 0
                 ) {
                     Ok(true) => { polymorph_progress.insert(poly_idx); },
                     Ok(false) => {},
                     Err(()) => { return Err(Self::construct_poly_arg_error(ctx, polymorph_data, outer_expr_id))}
+                }
+            }
+        }
         Ok((progress_sig, progress_expr))
+    }
     /// Applies equal2 constraints on the signature type for each of the
     /// polymorphic variables. If the signature type is progressed then we
     /// progress the expression type as well.
     ///
     /// This function assumes that the polymorphic variables have already been
     /// progressed as far as possible by calling
     /// `apply_equal2_signature_constraint`. As such, we expect to not encounter
     /// any errors.
     ///
     /// This function returns true if the expression's type has been progressed
     fn apply_equal2_polyvar_constraint(
         polymorph_data: &ExtraData, polymorph_progress: &HashSet<usize>,
         signature_type: *mut InferenceType, expr_type: *mut InferenceType
     ) -> bool {
         // Safety: all pointers should be distinct
         //         polymorph_data contains may not be modified
         debug_assert_ptrs_distinct!(signature_type, expr_type);
         let signature_type = unsafe{&mut *signature_type};
         let expr_type = unsafe{&mut *expr_type};
         // Iterate through markers in signature type to try and make progress
         // on the polymorphic variable
         let mut seek_idx = 0;
         let mut modified_sig = false;
         while seek_idx < signature_type.parts.len() {
             if let InferenceTypePart::MarkerBody(poly_idx) = &signature_type.parts[seek_idx] {
                 let poly_idx = *poly_idx;
                 if polymorph_progress.contains(&poly_idx) {
                     // Need to match subtrees
                     let polymorph_type = &polymorph_data.poly_vars[poly_idx];
                     let start_idx = seek_idx + 1;
                     let end_idx = InferenceType::find_subtree_end_idx(&signature_type.parts, start_idx);
                     let modified_at_marker = Self::apply_forced_constraint_types(
                         signature_type, start_idx,
                         &polymorph_type.parts, 0
                     ).expect("no failure when applying polyvar constraints");
                     modified_sig = modified_sig || modified_at_marker;
                     seek_idx = end_idx;
                     continue;
+                }
         while let Some((poly_idx, start_idx)) = signature_type.find_body_marker(seek_idx) {
             let end_idx = InferenceType::find_subtree_end_idx(&signature_type.parts, start_idx);
             if polymorph_progress.contains(&poly_idx) {
                 // Need to match subtrees
                 let polymorph_type = &polymorph_data.poly_vars[poly_idx];
                 let modified_at_marker = Self::apply_forced_constraint_types(
                     signature_type, start_idx,
                     &polymorph_type.parts, 0
                 ).expect("no failure when applying polyvar constraints");
                 modified_sig = modified_sig || modified_at_marker;
+            }
-            seek_idx += 1;
+            seek_idx = end_idx;
+        }
         // If we made any progress on the signature's type, then we also need to
         // apply it to the expression that is supposed to match the signature.
         if modified_sig {
             match InferenceType::infer_subtree_for_single_type(
                 expr_type, 0, &signature_type.parts, 0
             ) {
                 SingleInferenceResult::Modified => true,
                 SingleInferenceResult::Unmodified => false,
                 SingleInferenceResult::Incompatible =>
                     unreachable!("encountered failure while reapplying modified signature to expression after polyvar inference")
+            }
         } else {
             false
+        }
+    }
     /// Applies a type constraint that expects all three provided types to be
     /// equal. In case we can make progress in inferring the types then we
     /// attempt to do so. If the call is successful then the composition of all
     /// types is made equal.
     fn apply_equal3_constraint(
         &mut self, ctx: &Ctx, expr_id: ExpressionId,
         arg1_id: ExpressionId, arg2_id: ExpressionId,
         start_idx: usize
     ) -> Result<(bool, bool, bool), ParseError2> {
         // Safety: all expression IDs are always distinct, and we do not modify
         //  the container
         debug_assert_expr_ids_unique_and_known!(self, expr_id, arg1_id, arg2_id);
         let expr_type: *mut _ = self.expr_types.get_mut(&expr_id).unwrap();
         let arg1_type: *mut _ = self.expr_types.get_mut(&arg1_id).unwrap();
         let arg2_type: *mut _ = self.expr_types.get_mut(&arg2_id).unwrap();
         let expr_res = unsafe{
             InferenceType::infer_subtrees_for_both_types(expr_type, start_idx, arg1_type, start_idx)
         };
         if expr_res == DualInferenceResult::Incompatible {
             return Err(self.construct_expr_type_error(ctx, expr_id, arg1_id));
+        }
         let args_res = unsafe{
             InferenceType::infer_subtrees_for_both_types(arg1_type, start_idx, arg2_type, start_idx) };
         if args_res == DualInferenceResult::Incompatible {
             return Err(self.construct_arg_type_error(ctx, expr_id, arg1_id, arg2_id));
+        }
         // If all types are compatible, but the second call caused the arg1_type
@@ @@ -2396,98 +2519,96 @@ impl TypeResolvingVisitor { @@
         // on. Once done we need to update everything to the most-inferred type.
         let mut arg_iter = args.iter();
         let mut last_arg_id = *arg_iter.next().unwrap();
         let mut last_lhs_progressed = 0;
         let mut lhs_arg_idx = 0;
         while let Some(next_arg_id) = arg_iter.next() {
             let arg1_type: *mut _ = self.expr_types.get_mut(&last_arg_id).unwrap();
             let arg2_type: *mut _ = self.expr_types.get_mut(next_arg_id).unwrap();
             let res = unsafe {
                 InferenceType::infer_subtrees_for_both_types(arg1_type, 0, arg2_type, 0)
             };
             if res == DualInferenceResult::Incompatible {
                 return Err(self.construct_arg_type_error(ctx, expr_id, last_arg_id, *next_arg_id));
+            }
             if res.modified_lhs() {
                 // We re-inferred something on the left hand side, so everything
                 // up until now should be re-inferred.
                 progress[lhs_arg_idx] = true;
                 last_lhs_progressed = lhs_arg_idx;
+            }
             progress[lhs_arg_idx + 1] = res.modified_rhs();
             last_arg_id = *next_arg_id;
             lhs_arg_idx += 1;
+        }
         // Re-infer everything. Note that we do not need to re-infer the type
         // exactly at `last_lhs_progressed`, but only everything up to it.
         let last_type: *mut _ = self.expr_types.get_mut(args.last().unwrap()).unwrap();
         for arg_idx in 0..last_lhs_progressed {
             let arg_type: *mut _ = self.expr_types.get_mut(&args[arg_idx]).unwrap();
             unsafe{
                 (*arg_type).replace_subtree(0, &(*last_type).parts);
+            }
             progress[arg_idx] = true;
+        }
         Ok(progress)
+    }
     /// Determines the `InferenceType` for the expression based on the
     /// expression parent. Note that if the parent is another expression, we do
     /// not take special action, instead we let parent expressions fix the type
     /// of subexpressions before they have a chance to call this function.
     /// Hence: if the expression type is already set, this function doesn't do
     /// anything.
     fn insert_initial_expr_inference_type(
         &mut self, ctx: &mut Ctx, expr_id: ExpressionId
     ) -> Result<(), ParseError2> {
         use ExpressionParent as EP;
         use InferenceTypePart as ITP;
         let expr = &ctx.heap[expr_id];
         let inference_type = match expr.parent() {
             EP::None =>
                 // Should have been set by linker
                 unreachable!(),
             EP::ExpressionStmt(_) | EP::Expression(_, _) =>
                 // Determined during type inference
                 InferenceType::new(false, false, vec![ITP::Unknown]),
             EP::If(_) | EP::While(_) | EP::Assert(_) =>
                 // Must be a boolean
                 InferenceType::new(false, true, vec![ITP::Bool]),
             EP::Return(_) =>
                 // Must match the return type of the function
                 if let DefinitionType::Function(func_id) = self.definition_type {
                     let return_parser_type_id = ctx.heap[func_id].return_type;
                     self.determine_inference_type_from_parser_type(ctx, return_parser_type_id, true)
                 } else {
                     // Cannot happen: definition always set upon body traversal
                     // and "return" calls in components are illegal.
                     unreachable!();
                 },
             EP::New(_) =>
                 // Must be a component call, which we assign a "Void" return
                 // type
                 InferenceType::new(false, true, vec![ITP::Void]),
         };
         match self.expr_types.entry(expr_id) {
             Entry::Vacant(vacant) => {
                 vacant.insert(inference_type);
             },
             Entry::Occupied(mut preexisting) => {
                 // We already have an entry, this happens if our parent fixed
                 // our type (e.g. we're used in a conditional expression's test)
                 // but we have a different type.
                 // TODO: Is this ever called? Seems like it can't
                 debug_assert!(false, "I am actually called, my ID is {}", expr_id.index);
                 let old_type = preexisting.get_mut();
                 if let SingleInferenceResult::Incompatible = InferenceType::infer_subtree_for_single_type(
                     old_type, 0, &inference_type.parts, 0
                 ) {
                     return Err(self.construct_expr_type_error(ctx, expr_id, expr_id))
@@ @@ -2616,96 +2737,142 @@ impl TypeResolvingVisitor { @@
         // Handle parser types on struct definition
         let definition = &ctx.heap[literal.definition.unwrap()];
         let definition = match definition {
             Definition::Struct(definition) => {
                 debug_assert_eq!(poly_vars.len(), definition.poly_vars.len());
                 definition
             },
             _ => unreachable!("definition for struct literal does not point to struct definition")
         };
         // Note: programmer is capable of specifying fields in a struct literal
         // in a different order than on the definition. We take the programmer-
         // specified order to be leading.
         let mut embedded_types = Vec::with_capacity(definition.fields.len());
         for lit_field in literal.fields.iter() {
             let def_field = &definition.fields[lit_field.field_idx];
             let inference_type = self.determine_inference_type_from_parser_type(
                 ctx, def_field.parser_type, false
             );
             embedded_types.push(inference_type);
+        }
         // Return type is the struct type itself, with the appropriate
         // polymorphic variables. So:
         // - 1 part for definition
         // - N_poly_arg marker parts for each polymorphic argument
         // - all the parts for the currently known polymorphic arguments
         let parts_reserved = 1 + poly_vars.len() + total_num_poly_parts;
         let mut parts = Vec::with_capacity(parts_reserved);
         parts.push(ITP::Instance(definition.this.upcast(), poly_vars.len()));
         let mut return_type_done = true;
         for (poly_var_idx, poly_var) in poly_vars.iter().enumerate() {
             if !poly_var.is_done { return_type_done = false; }
             parts.push(ITP::MarkerBody(poly_var_idx));
             parts.extend(poly_var.parts.iter().cloned());
+        }
         debug_assert_eq!(parts.len(), parts_reserved);
         let return_type = InferenceType::new(true, return_type_done, parts);
         self.extra_data.insert(lit_id.upcast(), ExtraData{
             poly_vars,
             embedded: embedded_types,
             returned: return_type,
         });
+    }
     /// Inserts the extra polymorphic data struct. Assumes that the select
     /// expression's referenced (definition_id, field_idx) has been resolved.
     fn insert_initial_select_polymorph_data(
         &mut self, ctx: &Ctx, select_id: SelectExpressionId
     ) {
         use InferenceTypePart as ITP;
         // Retrieve relevant data
         let expr = &ctx.heap[select_id];
         let field = match &expr.field {
             Field::Symbolic(field) => field,
             _ => unreachable!(),
         };
         let definition_id = field.definition.unwrap();
         let definition = ctx.heap[definition_id].as_struct();
         let field_idx = field.field_idx;
         // Generate initial polyvar types and struct type
         let num_poly_vars = definition.poly_vars.len();
         let mut poly_vars = Vec::with_capacity(num_poly_vars);
         let struct_parts_reserved = 1 + 2 * num_poly_vars;
         let mut struct_parts = Vec::with_capacity(struct_parts_reserved);
         struct_parts.push(ITP::Instance(definition_id, num_poly_vars));
         for poly_idx in 0..num_poly_vars {
             poly_vars.push(InferenceType::new(true, false, vec![
                 ITP::MarkerBody(poly_idx), ITP::Unknown,
             ]));
             struct_parts.push(ITP::MarkerBody(poly_idx));
             struct_parts.push(ITP::Unknown);
+        }
         debug_assert_eq!(struct_parts.len(), struct_parts_reserved);
         // Generate initial field type
         let field_type = self.determine_inference_type_from_parser_type(
             ctx, definition.fields[field_idx].parser_type, false
         );
         self.extra_data.insert(select_id.upcast(), ExtraData{
             poly_vars,
             embedded: vec![InferenceType::new(true, false, struct_parts)],
             returned: field_type
         });
+    }
     /// Determines the initial InferenceType from the provided ParserType. This
     /// may be called with two kinds of intentions:
     /// 1. To resolve a ParserType within the body of a function, or on
     ///     polymorphic arguments to calls/instantiations within that body. This
     ///     means that the polymorphic variables are known and can be replaced
     ///     with the monomorph we're instantiating.
     /// 2. To resolve a ParserType on a called function's definition or on
     ///     an instantiated datatype's members. This means that the polymorphic
     ///     arguments inside those ParserTypes refer to the polymorphic
     ///     variables in the called/instantiated type's definition.
     /// In the second case we place InferenceTypePart::Marker instances such
     /// that we can perform type inference on the polymorphic variables.
     fn determine_inference_type_from_parser_type(
         &mut self, ctx: &Ctx, parser_type_id: ParserTypeId,
         parser_type_in_body: bool
     ) -> InferenceType {
         use ParserTypeVariant as PTV;
         use InferenceTypePart as ITP;
         let mut to_consider = VecDeque::with_capacity(16);
         to_consider.push_back(parser_type_id);
         let mut infer_type = Vec::new();
         let mut has_inferred = false;
         let mut has_markers = false;
         while !to_consider.is_empty() {
             let parser_type_id = to_consider.pop_front().unwrap();
             let parser_type = &ctx.heap[parser_type_id];
             match &parser_type.variant {
                 PTV::Message => {
                     // TODO: @types Remove the Message -> Byte hack at some point...
                     infer_type.push(ITP::Message);
                     infer_type.push(ITP::Byte);
                 },
                 PTV::Bool => { infer_type.push(ITP::Bool); },
                 PTV::Byte => { infer_type.push(ITP::Byte); },
                 PTV::Short => { infer_type.push(ITP::Short); },
                 PTV::Int => { infer_type.push(ITP::Int); },
                 PTV::Long => { infer_type.push(ITP::Long); },
                 PTV::String => { infer_type.push(ITP::String); },
                 PTV::IntegerLiteral => { unreachable!("integer literal type on variable type"); },
                 PTV::Inferred => {
                     infer_type.push(ITP::Unknown);
                     has_inferred = true;
                 },
                 PTV::Array(subtype_id) => {
                     infer_type.push(ITP::Array);

src/protocol/tests/parser_inference.rs

➞

Show inline comments

new file 100644

src/protocol/tests/parser_validation.rs

➞

Show inline comments

 /// parser_validation.rs
 ///
 /// Simple tests for the validation phase
 /// TODO: If semicolon behind struct definition: should be fine...
 use super::*;
 #[test]
 fn test_correct_struct_instance() {
     Tester::new_single_source_expect_ok(
         "single field",
+        "
         struct Foo { int a }
         Foo bar(int arg) { return Foo{ a: arg }; }
+        "
     );
     Tester::new_single_source_expect_ok(
         "multiple fields",
+        "
         struct Foo { int a, int b }
         Foo bar(int arg) { return Foo{ a: arg, b: arg }; }
+        "
     );
     Tester::new_single_source_expect_ok(
         "single field, explicit polymorph",
+        "
         struct Foo<T>{ T field }
         Foo<int> bar(int arg) { return Foo<int>{ field: arg }; }
+        "
     );
     Tester::new_single_source_expect_ok(
         "single field, implicit polymorph",
+        "
         struct Foo<T>{ T field }
         int bar(int arg) {
             auto thingo = Foo{ field: arg };
             return arg;
+        }
+        "
     );
     Tester::new_single_source_expect_ok(
         "multiple fields, same explicit polymorph",
+        "
         struct Pair<T1, T2>{ T1 first, T2 second }
         int bar(int arg) {
             auto qux = Pair<int, int>{ first: arg, second: arg };
             return arg;
+        }
+        "
     );
     Tester::new_single_source_expect_ok(
         "multiple fields, same implicit polymorph",
+        "
         struct Pair<T1, T2>{ T1 first, T2 second }
         int bar(int arg) {
             auto wup = Pair{ first: arg, second: arg };
             return arg;
+        }
+        "
     );
     Tester::new_single_source_expr_ok(
         "multiple fields, different explicit polymorph",
+        "
         struct Pair<T1, T2>{ T1 first, T2 second }
         int bar(int arg1, byte arg2) {
             auto shoo = Pair<int, byte>{ first: arg1, second: arg2 };
             return arg1;
+        }
+        "
     );
     Tester::new_single_source_expect_ok(
         "multiple fields, different implicit polymorph",
+        "
         struct Pair<T1, T2>{ T1 first, T2 second }
         int bar(int arg1, byte arg2) {
             auto shrubbery = Pair{ first: arg1, second: arg2 };
             return arg1;
+        }
+        "
     );
+}
@@ \ No newline at end of file @@

src/protocol/tests/utils.rs

➞

Show inline comments

@@ @@ -94,185 +94,259 @@ impl AstTesterResult { @@
             AstTesterResult::Err(err) => err,
+        }
+    }
+}
 //------------------------------------------------------------------------------
 // Interface for successful compilation
 //------------------------------------------------------------------------------
 pub(crate) struct AstOkTester {
     test_name: String,
     modules: Vec<LexedModule>,
     heap: Heap,
+}
 impl AstOkTester {
     fn new(test_name: String, parser: Parser) -> Self {
         Self {
             test_name,
             modules: parser.modules,
             heap: parser.heap
+        }
+    }
     pub(crate) fn for_struct<F: Fn(StructTester)>(self, name: &str, f: F) -> Self {
         let mut found = false;
         for definition in self.heap.definitions.iter() {
             if let Definition::Struct(definition) = definition {
                 if String::from_utf8_lossy(&definition.identifier.value) != name {
                     continue;
+                }
                 // Found struct with the same name
                 let tester = StructTester::new(&self.test_name, definition, &self.heap);
                 f(tester);
                 found = true;
                 break
+            }
+        }
         if found { return self }
         assert!(
             false, "[{}] Failed to find definition for struct '{}'",
             self.test_name, name
         );
         unreachable!()
+    }
     pub(crate) fn for_function<F: Fn(FunctionTester)>(self, name: &str, f: F) -> Self {
         let mut found = false;
         for definition in self.heap.definitions.iter() {
             if let Definition::Function(definition) = definition {
                 if String::from_utf8_lossy(&definition.identifier.value) != name {
                     continue;
+                }
                 // Found function
                 let tester = FunctionTester::new(&self.test_name, definition, &self.heap);
                 f(tester);
                 found = true;
                 break;
+            }
+        }
         if found { return self }
         assert!(
             false, "[{}] failed to find definition for function '{}'",
             self.test_name, name
         );
         unreachable!();
+    }
+}
 //------------------------------------------------------------------------------
 // Utilities for successful compilation
 //------------------------------------------------------------------------------
 pub(crate) struct StructTester<'a> {
     test_name: &'a str,
     def: &'a StructDefinition,
     heap: &'a Heap,
+}
 impl<'a> StructTester<'a> {
     fn new(test_name: &'a str, def: &'a StructDefinition, heap: &'a Heap) -> Self {
         Self{ test_name, def, heap }
+    }
     pub(crate) fn assert_num_fields(self, num: usize) -> Self {
         debug_assert_eq!(
             num, self.def.fields.len(),
             "[{}] Expected {} struct fields, but found {} for {}",
             self.test_name, num, self.def.fields.len(), self.assert_postfix()
         );
         self
+    }
     pub(crate) fn for_field<F: Fn(StructFieldTester)>(self, name: &str, f: F) -> Self {
         // Find field with specified name
         for field in &self.def.fields {
             if String::from_utf8_lossy(&field.field.value) == name {
                 let tester = StructFieldTester::new(self.test_name, field, self.heap);
                 f(tester);
                 return self;
+            }
+        }
         assert!(
             false, "[{}] Could not find struct field '{}' for {}",
             self.test_name, name, self.assert_postfix()
         );
         unreachable!();
+    }
     fn assert_postfix(&self) -> String {
         let mut v = String::new();
         v.push_str("Struct{ name: ");
         v.push_str(&String::from_utf8_lossy(&self.def.identifier.value));
         v.push_str(", fields: [");
         for (field_idx, field) in self.def.fields.iter().enumerate() {
             if field_idx != 0 { v.push_str(", "); }
             v.push_str(&String::from_utf8_lossy(&field.field.value));
+        }
         v.push_str("] }");
+        v
+    }
+}
 pub(crate) struct StructFieldTester<'a> {
     test_name: &'a str,
     def: &'a StructFieldDefinition,
     heap: &'a Heap,
+}
 impl<'a> StructFieldTester<'a> {
     fn new(test_name: &'a str, def: &'a StructFieldDefinition, heap: &'a Heap) -> Self {
         Self{ test_name, def, heap }
+    }
     pub(crate) fn assert_parser_type(self, expected: &str) -> Self {
         let mut serialized_type = String::new();
         serialize_parser_type(&mut serialized_type, &self.heap, self.def.parser_type);
         debug_assert_eq!(
             expected, &serialized_type,
             "[{}] Expected type '{}', but got '{}' for {}",
             self.test_name, expected, &serialized_type, self.assert_postfix()
         );
         self
+    }
     fn assert_postfix(&self) -> String {
         let mut serialized_type = String::new();
         serialize_parser_type(&mut serialized_type, &self.heap, self.def.parser_type);
         format!(
             "StructField{{ name: {}, parser_type: {} }}",
             String::from_utf8_lossy(&self.def.field.value), serialized_type
+        )
+    }
+}
 pub(crate) struct FunctionTester<'a> {
     test_name: &'a str,
     def: &'a Function,
     heap: &'a Heap,
+}
 impl<'a> FunctionTester<'a> {
     fn new(test_name: &'a str, def: &'a Function, heap: &'a Heap) -> Self {
         Self{ test_name, def, heap }
+    }
     pub(crate) fn for_variable<F: Fn(VariableTester)>(self, name: &str, f: F) -> Self {
         let mem_stmt_id = seek_stmt(
             self.heap, self.def.body,
             |stmt| {
                 if let Statement::Local(local) = stmt {
                     if let LocalStatement::Memory(memory) = local {
                         let local = &self.heap[memory.variable];
                         if local.identifier.value == name.as_bytes() {
                             return true;
+                        }
+                    }
+                }
                 false
+            }
         );
         match mem_stmt_id {
             Some(mem_stmt_id) => {
                 // TODO: Retrieve shit
             },
             None => {
                 // TODO: Throw error
+            }
+        }
+    }
+}
 pub(crate) struct VariableTester<'a> {
     test_name: &'a str,
     def: &'a Local,
     assignment: &'a AssignmentExpression,
     heap: &'a Heap,
+}
 //------------------------------------------------------------------------------
 // Interface for failed compilation
 //------------------------------------------------------------------------------
 pub(crate) struct AstErrTester {
     test_name: String,
     error: ParseError2,
+}
 impl AstErrTester {
     fn new(test_name: String, error: ParseError2) -> Self {
         Self{ test_name, error }
+    }
     pub(crate) fn error<F: Fn(ErrorTester)>(&self, f: F) {
         // Maybe multiple errors will be supported in the future
         let tester = ErrorTester{ test_name: &self.test_name, error: &self.error };
         f(tester)
+    }
+}
 //------------------------------------------------------------------------------
 // Utilities for failed compilation
 //------------------------------------------------------------------------------
 pub(crate) struct ErrorTester<'a> {
     test_name: &'a str,
     error: &'a ParseError2,
+}
 impl<'a> ErrorTester<'a> {
     pub(crate) fn assert_num(self, num: usize) -> Self {
         assert_eq!(
             num, self.error.statements.len(),
             "[{}] expected error to consist of '{}' parts, but encountered '{}' for {}",
             self.test_name, num, self.error.statements.len(), self.assert_postfix()
         );
         self
+    }
     pub(crate) fn assert_ctx_has(self, idx: usize, msg: &str) -> Self {
         assert!(
             self.error.statements[idx].context.contains(msg),
             "[{}] expected error statement {}'s context to contain '{}' for {}",
             self.test_name, idx, msg, self.assert_postfix()
         );
@@ @@ -323,49 +397,196 @@ impl<'a> ErrorTester<'a> { @@
+        v
+    }
+}
 //------------------------------------------------------------------------------
 // Generic utilities
 //------------------------------------------------------------------------------
 fn serialize_parser_type(buffer: &mut String, heap: &Heap, id: ParserTypeId) {
     use ParserTypeVariant as PTV;
     let p = &heap[id];
     match &p.variant {
         PTV::Message => buffer.push_str("msg"),
         PTV::Bool => buffer.push_str("bool"),
         PTV::Byte => buffer.push_str("byte"),
         PTV::Short => buffer.push_str("short"),
         PTV::Int => buffer.push_str("int"),
         PTV::Long => buffer.push_str("long"),
         PTV::String => buffer.push_str("string"),
         PTV::IntegerLiteral => buffer.push_str("intlit"),
         PTV::Inferred => buffer.push_str("auto"),
         PTV::Array(sub_id) => {
             serialize_parser_type(buffer, heap, *sub_id);
             buffer.push_str("[]");
         },
         PTV::Input(sub_id) => {
             buffer.push_str("in<");
             serialize_parser_type(buffer, heap, *sub_id);
             buffer.push('>');
         },
         PTV::Output(sub_id) => {
             buffer.push_str("out<");
             serialize_parser_type(buffer, heap, *sub_id);
             buffer.push('>');
         },
         PTV::Symbolic(symbolic) => {
             buffer.push_str(&String::from_utf8_lossy(&symbolic.identifier.value));
             if symbolic.poly_args.len() > 0 {
                 buffer.push('<');
                 for (poly_idx, poly_arg) in symbolic.poly_args.iter().enumerate() {
                     if poly_idx != 0 { buffer.push(','); }
                     serialize_parser_type(buffer, heap, *poly_arg);
+                }
                 buffer.push('>');
+            }
+        }
+    }
+}
 fn seek_stmt<F: Fn(&Statement) -> bool>(heap: &Heap, start: StatementId, f: F) -> Option<StatementId> {
     let stmt = &heap[start];
     if f(stmt) { return Some(start); }
     // This statement wasn't it, try to recurse
     let matched = match stmt {
         Statement::Block(block) => {
             for sub_id in &block.statements {
                 if let Some(id) = seek_stmt(heap, *sub_id, f) {
                     return Some(id);
+                }
+            }
             None
         },
         Statement::Labeled(stmt) => seek_stmt(heap, stmt.body, f),
         Statement::If(stmt) => {
             if let Some(id) = seek_stmt(heap,stmt.true_body, f) {
                 return Some(id);
             } else if let Some(id) = seek_stmt(heap, stmt.false_body, f) {
                 return Some(id);
+            }
             None
         },
         Statement::While(stmt) => seek_stmt(heap, stmt.body, f),
         Statement::Synchronous(stmt) => seek_stmt(heap, stmt.body, f),
         _ => None
     };
     matched
+}
 fn seek_expr_in_expr<F: Fn(&Expression) -> bool>(heap: &Heap, start: ExpressionId, f: F) -> Option<ExpressionId> {
     let expr = &heap[start];
     if f(expr) { return Some(start); }
     match expr {
         Expression::Assignment(expr) => {
             None
             .or_else(|| seek_expr_in_expr(heap, expr.left, f))
             .or_else(|| seek_expr_in_expr(heap, expr.right, f))
         },
         Expression::Conditional(expr) => {
             None
             .or_else(|| seek_expr_in_expr(heap, expr.test, f))
             .or_else(|| seek_expr_in_expr(heap, expr.true_expression, f))
             .or_else(|| seek_expr_in_expr(heap, expr.false_expression, f))
         },
         Expression::Binary(expr) => {
             None
             .or_else(|| seek_expr_in_expr(heap, expr.left, f))
             .or_else(|| seek_expr_in_expr(heap, expr.right, f))
         },
         Expression::Unary(expr) => {
             seek_expr_in_expr(heap, expr.expression, f)
         },
         Expression::Indexing(expr) => {
             None
             .or_else(|| seek_expr_in_expr(heap, expr.subject, f))
             .or_else(|| seek_expr_in_expr(heap, expr.index, f))
         },
         Expression::Slicing(expr) => {
             None
             .or_else(|| seek_expr_in_expr(heap, expr.subject, f))
             .or_else(|| seek_expr_in_expr(heap, expr.from_index, f))
             .or_else(|| seek_expr_in_expr(heap, expr.to_index, f))
         },
         Expression::Select(expr) => {
             seek_expr_in_expr(heap, expr.subject, f)
         },
         Expression::Array(expr) => {
             for element in &expr.elements {
                 if let Some(id) = seek_expr_in_expr(heap, *element, f) {
                     return Some(id)
+                }
+            }
             None
         },
         Expression::Literal(expr) => {
             if let Literal::Struct(lit) = expr.value {
                 for field in &lit.fields {
                     if let Some(id) = seek_expr_in_expr(heap, field.value, f) {
                         return Some(id)
+                    }
+                }
+            }
             None
         },
         Expression::Call(expr) => {
             for arg in &expr.arguments {
                 if let Some(id) = seek_expr_in_expr(heap, *arg, f) {
                     return Some(id)
+                }
+            }
             None
         },
         Expression::Variable(expr) => {
             None
+        }
+    }
+}
 fn seek_expr_in_stmt<F: Fn(&Expression) -> bool>(heap: &Heap, start: StatementId, f: F) -> Option<ExpressionId> {
     let stmt = &heap[start];
     match stmt {
         Statement::Block(stmt) => {
             for stmt_id in &stmt.statements {
                 if let Some(id) = seek_expr_in_stmt(heap, *stmt_id, f) {
                     return Some(id)
+                }
+            }
             None
         },
         Statement::Labeled(stmt) => {
             seek_expr_in_stmt(heap, stmt.body, f)
         },
         Statement::If(stmt) => {
             None
             .or_else(|| seek_expr_in_expr(heap, stmt.test, f))
             .or_else(|| seek_expr_in_stmt(heap, stmt.true_body, f))
             .or_else(|| seek_expr_in_stmt(heap, stmt.false_body, f))
         },
         Statement::While(stmt) => {
             None
             .or_else(|| seek_expr_in_expr(heap, stmt.test, f))
             .or_else(|| seek_expr_in_stmt(heap, stmt.body, f))
         },
         Statement::Synchronous(stmt) => {
             seek_expr_in_stmt(heap, stmt.body, f)
         },
         Statement::Return(stmt) => {
             seek_expr_in_expr(heap, stmt.expression, f)
         },
         Statement::Assert(stmt) => {
             seek_expr_in_expr(heap, stmt.expression, f)
         },
         Statement::New(stmt) => {
             seek_expr_in_expr(heap, stmt.expression.upcast(), f)
         },
         Statement::Expression(stmt) => {
             seek_expr_in_expr(heap, stmt.expression, f)
         },
         _ => None
+    }
+}
@@ \ No newline at end of file @@

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