CSY/reowolf Changeset - 7f9b23076d66 · Centrum Wiskunde & Informatica (CWI)

Changeset - 7f9b23076d66

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mh - 4 years ago 2021-12-15 16:56:29
contact@maxhenger.nl

Add some tests for tuple member access

6 files changed with 118 insertions and 4 deletions:

src/protocol/eval/executor.rs

src/protocol/eval/store.rs

src/protocol/parser/pass_typing.rs

src/protocol/tests/eval_operators.rs

src/protocol/tests/parser_inference.rs

src/protocol/tests/parser_validation.rs

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src/protocol/eval/executor.rs

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 use std::collections::VecDeque;
 use super::value::*;
 use super::store::*;
 use super::error::*;
 use crate::protocol::*;
 use crate::protocol::ast::*;
 use crate::protocol::type_table::*;
 macro_rules! debug_enabled { () => { false }; }
 macro_rules! debug_log {
     ($format:literal) => {
         enabled_debug_print!(false, "exec", $format);
     };
     ($format:literal, $($args:expr),*) => {
         enabled_debug_print!(false, "exec", $format, $($args),*);
     };
+}
 #[derive(Debug, Clone)]
 pub(crate) enum ExprInstruction {
     EvalExpr(ExpressionId),
     PushValToFront,
+}
 #[derive(Debug, Clone)]
 pub(crate) struct Frame {
     pub(crate) definition: DefinitionId,
     pub(crate) monomorph_idx: i32,
     pub(crate) position: StatementId,
     pub(crate) expr_stack: VecDeque<ExprInstruction>, // hack for expression evaluation, evaluated by popping from back
     pub(crate) expr_values: VecDeque<Value>, // hack for expression results, evaluated by popping from front/back
     pub(crate) max_stack_size: u32,
+}
 impl Frame {
     /// Creates a new execution frame. Does not modify the stack in any way.
     pub fn new(heap: &Heap, definition_id: DefinitionId, monomorph_idx: i32) -> Self {
         let definition = &heap[definition_id];
         let first_statement = match definition {
             Definition::Component(definition) => definition.body,
             Definition::Function(definition) => definition.body,
             _ => unreachable!("initializing frame with {:?} instead of a function/component", definition),
         };
         // Another not-so-pretty thing that has to be replaced somewhere in the
         // future...
         fn determine_max_stack_size(heap: &Heap, block_id: BlockStatementId, max_size: &mut u32) {
             let block_stmt = &heap[block_id];
             debug_assert!(block_stmt.next_unique_id_in_scope >= 0);
             // Check current block
             let cur_size = block_stmt.next_unique_id_in_scope as u32;
             if cur_size > *max_size { *max_size = cur_size; }
             // And child blocks
             for child_scope in &block_stmt.scope_node.nested {
                 determine_max_stack_size(heap, child_scope.to_block(), max_size);
+            }
+        }
         let mut max_stack_size = 0;
         determine_max_stack_size(heap, first_statement, &mut max_stack_size);
         Frame{
             definition: definition_id,
             monomorph_idx,
             position: first_statement.upcast(),
             expr_stack: VecDeque::with_capacity(128),
             expr_values: VecDeque::with_capacity(128),
             max_stack_size,
+        }
+    }
     /// Prepares a single expression for execution. This involves walking the
     /// expression tree and putting them in the `expr_stack` such that
     /// continuously popping from its back will evaluate the expression. The
     /// results of each expression will be stored by pushing onto `expr_values`.
     pub fn prepare_single_expression(&mut self, heap: &Heap, expr_id: ExpressionId) {
         debug_assert!(self.expr_stack.is_empty());
         self.expr_values.clear(); // May not be empty if last expression result(s) were discarded
         self.serialize_expression(heap, expr_id);
+    }
     /// Prepares multiple expressions for execution (i.e. evaluating all
     /// function arguments or all elements of an array/union literal). Per
     /// expression this works the same as `prepare_single_expression`. However
     /// after each expression is evaluated we insert a `PushValToFront`
     /// instruction
     pub fn prepare_multiple_expressions(&mut self, heap: &Heap, expr_ids: &[ExpressionId]) {
         debug_assert!(self.expr_stack.is_empty());
         self.expr_values.clear();
         for expr_id in expr_ids {
             self.expr_stack.push_back(ExprInstruction::PushValToFront);
             self.serialize_expression(heap, *expr_id);
+        }
+    }
     /// Performs depth-first serialization of expression tree. Let's not care
     /// about performance for a temporary runtime implementation
     fn serialize_expression(&mut self, heap: &Heap, id: ExpressionId) {
         self.expr_stack.push_back(ExprInstruction::EvalExpr(id));
         match &heap[id] {
             Expression::Assignment(expr) => {
                 self.serialize_expression(heap, expr.left);
                 self.serialize_expression(heap, expr.right);
             },
             Expression::Binding(expr) => {
                 self.serialize_expression(heap, expr.bound_to);
                 self.serialize_expression(heap, expr.bound_from);
             },
             Expression::Conditional(expr) => {
                 self.serialize_expression(heap, expr.test);
             },
             Expression::Binary(expr) => {
                 self.serialize_expression(heap, expr.left);
                 self.serialize_expression(heap, expr.right);
             },
             Expression::Unary(expr) => {
                 self.serialize_expression(heap, expr.expression);
             },
             Expression::Indexing(expr) => {
                 self.serialize_expression(heap, expr.index);
                 self.serialize_expression(heap, expr.subject);
             },
             Expression::Slicing(expr) => {
                 self.serialize_expression(heap, expr.from_index);
                 self.serialize_expression(heap, expr.to_index);
                 self.serialize_expression(heap, expr.subject);
             },
             Expression::Select(expr) => {
                 self.serialize_expression(heap, expr.subject);
             },
             Expression::Literal(expr) => {
                 // Here we only care about literals that have subexpressions
                 match &expr.value {
                     Literal::Null | Literal::True | Literal::False |
                     Literal::Character(_) | Literal::String(_) |
                     Literal::Integer(_) | Literal::Enum(_) => {
                         // No subexpressions
                     },
                     Literal::Struct(literal) => {
                         // Note: fields expressions are evaluated in programmer-
                         // specified order. But struct construction expects them
                         // in type-defined order. I might want to come back to
                         // this.
                         let mut _num_pushed = 0;
                         for want_field_idx in 0..literal.fields.len() {
                             for field in &literal.fields {
                                 if field.field_idx == want_field_idx {
                                     _num_pushed += 1;
                                     self.expr_stack.push_back(ExprInstruction::PushValToFront);
                                     self.serialize_expression(heap, field.value);
+                                }
+                            }
+                        }
                         debug_assert_eq!(_num_pushed, literal.fields.len())
                     },
                     Literal::Union(literal) => {
                         for value_expr_id in &literal.values {
                             self.expr_stack.push_back(ExprInstruction::PushValToFront);
                             self.serialize_expression(heap, *value_expr_id);
+                        }
                     },
                     Literal::Array(value_expr_ids) => {
                         for value_expr_id in value_expr_ids {
                             self.expr_stack.push_back(ExprInstruction::PushValToFront);
                             self.serialize_expression(heap, *value_expr_id);
+                        }
                     },
                     Literal::Tuple(value_expr_ids) => {
                         for value_expr_id in value_expr_ids {
                             self.expr_stack.push_back(ExprInstruction::PushValToFront);
                             self.serialize_expression(heap, *value_expr_id);
+                        }
+                    }
+                }
             },
             Expression::Cast(expr) => {
                 self.serialize_expression(heap, expr.subject);
+            }
             Expression::Call(expr) => {
                 for arg_expr_id in &expr.arguments {
                     self.expr_stack.push_back(ExprInstruction::PushValToFront);
                     self.serialize_expression(heap, *arg_expr_id);
+                }
             },
             Expression::Variable(_expr) => {
                 // No subexpressions
+            }
+        }
+    }
+}
 type EvalResult = Result<EvalContinuation, EvalError>;
 #[derive(Debug)]
 pub enum EvalContinuation {
     // Returned in both sync and non-sync modes
     Stepping,
     // Returned only in sync mode
     BranchInconsistent,
     SyncBlockEnd,
     NewFork,
     BlockFires(PortId),
     BlockGet(PortId),
     Put(PortId, ValueGroup),
     // Returned only in non-sync mode
     ComponentTerminated,
     SyncBlockStart,
     NewComponent(DefinitionId, i32, ValueGroup),
     NewChannel,
+}
 // Note: cloning is fine, methinks. cloning all values and the heap regions then
 // we end up with valid "pointers" to heap regions.
 #[derive(Debug, Clone)]
 pub struct Prompt {
     pub(crate) frames: Vec<Frame>,
     pub(crate) store: Store,
+}
 impl Prompt {
     pub fn new(_types: &TypeTable, heap: &Heap, def: DefinitionId, monomorph_idx: i32, args: ValueGroup) -> Self {
         let mut prompt = Self{
             frames: Vec::new(),
             store: Store::new(),
         };
         // Maybe do typechecking in the future?
         let new_frame = Frame::new(heap, def, monomorph_idx);
         let max_stack_size = new_frame.max_stack_size;
         prompt.frames.push(new_frame);
         args.into_store(&mut prompt.store);
         prompt.store.reserve_stack(max_stack_size);
         prompt
+    }
     /// Big 'ol function right here. Didn't want to break it up unnecessarily.
     /// It consists of, in sequence: executing any expressions that should be
     /// executed before the next statement can be evaluated, then a section that
     /// performs debug printing, and finally a section that takes the next
     /// statement and executes it. If the statement requires any expressions to
     /// be evaluated, then they will be added such that the next time `step` is
     /// called, all of these expressions are indeed evaluated.
     pub(crate) fn step(&mut self, types: &TypeTable, heap: &Heap, modules: &[Module], ctx: &mut impl RunContext) -> EvalResult {
         // Helper function to transfer multiple values from the expression value
         // array into a heap region (e.g. constructing arrays or structs).
         fn transfer_expression_values_front_into_heap(cur_frame: &mut Frame, store: &mut Store, num_values: usize) -> HeapPos {
             let heap_pos = store.alloc_heap();
             // Do the transformation first (because Rust...)
             for val_idx in 0..num_values {
                 cur_frame.expr_values[val_idx] = store.read_take_ownership(cur_frame.expr_values[val_idx].clone());
+            }
             // And now transfer to the heap region
             let values = &mut store.heap_regions[heap_pos as usize].values;
             debug_assert!(values.is_empty());
             values.reserve(num_values);
             for _ in 0..num_values {
                 values.push(cur_frame.expr_values.pop_front().unwrap());
+            }
             heap_pos
+        }
         // Helper function to make sure that an index into an aray is valid.
         fn array_inclusive_index_is_invalid(store: &Store, array_heap_pos: u32, idx: i64) -> bool {
             let array_len = store.heap_regions[array_heap_pos as usize].values.len();
             return idx < 0 || idx >= array_len as i64;
+        }
         fn array_exclusive_index_is_invalid(store: &Store, array_heap_pos: u32, idx: i64) -> bool {
             let array_len = store.heap_regions[array_heap_pos as usize].values.len();
             return idx < 0 || idx > array_len as i64;
+        }
         fn construct_array_error(prompt: &Prompt, modules: &[Module], heap: &Heap, expr_id: ExpressionId, heap_pos: u32, idx: i64) -> EvalError {
             let array_len = prompt.store.heap_regions[heap_pos as usize].values.len();
             return EvalError::new_error_at_expr(
                 prompt, modules, heap, expr_id,
                 format!("index {} is out of bounds: array length is {}", idx, array_len)
+            )
+        }
         // Checking if we're at the end of execution
         let cur_frame = self.frames.last_mut().unwrap();
         if cur_frame.position.is_invalid() {
             if heap[cur_frame.definition].is_function() {
                 todo!("End of function without return, return an evaluation error");
+            }
             return Ok(EvalContinuation::ComponentTerminated);
+        }
         debug_log!("Taking step in '{}'", heap[cur_frame.definition].identifier().value.as_str());
         // Execute all pending expressions
         while !cur_frame.expr_stack.is_empty() {
             let next = cur_frame.expr_stack.pop_back().unwrap();
             debug_log!("Expr stack: {:?}", next);
             match next {
                 ExprInstruction::PushValToFront => {
                     cur_frame.expr_values.rotate_right(1);
                 },
                 ExprInstruction::EvalExpr(expr_id) => {
                     let expr = &heap[expr_id];
                     match expr {
                         Expression::Assignment(expr) => {
                             let to = cur_frame.expr_values.pop_back().unwrap().as_ref();
                             let rhs = cur_frame.expr_values.pop_back().unwrap();
                             // Note: although not pretty, the assignment operator takes ownership
                             // of the right-hand side value when possible. So we do not drop the
                             // rhs's optionally owned heap data.
                             let rhs = self.store.read_take_ownership(rhs);
                             apply_assignment_operator(&mut self.store, to, expr.operation, rhs);
                         },
                         Expression::Binding(_expr) => {
                             let bind_to = cur_frame.expr_values.pop_back().unwrap();
                             let bind_from = cur_frame.expr_values.pop_back().unwrap();
                             let bind_to_heap_pos = bind_to.get_heap_pos();
                             let bind_from_heap_pos = bind_from.get_heap_pos();
                             let result = apply_binding_operator(&mut self.store, bind_to, bind_from);
                             self.store.drop_value(bind_to_heap_pos);
                             self.store.drop_value(bind_from_heap_pos);
                             cur_frame.expr_values.push_back(Value::Bool(result));
                         },
                         Expression::Conditional(expr) => {
                             // Evaluate testing expression, then extend the
                             // expression stack with the appropriate expression
                             let test_result = cur_frame.expr_values.pop_back().unwrap().as_bool();
                             if test_result {
                                 cur_frame.serialize_expression(heap, expr.true_expression);
                             } else {
                                 cur_frame.serialize_expression(heap, expr.false_expression);
+                            }
                         },
                         Expression::Binary(expr) => {
                             let lhs = cur_frame.expr_values.pop_back().unwrap();
                             let rhs = cur_frame.expr_values.pop_back().unwrap();
                             let result = apply_binary_operator(&mut self.store, &lhs, expr.operation, &rhs);
                             cur_frame.expr_values.push_back(result);
                             self.store.drop_value(lhs.get_heap_pos());
                             self.store.drop_value(rhs.get_heap_pos());
                         },
                         Expression::Unary(expr) => {
                             let val = cur_frame.expr_values.pop_back().unwrap();
                             let result = apply_unary_operator(&mut self.store, expr.operation, &val);
                             cur_frame.expr_values.push_back(result);
                             self.store.drop_value(val.get_heap_pos());
                         },
                         Expression::Indexing(_expr) => {
                             // Evaluate index. Never heap allocated so we do
                             // not have to drop it.
                             let index = cur_frame.expr_values.pop_back().unwrap();
                             let index = self.store.maybe_read_ref(&index);
                             debug_assert!(index.is_integer());
                             let index = if index.is_signed_integer() {
                                 index.as_signed_integer() as i64
                             } else {
                                 index.as_unsigned_integer() as i64
                             };
                             let subject = cur_frame.expr_values.pop_back().unwrap();
                             let (deallocate_heap_pos, value_to_push) = match subject {
                                 Value::Ref(value_ref) => {
                                     // Our expression stack value is a reference to something that
                                     // exists in the normal stack/heap. We don't want to deallocate
                                     // this thing. Rather we want to return a reference to it.
                                     let subject = self.store.read_ref(value_ref);
                                     let subject_heap_pos = match subject {
                                         Value::String(v) => *v,
                                         Value::Array(v) => *v,
                                         Value::Message(v) => *v,
                                         _ => unreachable!(),
                                     };
                                     if array_inclusive_index_is_invalid(&self.store, subject_heap_pos, index) {
                                         return Err(construct_array_error(self, modules, heap, expr_id, subject_heap_pos, index));
+                                    }
                                     (None, Value::Ref(ValueId::Heap(subject_heap_pos, index as u32)))
                                 },
                                 _ => {
                                     // Our value lives on the expression stack, hence we need to
                                     // clone whatever we're referring to. Then drop the subject.
                                     let subject_heap_pos = match &subject {
                                         Value::String(v) => *v,
                                         Value::Array(v) => *v,
                                         Value::Message(v) => *v,
                                         _ => unreachable!(),
                                     };
                                     if array_inclusive_index_is_invalid(&self.store, subject_heap_pos, index) {
                                         return Err(construct_array_error(self, modules, heap, expr_id, subject_heap_pos, index));
+                                    }
                                     let subject_indexed = Value::Ref(ValueId::Heap(subject_heap_pos, index as u32));
                                     (Some(subject_heap_pos), self.store.clone_value(subject_indexed))
                                 },
                             };
                             cur_frame.expr_values.push_back(value_to_push);
                             self.store.drop_value(deallocate_heap_pos);
                         },
                         Expression::Slicing(expr) => {
                             // Evaluate indices
                             let from_index = cur_frame.expr_values.pop_back().unwrap();
                             let from_index = self.store.maybe_read_ref(&from_index);
                             let to_index = cur_frame.expr_values.pop_back().unwrap();
                             let to_index = self.store.maybe_read_ref(&to_index);
                             debug_assert!(from_index.is_integer() && to_index.is_integer());
                             let from_index = if from_index.is_signed_integer() {
                                 from_index.as_signed_integer()
                             } else {
                                 from_index.as_unsigned_integer() as i64
                             };
                             let to_index = if to_index.is_signed_integer() {
                                 to_index.as_signed_integer()
                             } else {
                                 to_index.as_unsigned_integer() as i64
                             };
                             // Dereference subject if needed
                             let subject = cur_frame.expr_values.pop_back().unwrap();
                             let deref_subject = self.store.maybe_read_ref(&subject);
                             // Slicing needs to produce a copy anyway (with the
                             // current evaluator implementation)
                             enum ValueKind{ Array, String, Message }
                             let (value_kind, array_heap_pos) = match deref_subject {
                                 Value::Array(v) => (ValueKind::Array, *v),
                                 Value::String(v) => (ValueKind::String, *v),
                                 Value::Message(v) => (ValueKind::Message, *v),
                                 _ => unreachable!()
                             };
                             if array_inclusive_index_is_invalid(&self.store, array_heap_pos, from_index) {
                                 return Err(construct_array_error(self, modules, heap, expr.from_index, array_heap_pos, from_index));
+                            }
                             if array_exclusive_index_is_invalid(&self.store, array_heap_pos, to_index) {
                                 return Err(construct_array_error(self, modules, heap, expr.to_index, array_heap_pos, to_index));
+                            }
                             // Again: would love to push directly, but rust...
                             let new_heap_pos = self.store.alloc_heap();
                             debug_assert!(self.store.heap_regions[new_heap_pos as usize].values.is_empty());
                             if to_index > from_index {
                                 let from_index = from_index as usize;
                                 let to_index = to_index as usize;
                                 let mut values = Vec::with_capacity(to_index - from_index);
                                 for idx in from_index..to_index {
                                     let value = self.store.heap_regions[array_heap_pos as usize].values[idx].clone();
                                     values.push(self.store.clone_value(value));
+                                }
                                 self.store.heap_regions[new_heap_pos as usize].values = values;
                             } // else: empty range
                             cur_frame.expr_values.push_back(match value_kind {
                                 ValueKind::Array => Value::Array(new_heap_pos),
                                 ValueKind::String => Value::String(new_heap_pos),
                                 ValueKind::Message => Value::Message(new_heap_pos),
                             });
                             // Dropping the original subject, because we don't
                             // want to drop something on the stack
                             self.store.drop_value(subject.get_heap_pos());
                         },
                         Expression::Select(expr) => {
                             let subject= cur_frame.expr_values.pop_back().unwrap();
                             let mono_data = types.get_procedure_monomorph(cur_frame.monomorph_idx);
                             let field_idx = mono_data.expr_data[expr.unique_id_in_definition as usize].field_or_monomorph_idx as u32;
                             // Note: same as above: clone if value lives on expr stack, simply
                             // refer to it if it already lives on the stack/heap.
                             let (deallocate_heap_pos, value_to_push) = match subject {
                                 Value::Ref(value_ref) => {
                                     let subject = self.store.read_ref(value_ref);
                                     let subject_heap_pos = subject.as_struct();
                                     let subject_heap_pos = match expr.kind {
                                         SelectKind::StructField(_) => subject.as_struct(),
                                         SelectKind::TupleMember(_) => subject.as_tuple(),
                                     };
                                     (None, Value::Ref(ValueId::Heap(subject_heap_pos, field_idx)))
                                 },
                                 _ => {
                                     let subject_heap_pos = subject.as_struct();
                                     let subject_heap_pos = match expr.kind {
                                         SelectKind::StructField(_) => subject.as_struct(),
                                         SelectKind::TupleMember(_) => subject.as_tuple(),
                                     };
                                     let subject_indexed = Value::Ref(ValueId::Heap(subject_heap_pos, field_idx));
                                     (Some(subject_heap_pos), self.store.clone_value(subject_indexed))
                                 },
                             };
                             cur_frame.expr_values.push_back(value_to_push);
                             self.store.drop_value(deallocate_heap_pos);
                         },
                         Expression::Literal(expr) => {
                             let value = match &expr.value {
                                 Literal::Null => Value::Null,
                                 Literal::True => Value::Bool(true),
                                 Literal::False => Value::Bool(false),
                                 Literal::Character(lit_value) => Value::Char(*lit_value),
                                 Literal::String(lit_value) => {
                                     let heap_pos = self.store.alloc_heap();
                                     let values = &mut self.store.heap_regions[heap_pos as usize].values;
                                     let value = lit_value.as_str();
                                     debug_assert!(values.is_empty());
                                     values.reserve(value.len());
                                     for character in value.as_bytes() {
                                         debug_assert!(character.is_ascii());
                                         values.push(Value::Char(*character as char));
+                                    }
                                     Value::String(heap_pos)
+                                }
                                 Literal::Integer(lit_value) => {
                                     use ConcreteTypePart as CTP;
                                     let def_types = types.get_procedure_monomorph(cur_frame.monomorph_idx);
                                     let concrete_type = &def_types.expr_data[expr.unique_id_in_definition as usize].expr_type;
                                     debug_assert_eq!(concrete_type.parts.len(), 1);
                                     match concrete_type.parts[0] {
                                         CTP::UInt8  => Value::UInt8(lit_value.unsigned_value as u8),
                                         CTP::UInt16 => Value::UInt16(lit_value.unsigned_value as u16),
                                         CTP::UInt32 => Value::UInt32(lit_value.unsigned_value as u32),
                                         CTP::UInt64 => Value::UInt64(lit_value.unsigned_value as u64),
                                         CTP::SInt8  => Value::SInt8(lit_value.unsigned_value as i8),
                                         CTP::SInt16 => Value::SInt16(lit_value.unsigned_value as i16),
                                         CTP::SInt32 => Value::SInt32(lit_value.unsigned_value as i32),
                                         CTP::SInt64 => Value::SInt64(lit_value.unsigned_value as i64),
                                         _ => unreachable!("got concrete type {:?} for integer literal at expr {:?}", concrete_type, expr_id),
+                                    }
+                                }
                                 Literal::Struct(lit_value) => {
                                     let heap_pos = transfer_expression_values_front_into_heap(
                                         cur_frame, &mut self.store, lit_value.fields.len()
                                     );
                                     Value::Struct(heap_pos)
+                                }
                                 Literal::Enum(lit_value) => {
                                     Value::Enum(lit_value.variant_idx as i64)
+                                }
                                 Literal::Union(lit_value) => {
                                     let heap_pos = transfer_expression_values_front_into_heap(
                                         cur_frame, &mut self.store, lit_value.values.len()
                                     );
                                     Value::Union(lit_value.variant_idx as i64, heap_pos)
+                                }
                                 Literal::Array(lit_value) => {
                                     let heap_pos = transfer_expression_values_front_into_heap(
                                         cur_frame, &mut self.store, lit_value.len()
                                     );
                                     Value::Array(heap_pos)
+                                }
                                 Literal::Tuple(lit_value) => {
                                     let heap_pos = transfer_expression_values_front_into_heap(
                                         cur_frame, &mut self.store, lit_value.len()
                                     );
                                     Value::Tuple(heap_pos)
+                                }
                             };
                             cur_frame.expr_values.push_back(value);
                         },
                         Expression::Cast(expr) => {
                             let mono_data = types.get_procedure_monomorph(cur_frame.monomorph_idx);
                             let output_type = &mono_data.expr_data[expr.unique_id_in_definition as usize].expr_type;
                             // Typechecking reduced this to two cases: either we
                             // have casting noop (same types), or we're casting
                             // between integer/bool/char types.
                             let subject = cur_frame.expr_values.pop_back().unwrap();
                             match apply_casting(&mut self.store, output_type, &subject) {
                                 Ok(value) => cur_frame.expr_values.push_back(value),
                                 Err(msg) => {
                                     return Err(EvalError::new_error_at_expr(self, modules, heap, expr.this.upcast(), msg));
+                                }
+                            }
                             self.store.drop_value(subject.get_heap_pos());
+                        }
                         Expression::Call(expr) => {
                             // If we're dealing with a builtin we don't do any
                             // fancy shenanigans at all, just push the result.
                             match expr.method {
                                 Method::Get => {
                                     let value = cur_frame.expr_values.pop_front().unwrap();
                                     let value = self.store.maybe_read_ref(&value).clone();
                                     let port_id = if let Value::Input(port_id) = value {
                                         port_id
                                     } else {
                                         unreachable!("executor calling 'get' on value {:?}", value)
                                     };
                                     match ctx.performed_get(port_id) {
                                         Some(result) => {
                                             // We have the result. Merge the `ValueGroup` with the
                                             // stack/heap storage.
                                             debug_assert_eq!(result.values.len(), 1);
                                             result.into_stack(&mut cur_frame.expr_values, &mut self.store);
                                         },
                                         None => {
                                             // Don't have the result yet, prepare the expression to
                                             // get run again after we've received a message.
                                             cur_frame.expr_values.push_front(value.clone());
                                             cur_frame.expr_stack.push_back(ExprInstruction::EvalExpr(expr_id));
                                             return Ok(EvalContinuation::BlockGet(port_id));
+                                        }
+                                    }
                                 },
                                 Method::Put => {
                                     let port_value = cur_frame.expr_values.pop_front().unwrap();
                                     let deref_port_value = self.store.maybe_read_ref(&port_value).clone();
                                     let port_id = if let Value::Output(port_id) = deref_port_value {
                                         port_id
                                     } else {
                                         unreachable!("executor calling 'put' on value {:?}", deref_port_value)
                                     };
                                     let msg_value = cur_frame.expr_values.pop_front().unwrap();
                                     let deref_msg_value = self.store.maybe_read_ref(&msg_value).clone();
                                     if ctx.performed_put(port_id) {
                                         // We're fine, deallocate in case the expression value stack
                                         // held an owned value
                                         self.store.drop_value(msg_value.get_heap_pos());
                                     } else {
                                         // Prepare to execute again
                                         cur_frame.expr_values.push_front(msg_value);
                                         cur_frame.expr_values.push_front(port_value);
                                         cur_frame.expr_stack.push_back(ExprInstruction::EvalExpr(expr_id));
                                         let value_group = ValueGroup::from_store(&self.store, &[deref_msg_value]);
                                         return Ok(EvalContinuation::Put(port_id, value_group));
+                                    }
                                 },
                                 Method::Fires => {
                                     let port_value = cur_frame.expr_values.pop_front().unwrap();
                                     let port_value_deref = self.store.maybe_read_ref(&port_value).clone();
                                     let port_id = match port_value_deref {
                                         Value::Input(port_id) => port_id,
                                         Value::Output(port_id) => port_id,
                                         _ => unreachable!("executor calling 'fires' on value {:?}", port_value_deref),
                                     };
                                     match ctx.fires(port_id) {
                                         None => {
                                             cur_frame.expr_values.push_front(port_value);
                                             cur_frame.expr_stack.push_back(ExprInstruction::EvalExpr(expr_id));
                                             return Ok(EvalContinuation::BlockFires(port_id));
                                         },
                                         Some(value) => {
                                             cur_frame.expr_values.push_back(value);
+                                        }
+                                    }
                                 },
                                 Method::Create => {
                                     let length_value = cur_frame.expr_values.pop_front().unwrap();
                                     let length_value = self.store.maybe_read_ref(&length_value);
                                     let length = if length_value.is_signed_integer() {
                                         let length_value = length_value.as_signed_integer();
                                         if length_value < 0 {
                                             return Err(EvalError::new_error_at_expr(
                                                 self, modules, heap, expr_id,
                                                 format!("got length '{}', can only create a message with a non-negative length", length_value)
                                             ));
+                                        }
                                         length_value as u64
                                     } else {
                                         debug_assert!(length_value.is_unsigned_integer());
                                         length_value.as_unsigned_integer()
                                     };
                                     let heap_pos = self.store.alloc_heap();
                                     let values = &mut self.store.heap_regions[heap_pos as usize].values;
                                     debug_assert!(values.is_empty());
                                     values.resize(length as usize, Value::UInt8(0));
                                     cur_frame.expr_values.push_back(Value::Message(heap_pos));
                                 },
                                 Method::Length => {
                                     let value = cur_frame.expr_values.pop_front().unwrap();
                                     let value_heap_pos = value.get_heap_pos();
                                     let value = self.store.maybe_read_ref(&value);
                                     let heap_pos = match value {
                                         Value::Array(pos) => *pos,
                                         Value::String(pos) => *pos,
                                         _ => unreachable!("length(...) on {:?}", value),
                                     };
                                     let len = self.store.heap_regions[heap_pos as usize].values.len();
                                     // TODO: @PtrInt
                                     cur_frame.expr_values.push_back(Value::UInt32(len as u32));
                                     self.store.drop_value(value_heap_pos);
                                 },
                                 Method::Assert => {
                                     let value = cur_frame.expr_values.pop_front().unwrap();
                                     let value = self.store.maybe_read_ref(&value).clone();
                                     if !value.as_bool() {
                                         return Ok(EvalContinuation::BranchInconsistent)
+                                    }
                                 },
                                 Method::Print => {
                                     // Convert the runtime-variant of a string
                                     // into an actual string.
                                     let value = cur_frame.expr_values.pop_front().unwrap();
                                     let value_heap_pos = value.as_string();
                                     let elements = &self.store.heap_regions[value_heap_pos as usize].values;
                                     let mut message = String::with_capacity(elements.len());
                                     for element in elements {
                                         message.push(element.as_char());
+                                    }
                                     // Drop the heap-allocated value from the
                                     // store
                                     self.store.drop_heap_pos(value_heap_pos);
                                     println!("{}", message);
                                 },
                                 Method::UserComponent => {
                                     // This is actually handled by the evaluation
                                     // of the statement.
                                     debug_assert_eq!(heap[expr.definition].parameters().len(), cur_frame.expr_values.len());
                                     debug_assert_eq!(heap[cur_frame.position].as_new().expression, expr.this)
                                 },
                                 Method::UserFunction => {
                                     // Push a new frame. Note that all expressions have
                                     // been pushed to the front, so they're in the order
                                     // of the definition.
                                     let num_args = expr.arguments.len();
                                     // Determine stack boundaries
                                     let cur_stack_boundary = self.store.cur_stack_boundary;
                                     let new_stack_boundary = self.store.stack.len();
                                     // Push new boundary and function arguments for new frame
                                     self.store.stack.push(Value::PrevStackBoundary(cur_stack_boundary as isize));
                                     for _ in 0..num_args {
                                         let argument = self.store.read_take_ownership(cur_frame.expr_values.pop_front().unwrap());
                                         self.store.stack.push(argument);
+                                    }
                                     // Determine the monomorph index of the function we're calling
                                     let mono_data = types.get_procedure_monomorph(cur_frame.monomorph_idx);
                                     let call_data = &mono_data.expr_data[expr.unique_id_in_definition as usize];
                                     // Push the new frame and reserve its stack size
                                     let new_frame = Frame::new(heap, expr.definition, call_data.field_or_monomorph_idx);
                                     let new_stack_size = new_frame.max_stack_size;
                                     self.frames.push(new_frame);
                                     self.store.cur_stack_boundary = new_stack_boundary;
                                     self.store.reserve_stack(new_stack_size);
                                     // To simplify the logic a little bit we will now
                                     // return and ask our caller to call us again
                                     return Ok(EvalContinuation::Stepping);
                                 },
+                            }
                         },
                         Expression::Variable(expr) => {
                             let variable = &heap[expr.declaration.unwrap()];
                             let ref_value = if expr.used_as_binding_target {
                                 Value::Binding(variable.unique_id_in_scope as StackPos)
                             } else {
                                 Value::Ref(ValueId::Stack(variable.unique_id_in_scope as StackPos))
                             };
                             cur_frame.expr_values.push_back(ref_value);
+                        }
+                    }
+                }
+            }
+        }
         debug_log!("Frame [{:?}] at {:?}", cur_frame.definition, cur_frame.position);
         if debug_enabled!() {
             debug_log!("Expression value stack (size = {}):", cur_frame.expr_values.len());
             for (_stack_idx, _stack_val) in cur_frame.expr_values.iter().enumerate() {
                 debug_log!("  [{:03}] {:?}", _stack_idx, _stack_val);
+            }
             debug_log!("Stack (size = {}):", self.store.stack.len());
             for (_stack_idx, _stack_val) in self.store.stack.iter().enumerate() {
                 debug_log!("  [{:03}] {:?}", _stack_idx, _stack_val);
+            }
             debug_log!("Heap:");
             for (_heap_idx, _heap_region) in self.store.heap_regions.iter().enumerate() {
                 let _is_free = self.store.free_regions.iter().any(|idx| *idx as usize == _heap_idx);
                 debug_log!("  [{:03}] in_use: {}, len: {}, vals: {:?}", _heap_idx, !_is_free, _heap_region.values.len(), &_heap_region.values);
+            }
+        }
         // No (more) expressions to evaluate. So evaluate statement (that may
         // depend on the result on the last evaluated expression(s))
         let stmt = &heap[cur_frame.position];
         let return_value = match stmt {
             Statement::Block(stmt) => {
                 debug_assert!(stmt.statements.is_empty() || stmt.next == stmt.statements[0]);
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::Stepping)
             },
             Statement::EndBlock(stmt) => {
                 let block = &heap[stmt.start_block];
                 self.store.clear_stack(block.first_unique_id_in_scope as usize);
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::Stepping)
             },
             Statement::Local(stmt) => {
                 match stmt {
                     LocalStatement::Memory(stmt) => {
                         let variable = &heap[stmt.variable];
                         self.store.write(ValueId::Stack(variable.unique_id_in_scope as u32), Value::Unassigned);
                         cur_frame.position = stmt.next;
                         Ok(EvalContinuation::Stepping)
                     },
                     LocalStatement::Channel(stmt) => {
                         // Need to create a new channel by requesting it from
                         // the runtime.
                         match ctx.created_channel() {
                             None => {
                                 // No channel is pending. So request one
                                 Ok(EvalContinuation::NewChannel)
                             },
                             Some((put_port, get_port)) => {
                                 self.store.write(ValueId::Stack(heap[stmt.from].unique_id_in_scope as u32), put_port);
                                 self.store.write(ValueId::Stack(heap[stmt.to].unique_id_in_scope as u32), get_port);
                                 cur_frame.position = stmt.next;
                                 Ok(EvalContinuation::Stepping)
+                            }
+                        }
+                    }
+                }
             },
             Statement::Labeled(stmt) => {
                 cur_frame.position = stmt.body;
                 Ok(EvalContinuation::Stepping)
             },
             Statement::If(stmt) => {
                 debug_assert_eq!(cur_frame.expr_values.len(), 1, "expected one expr value for if statement");
                 let test_value = cur_frame.expr_values.pop_back().unwrap();
                 let test_value = self.store.maybe_read_ref(&test_value).as_bool();
                 if test_value {
                     cur_frame.position = stmt.true_body.upcast();
                 } else if let Some(false_body) = stmt.false_body {
                     cur_frame.position = false_body.upcast();
                 } else {
                     // Not true, and no false body
                     cur_frame.position = stmt.end_if.upcast();
+                }
                 Ok(EvalContinuation::Stepping)
             },
             Statement::EndIf(stmt) => {
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::Stepping)
             },
             Statement::While(stmt) => {
                 debug_assert_eq!(cur_frame.expr_values.len(), 1, "expected one expr value for while statement");
                 let test_value = cur_frame.expr_values.pop_back().unwrap();
                 let test_value = self.store.maybe_read_ref(&test_value).as_bool();
                 if test_value {
                     cur_frame.position = stmt.body.upcast();
                 } else {
                     cur_frame.position = stmt.end_while.upcast();
+                }
                 Ok(EvalContinuation::Stepping)
             },
             Statement::EndWhile(stmt) => {
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::Stepping)
             },
             Statement::Break(stmt) => {
                 cur_frame.position = stmt.target.unwrap().upcast();
                 Ok(EvalContinuation::Stepping)
             },
             Statement::Continue(stmt) => {
                 cur_frame.position = stmt.target.unwrap().upcast();
                 Ok(EvalContinuation::Stepping)
             },
             Statement::Synchronous(stmt) => {
                 cur_frame.position = stmt.body.upcast();
                 Ok(EvalContinuation::SyncBlockStart)
             },
             Statement::EndSynchronous(stmt) => {
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::SyncBlockEnd)
             },
             Statement::Fork(stmt) => {
                 if stmt.right_body.is_none() {
                     // No reason to fork
                     cur_frame.position = stmt.left_body.upcast();
                 } else {
                     // Need to fork
                     if let Some(go_left) = ctx.performed_fork() {
                         // Runtime has created a fork
                         if go_left {
                             cur_frame.position = stmt.left_body.upcast();
                         } else {
                             cur_frame.position = stmt.right_body.unwrap().upcast();
+                        }
                     } else {
                         // Request the runtime to create a fork of the current
                         // branch
                         return Ok(EvalContinuation::NewFork);
+                    }
+                }
                 Ok(EvalContinuation::Stepping)
             },
             Statement::EndFork(stmt) => {
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::Stepping)
+            }
             Statement::Return(_stmt) => {
                 debug_assert!(heap[cur_frame.definition].is_function());
                 debug_assert_eq!(cur_frame.expr_values.len(), 1, "expected one expr value for return statement");
                 // The preceding frame has executed a call, so is expecting the
                 // return expression on its expression value stack. Note that
                 // we may be returning a reference to something on our stack,
                 // so we need to read that value and clone it.
                 let return_value = cur_frame.expr_values.pop_back().unwrap();
                 let return_value = match return_value {
                     Value::Ref(value_id) => self.store.read_copy(value_id),
                     _ => return_value,
                 };
                 // Pre-emptively pop our stack frame
                 self.frames.pop();
                 // Clean up our section of the stack
                 self.store.clear_stack(0);
                 self.store.stack.truncate(self.store.cur_stack_boundary + 1);
                 let prev_stack_idx = self.store.stack.pop().unwrap().as_stack_boundary();
                 // TODO: Temporary hack for testing, remove at some point
                 if self.frames.is_empty() {
                     debug_assert!(prev_stack_idx == -1);
                     debug_assert!(self.store.stack.len() == 0);
                     self.store.stack.push(return_value);
                     return Ok(EvalContinuation::ComponentTerminated);
+                }
                 debug_assert!(prev_stack_idx >= 0);
                 // Return to original state of stack frame
                 self.store.cur_stack_boundary = prev_stack_idx as usize;
                 let cur_frame = self.frames.last_mut().unwrap();
                 cur_frame.expr_values.push_back(return_value);
                 // We just returned to the previous frame, which might be in
                 // the middle of evaluating expressions for a particular
                 // statement. So we don't want to enter the code below.
                 return Ok(EvalContinuation::Stepping);
             },
             Statement::Goto(stmt) => {
                 cur_frame.position = stmt.target.unwrap().upcast();
                 Ok(EvalContinuation::Stepping)
             },
             Statement::New(stmt) => {
                 let call_expr = &heap[stmt.expression];
                 debug_assert!(heap[call_expr.definition].is_component());
                 debug_assert_eq!(
                     cur_frame.expr_values.len(), heap[call_expr.definition].parameters().len(),
                     "mismatch in expr stack size and number of arguments for new statement"
                 );
                 let mono_data = types.get_procedure_monomorph(cur_frame.monomorph_idx);
                 let expr_data = &mono_data.expr_data[call_expr.unique_id_in_definition as usize];
                 // Note that due to expression value evaluation they exist in
                 // reverse order on the stack.
                 // TODO: Revise this code, keep it as is to be compatible with current runtime
                 let mut args = Vec::new();
                 while let Some(value) = cur_frame.expr_values.pop_front() {
                     args.push(value);
+                }
                 // Construct argument group, thereby copying heap regions
                 let argument_group = ValueGroup::from_store(&self.store, &args);
                 // println!("Creating {} with\n{:#?}", heap[call_expr.definition].identifier().value.as_str(), argument_group);
                 // Clear any heap regions
                 for arg in &args {
                     self.store.drop_value(arg.get_heap_pos());
+                }
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::NewComponent(call_expr.definition, expr_data.field_or_monomorph_idx, argument_group))
             },
             Statement::Expression(stmt) => {
                 // The expression has just been completely evaluated. Some
                 // values might have remained on the expression value stack.
                 // cur_frame.expr_values.clear(); PROPER CLEARING
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::Stepping)
             },
         };
         assert!(
             cur_frame.expr_values.is_empty(),
             "This is a debugging assertion that will fail if you perform expressions without \
             assigning to anything. This should be completely valid, and this assertion should be \
             replaced by something that clears the expression values if needed, but I'll keep this \
             in for now for debugging purposes."
         );
         // If the next statement requires evaluating expressions then we push
         // these onto the expression stack. This way we will evaluate this
         // stack in the next loop, then evaluate the statement using the result
         // from the expression evaluation.
         if !cur_frame.position.is_invalid() {
             let stmt = &heap[cur_frame.position];
             match stmt {
                 Statement::If(stmt) => cur_frame.prepare_single_expression(heap, stmt.test),
                 Statement::While(stmt) => cur_frame.prepare_single_expression(heap, stmt.test),
                 Statement::Return(stmt) => {
                     debug_assert_eq!(stmt.expressions.len(), 1); // TODO: @ReturnValues
                     cur_frame.prepare_single_expression(heap, stmt.expressions[0]);
                 },
                 Statement::New(stmt) => {
                     // Note that we will end up not evaluating the call itself.
                     // Rather we will evaluate its expressions and then
                     // instantiate the component upon reaching the "new" stmt.
                     let call_expr = &heap[stmt.expression];
                     cur_frame.prepare_multiple_expressions(heap, &call_expr.arguments);
                 },
                 Statement::Expression(stmt) => {
                     cur_frame.prepare_single_expression(heap, stmt.expression);
+                }
                 _ => {},
+            }
+        }
         return_value
+    }
     /// Constructs an error at the current expression that lives at the top of
     /// the expression stack. Falls back to constructing an error at the current
     /// statement if there is no expression.
     pub(crate) fn new_error_at_expr(&self, modules: &[Module], heap: &Heap, error_message: String) -> EvalError {
         let last_frame = self.frames.last().unwrap();
         for instruction in last_frame.expr_stack.iter().rev() {
             if let ExprInstruction::EvalExpr(expression_id) = instruction {
                 return EvalError::new_error_at_expr(
                     self, modules, heap, *expression_id, error_message
                 );
+            }
+        }
         // If here then expression stack was empty (cannot have just rotate
         // instructions)
         panic!("attempted to construct evaluation error without any expressions to evaluate in frame");
+    }
+}
@@ \ No newline at end of file @@

src/protocol/eval/store.rs

➞

Show inline comments

 use std::collections::VecDeque;
 use super::value::{Value, ValueId, HeapPos};
 #[derive(Debug, Clone)]
 pub(crate) struct HeapAllocation {
     pub values: Vec<Value>,
+}
 #[derive(Debug, Clone)]
 pub(crate) struct Store {
     // The stack where variables/parameters are stored. Note that this is a
     // non-shrinking stack. So it may be filled with garbage.
     pub(crate) stack: Vec<Value>,
     // Represents the place in the stack where we find the `PrevStackBoundary`
     // value containing the previous stack boundary. This is so we can pop from
     // the stack after function calls.
     pub(crate) cur_stack_boundary: usize,
     // A rather ridiculous simulated heap, but this allows us to "allocate"
     // things that occupy more then one stack slot.
     pub(crate) heap_regions: Vec<HeapAllocation>,
     pub(crate) free_regions: VecDeque<HeapPos>,
+}
 impl Store {
     pub(crate) fn new() -> Self {
         let mut store = Self{
             stack: Vec::with_capacity(64),
             cur_stack_boundary: 0,
             heap_regions: Vec::new(),
             free_regions: VecDeque::new(),
         };
         store.stack.push(Value::PrevStackBoundary(-1));
         store
+    }
     /// Resizes(!) the stack to fit the required number of values. Any
     /// unallocated slots are initialized to `Unassigned`. The specified stack
     /// index is exclusive.
     pub(crate) fn reserve_stack(&mut self, unique_stack_idx: u32) {
         let new_size = self.cur_stack_boundary + unique_stack_idx as usize + 1;
         if new_size > self.stack.len() {
             self.stack.resize(new_size, Value::Unassigned);
+        }
+    }
     /// Clears values on the stack and removes their heap allocations when
     /// applicable. The specified index itself will also be cleared (so if you
     /// specify 0 all values in the frame will be destroyed)
     pub(crate) fn clear_stack(&mut self, unique_stack_idx: usize) {
         let new_size = self.cur_stack_boundary + unique_stack_idx + 1;
         for idx in new_size..self.stack.len() {
             let heap_pos = self.stack[idx].get_heap_pos();
             self.drop_value(heap_pos);
             // TODO: @remove, somewhat temporarily not clearing pure stack
             //  values for testing purposes.
             if heap_pos.is_some() {
                 self.stack[idx] = Value::Unassigned;
+            }
+        }
+    }
     /// Reads a value and takes ownership. This is different from a move because
     /// the value might indirectly reference stack/heap values. For these kinds
     /// values we will actually return a cloned value.
     pub(crate) fn read_take_ownership(&mut self, value: Value) -> Value {
         match value {
             Value::Ref(ValueId::Stack(pos)) => {
                 let abs_pos = self.cur_stack_boundary + 1 + pos as usize;
                 return self.clone_value(self.stack[abs_pos].clone());
             },
             Value::Ref(ValueId::Heap(heap_pos, value_idx)) => {
                 let heap_pos = heap_pos as usize;
                 let value_idx = value_idx as usize;
                 return self.clone_value(self.heap_regions[heap_pos].values[value_idx].clone());
             },
             _ => value
+        }
+    }
     /// Reads a value from a specific address. The value is always copied, hence
     /// if the value ends up not being written, one should call `drop_value` on
     /// it.
     pub(crate) fn read_copy(&mut self, address: ValueId) -> Value {
         match address {
             ValueId::Stack(pos) => {
                 let cur_pos = self.cur_stack_boundary + 1 + pos as usize;
                 return self.clone_value(self.stack[cur_pos].clone());
             },
             ValueId::Heap(heap_pos, region_idx) => {
                 return self.clone_value(self.heap_regions[heap_pos as usize].values[region_idx as usize].clone())
+            }
+        }
+    }
     /// Potentially reads a reference value. The supplied `Value` might not
     /// actually live in the store's stack or heap, but live on the expression
     /// stack. Generally speaking you only want to call this if the value comes
     /// from the expression stack due to borrowing issues.
     pub(crate) fn maybe_read_ref<'a>(&'a self, value: &'a Value) -> &'a Value {
         match value {
             Value::Ref(value_id) => self.read_ref(*value_id),
             _ => value,
+        }
+    }
     /// Returns an immutable reference to the value pointed to by an address
     pub(crate) fn read_ref(&self, address: ValueId) -> &Value {
         match address {
             ValueId::Stack(pos) => {
                 let cur_pos = self.cur_stack_boundary + 1 + pos as usize;
                 return &self.stack[cur_pos];
             },
             ValueId::Heap(heap_pos, region_idx) => {
                 return &self.heap_regions[heap_pos as usize].values[region_idx as usize];
+            }
+        }
+    }
     /// Returns a mutable reference to the value pointed to by an address
     pub(crate) fn read_mut_ref(&mut self, address: ValueId) -> &mut Value {
         match address {
             ValueId::Stack(pos) => {
                 let cur_pos = self.cur_stack_boundary + 1 + pos as usize;
                 return &mut self.stack[cur_pos];
             },
             ValueId::Heap(heap_pos, region_idx) => {
                 return &mut self.heap_regions[heap_pos as usize].values[region_idx as usize];
+            }
+        }
+    }
     /// Writes a value
     pub(crate) fn write(&mut self, address: ValueId, value: Value) {
         match address {
             ValueId::Stack(pos) => {
                 let cur_pos = self.cur_stack_boundary + 1 + pos as usize;
                 self.drop_value(self.stack[cur_pos].get_heap_pos());
                 self.stack[cur_pos] = value;
             },
             ValueId::Heap(heap_pos, region_idx) => {
                 let heap_pos = heap_pos as usize;
                 let region_idx = region_idx as usize;
                 self.drop_value(self.heap_regions[heap_pos].values[region_idx].get_heap_pos());
                 self.heap_regions[heap_pos].values[region_idx] = value
+            }
+        }
+    }
     /// This thing takes a cloned Value, because of borrowing issues (which is
     /// either a direct value, or might contain an index to a heap value), but
     /// should be treated by the programmer as a reference (i.e. don't call
     /// `drop_value(thing)` after calling `clone_value(thing.clone())`.
     pub(crate) fn clone_value(&mut self, value: Value) -> Value {
         // Quickly check if the value is not on the heap
         let source_heap_pos = value.get_heap_pos();
         if source_heap_pos.is_none() {
             // We can do a trivial copy, unless we're dealing with a value
             // reference
             return match value {
                 Value::Ref(ValueId::Stack(stack_pos)) => {
                     let abs_stack_pos = self.cur_stack_boundary + stack_pos as usize + 1;
                     self.clone_value(self.stack[abs_stack_pos].clone())
                 },
                 Value::Ref(ValueId::Heap(heap_pos, val_idx)) => {
                     self.clone_value(self.heap_regions[heap_pos as usize].values[val_idx as usize].clone())
                 },
                 _ => value,
             };
+        }
         // Value does live on heap, copy it
         let source_heap_pos = source_heap_pos.unwrap() as usize;
         let target_heap_pos = self.alloc_heap();
         let target_heap_pos_usize = target_heap_pos as usize;
         let num_values = self.heap_regions[source_heap_pos].values.len();
         for value_idx in 0..num_values {
             let cloned = self.clone_value(self.heap_regions[source_heap_pos].values[value_idx].clone());
             self.heap_regions[target_heap_pos_usize].values.push(cloned);
+        }
         match value {
             Value::Message(_) => Value::Message(target_heap_pos),
             Value::String(_) => Value::String(target_heap_pos),
             Value::Array(_) => Value::Array(target_heap_pos),
             Value::Union(tag, _) => Value::Union(tag, target_heap_pos),
             Value::Struct(_) => Value::Struct(target_heap_pos),
             Value::Tuple(_) => Value::Tuple(target_heap_pos),
             _ => unreachable!("performed clone_value on heap, but {:?} is not a heap value", value),
+        }
+    }
     pub(crate) fn drop_value(&mut self, value: Option<HeapPos>) {
         if let Some(heap_pos) = value {
             self.drop_heap_pos(heap_pos);
+        }
+    }
     pub(crate) fn drop_heap_pos(&mut self, heap_pos: HeapPos) {
         let num_values = self.heap_regions[heap_pos as usize].values.len();
         for value_idx in 0..num_values {
             if let Some(other_heap_pos) = self.heap_regions[heap_pos as usize].values[value_idx].get_heap_pos() {
                 self.drop_heap_pos(other_heap_pos);
+            }
+        }
         self.heap_regions[heap_pos as usize].values.clear();
         self.free_regions.push_back(heap_pos);
+    }
     pub(crate) fn alloc_heap(&mut self) -> HeapPos {
         if self.free_regions.is_empty() {
             let idx = self.heap_regions.len() as HeapPos;
             self.heap_regions.push(HeapAllocation{ values: Vec::new() });
             return idx;
         } else {
             let idx = self.free_regions.pop_back().unwrap();
             return idx;
+        }
+    }
+}
@@ \ No newline at end of file @@

src/protocol/parser/pass_typing.rs

➞

Show inline comments

 /// pass_typing
 ///
 /// 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 case we return an
 /// error.
 ///
 /// TODO: Needs a thorough rewrite:
 ///  0. polymorph_progress is intentionally broken at the moment. Make it work
 ///     again and use a normal VecSomething.
 ///  1. The foundation for doing all of the work with predetermined indices
 ///     instead of with HashMaps is there, but it is not really used because of
 ///     time constraints. When time is available, rewrite the system such that
 ///     AST IDs are not needed, and only indices into arrays are used.
 ///  2. We're doing a lot of extra work. It seems better to apply the initial
 ///     type based on expression parents, and immediately apply forced
 ///     constraints (arg to a fires() call must be port-like). All of the \
 ///     progress_xxx calls should then only be concerned with "transmitting"
 ///     type inference across their parent/child expressions.
 ///  3. Remove the `msg` type?
 ///  4. Disallow certain types in certain operations (e.g. `Void`).
 macro_rules! debug_log_enabled {
     () => { false };
+}
 macro_rules! debug_log {
     ($format:literal) => {
         enabled_debug_print!(false, "types", $format);
     };
     ($format:literal, $($args:expr),*) => {
         enabled_debug_print!(false, "types", $format, $($args),*);
     };
+}
 use std::collections::{HashMap, HashSet};
 use crate::collections::DequeSet;
 use crate::protocol::ast::*;
 use crate::protocol::input_source::ParseError;
 use crate::protocol::parser::ModuleCompilationPhase;
 use crate::protocol::parser::type_table::*;
 use crate::protocol::parser::token_parsing::*;
 use super::visitor::{
     STMT_BUFFER_INIT_CAPACITY,
     EXPR_BUFFER_INIT_CAPACITY,
     Ctx,
     Visitor,
     VisitorResult
 };
 const VOID_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::Void ];
 const MESSAGE_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::Message, InferenceTypePart::UInt8 ];
 const BOOL_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::Bool ];
 const CHARACTER_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::Character ];
 const STRING_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::String, InferenceTypePart::Character ];
 const NUMBERLIKE_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::NumberLike ];
 const INTEGERLIKE_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::IntegerLike ];
 const ARRAY_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::Array, InferenceTypePart::Unknown ];
 const SLICE_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::Slice, InferenceTypePart::Unknown ];
 const ARRAYLIKE_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::ArrayLike, InferenceTypePart::Unknown ];
 /// TODO: @performance Turn into PartialOrd+Ord to simplify checks
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub(crate) enum InferenceTypePart {
     // When we infer types of AST elements that support polymorphic arguments,
     // then we might have the case that multiple embedded types depend on the
     // polymorphic type (e.g. func bla(T a, T[] b) -> T[][]). If we can infer
     // the type in one place (e.g. argument a), then we may propagate this
     // information to other types (e.g. argument b and the return type). For
     // this reason we place markers in the `InferenceType` instances such that
     // we know which part of the type was originally a polymorphic argument.
     Marker(u32),
     // Completely unknown type, needs to be inferred
     Unknown,
     // Partially known type, may be inferred to to be the appropriate related
     // type.
     // IndexLike,      // index into array/slice
     NumberLike,     // any kind of integer/float
     IntegerLike,    // any kind of integer
     ArrayLike,      // array or slice. Note that this must have a subtype
     PortLike,       // input or output port
     // Special types that cannot be instantiated by the user
     Void, // For builtin functions that do not return anything
     // Concrete types without subtypes
     Bool,
     UInt8,
     UInt16,
     UInt32,
     UInt64,
     SInt8,
     SInt16,
     SInt32,
     SInt64,
     Character,
     String,
     // One subtype
     Message,
     Array,
     Slice,
     Input,
     Output,
     // Tuple with any number of subtypes (for practical reasons 1 element is impossible)
     Tuple(u32),
     // A user-defined type with any number of subtypes
     Instance(DefinitionId, u32)
+}
 impl InferenceTypePart {
     fn is_marker(&self) -> bool {
         match self {
             InferenceTypePart::Marker(_) => true,
             _ => false,
+        }
+    }
     /// Checks if the type is concrete, markers are interpreted as concrete
     /// types.
     fn is_concrete(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::Unknown | ITP::NumberLike |
             ITP::IntegerLike | ITP::ArrayLike | ITP::PortLike => false,
             _ => true
+        }
+    }
     fn is_concrete_number(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::UInt8 | ITP::UInt16 | ITP::UInt32 | ITP::UInt64 |
             ITP::SInt8 | ITP::SInt16 | ITP::SInt32 | ITP::SInt64 => true,
             _ => false,
+        }
+    }
     fn is_concrete_integer(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::UInt8 | ITP::UInt16 | ITP::UInt32 | ITP::UInt64 |
             ITP::SInt8 | ITP::SInt16 | ITP::SInt32 | ITP::SInt64 => true,
             _ => false,
+        }
+    }
     fn is_concrete_arraylike(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::Array | ITP::Slice | ITP::String | ITP::Message => true,
             _ => false,
+        }
+    }
     fn is_concrete_port(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::Input | ITP::Output => true,
             _ => false,
+        }
+    }
     /// Checks if a part is less specific than the argument. Only checks for
     /// single-part inference (i.e. not the replacement of an `Unknown` variant
     /// with the argument)
     fn may_be_inferred_from(&self, arg: &InferenceTypePart) -> bool {
         use InferenceTypePart as ITP;
         (*self == ITP::IntegerLike && arg.is_concrete_integer()) ||
         (*self == ITP::NumberLike && (arg.is_concrete_number() || *arg == ITP::IntegerLike)) ||
         (*self == ITP::ArrayLike && arg.is_concrete_arraylike()) ||
         (*self == ITP::PortLike && arg.is_concrete_port())
+    }
     /// Checks if a part is more specific
     /// Returns the change in "iteration depth" when traversing this particular
     /// part. The iteration depth is used to traverse the tree in a linear
     /// fashion. It is basically `number_of_subtypes - 1`
     fn depth_change(&self) -> i32 {
         use InferenceTypePart as ITP;
         match &self {
             ITP::Unknown | ITP::NumberLike | ITP::IntegerLike |
             ITP::Void | ITP::Bool |
             ITP::UInt8 | ITP::UInt16 | ITP::UInt32 | ITP::UInt64 |
             ITP::SInt8 | ITP::SInt16 | ITP::SInt32 | ITP::SInt64 |
             ITP::Character => {
                 -1
             },
             ITP::Marker(_) |
             ITP::ArrayLike | ITP::Message | ITP::Array | ITP::Slice |
             ITP::PortLike | ITP::Input | ITP::Output | ITP::String => {
                 // One subtype, so do not modify depth
             },
             ITP::Tuple(num) | ITP::Instance(_, num) => {
                 (*num as i32) - 1
+            }
+        }
+    }
+}
 #[derive(Debug, Clone)]
 struct InferenceType {
     has_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_marker: bool, is_done: bool, parts: Vec<InferenceTypePart>) -> Self {
         if cfg!(debug_assertions) {
             debug_assert!(!parts.is_empty());
             let parts_body_marker = parts.iter().any(|v| v.is_marker());
             debug_assert_eq!(has_marker, parts_body_marker);
             let parts_done = parts.iter().all(|v| v.is_concrete());
             debug_assert_eq!(is_done, parts_done, "{:?}", parts);
+        }
         Self{ has_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_marker(&self, mut start_idx: usize) -> Option<(u32, usize)> {
         while start_idx < self.parts.len() {
             if let InferenceTypePart::Marker(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. If it is a problem that `InferenceType` is
     /// borrowed by the iterator, then use `find_body_marker`.
     fn 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!("Malformed type: {:?}", parts);
+    }
     /// 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];
         // Check for programmer mistakes
         debug_assert_ne!(to_infer_part, template_part);
         debug_assert!(!to_infer_part.is_marker(), "marker encountered in 'infer part'");
         debug_assert!(!template_part.is_marker(), "marker encountered in 'template part'");
         // Inference of a somewhat-specified type
         if to_infer_part.may_be_inferred_from(template_part) {
             let depth_change = to_infer_part.depth_change();
             debug_assert_eq!(depth_change, template_part.depth_change());
             to_infer.parts[*to_infer_idx] = template_part.clone();
             *to_infer_idx += 1;
             *template_idx += 1;
             return Some(depth_change);
+        }
         // Inference of a completely unknown type
         if *to_infer_part == ITP::Unknown {
             // template part is different, so cannot be unknown, hence copy the
             // entire subtree. Make sure not to copy markers.
             let template_end_idx = Self::find_subtree_end_idx(template_parts, *template_idx);
             to_infer.parts[*to_infer_idx] = template_parts[*template_idx].clone(); // first element
             *to_infer_idx += 1;
             for template_idx in *template_idx + 1..template_end_idx {
                 let template_part = &template_parts[template_idx];
                 if !template_part.is_marker() {
                     to_infer.parts.insert(*to_infer_idx, template_part.clone());
                     *to_infer_idx += 1;
+                }
+            }
             *template_idx = template_end_idx;
             // Note: by definition the LHS was Unknown and the RHS traversed a
             // full subtree.
             return Some(-1);
+        }
         None
+    }
     /// Call that checks if the `to_check` part is compatible with the `infer`
     /// part. This is essentially a copy of `infer_part_for_single_type`, but
     /// without actually copying the type parts.
     fn check_part_for_single_type(
         to_check_parts: &[InferenceTypePart], to_check_idx: &mut usize,
         template_parts: &[InferenceTypePart], template_idx: &mut usize
     ) -> Option<i32> {
         use InferenceTypePart as ITP;
         let to_check_part = &to_check_parts[*to_check_idx];
         let template_part = &template_parts[*template_idx];
         // Checking programmer errors
         debug_assert_ne!(to_check_part, template_part);
         debug_assert!(!to_check_part.is_marker(), "marker encountered in 'to_check part'");
         debug_assert!(!template_part.is_marker(), "marker encountered in 'template part'");
         if to_check_part.may_be_inferred_from(template_part) {
             let depth_change = to_check_part.depth_change();
             debug_assert_eq!(depth_change, template_part.depth_change());
             *to_check_idx += 1;
             *template_idx += 1;
             return Some(depth_change);
+        }
         if *to_check_part == ITP::Unknown {
             *to_check_idx += 1;
             *template_idx = Self::find_subtree_end_idx(template_parts, *template_idx);
             // By definition LHS and RHS had depth change of -1
             return Some(-1);
+        }
         None
+    }
     /// Attempts to infer types between two `InferenceType` instances. This
     /// function is unsafe as it accepts pointers to work around Rust's
     /// borrowing rules. The caller must ensure that the pointers are distinct.
     unsafe fn infer_subtrees_for_both_types(
         type_a: *mut InferenceType, start_idx_a: usize,
         type_b: *mut InferenceType, start_idx_b: usize
     ) -> DualInferenceResult {
         debug_assert!(!std::ptr::eq(type_a, type_b), "encountered pointers to the same inference type");
         let type_a = &mut *type_a;
         let type_b = &mut *type_b;
         let mut modified_a = false;
         let mut modified_b = false;
         let mut idx_a = start_idx_a;
         let mut idx_b = start_idx_b;
         let mut depth = 1;
         while depth > 0 {
             // Advance indices if we encounter markers or equal parts
             let part_a = &type_a.parts[idx_a];
             let part_b = &type_b.parts[idx_b];
             if part_a == part_b {
                 let depth_change = part_a.depth_change();
                 depth += depth_change;
                 debug_assert_eq!(depth_change, part_b.depth_change());
                 idx_a += 1;
                 idx_b += 1;
                 continue;
+            }
             if part_a.is_marker() { idx_a += 1; continue; }
             if part_b.is_marker() { idx_b += 1; continue; }
             // Types are not equal and are both not markers
             if let Some(depth_change) = Self::infer_part_for_single_type(type_a, &mut idx_a, &type_b.parts, &mut idx_b) {
                 depth += depth_change;
                 modified_a = true;
                 continue;
+            }
             if let Some(depth_change) = Self::infer_part_for_single_type(type_b, &mut idx_b, &type_a.parts, &mut idx_a) {
                 depth += depth_change;
                 modified_b = true;
                 continue;
+            }
             // Types can not be inferred in any way: types must be incompatible
             return DualInferenceResult::Incompatible;
+        }
         if modified_a { type_a.recompute_is_done(); }
         if modified_b { type_b.recompute_is_done(); }
         // If here then we completely inferred the subtrees.
         match (modified_a, modified_b) {
             (false, false) => DualInferenceResult::Neither,
             (false, true) => DualInferenceResult::Second,
             (true, false) => DualInferenceResult::First,
             (true, true) => DualInferenceResult::Both
+        }
+    }
     /// Attempts to infer the first subtree based on the template. Like
     /// `infer_subtrees_for_both_types`, but now only applying inference to
     /// `to_infer` based on the type information in `template`.
     ///
     /// The `forced_template` flag controls whether `to_infer` is considered
     /// valid if it is more specific then the template. When `forced_template`
     /// is false, then as long as the `to_infer` and `template` types are
     /// compatible the inference will succeed. If `forced_template` is true,
     /// then `to_infer` MUST be less specific than `template` (e.g.
     /// `IntegerLike` is less specific than `UInt32`)
     fn infer_subtree_for_single_type(
         to_infer: &mut InferenceType, mut to_infer_idx: usize,
         template: &[InferenceTypePart], mut template_idx: usize,
         forced_template: bool,
     ) -> SingleInferenceResult {
         let mut modified = false;
         let mut depth = 1;
         while depth > 0 {
             let to_infer_part = &to_infer.parts[to_infer_idx];
             let template_part = &template[template_idx];
             if to_infer_part == template_part {
                 let depth_change = to_infer_part.depth_change();
                 depth += depth_change;
                 debug_assert_eq!(depth_change, template_part.depth_change());
                 to_infer_idx += 1;
                 template_idx += 1;
                 continue;
+            }
             if to_infer_part.is_marker() { to_infer_idx += 1; continue; }
             if template_part.is_marker() { template_idx += 1; continue; }
             // Types are not equal and not markers. So check if we can infer
             // anything
             if let Some(depth_change) = Self::infer_part_for_single_type(
                 to_infer, &mut to_infer_idx, template, &mut template_idx
             ) {
                 depth += depth_change;
                 modified = true;
                 continue;
+            }
             if !forced_template {
                 // We cannot infer anything, but the template may still be
                 // compatible with the type we're inferring
                 if let Some(depth_change) = Self::check_part_for_single_type(
                     template, &mut template_idx, &to_infer.parts, &mut to_infer_idx
                 ) {
                     depth += depth_change;
                     continue;
+                }
+            }
             return SingleInferenceResult::Incompatible
+        }
         if modified {
             to_infer.recompute_is_done();
             return SingleInferenceResult::Modified;
         } else {
             return SingleInferenceResult::Unmodified;
+        }
+    }
     /// Checks if both types are compatible, doesn't perform any inference
     fn check_subtrees(
         type_parts_a: &[InferenceTypePart], start_idx_a: usize,
         type_parts_b: &[InferenceTypePart], start_idx_b: usize
     ) -> bool {
         let mut depth = 1;
         let mut idx_a = start_idx_a;
         let mut idx_b = start_idx_b;
         while depth > 0 {
             let part_a = &type_parts_a[idx_a];
             let part_b = &type_parts_b[idx_b];
             if part_a == part_b {
                 let depth_change = part_a.depth_change();
                 depth += depth_change;
                 debug_assert_eq!(depth_change, part_b.depth_change());
                 idx_a += 1;
                 idx_b += 1;
                 continue;
+            }
             if part_a.is_marker() { idx_a += 1; continue; }
             if part_b.is_marker() { idx_b += 1; continue; }
             if let Some(depth_change) = Self::check_part_for_single_type(
                 type_parts_a, &mut idx_a, type_parts_b, &mut idx_b
             ) {
                 depth += depth_change;
                 continue;
+            }
             if let Some(depth_change) = Self::check_part_for_single_type(
                 type_parts_b, &mut idx_b, type_parts_a, &mut idx_a
             ) {
                 depth += depth_change;
                 continue;
+            }
             return false;
+        }
         true
+    }
     /// Performs the conversion of the inference type into a concrete type.
     /// By calling this function you must make sure that no unspecified types
     /// (e.g. Unknown or IntegerLike) exist in the type. Will not clear or check
     /// if the supplied `ConcreteType` is empty, will simply append to the parts
     /// vector.
     fn write_concrete_type(&self, concrete_type: &mut ConcreteType) {
         use InferenceTypePart as ITP;
         use ConcreteTypePart as CTP;
         // Make sure inference type is specified but concrete type is not yet specified
         debug_assert!(!self.parts.is_empty());
         concrete_type.parts.reserve(self.parts.len());
         let mut idx = 0;
         while idx < self.parts.len() {
             let part = &self.parts[idx];
             let converted_part = match part {
                 ITP::Marker(_) => {
                     // Markers are removed when writing to the concrete type.
                     idx += 1;
                     continue;
                 },
                 ITP::Unknown | ITP::NumberLike |
                 ITP::IntegerLike | ITP::ArrayLike | ITP::PortLike => {
                     // Should not happen if type inferencing works correctly: we
                     // should have returned a programmer-readable error or have
                     // inferred all types.
                     unreachable!("attempted to convert inference type part {:?} into concrete type", part);
                 },
                 ITP::Void => CTP::Void,
                 ITP::Message => CTP::Message,
                 ITP::Bool => CTP::Bool,
                 ITP::UInt8 => CTP::UInt8,
                 ITP::UInt16 => CTP::UInt16,
                 ITP::UInt32 => CTP::UInt32,
                 ITP::UInt64 => CTP::UInt64,
                 ITP::SInt8 => CTP::SInt8,
                 ITP::SInt16 => CTP::SInt16,
                 ITP::SInt32 => CTP::SInt32,
                 ITP::SInt64 => CTP::SInt64,
                 ITP::Character => CTP::Character,
                 ITP::String => {
                     // Inferred type has a 'char' subtype to simplify array
                     // checking, we remove it here.
                     debug_assert_eq!(self.parts[idx + 1], InferenceTypePart::Character);
                     idx += 1;
                     CTP::String
                 },
                 ITP::Array => CTP::Array,
                 ITP::Slice => CTP::Slice,
                 ITP::Input => CTP::Input,
                 ITP::Output => CTP::Output,
                 ITP::Tuple(num) => CTP::Tuple(*num),
                 ITP::Instance(id, num) => CTP::Instance(*id, *num),
             };
             concrete_type.parts.push(converted_part);
             idx += 1;
+        }
+    }
     /// Writes a human-readable version of the type to a string. This is used
     /// to display error messages
     fn write_display_name(
         buffer: &mut String, heap: &Heap, parts: &[InferenceTypePart], mut idx: usize
     ) -> usize {
         use InferenceTypePart as ITP;
         match &parts[idx] {
             ITP::Marker(_marker_idx) => {
                 if debug_log_enabled!() {
                     buffer.push_str(&format!("{{Marker:{}}}", *_marker_idx));
+                }
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
             },
             ITP::Unknown => buffer.push_str("?"),
             ITP::NumberLike => buffer.push_str("numberlike"),
             ITP::IntegerLike => buffer.push_str("integerlike"),
             ITP::ArrayLike => {
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push_str("[?]");
             },
             ITP::PortLike => {
                 buffer.push_str("portlike<");
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push('>');
+            }
             ITP::Void => buffer.push_str("void"),
             ITP::Bool => buffer.push_str(KW_TYPE_BOOL_STR),
             ITP::UInt8 => buffer.push_str(KW_TYPE_UINT8_STR),
             ITP::UInt16 => buffer.push_str(KW_TYPE_UINT16_STR),
             ITP::UInt32 => buffer.push_str(KW_TYPE_UINT32_STR),
             ITP::UInt64 => buffer.push_str(KW_TYPE_UINT64_STR),
             ITP::SInt8 => buffer.push_str(KW_TYPE_SINT8_STR),
             ITP::SInt16 => buffer.push_str(KW_TYPE_SINT16_STR),
             ITP::SInt32 => buffer.push_str(KW_TYPE_SINT32_STR),
             ITP::SInt64 => buffer.push_str(KW_TYPE_SINT64_STR),
             ITP::Character => buffer.push_str(KW_TYPE_CHAR_STR),
             ITP::String => {
                 buffer.push_str(KW_TYPE_STRING_STR);
                 idx += 1; // skip the 'char' subtype
             },
             ITP::Message => {
                 buffer.push_str(KW_TYPE_MESSAGE_STR);
                 buffer.push('<');
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push('>');
             },
             ITP::Array => {
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push_str("[]");
             },
             ITP::Slice => {
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push_str("[..]");
             },
             ITP::Input => {
                 buffer.push_str(KW_TYPE_IN_PORT_STR);
                 buffer.push('<');
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push('>');
             },
             ITP::Output => {
                 buffer.push_str(KW_TYPE_OUT_PORT_STR);
                 buffer.push('<');
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push('>');
             },
             ITP::Tuple(num_sub) => {
                 buffer.push('(');
                 if *num_sub > 0 {
                     idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                     for _sub_idx in 1..*num_sub {
                         buffer.push_str(", ");
                         idx = Self::write_display_name(buffer, heap, parts, idx + 1);
+                    }
+                }
                 buffer.push(')');
+            }
             ITP::Instance(definition_id, num_sub) => {
                 let definition = &heap[*definition_id];
                 buffer.push_str(definition.identifier().value.as_str());
                 if *num_sub > 0 {
                     buffer.push('<');
                     idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                     for _sub_idx in 1..*num_sub {
                         buffer.push_str(", ");
                         idx = Self::write_display_name(buffer, heap, parts, idx + 1);
+                    }
                     buffer.push('>');
+                }
             },
+        }
         idx
+    }
     /// Returns the display name of a (part of) the type tree. Will allocate a
     /// string.
     fn partial_display_name(heap: &Heap, parts: &[InferenceTypePart]) -> String {
         let mut buffer = String::with_capacity(parts.len() * 6);
         Self::write_display_name(&mut buffer, heap, parts, 0);
         buffer
+    }
     /// Returns the display name of the full type tree. Will allocate a string.
     fn display_name(&self, heap: &Heap) -> String {
         Self::partial_display_name(heap, &self.parts)
+    }
+}
 impl Default for InferenceType {
     fn default() -> Self {
         Self{
             has_marker: false,
             is_done: false,
             parts: Vec::new(),
+        }
+    }
+}
 /// Iterator over the subtrees that follow a marker in an `InferenceType`
 /// instance. Returns immutable slices over the internal parts
 struct InferenceTypeMarkerIter<'a> {
     parts: &'a [InferenceTypePart],
     idx: usize,
+}
 impl<'a> InferenceTypeMarkerIter<'a> {
     fn new(parts: &'a [InferenceTypePart]) -> Self {
         Self{ parts, idx: 0 }
+    }
+}
 impl<'a> Iterator for InferenceTypeMarkerIter<'a> {
     type Item = (u32, &'a [InferenceTypePart]);
     fn next(&mut self) -> Option<Self::Item> {
         // Iterate until we find a marker
         while self.idx < self.parts.len() {
             if let InferenceTypePart::Marker(marker) = self.parts[self.idx] {
                 // Found a marker, find the subtree end
                 let start_idx = self.idx + 1;
                 let end_idx = InferenceType::find_subtree_end_idx(self.parts, start_idx);
                 // Modify internal index, then return items
                 self.idx = end_idx;
                 return Some((marker, &self.parts[start_idx..end_idx]));
+            }
             self.idx += 1;
+        }
         None
+    }
+}
 #[derive(Debug, PartialEq, Eq)]
 enum DualInferenceResult {
     Neither,        // neither argument is clarified
     First,          // first argument is clarified using the second one
     Second,         // second argument is clarified using the first one
     Both,           // both arguments are clarified
     Incompatible,   // types are incompatible: programmer error
+}
 impl DualInferenceResult {
     fn modified_lhs(&self) -> bool {
         match self {
             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{
     Component(ComponentDefinitionId),
     Function(FunctionDefinitionId),
+}
 impl DefinitionType {
     fn definition_id(&self) -> DefinitionId {
         match self {
             DefinitionType::Component(v) => v.upcast(),
             DefinitionType::Function(v) => v.upcast(),
+        }
+    }
+}
 pub(crate) struct ResolveQueueElement {
     // Note that using the `definition_id` and the `monomorph_idx` one may
     // query the type table for the full procedure type, thereby retrieving
     // the polymorphic arguments to the procedure.
     pub(crate) root_id: RootId,
     pub(crate) definition_id: DefinitionId,
     pub(crate) reserved_monomorph_idx: i32,
+}
 pub(crate) type ResolveQueue = Vec<ResolveQueueElement>;
 #[derive(Clone)]
 struct InferenceExpression {
     expr_type: InferenceType,       // result type from expression
     expr_id: ExpressionId,          // expression that is evaluated
     field_or_monomorph_idx: i32,    // index of field, of index of monomorph array in type table
     extra_data_idx: i32,            // index of extra data needed for inference
+}
 impl Default for InferenceExpression {
     fn default() -> Self {
         Self{
             expr_type: InferenceType::default(),
             expr_id: ExpressionId::new_invalid(),
             field_or_monomorph_idx: -1,
             extra_data_idx: -1,
+        }
+    }
+}
 /// This particular visitor will recurse depth-first into the AST and ensures
 /// that all expressions have the appropriate types.
 pub(crate) struct PassTyping {
     // Current definition we're typechecking.
     reserved_idx: i32,
     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: Vec<InferenceExpression>,                     // will be transferred to type table at end
     extra_data: Vec<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: DequeSet<i32>,
+}
 // TODO: @Rename, this is used for a lot of type inferencing. It seems like
 //  there is a different underlying architecture waiting to surface.
 struct ExtraData {
     expr_id: ExpressionId, // the expression with which this data is associated
     definition_id: DefinitionId, // the definition, only used for user feedback
     /// Progression of polymorphic variables (if any)
     poly_vars: Vec<InferenceType>,
     /// Progression of types of call arguments or struct members
     embedded: Vec<InferenceType>,
     returned: InferenceType,
+}
 impl Default for ExtraData {
     fn default() -> Self {
         Self{
             expr_id: ExpressionId::new_invalid(),
             definition_id: DefinitionId::new_invalid(),
             poly_vars: Vec::new(),
             embedded: Vec::new(),
             returned: InferenceType::default(),
+        }
+    }
+}
 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 PassTyping {
     pub(crate) fn new() -> Self {
         PassTyping {
             reserved_idx: -1,
             definition_type: DefinitionType::Function(FunctionDefinitionId::new_invalid()),
             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: Vec::new(),
             extra_data: Vec::new(),
             expr_queued: DequeSet::new(),
+        }
+    }
     pub(crate) fn queue_module_definitions(ctx: &mut Ctx, queue: &mut ResolveQueue) {
         debug_assert_eq!(ctx.module().phase, ModuleCompilationPhase::ValidatedAndLinked);
         let root_id = ctx.module().root_id;
         let root = &ctx.heap.protocol_descriptions[root_id];
         for definition_id in &root.definitions {
             let definition = &ctx.heap[*definition_id];
             let first_concrete_part = match definition {
                 Definition::Function(definition) => {
                     if definition.poly_vars.is_empty() {
                         Some(ConcreteTypePart::Function(*definition_id, 0))
                     } else {
                         None
+                    }
+                }
                 Definition::Component(definition) => {
                     if definition.poly_vars.is_empty() {
                         Some(ConcreteTypePart::Component(*definition_id, 0))
                     } else {
                         None
+                    }
                 },
                 Definition::Enum(_) | Definition::Struct(_) | Definition::Union(_) => None,
             };
             if let Some(first_concrete_part) = first_concrete_part {
                 let concrete_type = ConcreteType{ parts: vec![first_concrete_part] };
                 let reserved_idx = ctx.types.reserve_procedure_monomorph_index(definition_id, concrete_type);
                 queue.push(ResolveQueueElement{
                     root_id,
                     definition_id: *definition_id,
                     reserved_monomorph_idx: reserved_idx,
                 })
+            }
+        }
+    }
     pub(crate) fn handle_module_definition(
         &mut self, ctx: &mut Ctx, queue: &mut ResolveQueue, element: ResolveQueueElement
     ) -> VisitorResult {
         self.reset();
         debug_assert_eq!(ctx.module().root_id, element.root_id);
         debug_assert!(self.poly_vars.is_empty());
         // Prepare for visiting the definition
         self.reserved_idx = element.reserved_monomorph_idx;
         let proc_base = ctx.types.get_base_definition(&element.definition_id).unwrap();
         if proc_base.is_polymorph {
             let monomorph = ctx.types.get_monomorph(element.reserved_monomorph_idx);
             for poly_arg in monomorph.concrete_type.embedded_iter(0) {
                 self.poly_vars.push(ConcreteType{ parts: Vec::from(poly_arg) });
+            }
+        }
         // Visit the definition, setting up the type resolving process, then
         // (attempt to) resolve all types
         self.visit_definition(ctx, element.definition_id)?;
         self.resolve_types(ctx, queue)?;
         Ok(())
+    }
     fn reset(&mut self) {
         self.reserved_idx = -1;
         self.definition_type = DefinitionType::Function(FunctionDefinitionId::new_invalid());
         self.poly_vars.clear();
         self.stmt_buffer.clear();
         self.expr_buffer.clear();
         self.var_types.clear();
         self.expr_types.clear();
         self.extra_data.clear();
         self.expr_queued.clear();
+    }
+}
 impl Visitor for PassTyping {
     // Definitions
     fn visit_component_definition(&mut self, ctx: &mut Ctx, id: ComponentDefinitionId) -> VisitorResult {
         self.definition_type = DefinitionType::Component(id);
         let comp_def = &ctx.heap[id];
         debug_assert_eq!(comp_def.poly_vars.len(), self.poly_vars.len(), "component polyvars do not match imposed polyvars");
         debug_log!("{}", "-".repeat(50));
         debug_log!("Visiting component '{}': {}", comp_def.identifier.value.as_str(), id.0.index);
         debug_log!("{}", "-".repeat(50));
         // Reserve data for expression types
         debug_assert!(self.expr_types.is_empty());
         self.expr_types.resize(comp_def.num_expressions_in_body as usize, Default::default());
         // Visit parameters
         for param_id in comp_def.parameters.clone() {
             let param = &ctx.heap[param_id];
             let var_type = self.determine_inference_type_from_parser_type_elements(&param.parser_type.elements, true);
             debug_assert!(var_type.is_done, "expected component arguments to be concrete types");
             self.var_types.insert(param_id, VarData::new_local(var_type));
+        }
         // Visit the body and all of its expressions
         let body_stmt_id = ctx.heap[id].body;
         self.visit_block_stmt(ctx, body_stmt_id)
+    }
     fn visit_function_definition(&mut self, ctx: &mut Ctx, id: FunctionDefinitionId) -> VisitorResult {
         self.definition_type = DefinitionType::Function(id);
         let func_def = &ctx.heap[id];
         debug_assert_eq!(func_def.poly_vars.len(), self.poly_vars.len(), "function polyvars do not match imposed polyvars");
         debug_log!("{}", "-".repeat(50));
         debug_log!("Visiting function '{}': {}", func_def.identifier.value.as_str(), id.0.index);
         if debug_log_enabled!() {
             debug_log!("Polymorphic variables:");
             for (_idx, poly_var) in self.poly_vars.iter().enumerate() {
                 let mut infer_type_parts = Vec::new();
                 Self::determine_inference_type_from_concrete_type(
                     &mut infer_type_parts, &poly_var.parts
                 );
                 let _infer_type = InferenceType::new(false, true, infer_type_parts);
                 debug_log!(" - [{:03}] {:?}", _idx, _infer_type.display_name(&ctx.heap));
+            }
+        }
         debug_log!("{}", "-".repeat(50));
         // Reserve data for expression types
         debug_assert!(self.expr_types.is_empty());
         self.expr_types.resize(func_def.num_expressions_in_body as usize, Default::default());
         // Visit parameters
         for param_id in func_def.parameters.clone() {
             let param = &ctx.heap[param_id];
             let var_type = self.determine_inference_type_from_parser_type_elements(&param.parser_type.elements, true);
             debug_assert!(var_type.is_done, "expected function arguments to be concrete types");
             self.var_types.insert(param_id, VarData::new_local(var_type));
+        }
         // Visit all of the expressions within the body
         let body_stmt_id = ctx.heap[id].body;
         self.visit_block_stmt(ctx, body_stmt_id)
+    }
     // Statements
     fn visit_block_stmt(&mut self, ctx: &mut Ctx, id: BlockStatementId) -> VisitorResult {
         // Transfer statements for traversal
         let block = &ctx.heap[id];
         for stmt_id in block.statements.clone() {
             self.visit_stmt(ctx, stmt_id)?;
+        }
         Ok(())
+    }
     fn visit_local_memory_stmt(&mut self, ctx: &mut Ctx, id: MemoryStatementId) -> VisitorResult {
         let memory_stmt = &ctx.heap[id];
         let local = &ctx.heap[memory_stmt.variable];
         let var_type = self.determine_inference_type_from_parser_type_elements(&local.parser_type.elements, true);
         self.var_types.insert(memory_stmt.variable, VarData::new_local(var_type));
         Ok(())
+    }
     fn visit_local_channel_stmt(&mut self, ctx: &mut Ctx, id: ChannelStatementId) -> VisitorResult {
         let channel_stmt = &ctx.heap[id];
         let from_local = &ctx.heap[channel_stmt.from];
         let from_var_type = self.determine_inference_type_from_parser_type_elements(&from_local.parser_type.elements, true);
         self.var_types.insert(from_local.this, VarData::new_channel(from_var_type, channel_stmt.to));
         let to_local = &ctx.heap[channel_stmt.to];
         let to_var_type = self.determine_inference_type_from_parser_type_elements(&to_local.parser_type.elements, true);
         self.var_types.insert(to_local.this, VarData::new_channel(to_var_type, channel_stmt.from));
         Ok(())
+    }
     fn visit_labeled_stmt(&mut self, ctx: &mut Ctx, id: LabeledStatementId) -> VisitorResult {
         let labeled_stmt = &ctx.heap[id];
         let substmt_id = labeled_stmt.body;
         self.visit_stmt(ctx, substmt_id)
+    }
     fn visit_if_stmt(&mut self, ctx: &mut Ctx, id: IfStatementId) -> VisitorResult {
         let if_stmt = &ctx.heap[id];
         let true_body_id = if_stmt.true_body;
         let false_body_id = if_stmt.false_body;
         let test_expr_id = if_stmt.test;
         self.visit_expr(ctx, test_expr_id)?;
         self.visit_block_stmt(ctx, true_body_id)?;
         if let Some(false_body_id) = false_body_id {
             self.visit_block_stmt(ctx, false_body_id)?;
+        }
         Ok(())
+    }
     fn visit_while_stmt(&mut self, ctx: &mut Ctx, id: WhileStatementId) -> VisitorResult {
         let while_stmt = &ctx.heap[id];
         let body_id = while_stmt.body;
         let test_expr_id = while_stmt.test;
         self.visit_expr(ctx, test_expr_id)?;
         self.visit_block_stmt(ctx, body_id)?;
         Ok(())
+    }
     fn visit_synchronous_stmt(&mut self, ctx: &mut Ctx, id: SynchronousStatementId) -> VisitorResult {
         let sync_stmt = &ctx.heap[id];
         let body_id = sync_stmt.body;
         self.visit_block_stmt(ctx, body_id)
+    }
     fn visit_fork_stmt(&mut self, ctx: &mut Ctx, id: ForkStatementId) -> VisitorResult {
         let fork_stmt = &ctx.heap[id];
         let left_body_id = fork_stmt.left_body;
         let right_body_id = fork_stmt.right_body;
         self.visit_block_stmt(ctx, left_body_id)?;
         if let Some(right_body_id) = right_body_id {
             self.visit_block_stmt(ctx, right_body_id)?;
+        }
         Ok(())
+    }
     fn visit_return_stmt(&mut self, ctx: &mut Ctx, id: ReturnStatementId) -> VisitorResult {
         let return_stmt = &ctx.heap[id];
         debug_assert_eq!(return_stmt.expressions.len(), 1);
         let expr_id = return_stmt.expressions[0];
         self.visit_expr(ctx, expr_id)
+    }
     fn visit_new_stmt(&mut self, ctx: &mut Ctx, id: NewStatementId) -> VisitorResult {
         let new_stmt = &ctx.heap[id];
         let call_expr_id = new_stmt.expression;
         self.visit_call_expr(ctx, call_expr_id)
+    }
     fn visit_expr_stmt(&mut self, ctx: &mut Ctx, id: ExpressionStatementId) -> VisitorResult {
         let expr_stmt = &ctx.heap[id];
         let subexpr_id = expr_stmt.expression;
         self.visit_expr(ctx, subexpr_id)
+    }
     // Expressions
     fn visit_assignment_expr(&mut self, ctx: &mut Ctx, id: AssignmentExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let assign_expr = &ctx.heap[id];
         let left_expr_id = assign_expr.left;
         let right_expr_id = assign_expr.right;
         self.visit_expr(ctx, left_expr_id)?;
         self.visit_expr(ctx, right_expr_id)?;
         self.progress_assignment_expr(ctx, id)
+    }
     fn visit_binding_expr(&mut self, ctx: &mut Ctx, id: BindingExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let binding_expr = &ctx.heap[id];
         let bound_to_id = binding_expr.bound_to;
         let bound_from_id = binding_expr.bound_from;
         self.visit_expr(ctx, bound_to_id)?;
         self.visit_expr(ctx, bound_from_id)?;
         self.progress_binding_expr(ctx, id)
+    }
     fn visit_conditional_expr(&mut self, ctx: &mut Ctx, id: ConditionalExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let conditional_expr = &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;
         self.visit_expr(ctx, test_expr_id)?;
         self.visit_expr(ctx, true_expr_id)?;
         self.visit_expr(ctx, false_expr_id)?;
         self.progress_conditional_expr(ctx, id)
+    }
     fn visit_binary_expr(&mut self, ctx: &mut Ctx, id: BinaryExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let binary_expr = &ctx.heap[id];
         let lhs_expr_id = binary_expr.left;
         let rhs_expr_id = binary_expr.right;
         self.visit_expr(ctx, lhs_expr_id)?;
         self.visit_expr(ctx, rhs_expr_id)?;
         self.progress_binary_expr(ctx, id)
+    }
     fn visit_unary_expr(&mut self, ctx: &mut Ctx, id: UnaryExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let unary_expr = &ctx.heap[id];
         let arg_expr_id = unary_expr.expression;
         self.visit_expr(ctx, arg_expr_id)?;
         self.progress_unary_expr(ctx, id)
+    }
     fn visit_indexing_expr(&mut self, ctx: &mut Ctx, id: IndexingExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let indexing_expr = &ctx.heap[id];
         let subject_expr_id = indexing_expr.subject;
         let index_expr_id = indexing_expr.index;
         self.visit_expr(ctx, subject_expr_id)?;
         self.visit_expr(ctx, index_expr_id)?;
         self.progress_indexing_expr(ctx, id)
+    }
     fn visit_slicing_expr(&mut self, ctx: &mut Ctx, id: SlicingExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let slicing_expr = &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;
         self.visit_expr(ctx, subject_expr_id)?;
         self.visit_expr(ctx, from_expr_id)?;
         self.visit_expr(ctx, to_expr_id)?;
         self.progress_slicing_expr(ctx, id)
+    }
     fn visit_select_expr(&mut self, ctx: &mut Ctx, id: SelectExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let select_expr = &ctx.heap[id];
         let subject_expr_id = select_expr.subject;
         self.visit_expr(ctx, subject_expr_id)?;
         self.progress_select_expr(ctx, id)
+    }
     fn visit_literal_expr(&mut self, ctx: &mut Ctx, id: LiteralExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let literal_expr = &ctx.heap[id];
         match &literal_expr.value {
             Literal::Null | Literal::False | Literal::True |
             Literal::Integer(_) | Literal::Character(_) | Literal::String(_) => {
                 // No subexpressions
             },
             Literal::Struct(literal) => {
                 // TODO: @performance
                 let expr_ids: Vec<_> = literal.fields
                     .iter()
                     .map(|f| f.value)
                     .collect();
                 self.insert_initial_struct_polymorph_data(ctx, id);
                 for expr_id in expr_ids {
                     self.visit_expr(ctx, expr_id)?;
+                }
             },
             Literal::Enum(_) => {
                 // Enumerations do not carry any subexpressions, but may still
                 // have a user-defined polymorphic marker variable. For this
                 // reason we may still have to apply inference to this
                 // polymorphic variable
                 self.insert_initial_enum_polymorph_data(ctx, id);
             },
             Literal::Union(literal) => {
                 // May carry subexpressions and polymorphic arguments
                 // TODO: @performance
                 let expr_ids = literal.values.clone();
                 self.insert_initial_union_polymorph_data(ctx, id);
                 for expr_id in expr_ids {
                     self.visit_expr(ctx, expr_id)?;
+                }
             },
             Literal::Array(expressions) | Literal::Tuple(expressions) => {
                 // TODO: @performance
                 let expr_ids = expressions.clone();
                 for expr_id in expr_ids {
                     self.visit_expr(ctx, expr_id)?;
+                }
+            }
+        }
         self.progress_literal_expr(ctx, id)
+    }
     fn visit_cast_expr(&mut self, ctx: &mut Ctx, id: CastExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let cast_expr = &ctx.heap[id];
         let subject_expr_id = cast_expr.subject;
         self.visit_expr(ctx, subject_expr_id)?;
         self.progress_cast_expr(ctx, id)
+    }
     fn visit_call_expr(&mut self, ctx: &mut Ctx, id: CallExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         self.insert_initial_call_polymorph_data(ctx, id);
         // By default we set the polymorph idx for calls to 0. If the call ends
         // up not being a polymorphic one, then we will select the default
         // expression types in the type table
         let call_expr = &ctx.heap[id];
         self.expr_types[call_expr.unique_id_in_definition as usize].field_or_monomorph_idx = 0;
         // Visit all arguments
         for arg_expr_id in call_expr.arguments.clone() { // TODO: @Performance
             self.visit_expr(ctx, arg_expr_id)?;
+        }
         self.progress_call_expr(ctx, id)
+    }
     fn visit_variable_expr(&mut self, ctx: &mut Ctx, id: VariableExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let var_expr = &ctx.heap[id];
         debug_assert!(var_expr.declaration.is_some());
         // Not pretty: if a binding expression, then this is the first time we
         // encounter the variable, so we still need to insert the variable data.
         let declaration = &ctx.heap[var_expr.declaration.unwrap()];
         if !self.var_types.contains_key(&declaration.this)  {
             debug_assert!(declaration.kind == VariableKind::Binding);
             let var_type = self.determine_inference_type_from_parser_type_elements(
                 &declaration.parser_type.elements, true
             );
             self.var_types.insert(declaration.this, VarData{
                 var_type,
                 used_at: vec![upcast_id],
                 linked_var: None
             });
         } else {
             let var_data = self.var_types.get_mut(&declaration.this).unwrap();
             var_data.used_at.push(upcast_id);
+        }
         self.progress_variable_expr(ctx, id)
+    }
+}
 impl PassTyping {
     #[allow(dead_code)] // used when debug flag at the top of this file is true.
     fn debug_get_display_name(&self, ctx: &Ctx, expr_id: ExpressionId) -> String {
         let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition();
         let expr_type = &self.expr_types[expr_idx as usize].expr_type;
         expr_type.display_name(&ctx.heap)
+    }
     fn resolve_types(&mut self, ctx: &mut Ctx, queue: &mut ResolveQueue) -> Result<(), ParseError> {
         // Keep inferring until we can no longer make any progress
         while !self.expr_queued.is_empty() {
             // Make as much progress as possible without forced integer
             // inference.
             while !self.expr_queued.is_empty() {
                 let next_expr_idx = self.expr_queued.pop_front().unwrap();
                 self.progress_expr(ctx, next_expr_idx)?;
+            }
             // Nothing is queued anymore. However we might have integer literals
             // whose type cannot be inferred. For convenience's sake we'll
             // infer these to be s32.
             for (infer_expr_idx, infer_expr) in self.expr_types.iter_mut().enumerate() {
                 let expr_type = &mut infer_expr.expr_type;
                 if !expr_type.is_done && expr_type.parts.len() == 1 && expr_type.parts[0] == InferenceTypePart::IntegerLike {
                     // Force integer type to s32
                     println!("DEBUG: Autoinferring (idx {}) {}", infer_expr.expr_id.index, String::from_utf8_lossy(ctx.module().source.section_at_span(ctx.heap[infer_expr.expr_id].full_span())));
                     expr_type.parts[0] = InferenceTypePart::SInt32;
                     expr_type.is_done = true;
                     // Requeue expression (and its parent, if it exists)
                     self.expr_queued.push_back(infer_expr_idx as i32);
                     if let Some(parent_expr) = ctx.heap[infer_expr.expr_id].parent_expr_id() {
                         let parent_idx = ctx.heap[parent_expr].get_unique_id_in_definition();
                         self.expr_queued.push_back(parent_idx);
+                    }
+                }
+            }
+        }
         // Helper for transferring polymorphic variables to concrete types and
         // checking if they're completely specified
         fn inference_type_to_concrete_type(
             ctx: &Ctx, expr_id: ExpressionId, inference: &Vec<InferenceType>,
             first_concrete_part: ConcreteTypePart,
         ) -> Result<ConcreteType, ParseError> {
             // Prepare storage vector
             let mut num_inference_parts = 0;
             for inference_type in inference {
                 num_inference_parts += inference_type.parts.len();
+            }
             let mut concrete_type = ConcreteType{
                 parts: Vec::with_capacity(1 + num_inference_parts),
             };
             concrete_type.parts.push(first_concrete_part);
             // Go through all polymorphic arguments and add them to the concrete
             // types.
             for (poly_idx, poly_type) in inference.iter().enumerate() {
                 if !poly_type.is_done {
                     let expr = &ctx.heap[expr_id];
                     let definition = match expr {
                         Expression::Call(expr) => expr.definition,
                         Expression::Literal(expr) => match &expr.value {
                             Literal::Enum(lit) => lit.definition,
                             Literal::Union(lit) => lit.definition,
                             Literal::Struct(lit) => lit.definition,
                             _ => unreachable!()
                         },
                         _ => unreachable!(),
                     };
                     let poly_vars = ctx.heap[definition].poly_vars();
                     return Err(ParseError::new_error_at_span(
                         &ctx.module().source, expr.operation_span(), format!(
                             "could not fully infer the type of polymorphic variable '{}' of this expression (got '{}')",
                             poly_vars[poly_idx].value.as_str(), poly_type.display_name(&ctx.heap)
+                        )
                     ));
+                }
                 poly_type.write_concrete_type(&mut concrete_type);
+            }
             Ok(concrete_type)
+        }
         // Inference is now done. But we may still have uninferred types. So we
         // check for these.
         for infer_expr in self.expr_types.iter_mut() {
             if !infer_expr.expr_type.is_done {
                 let expr = &ctx.heap[infer_expr.expr_id];
                 return Err(ParseError::new_error_at_span(
                     &ctx.module().source, expr.full_span(), format!(
                         "could not fully infer the type of this expression (got '{}')",
                         infer_expr.expr_type.display_name(&ctx.heap)
+                    )
                 ));
+            }
             // Expression is fine, check if any extra data is attached
             if infer_expr.extra_data_idx < 0 { continue; }
             // Extra data is attached, perform typechecking and transfer
             // resolved information to the expression
             let extra_data = &self.extra_data[infer_expr.extra_data_idx as usize];
             // Note that only call and literal expressions need full inference.
             // Select expressions also use `extra_data`, but only for temporary
             // storage of the struct type whose field it is selecting.
             match &ctx.heap[extra_data.expr_id] {
                 Expression::Call(expr) => {
                     // Check if it is not a builtin function. If not, then
                     // construct the first part of the concrete type.
                     let first_concrete_part = if expr.method == Method::UserFunction {
                         ConcreteTypePart::Function(expr.definition, extra_data.poly_vars.len() as u32)
                     } else if expr.method == Method::UserComponent {
                         ConcreteTypePart::Component(expr.definition, extra_data.poly_vars.len() as u32)
                     } else {
                         // Builtin function
                         continue;
                     };
                     let definition_id = expr.definition;
                     let concrete_type = inference_type_to_concrete_type(
                         ctx, extra_data.expr_id, &extra_data.poly_vars, first_concrete_part
                     )?;
                     match ctx.types.get_procedure_monomorph_index(&definition_id, &concrete_type.parts) {
                         Some(reserved_idx) => {
                             // Already typechecked, or already put into the resolve queue
                             infer_expr.field_or_monomorph_idx = reserved_idx;
                         },
                         None => {
                             // Not typechecked yet, so add an entry in the queue
                             let reserved_idx = ctx.types.reserve_procedure_monomorph_index(&definition_id, concrete_type);
                             infer_expr.field_or_monomorph_idx = reserved_idx;
                             queue.push(ResolveQueueElement {
                                 root_id: ctx.heap[definition_id].defined_in(),
                                 definition_id,
                                 reserved_monomorph_idx: reserved_idx,
                             });
+                        }
+                    }
                 },
                 Expression::Literal(expr) => {
                     let definition_id = match &expr.value {
                         Literal::Enum(lit) => lit.definition,
                         Literal::Union(lit) => lit.definition,
                         Literal::Struct(lit) => lit.definition,
                         _ => unreachable!(),
                     };
                     let first_concrete_part = ConcreteTypePart::Instance(definition_id, extra_data.poly_vars.len() as u32);
                     let concrete_type = inference_type_to_concrete_type(
                         ctx, extra_data.expr_id, &extra_data.poly_vars, first_concrete_part
                     )?;
                     let mono_index = ctx.types.add_data_monomorph(ctx.modules, ctx.heap, ctx.arch, definition_id, concrete_type)?;
                     infer_expr.field_or_monomorph_idx = mono_index;
                 },
                 Expression::Select(_) => {
                     debug_assert!(infer_expr.field_or_monomorph_idx >= 0);
                 },
                 _ => {
                     unreachable!("handling extra data for expression {:?}", &ctx.heap[extra_data.expr_id]);
+                }
+            }
+        }
         // Every expression checked, and new monomorphs are queued. Transfer the
         // expression information to the type table.
         let procedure_arguments = match &self.definition_type {
             DefinitionType::Component(id) => {
                 let definition = &ctx.heap[*id];
                 &definition.parameters
             },
             DefinitionType::Function(id) => {
                 let definition = &ctx.heap[*id];
                 &definition.parameters
             },
         };
         let target = ctx.types.get_procedure_monomorph_mut(self.reserved_idx);
         debug_assert!(target.arg_types.is_empty()); // makes sure we never queue a procedure's type inferencing twice
         debug_assert!(target.expr_data.is_empty());
         // - Write the arguments to the procedure
         target.arg_types.reserve(procedure_arguments.len());
         for argument_id in procedure_arguments {
             let mut concrete = ConcreteType::default();
             let argument_type = self.var_types.get(argument_id).unwrap();
             argument_type.var_type.write_concrete_type(&mut concrete);
             target.arg_types.push(concrete);
+        }
         // - Write the expression data
         target.expr_data.reserve(self.expr_types.len());
         for infer_expr in self.expr_types.iter() {
             let mut concrete = ConcreteType::default();
             infer_expr.expr_type.write_concrete_type(&mut concrete);
             target.expr_data.push(MonomorphExpression{
                 expr_type: concrete,
                 field_or_monomorph_idx: infer_expr.field_or_monomorph_idx
             });
+        }
         Ok(())
+    }
     fn progress_expr(&mut self, ctx: &mut Ctx, idx: i32) -> Result<(), ParseError> {
         let id = self.expr_types[idx as usize].expr_id; // TODO: @Temp
         match &ctx.heap[id] {
             Expression::Assignment(expr) => {
                 let id = expr.this;
                 self.progress_assignment_expr(ctx, id)
             },
             Expression::Binding(expr) => {
                 let id = expr.this;
                 self.progress_binding_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::Literal(expr) => {
                 let id = expr.this;
                 self.progress_literal_expr(ctx, id)
             },
             Expression::Cast(expr) => {
                 let id = expr.this;
                 self.progress_cast_expr(ctx, id)
             },
             Expression::Call(expr) => {
                 let id = expr.this;
                 self.progress_call_expr(ctx, id)
             },
             Expression::Variable(expr) => {
                 let id = expr.this;
                 self.progress_variable_expr(ctx, id)
+            }
+        }
+    }
     fn progress_assignment_expr(&mut self, ctx: &mut Ctx, id: AssignmentExpressionId) -> Result<(), ParseError> {
         use AssignmentOperator as AO;
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let arg1_expr_id = expr.left;
         let arg2_expr_id = expr.right;
         debug_log!("Assignment expr '{:?}': {}", expr.operation, upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Arg1 type: {}", self.debug_get_display_name(ctx, arg1_expr_id));
         debug_log!("   - Arg2 type: {}", self.debug_get_display_name(ctx, arg2_expr_id));
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         // Assignment does not return anything (it operates like a statement)
         let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &VOID_TEMPLATE)?;
         // Apply forced constraint to LHS value
         let progress_forced = match expr.operation {
             AO::Set =>
                 false,
             AO::Concatenated =>
                 self.apply_template_constraint(ctx, arg1_expr_id, &ARRAYLIKE_TEMPLATE)?,
             AO::Multiplied | AO::Divided | AO::Added | AO::Subtracted =>
                 self.apply_template_constraint(ctx, arg1_expr_id, &NUMBERLIKE_TEMPLATE)?,
             AO::Remained | AO::ShiftedLeft | AO::ShiftedRight |
             AO::BitwiseAnded | AO::BitwiseXored | AO::BitwiseOred =>
                 self.apply_template_constraint(ctx, arg1_expr_id, &INTEGERLIKE_TEMPLATE)?,
         };
         let (progress_arg1, progress_arg2) = self.apply_equal2_constraint(
             ctx, upcast_id, arg1_expr_id, 0, arg2_expr_id, 0
         )?;
         debug_log!(" * After:");
         debug_log!("   - Arg1 type [{}]: {}", progress_forced || progress_arg1, self.debug_get_display_name(ctx, arg1_expr_id));
         debug_log!("   - Arg2 type [{}]: {}", progress_arg2, self.debug_get_display_name(ctx, arg2_expr_id));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_forced || progress_arg1 { self.queue_expr(ctx, arg1_expr_id); }
         if progress_arg2 { self.queue_expr(ctx, arg2_expr_id); }
         Ok(())
+    }
     fn progress_binding_expr(&mut self, ctx: &mut Ctx, id: BindingExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let binding_expr = &ctx.heap[id];
         let bound_from_id = binding_expr.bound_from;
         let bound_to_id = binding_expr.bound_to;
         // Output is always a boolean. The two arguments should be of equal
         // type.
         let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
         let (progress_from, progress_to) = self.apply_equal2_constraint(ctx, upcast_id, bound_from_id, 0, bound_to_id, 0)?;
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_from { self.queue_expr(ctx, bound_from_id); }
         if progress_to { self.queue_expr(ctx, bound_to_id); }
         Ok(())
+    }
     fn progress_conditional_expr(&mut self, ctx: &mut Ctx, id: ConditionalExpressionId) -> Result<(), ParseError> {
         // Note: test expression type is already enforced
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let arg1_expr_id = expr.true_expression;
         let arg2_expr_id = expr.false_expression;
         debug_log!("Conditional expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Arg1 type: {}", self.debug_get_display_name(ctx, arg1_expr_id));
         debug_log!("   - Arg2 type: {}", self.debug_get_display_name(ctx, arg2_expr_id));
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         // I keep confusing myself: this applies equality of types between the
         // condition branches' types, and the result from the conditional
         // expression, because the result from the conditional is one of the
         // branches.
         let (progress_expr, progress_arg1, progress_arg2) = self.apply_equal3_constraint(
             ctx, upcast_id, arg1_expr_id, arg2_expr_id, 0
         )?;
         debug_log!(" * After:");
         debug_log!("   - Arg1 type [{}]: {}", progress_arg1, self.debug_get_display_name(ctx, arg1_expr_id));
         debug_log!("   - Arg2 type [{}]: {}", progress_arg2, self.debug_get_display_name(ctx, arg2_expr_id));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_arg1 { self.queue_expr(ctx, arg1_expr_id); }
         if progress_arg2 { self.queue_expr(ctx, arg2_expr_id); }
         Ok(())
+    }
     fn progress_binary_expr(&mut self, ctx: &mut Ctx, id: BinaryExpressionId) -> Result<(), ParseError> {
         // Note: our expression type might be fixed by our parent, but we still
         // need to make sure it matches the type associated with our operation.
         use BinaryOperator as BO;
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let arg1_id = expr.left;
         let arg2_id = expr.right;
         debug_log!("Binary expr '{:?}': {}", expr.operation, upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Arg1 type: {}", self.debug_get_display_name(ctx, arg1_id));
         debug_log!("   - Arg2 type: {}", self.debug_get_display_name(ctx, arg2_id));
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         let (progress_expr, progress_arg1, progress_arg2) = match expr.operation {
             BO::Concatenate => {
                 // Two cases: if one of the arguments or the output type is a
                 // string, then all must be strings. Otherwise the arguments
                 // must be arraylike and the output will be a array.
                 let (expr_is_str, expr_is_not_str) = self.type_is_certainly_or_certainly_not_string(ctx, upcast_id);
                 let (arg1_is_str, arg1_is_not_str) = self.type_is_certainly_or_certainly_not_string(ctx, arg1_id);
                 let (arg2_is_str, arg2_is_not_str) = self.type_is_certainly_or_certainly_not_string(ctx, arg2_id);
                 let someone_is_str = expr_is_str || arg1_is_str || arg2_is_str;
                 let someone_is_not_str = expr_is_not_str || arg1_is_not_str || arg2_is_not_str;
                 // Note: this statement is an expression returning the progression bools
                 if someone_is_str {
                     // One of the arguments is a string, then all must be strings
                     self.apply_equal3_constraint(ctx, upcast_id, arg1_id, arg2_id, 0)?
                 } else {
                     let progress_expr = if someone_is_not_str {
                         // Output must be a normal array
                         self.apply_template_constraint(ctx, upcast_id, &ARRAY_TEMPLATE)?
                     } else {
                         // Output may still be anything
                         self.apply_template_constraint(ctx, upcast_id, &ARRAYLIKE_TEMPLATE)?
                     };
                     let progress_arg1 = self.apply_template_constraint(ctx, arg1_id, &ARRAYLIKE_TEMPLATE)?;
                     let progress_arg2 = self.apply_template_constraint(ctx, arg2_id, &ARRAYLIKE_TEMPLATE)?;
                     // If they're all arraylike, then we want the subtype to match
                     let (subtype_expr, subtype_arg1, subtype_arg2) =
                         self.apply_equal3_constraint(ctx, upcast_id, arg1_id, arg2_id, 1)?;
                     (progress_expr || subtype_expr, progress_arg1 || subtype_arg1, progress_arg2 || subtype_arg2)
+                }
             },
             BO::LogicalAnd => {
                 // Forced boolean on all
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let progress_arg1 = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let progress_arg2 = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 (progress_expr, progress_arg1, progress_arg2)
             },
             BO::LogicalOr => {
                 // Forced boolean on all
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let progress_arg1 = self.apply_forced_constraint(ctx, arg1_id, &BOOL_TEMPLATE)?;
                 let progress_arg2 = self.apply_forced_constraint(ctx, arg2_id, &BOOL_TEMPLATE)?;
                 (progress_expr, progress_arg1, progress_arg2)
             },
             BO::BitwiseOr | BO::BitwiseXor | BO::BitwiseAnd | BO::Remainder | BO::ShiftLeft | BO::ShiftRight => {
                 // All equal of integer type
                 let progress_base = self.apply_template_constraint(ctx, upcast_id, &INTEGERLIKE_TEMPLATE)?;
                 let (progress_expr, progress_arg1, progress_arg2) =
                     self.apply_equal3_constraint(ctx, upcast_id, arg1_id, arg2_id, 0)?;
                 (progress_base || progress_expr, progress_base || progress_arg1, progress_base || progress_arg2)
             },
             BO::Equality | BO::Inequality => {
                 // Equal2 on args, forced boolean output
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let (progress_arg1, progress_arg2) =
                     self.apply_equal2_constraint(ctx, upcast_id, arg1_id, 0, arg2_id, 0)?;
                 (progress_expr, progress_arg1, progress_arg2)
             },
             BO::LessThan | BO::GreaterThan | BO::LessThanEqual | BO::GreaterThanEqual => {
                 // Equal2 on args with numberlike type, forced boolean output
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let progress_arg_base = self.apply_template_constraint(ctx, arg1_id, &NUMBERLIKE_TEMPLATE)?;
                 let (progress_arg1, progress_arg2) =
                     self.apply_equal2_constraint(ctx, upcast_id, arg1_id, 0, arg2_id, 0)?;
                 (progress_expr, progress_arg_base || progress_arg1, progress_arg_base || progress_arg2)
             },
             BO::Add | BO::Subtract | BO::Multiply | BO::Divide => {
                 // All equal of number type
                 let progress_base = self.apply_template_constraint(ctx, upcast_id, &NUMBERLIKE_TEMPLATE)?;
                 let (progress_expr, progress_arg1, progress_arg2) =
                     self.apply_equal3_constraint(ctx, upcast_id, arg1_id, arg2_id, 0)?;
                 (progress_base || progress_expr, progress_base || progress_arg1, progress_base || progress_arg2)
             },
         };
         debug_log!(" * After:");
         debug_log!("   - Arg1 type [{}]: {}", progress_arg1, self.debug_get_display_name(ctx, arg1_id));
         debug_log!("   - Arg2 type [{}]: {}", progress_arg2, self.debug_get_display_name(ctx, arg2_id));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_arg1 { self.queue_expr(ctx, arg1_id); }
         if progress_arg2 { self.queue_expr(ctx, arg2_id); }
         Ok(())
+    }
     fn progress_unary_expr(&mut self, ctx: &mut Ctx, id: UnaryExpressionId) -> Result<(), ParseError> {
         use UnaryOperator as UO;
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let arg_id = expr.expression;
         debug_log!("Unary expr '{:?}': {}", expr.operation, upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Arg  type: {}", self.debug_get_display_name(ctx, arg_id));
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         let (progress_expr, progress_arg) = match expr.operation {
             UO::Positive | UO::Negative => {
                 // Equal types of numeric class
                 let progress_base = self.apply_template_constraint(ctx, upcast_id, &NUMBERLIKE_TEMPLATE)?;
                 let (progress_expr, progress_arg) =
                     self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 0, arg_id, 0)?;
                 (progress_base || progress_expr, progress_base || progress_arg)
             },
             UO::BitwiseNot => {
                 // Equal types of integer class
                 let progress_base = self.apply_template_constraint(ctx, upcast_id, &INTEGERLIKE_TEMPLATE)?;
                 let (progress_expr, progress_arg) =
                     self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 0, arg_id, 0)?;
                 (progress_base || progress_expr, progress_base || progress_arg)
             },
             UO::LogicalNot => {
                 // Both bools
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let progress_arg = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 (progress_expr, progress_arg)
+            }
         };
         debug_log!(" * After:");
         debug_log!("   - Arg  type [{}]: {}", progress_arg, self.debug_get_display_name(ctx, arg_id));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_arg { self.queue_expr(ctx, arg_id); }
         Ok(())
+    }
     fn progress_indexing_expr(&mut self, ctx: &mut Ctx, id: IndexingExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let subject_id = expr.subject;
         let index_id = expr.index;
         debug_log!("Indexing expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Subject type: {}", self.debug_get_display_name(ctx, subject_id));
         debug_log!("   - Index   type: {}", self.debug_get_display_name(ctx, index_id));
         debug_log!("   - Expr    type: {}", self.debug_get_display_name(ctx, upcast_id));
         // Make sure subject is arraylike and index is integerlike
         let progress_subject_base = self.apply_template_constraint(ctx, subject_id, &ARRAYLIKE_TEMPLATE)?;
         let progress_index = self.apply_template_constraint(ctx, index_id, &INTEGERLIKE_TEMPLATE)?;
         // 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.debug_get_display_name(ctx, subject_id));
         debug_log!("   - Index   type [{}]: {}", progress_index, self.debug_get_display_name(ctx, index_id));
         debug_log!("   - Expr    type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_subject_base || progress_subject { self.queue_expr(ctx, subject_id); }
         if progress_index { self.queue_expr(ctx, index_id); }
         Ok(())
+    }
     fn progress_slicing_expr(&mut self, ctx: &mut Ctx, id: SlicingExpressionId) -> Result<(), ParseError> {
         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.debug_get_display_name(ctx, subject_id));
         debug_log!("   - FromIdx type: {}", self.debug_get_display_name(ctx, from_id));
         debug_log!("   - ToIdx   type: {}", self.debug_get_display_name(ctx, to_id));
         debug_log!("   - Expr    type: {}", self.debug_get_display_name(ctx, upcast_id));
         // Make sure subject is arraylike and indices are of equal integerlike
         let progress_subject_base = self.apply_template_constraint(ctx, subject_id, &ARRAYLIKE_TEMPLATE)?;
         let progress_idx_base = self.apply_template_constraint(ctx, from_id, &INTEGERLIKE_TEMPLATE)?;
         let (progress_from, progress_to) = self.apply_equal2_constraint(ctx, upcast_id, from_id, 0, to_id, 0)?;
         let (progress_expr, progress_subject) = match self.type_is_certainly_or_certainly_not_string(ctx, subject_id) {
             (true, _) => {
                 // Certainly a string
                 (self.apply_forced_constraint(ctx, upcast_id, &STRING_TEMPLATE)?, false)
             },
             (_, true) => {
                 // Certainly not a string
                 let progress_expr_base = self.apply_template_constraint(ctx, upcast_id, &SLICE_TEMPLATE)?;
                 let (progress_expr, progress_subject) =
                     self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 1, subject_id, 1)?;
                 (progress_expr_base || progress_expr, progress_subject)
             },
             _ => {
                 // Could be anything, at least attempt to progress subtype
                 let progress_expr_base = self.apply_template_constraint(ctx, upcast_id, &ARRAYLIKE_TEMPLATE)?;
                 let (progress_expr, progress_subject) =
                     self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 1, subject_id, 1)?;
                 (progress_expr_base || progress_expr, progress_subject)
+            }
         };
         debug_log!(" * After:");
         debug_log!("   - Subject type [{}]: {}", progress_subject_base || progress_subject, self.debug_get_display_name(ctx, subject_id));
         debug_log!("   - FromIdx type [{}]: {}", progress_idx_base || progress_from, self.debug_get_display_name(ctx, from_id));
         debug_log!("   - ToIdx   type [{}]: {}", progress_idx_base || progress_to, self.debug_get_display_name(ctx, to_id));
         debug_log!("   - Expr    type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_subject_base || progress_subject { self.queue_expr(ctx, subject_id); }
         if progress_idx_base || progress_from { self.queue_expr(ctx, from_id); }
         if progress_idx_base || progress_to { self.queue_expr(ctx, to_id); }
         Ok(())
+    }
     fn progress_select_expr(&mut self, ctx: &mut Ctx, id: SelectExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         debug_log!("Select expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Subject type: {}", self.debug_get_display_name(ctx, ctx.heap[id].subject));
         debug_log!("   - Expr    type: {}", self.debug_get_display_name(ctx, upcast_id));
         let subject_id = ctx.heap[id].subject;
         let subject_expr_idx = ctx.heap[subject_id].get_unique_id_in_definition();
         let select_expr = &ctx.heap[id];
         let expr_idx = select_expr.unique_id_in_definition;
         let infer_expr = &self.expr_types[expr_idx as usize];
         let extra_idx = infer_expr.extra_data_idx;
         fn try_get_definition_id_from_inference_type<'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)
+        }
         fn try_get_tuple_size_from_inference_type(infer_type: &InferenceType) -> Result<Option<u32>, ()> {
             for part in &infer_type.parts {
                 if part.is_marker() || !part.is_concrete() {
                     continue;
+                }
                 if let InferenceTypePart::Tuple(size) = part {
                     return Ok(Some(*size));
                 } else {
                     // Expected a tuple
                     return Err(());
+                }
+            }
             // Type is not "defined enough" yet
             Ok(None)
+        }
         let (progress_subject, progress_expr) = match &select_expr.kind {
             SelectKind::StructField(field_name) => {
                 // Handle select of a struct's field
                 if infer_expr.field_or_monomorph_idx < 0 {
                     // We don't know the field or the definition it is pointing to yet
                     // Not yet known, check if we can determine it
                     let subject_type = &self.expr_types[subject_expr_idx as usize].expr_type;
                     let type_def = try_get_definition_id_from_inference_type(&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(ParseError::new_error_at_span(
                                     &ctx.module().source, field_name.span, format!(
                                         "Can only apply field access to structs, got a subject of type '{}'",
                                         subject_type.display_name(&ctx.heap)
+                                    )
                                 ));
                             };
                             let mut struct_def_id = None;
                             for (field_def_idx, field_def) in struct_def.fields.iter().enumerate() {
                                 if field_def.identifier == *field_name {
                                     // Set field definition and index
                                     let infer_expr = &mut self.expr_types[expr_idx as usize];
                                     infer_expr.field_or_monomorph_idx = field_def_idx as i32;
                                     struct_def_id = Some(type_def.ast_definition);
                                     break;
+                                }
+                            }
                             if struct_def_id.is_none() {
                                 let ast_struct_def = ctx.heap[type_def.ast_definition].as_struct();
                                 return Err(ParseError::new_error_at_span(
                                     &ctx.module().source, field_name.span, format!(
                                         "this field does not exist on the struct '{}'",
                                         ast_struct_def.identifier.value.as_str()
+                                    )
                                 ))
+                            }
                             // Encountered definition and field index for the
                             // first time
                             self.insert_initial_select_polymorph_data(ctx, id, struct_def_id.unwrap());
                         },
                         Ok(None) => {
                             // Type of subject is not yet known, so we
                             // cannot make any progress yet
                             return Ok(())
                         },
                         Err(()) => {
                             return Err(ParseError::new_error_at_span(
                                 &ctx.module().source, field_name.span, format!(
                                     "Can only apply field access to structs, got a subject of type '{}'",
                                     subject_type.display_name(&ctx.heap)
+                                )
                             ));
+                        }
+                    }
+                }
                 // If here then field index is known, and the referenced struct type
                 // information is inserted into `extra_data`. Check to see if we can
                 // do some mutual inference.
                 let poly_data = &mut self.extra_data[extra_idx as usize];
                 let mut poly_progress = HashSet::new();
                 // Apply to struct's type
                 let signature_type: *mut _ = &mut poly_data.embedded[0];
                 let subject_type: *mut _ = &mut self.expr_types[subject_expr_idx as usize].expr_type;
                 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.push_back(subject_expr_idx);
+                }
                 // Apply to field's type
                 let signature_type: *mut _ = &mut poly_data.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let (_, progress_expr) = Self::apply_equal2_signature_constraint(
                     ctx, upcast_id, None, poly_data, &mut poly_progress,
                     signature_type, 0, expr_type, 0
                 )?;
                 if progress_expr {
                     if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
                         let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
                         self.expr_queued.push_back(parent_idx);
+                    }
+                }
                 // Reapply progress in polymorphic variables to struct's type
                 let signature_type: *mut _ = &mut poly_data.embedded[0];
                 let subject_type: *mut _ = &mut self.expr_types[subject_expr_idx as usize].expr_type;
                 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 _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let progress_expr = Self::apply_equal2_polyvar_constraint(
                     poly_data, &poly_progress, signature_type, expr_type
                 );
                 (progress_subject, progress_expr)
             },
             SelectKind::TupleMember(member_index) => {
                 let member_index = *member_index;
                 if infer_expr.field_or_monomorph_idx < 0 {
                     // We don't know what kind of tuple we're accessing yet
                     let subject_type = &self.expr_types[subject_expr_idx as usize].expr_type;
                     let tuple_size = try_get_tuple_size_from_inference_type(subject_type);
                     match tuple_size {
                         Ok(Some(enum_size)) => {
                             // Make sure we don't access an element outside of
                             // the tuple's bounds
                             if member_index >= enum_size as u64 {
                                 return Err(ParseError::new_error_at_span(
                                     &ctx.module().source, select_expr.full_span, format!(
                                         "element index {} is out of bounds, tuple has {} elements",
                                         member_index, enum_size
+                                    )
                                 ));
+                            }
                             // Within bounds, so set the index (such that we
                             // will not perform this lookup again)
                             let infer_expr = &mut self.expr_types[expr_idx as usize];
                             infer_expr.field_or_monomorph_idx = member_index as i32;
                         },
                         Ok(None) => {
                             // Nothing is known about the tuple yet
                             return Ok(());
                         },
                         Err(()) => {
                             return Err(ParseError::new_error_at_span(
                                 &ctx.module().source, select_expr.full_span, format!(
                                     "Can only apply tuple element selection to tuples, got a subject of type '{}'",
                                     subject_type.display_name(&ctx.heap)
+                                )
                             ));
+                        }
+                    }
+                }
                 // If here then we know which member we're accessing. So seek
                 // that member in the subject type and apply inference.
                 let subject_type = &self.expr_types[subject_expr_idx as usize].expr_type;
                 let mut member_start_idx = 1;
                 for _ in 0..member_index {
                     member_start_idx = InferenceType::find_subtree_end_idx(&subject_type.parts, member_start_idx);
+                }
                 let (progress_expr, progress_subject) = self.apply_equal2_constraint(
                     ctx, upcast_id, upcast_id, 0, subject_id, member_start_idx
                 )?;
                 (progress_subject, progress_expr)
             },
         };
         if progress_subject { self.queue_expr(ctx, subject_id); }
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         debug_log!(" * After:");
         debug_log!("   - Subject type [{}]: {}", progress_subject, self.debug_get_display_name(ctx, subject_id));
         debug_log!("   - Expr    type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         Ok(())
+    }
     fn progress_literal_expr(&mut self, ctx: &mut Ctx, id: LiteralExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let expr_idx = expr.unique_id_in_definition;
         let extra_idx = self.expr_types[expr_idx as usize].extra_data_idx;
         debug_log!("Literal expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         let progress_expr = match &expr.value {
             Literal::Null => {
                 self.apply_template_constraint(ctx, upcast_id, &MESSAGE_TEMPLATE)?
             },
             Literal::Integer(_) => {
                 self.apply_template_constraint(ctx, upcast_id, &INTEGERLIKE_TEMPLATE)?
             },
             Literal::True | Literal::False => {
                 self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?
             },
             Literal::Character(_) => {
                 self.apply_forced_constraint(ctx, upcast_id, &CHARACTER_TEMPLATE)?
             },
             Literal::String(_) => {
                 self.apply_forced_constraint(ctx, upcast_id, &STRING_TEMPLATE)?
             },
             Literal::Struct(data) => {
                 let extra = &mut self.extra_data[extra_idx as usize];
                 for _poly in &extra.poly_vars {
                     debug_log!(" * Poly: {}", _poly.display_name(&ctx.heap));
+                }
                 let mut poly_progress = HashSet::new();
                 debug_assert_eq!(extra.embedded.len(), data.fields.len());
                 debug_log!(" * During (inferring types from fields and struct type):");
                 // Mutually infer field signature/expression types
                 for (field_idx, field) in data.fields.iter().enumerate() {
                     let field_expr_id = field.value;
                     let field_expr_idx = ctx.heap[field_expr_id].get_unique_id_in_definition();
                     let signature_type: *mut _ = &mut extra.embedded[field_idx];
                     let field_type: *mut _ = &mut self.expr_types[field_expr_idx as usize].expr_type;
                     let (_, progress_arg) = Self::apply_equal2_signature_constraint(
                         ctx, upcast_id, Some(field_expr_id), extra, &mut poly_progress,
                         signature_type, 0, field_type, 0
                     )?;
                     debug_log!(
                         "   - Field {} type | sig: {}, field: {}", field_idx,
                         unsafe{&*signature_type}.display_name(&ctx.heap),
                         unsafe{&*field_type}.display_name(&ctx.heap)
                     );
                     if progress_arg {
                         self.expr_queued.push_back(field_expr_idx);
+                    }
+                }
                 debug_log!("   - Field poly progress | {:?}", poly_progress);
                 // Same for the type of the struct itself
                 let signature_type: *mut _ = &mut extra.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let (_, progress_expr) = Self::apply_equal2_signature_constraint(
                     ctx, upcast_id, None, extra, &mut poly_progress,
                     signature_type, 0, expr_type, 0
                 )?;
                 debug_log!(
                     "   - Ret type | sig: {}, expr: {}",
                     unsafe{&*signature_type}.display_name(&ctx.heap),
                     unsafe{&*expr_type}.display_name(&ctx.heap)
                 );
                 debug_log!("   - Ret poly progress | {:?}", poly_progress);
                 if progress_expr {
                     // TODO: @cleanup, cannot call utility self.queue_parent thingo
                     if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
                         let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
                         self.expr_queued.push_back(parent_idx);
+                    }
+                }
                 // Check which expressions use the polymorphic arguments. If the
                 // polymorphic variables have been progressed then we try to
                 // progress them inside the expression as well.
                 debug_log!(" * During (reinferring from progressed polyvars):");
                 // For all field expressions
                 for field_idx in 0..extra.embedded.len() {
                     // Note: fields in extra.embedded are in the same order as
                     // they are specified in the literal. Whereas
                     // `data.fields[...].field_idx` points to the field in the
                     // struct definition.
                     let signature_type: *mut _ = &mut extra.embedded[field_idx];
                     let field_expr_id = data.fields[field_idx].value;
                     let field_expr_idx = ctx.heap[field_expr_id].get_unique_id_in_definition();
                     let field_type: *mut _ = &mut self.expr_types[field_expr_idx as usize].expr_type;
                     let progress_arg = Self::apply_equal2_polyvar_constraint(
                         extra, &poly_progress, signature_type, field_type
                     );
                     debug_log!(
                         "   - Field {} type | sig: {}, field: {}", field_idx,
                         unsafe{&*signature_type}.display_name(&ctx.heap),
                         unsafe{&*field_type}.display_name(&ctx.heap)
                     );
                     if progress_arg {
                         self.expr_queued.push_back(field_expr_idx);
+                    }
+                }
                 // For the return type
                 let signature_type: *mut _ = &mut extra.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let progress_expr = Self::apply_equal2_polyvar_constraint(
                     extra, &poly_progress, signature_type, expr_type
                 );
                 progress_expr
             },
             Literal::Enum(_) => {
                 let extra = &mut self.extra_data[extra_idx as usize];
                 for _poly in &extra.poly_vars {
                     debug_log!(" * Poly: {}", _poly.display_name(&ctx.heap));
+                }
                 let mut poly_progress = HashSet::new();
                 debug_log!(" * During (inferring types from return type)");
                 let signature_type: *mut _ = &mut extra.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let (_, progress_expr) = Self::apply_equal2_signature_constraint(
                     ctx, upcast_id, None, extra, &mut poly_progress,
                     signature_type, 0, expr_type, 0
                 )?;
                 debug_log!(
                     "   - Ret type | sig: {}, expr: {}",
                     unsafe{&*signature_type}.display_name(&ctx.heap),
                     unsafe{&*expr_type}.display_name(&ctx.heap)
                 );
                 if progress_expr {
                     // TODO: @cleanup
                     if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
                         let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
                         self.expr_queued.push_back(parent_idx);
+                    }
+                }
                 debug_log!(" * During (reinferring from progress polyvars):");
                 let progress_expr = Self::apply_equal2_polyvar_constraint(
                     extra, &poly_progress, signature_type, expr_type
                 );
                 progress_expr
             },
             Literal::Union(data) => {
                 let extra = &mut self.extra_data[extra_idx as usize];
                 for _poly in &extra.poly_vars {
                     debug_log!(" * Poly: {}", _poly.display_name(&ctx.heap));
+                }
                 let mut poly_progress = HashSet::new();
                 debug_assert_eq!(extra.embedded.len(), data.values.len());
                 debug_log!(" * During (inferring types from variant values and union type):");
                 // Mutually infer union variant values
                 for (value_idx, value_expr_id) in data.values.iter().enumerate() {
                     let value_expr_id = *value_expr_id;
                     let value_expr_idx = ctx.heap[value_expr_id].get_unique_id_in_definition();
                     let signature_type: *mut _ = &mut extra.embedded[value_idx];
                     let value_type: *mut _ = &mut self.expr_types[value_expr_idx as usize].expr_type;
                     let (_, progress_arg) = Self::apply_equal2_signature_constraint(
                         ctx, upcast_id, Some(value_expr_id), extra, &mut poly_progress,
                         signature_type, 0, value_type, 0
                     )?;
                     debug_log!(
                         "   - Value {} type | sig: {}, field: {}", value_idx,
                         unsafe{&*signature_type}.display_name(&ctx.heap),
                         unsafe{&*value_type}.display_name(&ctx.heap)
                     );
                     if progress_arg {
                         self.expr_queued.push_back(value_expr_idx);
+                    }
+                }
                 debug_log!("   - Field poly progress | {:?}", poly_progress);
                 // Infer type of union itself
                 let signature_type: *mut _ = &mut extra.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let (_, progress_expr) = Self::apply_equal2_signature_constraint(
                     ctx, upcast_id, None, extra, &mut poly_progress,
                     signature_type, 0, expr_type, 0
                 )?;
                 debug_log!(
                     "   - Ret type | sig: {}, expr: {}",
                     unsafe{&*signature_type}.display_name(&ctx.heap),
                     unsafe{&*expr_type}.display_name(&ctx.heap)
                 );
                 debug_log!("   - Ret poly progress | {:?}", poly_progress);
                 if progress_expr {
                     // TODO: @cleanup, borrowing rules
                     if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
                         let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
                         self.expr_queued.push_back(parent_idx);
+                    }
+                }
                 debug_log!(" * During (reinferring from progress polyvars):");
                 // For all embedded values of the union variant
                 for value_idx in 0..extra.embedded.len() {
                     let signature_type: *mut _ = &mut extra.embedded[value_idx];
                     let value_expr_id = data.values[value_idx];
                     let value_expr_idx = ctx.heap[value_expr_id].get_unique_id_in_definition();
                     let value_type: *mut _ = &mut self.expr_types[value_expr_idx as usize].expr_type;
                     let progress_arg = Self::apply_equal2_polyvar_constraint(
                         extra, &poly_progress, signature_type, value_type
                     );
                     debug_log!(
                         "   - Value {} type | sig: {}, value: {}", value_idx,
                         unsafe{&*signature_type}.display_name(&ctx.heap),
                         unsafe{&*value_type}.display_name(&ctx.heap)
                     );
                     if progress_arg {
                         self.expr_queued.push_back(value_expr_idx);
+                    }
+                }
                 // And for the union type itself
                 let signature_type: *mut _ = &mut extra.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let progress_expr = Self::apply_equal2_polyvar_constraint(
                     extra, &poly_progress, signature_type, expr_type
                 );
                 progress_expr
             },
             Literal::Array(data) => {
                 let expr_elements = data.clone(); // TODO: @performance
                 debug_log!("Array expr ({} elements): {}", expr_elements.len(), upcast_id.index);
                 debug_log!(" * Before:");
                 debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
                 // 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(ctx, *arg_id);
+                    }
+                }
                 // And the output should be an array of the element types
                 let mut progress_expr = self.apply_template_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
                     )?;
                     progress_expr = progress_expr || 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(ctx, upcast_id); }
+                }
                 debug_log!(" * After:");
                 debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
                 progress_expr
             },
             Literal::Tuple(data) => {
                 let expr_elements = data.clone(); // TODO: @performance
                 debug_log!("Tuple expr ({} elements): {}", expr_elements.len(), upcast_id.index);
                 debug_log!(" * Before:");
                 debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
                 // Initial tuple constraint
                 let num_members = expr_elements.len();
                 let mut initial_type = Vec::with_capacity(num_members + 1); // TODO: @performance
                 initial_type.push(InferenceTypePart::Tuple(num_members as u32));
                 for _ in 0..num_members {
                     initial_type.push(InferenceTypePart::Unknown);
+                }
                 let mut progress_expr = self.apply_template_constraint(ctx, upcast_id, &initial_type)?;
                 // The elements of the tuple can have any type, but they must
                 // end up as arguments to the output tuple type.
                 debug_log!(" * During (checking expressions constituting tuple):");
                 for (member_expr_index, member_expr_id) in expr_elements.iter().enumerate() {
                     // For the current expression index, (re)compute the
                     // position in the tuple type where the types should match.
                     let mut start_index = 1; // first element is Tuple type, second is the first child
                     for _ in 0..member_expr_index {
                         let tuple_expr_index = ctx.heap[id].unique_id_in_definition;
                         let tuple_type = &self.expr_types[tuple_expr_index as usize].expr_type;
                         start_index = InferenceType::find_subtree_end_idx(&tuple_type.parts, start_index);
                         debug_assert_ne!(start_index, tuple_type.parts.len()); // would imply less tuple type children than member expressions
+                    }
                     // Apply the constraint
                     let (member_progress_expr, member_progress) = self.apply_equal2_constraint(
                         ctx, upcast_id, upcast_id, start_index, *member_expr_id, 0
                     )?;
                     debug_log!("   - Member {} type | {}", member_expr_index, self.debug_get_display_name(ctx, *member_expr_id));
                     progress_expr = progress_expr || member_progress_expr;
                     if member_progress {
                         self.queue_expr(ctx, *member_expr_id);
+                    }
+                }
                 progress_expr
+            }
         };
         debug_log!(" * After:");
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         Ok(())
+    }
     fn progress_cast_expr(&mut self, ctx: &mut Ctx, id: CastExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let expr_idx = expr.unique_id_in_definition;
         debug_log!("Casting expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Expr type:    {}", self.debug_get_display_name(ctx, upcast_id));
         debug_log!("   - Subject type: {}", self.debug_get_display_name(ctx, expr.subject));
         // The cast expression might have its output type fixed by the
         // programmer, so apply that type to the output. Apart from that casting
         // acts like a blocker for two-way inference. So we'll just have to wait
         // until we know if the cast is valid.
         // TODO: Another thing that has to be updated the moment the type
         //  inferencer is fully index/job-based
         let infer_type = self.determine_inference_type_from_parser_type_elements(&expr.to_type.elements, true);
         let expr_progress = self.apply_template_constraint(ctx, upcast_id, &infer_type.parts)?;
         if expr_progress {
             self.queue_expr_parent(ctx, upcast_id);
+        }
         // Check if the two types are compatible
         debug_log!(" * After:");
         debug_log!("   - Expr type [{}]: {}", expr_progress, self.debug_get_display_name(ctx, upcast_id));
         debug_log!("   - Note that the subject type can never be inferred");
         debug_log!(" * Decision:");
         let subject_idx = ctx.heap[expr.subject].get_unique_id_in_definition();
         let expr_type = &self.expr_types[expr_idx as usize].expr_type;
         let subject_type = &self.expr_types[subject_idx as usize].expr_type;
         if !expr_type.is_done || !subject_type.is_done {
             // Not yet done
             debug_log!("   - Casting is valid: unknown as the types are not yet complete");
             return Ok(())
+        }
         // Valid casts: (bool, integer, character) can always be cast to one
         // another. A cast from a type to itself is also valid.
         fn is_bool_int_or_char(parts: &[InferenceTypePart]) -> bool {
             return parts.len() == 1 && (
                 parts[0] == InferenceTypePart::Bool ||
                 parts[0] == InferenceTypePart::Character ||
                 parts[0].is_concrete_integer()
             );
+        }
         let is_valid = if is_bool_int_or_char(&expr_type.parts) && is_bool_int_or_char(&subject_type.parts) {
             true
         } else if expr_type.parts == subject_type.parts {
             true
         } else {
             false
         };
         debug_log!("   - Casting is valid: {}", is_valid);
         if !is_valid {
             let cast_expr = &ctx.heap[id];
             let subject_expr = &ctx.heap[cast_expr.subject];
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, cast_expr.full_span, "invalid casting operation"
             ).with_info_at_span(
                 &ctx.module().source, subject_expr.full_span(), format!(
                     "cannot cast the argument type '{}' to the cast type '{}'",
                     subject_type.display_name(&ctx.heap),
                     expr_type.display_name(&ctx.heap)
+                )
             ));
+        }
         Ok(())
+    }
     // TODO: @cleanup, see how this can be cleaned up once I implement
     //  polymorphic struct/enum/union literals. These likely follow the same
     //  pattern as here.
     fn progress_call_expr(&mut self, ctx: &mut Ctx, id: CallExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let expr_idx = expr.unique_id_in_definition;
         let extra_idx = self.expr_types[expr_idx as usize].extra_data_idx;
         debug_log!("Call expr '{}': {}", ctx.heap[expr.definition].identifier().value.as_str(), upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         debug_log!(" * During (inferring types from arguments and return type):");
         let extra = &mut self.extra_data[extra_idx as usize];
         // Check if we can make progress using the arguments and/or return types
         // while keeping track of the polyvars we've extended
         let mut poly_progress = HashSet::new();
         debug_assert_eq!(extra.embedded.len(), expr.arguments.len());
         for (call_arg_idx, arg_id) in expr.arguments.clone().into_iter().enumerate() {
             let arg_expr_idx = ctx.heap[arg_id].get_unique_id_in_definition();
             let signature_type: *mut _ = &mut extra.embedded[call_arg_idx];
             let argument_type: *mut _ = &mut self.expr_types[arg_expr_idx as usize].expr_type;
             let (_, progress_arg) = Self::apply_equal2_signature_constraint(
                 ctx, upcast_id, Some(arg_id), extra, &mut poly_progress,
                 signature_type, 0, argument_type, 0
             )?;
             debug_log!(
                 "   - Arg {} type | sig: {}, arg: {}", call_arg_idx,
                 unsafe{&*signature_type}.display_name(&ctx.heap),
                 unsafe{&*argument_type}.display_name(&ctx.heap));
             if progress_arg {
                 // Progressed argument expression
                 self.expr_queued.push_back(arg_expr_idx);
+            }
+        }
         // Do the same for the return type
         let signature_type: *mut _ = &mut extra.returned;
         let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
         let (_, progress_expr) = Self::apply_equal2_signature_constraint(
             ctx, upcast_id, None, extra, &mut poly_progress,
             signature_type, 0, expr_type, 0
         )?;
         debug_log!(
             "   - Ret type | sig: {}, expr: {}",
             unsafe{&*signature_type}.display_name(&ctx.heap),
             unsafe{&*expr_type}.display_name(&ctx.heap)
         );
         if progress_expr {
             // TODO: @cleanup, cannot call utility self.queue_parent thingo
             if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
                 let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
                 self.expr_queued.push_back(parent_idx);
+            }
+        }
         // If we did not have an error in the polymorph inference above, then
         // reapplying the polymorph type to each argument type and the return
         // type should always succeed.
         debug_log!(" * During (reinferring from progressed polyvars):");
         for (_poly_idx, _poly_var) in extra.poly_vars.iter().enumerate() {
             debug_log!("   - Poly {} | sig: {}", _poly_idx, _poly_var.display_name(&ctx.heap));
+        }
         // TODO: @performance If the algorithm is changed to be more "on demand
         //  argument re-evaluation", instead of "all-argument re-evaluation",
         //  then this is no longer true
         for arg_idx in 0..extra.embedded.len() {
             let signature_type: *mut _ = &mut extra.embedded[arg_idx];
             let arg_expr_id = expr.arguments[arg_idx];
             let arg_expr_idx = ctx.heap[arg_expr_id].get_unique_id_in_definition();
             let arg_type: *mut _ = &mut self.expr_types[arg_expr_idx as usize].expr_type;
             let progress_arg = Self::apply_equal2_polyvar_constraint(
                 extra, &poly_progress,
                 signature_type, arg_type
             );
             debug_log!(
                 "   - Arg {} type | sig: {}, arg: {}", arg_idx,
                 unsafe{&*signature_type}.display_name(&ctx.heap),
                 unsafe{&*arg_type}.display_name(&ctx.heap)
             );
             if progress_arg {
                 self.expr_queued.push_back(arg_expr_idx);
+            }
+        }
         // Once more for the return type
         let signature_type: *mut _ = &mut extra.returned;
         let ret_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
         let progress_ret = Self::apply_equal2_polyvar_constraint(
             extra, &poly_progress, signature_type, ret_type
         );
         debug_log!(
             "   - Ret type | sig: {}, arg: {}",
             unsafe{&*signature_type}.display_name(&ctx.heap),
             unsafe{&*ret_type}.display_name(&ctx.heap)
         );
         if progress_ret {
             self.queue_expr_parent(ctx, upcast_id);
+        }
         debug_log!(" * After:");
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         Ok(())
+    }
     fn progress_variable_expr(&mut self, ctx: &mut Ctx, id: VariableExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let var_expr = &ctx.heap[id];
         let var_expr_idx = var_expr.unique_id_in_definition;
         let var_id = var_expr.declaration.unwrap();
         debug_log!("Variable expr '{}': {}", ctx.heap[var_id].identifier.value.as_str(), upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Var  type: {}", self.var_types.get(&var_id).unwrap().var_type.display_name(&ctx.heap));
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         // Retrieve shared variable type and expression type and apply inference
         let var_data = self.var_types.get_mut(&var_id).unwrap();
         let expr_type = &mut self.expr_types[var_expr_idx as usize].expr_type;
         let infer_res = unsafe{ InferenceType::infer_subtrees_for_both_types(
             &mut var_data.var_type as *mut _, 0, expr_type, 0
         ) };
         if infer_res == DualInferenceResult::Incompatible {
             let var_decl = &ctx.heap[var_id];
             return Err(ParseError::new_error_at_span(
                 &ctx.module().source, var_decl.identifier.span, format!(
                     "Conflicting types for this variable, previously assigned the type '{}'",
                     var_data.var_type.display_name(&ctx.heap)
+                )
             ).with_info_at_span(
                 &ctx.module().source, var_expr.identifier.span, format!(
                     "But inferred to have incompatible type '{}' here",
                     expr_type.display_name(&ctx.heap)
+                )
             ))
+        }
         let progress_var = infer_res.modified_lhs();
         let progress_expr = infer_res.modified_rhs();
         if progress_var {
             // Let other variable expressions using this type progress as well
             for other_expr in var_data.used_at.iter() {
                 if *other_expr != upcast_id {
                     let other_expr_idx = ctx.heap[*other_expr].get_unique_id_in_definition();
                     self.expr_queued.push_back(other_expr_idx);
+                }
+            }
             // Let a linked port know that our type has updated
             if let Some(linked_id) = var_data.linked_var {
                 // Only perform one-way inference to prevent updating our type,
                 // this would lead to an inconsistency in the type inference
                 // algorithm otherwise.
                 let var_type: *mut _ = &mut var_data.var_type;
                 let link_data = self.var_types.get_mut(&linked_id).unwrap();
                 debug_assert!(
                     unsafe{&*var_type}.parts[0] == InferenceTypePart::Input ||
                     unsafe{&*var_type}.parts[0] == InferenceTypePart::Output
                 );
                 debug_assert!(
                     link_data.var_type.parts[0] == InferenceTypePart::Input ||
                     link_data.var_type.parts[0] == InferenceTypePart::Output
                 );
                 match InferenceType::infer_subtree_for_single_type(&mut link_data.var_type, 1, &unsafe{&*var_type}.parts, 1, false) {
                     SingleInferenceResult::Modified => {
                         for other_expr in &link_data.used_at {
                             let other_expr_idx = ctx.heap[*other_expr].get_unique_id_in_definition();
                             self.expr_queued.push_back(other_expr_idx);
+                        }
                     },
                     SingleInferenceResult::Unmodified => {},
                     SingleInferenceResult::Incompatible => {
                         let var_data = self.var_types.get(&var_id).unwrap();
                         let link_data = self.var_types.get(&linked_id).unwrap();
                         let var_decl = &ctx.heap[var_id];
                         let link_decl = &ctx.heap[linked_id];
                         return Err(ParseError::new_error_at_span(
                             &ctx.module().source, var_decl.identifier.span, format!(
                                 "Conflicting types for this variable, assigned the type '{}'",
                                 var_data.var_type.display_name(&ctx.heap)
+                            )
                         ).with_info_at_span(
                             &ctx.module().source, link_decl.identifier.span, format!(
                                 "Because it is incompatible with this variable, assigned the type '{}'",
                                 link_data.var_type.display_name(&ctx.heap)
+                            )
                         ));
+                    }
+                }
+            }
+        }
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         debug_log!(" * After:");
         debug_log!("   - Var  type [{}]: {}", progress_var, self.var_types.get(&var_id).unwrap().var_type.display_name(&ctx.heap));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         Ok(())
+    }
     fn queue_expr_parent(&mut self, ctx: &Ctx, expr_id: ExpressionId) {
         if let ExpressionParent::Expression(parent_expr_id, _) = &ctx.heap[expr_id].parent() {
             let expr_idx = ctx.heap[*parent_expr_id].get_unique_id_in_definition();
             self.expr_queued.push_back(expr_idx);
+        }
+    }
     fn queue_expr(&mut self, ctx: &Ctx, expr_id: ExpressionId) {
         let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition();
         self.expr_queued.push_back(expr_idx);
+    }
     // first returned is certainly string, second is certainly not
     fn type_is_certainly_or_certainly_not_string(&self, ctx: &Ctx, expr_id: ExpressionId) -> (bool, bool) {
         let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition();
         let expr_type = &self.expr_types[expr_idx as usize].expr_type;
         if expr_type.is_done {
             if expr_type.parts[0] == InferenceTypePart::String {
                 return (true, false);
             } else {
                 return (false, true);
+            }
+        }
         (false, false)
+    }
     /// Applies a template type constraint: the type associated with the
     /// supplied expression will be molded into the provided `template`. But
     /// will be considered valid if the template could've been molded into the
     /// expression type as well. Hence the template may be fully specified (e.g.
     /// a bool) or contain "inference" variables (e.g. an array of T)
     fn apply_template_constraint(
         &mut self, ctx: &Ctx, expr_id: ExpressionId, template: &[InferenceTypePart]
     ) -> Result<bool, ParseError> {
         let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition(); // TODO: @Temp
         let expr_type = &mut self.expr_types[expr_idx as usize].expr_type;
         match InferenceType::infer_subtree_for_single_type(expr_type, 0, template, 0, false) {
             SingleInferenceResult::Modified => Ok(true),
             SingleInferenceResult::Unmodified => Ok(false),
             SingleInferenceResult::Incompatible => Err(
                 self.construct_template_type_error(ctx, expr_id, template)
+            )
+        }
+    }
     fn apply_template_constraint_to_types(
         to_infer: *mut InferenceType, to_infer_start_idx: usize,
         template: &[InferenceTypePart], template_start_idx: usize
     ) -> Result<bool, ()> {
         match InferenceType::infer_subtree_for_single_type(
             unsafe{ &mut *to_infer }, to_infer_start_idx,
             template, template_start_idx, false
         ) {
             SingleInferenceResult::Modified => Ok(true),
             SingleInferenceResult::Unmodified => Ok(false),
             SingleInferenceResult::Incompatible => Err(()),
+        }
+    }
     /// Applies a forced constraint: the supplied expression's type MUST be
     /// inferred from the template, the other way around is considered invalid.
     fn apply_forced_constraint(
         &mut self, ctx: &Ctx, expr_id: ExpressionId, template: &[InferenceTypePart]
     ) -> Result<bool, ParseError> {
         let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition();
         let expr_type = &mut self.expr_types[expr_idx as usize].expr_type;
         match InferenceType::infer_subtree_for_single_type(expr_type, 0, template, 0, true) {
             SingleInferenceResult::Modified => Ok(true),
             SingleInferenceResult::Unmodified => Ok(false),
             SingleInferenceResult::Incompatible => Err(
                 self.construct_template_type_error(ctx, expr_id, template)
+            )
+        }
+    }
     /// Applies a type constraint that expects the two provided types to be
     /// equal. We attempt to make progress in inferring the types. If the call
     /// is successful then the composition of all types are made equal.
     /// The "parent" `expr_id` is provided to construct errors.
     fn apply_equal2_constraint(
         &mut self, ctx: &Ctx, expr_id: ExpressionId,
         arg1_id: ExpressionId, arg1_start_idx: usize,
         arg2_id: ExpressionId, arg2_start_idx: usize
     ) -> Result<(bool, bool), ParseError> {
         let arg1_expr_idx = ctx.heap[arg1_id].get_unique_id_in_definition(); // TODO: @Temp
         let arg2_expr_idx = ctx.heap[arg2_id].get_unique_id_in_definition();
         let arg1_type: *mut _ = &mut self.expr_types[arg1_expr_idx as usize].expr_type;
         let arg2_type: *mut _ = &mut self.expr_types[arg2_expr_idx as usize].expr_type;
         let infer_res = unsafe{ InferenceType::infer_subtrees_for_both_types(
             arg1_type, arg1_start_idx,
             arg2_type, arg2_start_idx
         ) };
         if infer_res == DualInferenceResult::Incompatible {
             return Err(self.construct_arg_type_error(ctx, expr_id, arg1_id, arg2_id));
+        }
         Ok((infer_res.modified_lhs(), infer_res.modified_rhs()))
+    }
     /// Applies an equal2 constraint between a signature type (e.g. a function
     /// argument or struct field) and an expression whose type should match that
     /// expression. If we make progress on the signature, then we try to see if
     /// any of the embedded polymorphic types can be progressed.
     ///
     /// `outer_expr_id` is the main expression we're progressing (e.g. a
     /// function call), while `expr_id` is the embedded expression we're
     /// matching against the signature. `expression_type` and
     /// `expression_start_idx` belong to `expr_id`.
     fn apply_equal2_signature_constraint(
         ctx: &Ctx, outer_expr_id: ExpressionId, expr_id: Option<ExpressionId>,
         polymorph_data: &mut ExtraData, polymorph_progress: &mut HashSet<u32>,
         signature_type: *mut InferenceType, signature_start_idx: usize,
         expression_type: *mut InferenceType, expression_start_idx: usize
     ) -> Result<(bool, bool), ParseError> {
         // Safety: all pointers distinct
         // Infer the signature and expression type
         let infer_res = unsafe {
             InferenceType::infer_subtrees_for_both_types(
                 signature_type, signature_start_idx,
                 expression_type, expression_start_idx
+            )
         };
         if infer_res == DualInferenceResult::Incompatible {
             // TODO: Check if I still need to use this
             let outer_span = ctx.heap[outer_expr_id].full_span();
             let (span_name, span) = match expr_id {
                 Some(expr_id) => ("argument's", ctx.heap[expr_id].full_span()),
                 None => ("type's", outer_span)
             };
             let (signature_display_type, expression_display_type) = unsafe { (
                 (&*signature_type).display_name(&ctx.heap),
                 (&*expression_type).display_name(&ctx.heap)
             ) };
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, outer_span,
                 "failed to fully resolve the types of this expression"
             ).with_info_at_span(
                 &ctx.module().source, span, format!(
                     "because the {} signature has been resolved to '{}', but the expression has been resolved to '{}'",
                     span_name, signature_display_type, expression_display_type
+                )
             ));
+        }
         // Try to see if we can progress any of the polymorphic variables
         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_marker,
                 "made progress on signature type, but it doesn't have a marker"
             );
             for (poly_idx, poly_section) in signature_type.marker_iter() {
                 let polymorph_type = &mut polymorph_data.poly_vars[poly_idx as usize];
                 match Self::apply_template_constraint_to_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<u32>,
         signature_type: *mut InferenceType, expr_type: *mut InferenceType
     ) -> bool {
         // Safety: all pointers should be distinct
         //         polymorph_data containers may not be modified
         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 let Some((poly_idx, start_idx)) = signature_type.find_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 as usize];
                 let modified_at_marker = Self::apply_template_constraint_to_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;
+        }
         // 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, true
             ) {
                 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), ParseError> {
         // Safety: all points are unique
         //         containers may not be modified
         let expr_expr_idx = ctx.heap[expr_id].get_unique_id_in_definition(); // TODO: @Temp
         let arg1_expr_idx = ctx.heap[arg1_id].get_unique_id_in_definition();
         let arg2_expr_idx = ctx.heap[arg2_id].get_unique_id_in_definition();
         let expr_type: *mut _ = &mut self.expr_types[expr_expr_idx as usize].expr_type;
         let arg1_type: *mut _ = &mut self.expr_types[arg1_expr_idx as usize].expr_type;
         let arg2_type: *mut _ = &mut self.expr_types[arg2_expr_idx as usize].expr_type;
         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
         // to be expanded, then we must also assign this to expr_type.
         let mut progress_expr = expr_res.modified_lhs();
         let mut progress_arg1 = expr_res.modified_rhs();
         let progress_arg2 = args_res.modified_rhs();
         if args_res.modified_lhs() {
             unsafe {
                 let end_idx = InferenceType::find_subtree_end_idx(&(*arg2_type).parts, start_idx);
                 let subtree = &((*arg2_type).parts[start_idx..end_idx]);
                 (*expr_type).replace_subtree(start_idx, subtree);
+            }
             progress_expr = true;
             progress_arg1 = true;
+        }
         Ok((progress_expr, progress_arg1, progress_arg2))
+    }
     // TODO: @optimize Since we only deal with a single type this might be done
     //  a lot more efficiently, methinks (disregarding the allocations here)
     fn apply_equal_n_constraint(
         &mut self, ctx: &Ctx, expr_id: ExpressionId, args: &[ExpressionId],
     ) -> Result<Vec<bool>, ParseError> {
         // Early exit
         match args.len() {
 => return Ok(vec!()),         // nothing to progress
 => return Ok(vec![false]),    // only one type, so nothing to infer
             _ => {}
+        }
         let mut progress = Vec::new(); // TODO: @Performance
         progress.resize(args.len(), false);
         // Do pairwise inference, keep track of the last entry we made progress
         // 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 last_expr_idx = ctx.heap[last_arg_id].get_unique_id_in_definition(); // TODO: @Temp
             let next_expr_idx = ctx.heap[*next_arg_id].get_unique_id_in_definition();
             let last_type: *mut _ = &mut self.expr_types[last_expr_idx as usize].expr_type;
             let next_type: *mut _ = &mut self.expr_types[next_expr_idx as usize].expr_type;
             let res = unsafe {
                 InferenceType::infer_subtrees_for_both_types(last_type, 0, next_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_arg_expr_idx = ctx.heap[*args.last().unwrap()].get_unique_id_in_definition();
         let last_type: *mut _ = &mut self.expr_types[last_arg_expr_idx as usize].expr_type;
         for arg_idx in 0..last_lhs_progressed {
             let other_arg_expr_idx = ctx.heap[args[arg_idx]].get_unique_id_in_definition();
             let arg_type: *mut _ = &mut self.expr_types[other_arg_expr_idx as usize].expr_type;
             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.
     fn insert_initial_expr_inference_type(
         &mut self, ctx: &mut Ctx, expr_id: ExpressionId
     ) -> Result<(), ParseError> {
         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(_) =>
                 // Determined during type inference
                 InferenceType::new(false, false, vec![ITP::Unknown]),
             EP::Expression(parent_id, idx_in_parent) => {
                 // If we are the test expression of a conditional expression,
                 // then we must resolve to a boolean
                 let is_conditional = if let Expression::Conditional(_) = &ctx.heap[*parent_id] {
                     true
                 } else {
                     false
                 };
                 if is_conditional && *idx_in_parent == 0 {
                     InferenceType::new(false, true, vec![ITP::Bool])
                 } else {
                     InferenceType::new(false, false, vec![ITP::Unknown])
+                }
             },
             EP::If(_) | EP::While(_) =>
                 // 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 {
                     debug_assert_eq!(ctx.heap[func_id].return_types.len(), 1);
                     let returned = &ctx.heap[func_id].return_types[0];
                     self.determine_inference_type_from_parser_type_elements(&returned.elements, 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]),
         };
         let infer_expr = &mut self.expr_types[expr.get_unique_id_in_definition() as usize];
         let needs_extra_data = match expr {
             Expression::Call(_) => true,
             Expression::Literal(expr) => match expr.value {
                 Literal::Enum(_) | Literal::Union(_) | Literal::Struct(_) => true,
                 _ => false,
             },
             Expression::Select(_) => true,
             Expression::Select(expr) => match expr.kind {
                 SelectKind::StructField(_) => true,
                 SelectKind::TupleMember(_) => false,
             },
             _ => false,
         };
         if infer_expr.expr_id.is_invalid() {
             // Nothing is set yet
             infer_expr.expr_type = inference_type;
             infer_expr.expr_id = expr_id;
             if needs_extra_data {
                 let extra_idx = self.extra_data.len() as i32;
                 self.extra_data.push(ExtraData::default());
                 infer_expr.extra_data_idx = extra_idx;
+            }
         } else {
             // We already have an entry
             debug_assert!(false, "does this ever happen?");
             if let SingleInferenceResult::Incompatible = InferenceType::infer_subtree_for_single_type(
                 &mut infer_expr.expr_type, 0, &inference_type.parts, 0, false
             ) {
                 return Err(self.construct_expr_type_error(ctx, expr_id, expr_id));
+            }
             debug_assert!((infer_expr.extra_data_idx != -1) == needs_extra_data);
+        }
         Ok(())
+    }
     fn insert_initial_call_polymorph_data(
         &mut self, ctx: &mut Ctx, call_id: CallExpressionId
     ) {
         // Note: the polymorph variables may be partially specified and may
         // contain references to the wrapping definition's (i.e. the proctype
         // we are currently visiting) polymorphic arguments.
         //
         // The arguments of the call may refer to polymorphic variables in the
         // definition of the function we're calling, not of the wrapping
         // definition. We insert markers in these inferred types to be able to
         // map them back and forth to the polymorphic arguments of the function
         // we are calling.
         let call = &ctx.heap[call_id];
         let extra_data_idx = self.expr_types[call.unique_id_in_definition as usize].extra_data_idx; // TODO: @Temp
         debug_assert!(extra_data_idx != -1, "insert initial call polymorph data, no preallocated ExtraData");
         // Handle the polymorphic arguments (if there are any)
         let num_poly_args = call.parser_type.elements[0].variant.num_embedded();
         let mut poly_args = Vec::with_capacity(num_poly_args);
         for embedded_elements in call.parser_type.iter_embedded(0) {
             poly_args.push(self.determine_inference_type_from_parser_type_elements(embedded_elements, true));
+        }
         // Handle the arguments and return types
         let definition = &ctx.heap[call.definition];
         let (parameters, returned) = match definition {
             Definition::Component(definition) => {
                 debug_assert_eq!(poly_args.len(), definition.poly_vars.len());
                 (&definition.parameters, None)
             },
             Definition::Function(definition) => {
                 debug_assert_eq!(poly_args.len(), definition.poly_vars.len());
                 (&definition.parameters, Some(&definition.return_types))
             },
             Definition::Struct(_) | Definition::Enum(_) | Definition::Union(_) => {
                 unreachable!("insert_initial_call_polymorph data for non-procedure type");
             },
         };
         let mut parameter_types = Vec::with_capacity(parameters.len());
         for parameter_id in parameters.clone().into_iter() { // TODO: @Performance @Now
             let param = &ctx.heap[parameter_id];
             parameter_types.push(self.determine_inference_type_from_parser_type_elements(&param.parser_type.elements, false));
+        }
         let return_type = match returned {
             None => {
                 // Component, so returns a "Void"
                 InferenceType::new(false, true, vec![InferenceTypePart::Void])
             },
             Some(returned) => {
                 debug_assert_eq!(returned.len(), 1); // TODO: @ReturnTypes
                 let returned = &returned[0];
                 self.determine_inference_type_from_parser_type_elements(&returned.elements, false)
+            }
         };
         self.extra_data[extra_data_idx as usize] = ExtraData{
             expr_id: call_id.upcast(),
             definition_id: call.definition,
             poly_vars: poly_args,
             embedded: parameter_types,
             returned: return_type
         };
+    }
     fn insert_initial_struct_polymorph_data(
         &mut self, ctx: &mut Ctx, lit_id: LiteralExpressionId,
     ) {
         use InferenceTypePart as ITP;
         let literal = &ctx.heap[lit_id];
         let extra_data_idx = self.expr_types[literal.unique_id_in_definition as usize].extra_data_idx; // TODO: @Temp
         debug_assert!(extra_data_idx != -1, "initial struct polymorph data, but no preallocated ExtraData");
         let literal = ctx.heap[lit_id].value.as_struct();
         // Handle polymorphic arguments
         let num_embedded = literal.parser_type.elements[0].variant.num_embedded();
         let mut total_num_poly_parts = 0;
         let mut poly_args = Vec::with_capacity(num_embedded);
         for embedded_elements in literal.parser_type.iter_embedded(0) {
             let poly_type = self.determine_inference_type_from_parser_type_elements(embedded_elements, true);
             total_num_poly_parts += poly_type.parts.len();
             poly_args.push(poly_type);
+        }
         // Handle parser types on struct definition
         let defined_type = ctx.types.get_base_definition(&literal.definition).unwrap();
         let struct_type = defined_type.definition.as_struct();
         debug_assert_eq!(poly_args.len(), defined_type.poly_vars.len());
         // Note: programmer is capable of specifying fields in a struct literal
         // in a different order than on the definition. We take the literal-
         // specified order to be leading.
         let mut embedded_types = Vec::with_capacity(struct_type.fields.len());
         for lit_field in literal.fields.iter() {
             let def_field = &struct_type.fields[lit_field.field_idx];
             let inference_type = self.determine_inference_type_from_parser_type_elements(&def_field.parser_type.elements, 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_args.len() + total_num_poly_parts;
         let mut parts = Vec::with_capacity(parts_reserved);
         parts.push(ITP::Instance(literal.definition, poly_args.len() as u32));
         let mut return_type_done = true;
         for (poly_var_idx, poly_var) in poly_args.iter().enumerate() {
             if !poly_var.is_done { return_type_done = false; }
             parts.push(ITP::Marker(poly_var_idx as u32));
             parts.extend(poly_var.parts.iter().cloned());
+        }
         debug_assert_eq!(parts.len(), parts_reserved);
         let return_type = InferenceType::new(!poly_args.is_empty(), return_type_done, parts);
         self.extra_data[extra_data_idx as usize] = ExtraData{
             expr_id: lit_id.upcast(),
             definition_id: literal.definition,
             poly_vars: poly_args,
             embedded: embedded_types,
             returned: return_type,
         };
+    }
     /// Inserts the extra polymorphic data struct for enum expressions. These
     /// can never be determined from the enum itself, but may be inferred from
     /// the use of the enum.
     fn insert_initial_enum_polymorph_data(
         &mut self, ctx: &Ctx, lit_id: LiteralExpressionId
     ) {
         use InferenceTypePart as ITP;
         let literal = &ctx.heap[lit_id];
         let extra_data_idx = self.expr_types[literal.unique_id_in_definition as usize].extra_data_idx; // TODO: @Temp
         debug_assert!(extra_data_idx != -1, "initial enum polymorph data, but no preallocated ExtraData");
         let literal = ctx.heap[lit_id].value.as_enum();
         // Handle polymorphic arguments to the enum
         let num_poly_args = literal.parser_type.elements[0].variant.num_embedded();
         let mut total_num_poly_parts = 0;
         let mut poly_args = Vec::with_capacity(num_poly_args);
         for embedded_elements in literal.parser_type.iter_embedded(0) {
             let poly_type = self.determine_inference_type_from_parser_type_elements(embedded_elements, true);
             total_num_poly_parts += poly_type.parts.len();
             poly_args.push(poly_type);
+        }
         // Handle enum type itself
         let parts_reserved = 1 + poly_args.len() + total_num_poly_parts;
         let mut parts = Vec::with_capacity(parts_reserved);
         parts.push(ITP::Instance(literal.definition, poly_args.len() as u32));
         let mut enum_type_done = true;
         for (poly_var_idx, poly_var) in poly_args.iter().enumerate() {
             if !poly_var.is_done { enum_type_done = false; }
             parts.push(ITP::Marker(poly_var_idx as u32));
             parts.extend(poly_var.parts.iter().cloned());
+        }
         debug_assert_eq!(parts.len(), parts_reserved);
         let enum_type = InferenceType::new(!poly_args.is_empty(), enum_type_done, parts);
         self.extra_data[extra_data_idx as usize] = ExtraData{
             expr_id: lit_id.upcast(),
             definition_id: literal.definition,
             poly_vars: poly_args,
             embedded: Vec::new(),
             returned: enum_type,
         };
+    }
     /// Inserts the extra polymorphic data struct for unions. The polymorphic
     /// arguments may be partially determined from embedded values in the union.
     fn insert_initial_union_polymorph_data(
         &mut self, ctx: &Ctx, lit_id: LiteralExpressionId
     ) {
         use InferenceTypePart as ITP;
         let literal = &ctx.heap[lit_id];
         let extra_data_idx = self.expr_types[literal.unique_id_in_definition as usize].extra_data_idx; // TODO: @Temp
         debug_assert!(extra_data_idx != -1, "initial union polymorph data, but no preallocated ExtraData");
         let literal = ctx.heap[lit_id].value.as_union();
         // Construct the polymorphic variables
         let num_poly_args = literal.parser_type.elements[0].variant.num_embedded();
         let mut total_num_poly_parts = 0;
         let mut poly_args = Vec::with_capacity(num_poly_args);
         for embedded_elements in literal.parser_type.iter_embedded(0) {
             let poly_type = self.determine_inference_type_from_parser_type_elements(embedded_elements, true);
             total_num_poly_parts += poly_type.parts.len();
             poly_args.push(poly_type);
+        }
         // Handle any of the embedded values in the variant, if specified
         let definition_id = literal.definition;
         let type_definition = ctx.types.get_base_definition(&definition_id).unwrap();
         let union_definition = type_definition.definition.as_union();
         debug_assert_eq!(poly_args.len(), type_definition.poly_vars.len());
         let variant_definition = &union_definition.variants[literal.variant_idx];
         debug_assert_eq!(variant_definition.embedded.len(), literal.values.len());
         let mut embedded = Vec::with_capacity(variant_definition.embedded.len());
         for embedded_parser_type in &variant_definition.embedded {
             let inference_type = self.determine_inference_type_from_parser_type_elements(&embedded_parser_type.elements, false);
             embedded.push(inference_type);
+        }
         // Handle the type of the union itself
         let parts_reserved = 1 + poly_args.len() + total_num_poly_parts;
         let mut parts = Vec::with_capacity(parts_reserved);
         parts.push(ITP::Instance(definition_id, poly_args.len() as u32));
         let mut union_type_done = true;
         for (poly_var_idx, poly_var) in poly_args.iter().enumerate() {
             if !poly_var.is_done { union_type_done = false; }
             parts.push(ITP::Marker(poly_var_idx as u32));
             parts.extend(poly_var.parts.iter().cloned());
+        }
         debug_assert_eq!(parts_reserved, parts.len());
         let union_type = InferenceType::new(!poly_args.is_empty(), union_type_done, parts);
         self.extra_data[extra_data_idx as usize] = ExtraData{
             expr_id: lit_id.upcast(),
             definition_id: literal.definition,
             poly_vars: poly_args,
             embedded,
             returned: union_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, struct_def_id: DefinitionId
     ) {
         use InferenceTypePart as ITP;
         // Retrieve relevant data
         let expr = &ctx.heap[select_id];
         let expr_type = &self.expr_types[expr.unique_id_in_definition as usize];
         let field_idx = expr_type.field_or_monomorph_idx as usize;
         let extra_data_idx = expr_type.extra_data_idx; // TODO: @Temp
         debug_assert!(extra_data_idx != -1, "initial select polymorph data, but no preallocated ExtraData");
         let definition = ctx.heap[struct_def_id].as_struct();
         // Generate initial polyvar types and struct type
         // TODO: @Performance: we can immediately set the polyvars of the subject's 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(struct_def_id, num_poly_vars as u32));
         for poly_idx in 0..num_poly_vars {
             poly_vars.push(InferenceType::new(true, false, vec![
                 ITP::Marker(poly_idx as u32), ITP::Unknown,
             ]));
             struct_parts.push(ITP::Marker(poly_idx as u32));
             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_elements(&definition.fields[field_idx].parser_type.elements, false);
         self.extra_data[extra_data_idx as usize] = ExtraData{
             expr_id: select_id.upcast(),
             definition_id: struct_def_id,
             poly_vars,
             embedded: vec![InferenceType::new(num_poly_vars != 0, num_poly_vars == 0, 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_elements(
         &mut self, elements: &[ParserTypeElement],
         use_definitions_known_poly_args: bool
     ) -> InferenceType {
         use ParserTypeVariant as PTV;
         use InferenceTypePart as ITP;
         let mut infer_type = Vec::with_capacity(elements.len());
         let mut has_inferred = false;
         let mut has_markers = false;
         for element in elements {
             match &element.variant {
                 // Compiler-only types
                 PTV::Void => { infer_type.push(ITP::Void); },
                 PTV::InputOrOutput => { infer_type.push(ITP::PortLike); has_inferred = true },
                 PTV::ArrayLike => { infer_type.push(ITP::ArrayLike); has_inferred = true },
                 PTV::IntegerLike => { infer_type.push(ITP::IntegerLike); has_inferred = true },
                 // Builtins
                 PTV::Message => {
                     // TODO: @types Remove the Message -> Byte hack at some point...
                     infer_type.push(ITP::Message);
                     infer_type.push(ITP::UInt8);
                 },
                 PTV::Bool => { infer_type.push(ITP::Bool); },
                 PTV::UInt8 => { infer_type.push(ITP::UInt8); },
                 PTV::UInt16 => { infer_type.push(ITP::UInt16); },
                 PTV::UInt32 => { infer_type.push(ITP::UInt32); },
                 PTV::UInt64 => { infer_type.push(ITP::UInt64); },
                 PTV::SInt8 => { infer_type.push(ITP::SInt8); },
                 PTV::SInt16 => { infer_type.push(ITP::SInt16); },
                 PTV::SInt32 => { infer_type.push(ITP::SInt32); },
                 PTV::SInt64 => { infer_type.push(ITP::SInt64); },
                 PTV::Character => { infer_type.push(ITP::Character); },
                 PTV::String => {
                     infer_type.push(ITP::String);
                     infer_type.push(ITP::Character);
                 },
                 // Special markers
                 PTV::IntegerLiteral => { unreachable!("integer literal type on variable type"); },
                 PTV::Inferred => {
                     infer_type.push(ITP::Unknown);
                     has_inferred = true;
                 },
                 // With nested types
                 PTV::Array => { infer_type.push(ITP::Array); },
                 PTV::Input => { infer_type.push(ITP::Input); },
                 PTV::Output => { infer_type.push(ITP::Output); },
                 PTV::Tuple(num_embedded) => { infer_type.push(ITP::Tuple(*num_embedded)); },
                 PTV::PolymorphicArgument(belongs_to_definition, poly_arg_idx) => {
                     let poly_arg_idx = *poly_arg_idx;
                     if use_definitions_known_poly_args {
                         // Refers to polymorphic argument on procedure we're currently processing.
                         // This argument is already known.
                         debug_assert_eq!(*belongs_to_definition, self.definition_type.definition_id());
                         debug_assert!((poly_arg_idx as usize) < self.poly_vars.len());
                         Self::determine_inference_type_from_concrete_type(
                             &mut infer_type, &self.poly_vars[poly_arg_idx as usize].parts
                         );
                     } else {
                         // Polymorphic argument has to be inferred
                         has_markers = true;
                         has_inferred = true;
                         infer_type.push(ITP::Marker(poly_arg_idx));
                         infer_type.push(ITP::Unknown)
+                    }
                 },
                 PTV::Definition(definition_id, num_embedded) => {
                     infer_type.push(ITP::Instance(*definition_id, *num_embedded));
+                }
+            }
+        }
         InferenceType::new(has_markers, !has_inferred, infer_type)
+    }
     /// Determines the inference type from an already concrete type. Applies the
     /// various type "hacks" inside the type inferencer.
     fn determine_inference_type_from_concrete_type(parser_type: &mut Vec<InferenceTypePart>, concrete_type: &[ConcreteTypePart]) {
         use InferenceTypePart as ITP;
         use ConcreteTypePart as CTP;
         for concrete_part in concrete_type {
             match concrete_part {
                 CTP::Void => parser_type.push(ITP::Void),
                 CTP::Message => {
                     parser_type.push(ITP::Message);
                     parser_type.push(ITP::UInt8)
                 },
                 CTP::Bool => parser_type.push(ITP::Bool),
                 CTP::UInt8 => parser_type.push(ITP::UInt8),
                 CTP::UInt16 => parser_type.push(ITP::UInt16),
                 CTP::UInt32 => parser_type.push(ITP::UInt32),
                 CTP::UInt64 => parser_type.push(ITP::UInt64),
                 CTP::SInt8 => parser_type.push(ITP::SInt8),
                 CTP::SInt16 => parser_type.push(ITP::SInt16),
                 CTP::SInt32 => parser_type.push(ITP::SInt32),
                 CTP::SInt64 => parser_type.push(ITP::SInt64),
                 CTP::Character => parser_type.push(ITP::Character),
                 CTP::String => {
                     parser_type.push(ITP::String);
                     parser_type.push(ITP::Character)
                 },
                 CTP::Array => parser_type.push(ITP::Array),
                 CTP::Slice => parser_type.push(ITP::Slice),
                 CTP::Input => parser_type.push(ITP::Input),
                 CTP::Output => parser_type.push(ITP::Output),
                 CTP::Tuple(num) => parser_type.push(ITP::Tuple(*num)),
                 CTP::Instance(id, num) => parser_type.push(ITP::Instance(*id, *num)),
                 CTP::Function(_, _) => unreachable!("function type during concrete to inference type conversion"),
                 CTP::Component(_, _) => unreachable!("component type during concrete to inference type conversion"),
+            }
+        }
+    }
     /// Construct an error when an expression's type does not match. This
     /// happens if we infer the expression type from its arguments (e.g. the
     /// expression type of an addition operator is the type of the arguments)
     /// But the expression type was already set due to our parent (e.g. an
     /// "if statement" or a "logical not" always expecting a boolean)
     fn construct_expr_type_error(
         &self, ctx: &Ctx, expr_id: ExpressionId, arg_id: ExpressionId
     ) -> ParseError {
         // TODO: Expand and provide more meaningful information for humans
         let expr = &ctx.heap[expr_id];
         let arg_expr = &ctx.heap[arg_id];
         let expr_idx = expr.get_unique_id_in_definition();
         let arg_expr_idx = arg_expr.get_unique_id_in_definition();
         let expr_type = &self.expr_types[expr_idx as usize].expr_type;
         let arg_type = &self.expr_types[arg_expr_idx as usize].expr_type;
         return ParseError::new_error_at_span(
             &ctx.module().source, expr.operation_span(), format!(
                 "incompatible types: this expression expected a '{}'",
                 expr_type.display_name(&ctx.heap)
+            )
         ).with_info_at_span(
             &ctx.module().source, arg_expr.full_span(), format!(
                 "but this expression yields a '{}'",
                 arg_type.display_name(&ctx.heap)
+            )
+        )
+    }
     fn construct_arg_type_error(
         &self, ctx: &Ctx, expr_id: ExpressionId,
         arg1_id: ExpressionId, arg2_id: ExpressionId
     ) -> ParseError {
         let expr = &ctx.heap[expr_id];
         let arg1 = &ctx.heap[arg1_id];
         let arg2 = &ctx.heap[arg2_id];
         let arg1_idx = arg1.get_unique_id_in_definition();
         let arg1_type = &self.expr_types[arg1_idx as usize].expr_type;
         let arg2_idx = arg2.get_unique_id_in_definition();
         let arg2_type = &self.expr_types[arg2_idx as usize].expr_type;
         return ParseError::new_error_str_at_span(
             &ctx.module().source, expr.operation_span(),
             "incompatible types: cannot apply this expression"
         ).with_info_at_span(
             &ctx.module().source, arg1.full_span(), format!(
                 "Because this expression has type '{}'",
                 arg1_type.display_name(&ctx.heap)
+            )
         ).with_info_at_span(
             &ctx.module().source, arg2.full_span(), format!(
                 "But this expression has type '{}'",
                 arg2_type.display_name(&ctx.heap)
+            )
+        )
+    }
     fn construct_template_type_error(
         &self, ctx: &Ctx, expr_id: ExpressionId, template: &[InferenceTypePart]
     ) -> ParseError {
         let expr = &ctx.heap[expr_id];
         let expr_idx = expr.get_unique_id_in_definition();
         let expr_type = &self.expr_types[expr_idx as usize].expr_type;
         return ParseError::new_error_at_span(
             &ctx.module().source, expr.full_span(), format!(
                 "incompatible types: got a '{}' but expected a '{}'",
                 expr_type.display_name(&ctx.heap),
                 InferenceType::partial_display_name(&ctx.heap, template)
+            )
+        )
+    }
     /// Constructs a human interpretable error in the case that type inference
     /// on a polymorphic variable to a function call or literal construction
     /// failed. This may only be caused by a pair of inference types (which may
     /// come from arguments or the return type) having two different inferred
     /// values for that polymorphic variable.
     ///
     /// So we find this pair and construct the error using it.
     ///
     /// We assume that the expression is a function call or a struct literal,
     /// and that an actual error has occurred.
     fn construct_poly_arg_error(
         ctx: &Ctx, poly_data: &ExtraData, expr_id: ExpressionId
     ) -> ParseError {
         // Helper function to check for polymorph mismatch between two inference
         // types.
         fn has_poly_mismatch<'a>(type_a: &'a InferenceType, type_b: &'a InferenceType) -> Option<(u32, &'a [InferenceTypePart], &'a [InferenceTypePart])> {
             if !type_a.has_marker || !type_b.has_marker {
                 return None
+            }
             for (marker_a, section_a) in type_a.marker_iter() {
                 for (marker_b, section_b) in type_b.marker_iter() {
                     if marker_a != marker_b {
                         // Not the same polymorphic variable
                         continue;
+                    }
                     if !InferenceType::check_subtrees(section_a, 0, section_b, 0) {
                         // Not compatible
                         return Some((marker_a, section_a, section_b))
+                    }
+                }
+            }
             None
+        }
         // Helper function to check for polymorph mismatch between an inference
         // type and the polymorphic variables in the poly_data struct.
         fn has_explicit_poly_mismatch<'a>(
             poly_vars: &'a [InferenceType], arg: &'a InferenceType
         ) -> Option<(u32, &'a [InferenceTypePart], &'a [InferenceTypePart])> {
             for (marker, section) in arg.marker_iter() {
                 debug_assert!((marker as usize) < poly_vars.len());
                 let poly_section = &poly_vars[marker as usize].parts;
                 if !InferenceType::check_subtrees(poly_section, 0, section, 0) {
                     return Some((marker, poly_section, section))
+                }
+            }
             None
+        }
         // Helpers function to retrieve polyvar name and definition name
         fn get_poly_var_and_definition_name<'a>(ctx: &'a Ctx, poly_var_idx: u32, definition_id: DefinitionId) -> (&'a str, &'a str) {
             let definition = &ctx.heap[definition_id];
             let poly_var = definition.poly_vars()[poly_var_idx as usize].value.as_str();
             let func_name = definition.identifier().value.as_str();
             (poly_var, func_name)
+        }
         // Helper function to construct initial error
         fn construct_main_error(ctx: &Ctx, poly_data: &ExtraData, poly_var_idx: u32, expr: &Expression) -> ParseError {
             match expr {
                 Expression::Call(expr) => {
                     let (poly_var, func_name) = get_poly_var_and_definition_name(ctx, poly_var_idx, poly_data.definition_id);
                     return ParseError::new_error_at_span(
                         &ctx.module().source, expr.func_span, format!(
                             "Conflicting type for polymorphic variable '{}' of '{}'",
                             poly_var, func_name
+                        )
+                    )
                 },
                 Expression::Literal(expr) => {
                     let (poly_var, type_name) = get_poly_var_and_definition_name(ctx, poly_var_idx, poly_data.definition_id);
                     return ParseError::new_error_at_span(
                         &ctx.module().source, expr.span, format!(
                             "Conflicting type for polymorphic variable '{}' of instantiation of '{}'",
                             poly_var, type_name
+                        )
                     );
                 },
                 Expression::Select(expr) => {
                     let (poly_var, struct_name) = get_poly_var_and_definition_name(ctx, poly_var_idx, poly_data.definition_id);
                     let field_name = match &expr.kind {
                         SelectKind::StructField(v) => v,
                         SelectKind::TupleMember(_) => unreachable!(), // because we're constructing a polymorph error, and tuple access does not deal with polymorphs
                     };
                     return ParseError::new_error_at_span(
                         &ctx.module().source, expr.full_span, format!(
                             "Conflicting type for polymorphic variable '{}' while accessing field '{}' of '{}'",
                             poly_var, field_name.value.as_str(), struct_name
+                        )
+                    )
+                }
                 _ => unreachable!("called construct_poly_arg_error without an expected expression, got: {:?}", expr)
+            }
+        }
         // Actual checking
         let expr = &ctx.heap[expr_id];
         let (expr_args, expr_return_name) = match expr {
             Expression::Call(expr) =>
+                (
                     expr.arguments.clone(),
                     "return type"
                 ),
             Expression::Literal(expr) => {
                 let expressions = match &expr.value {
                     Literal::Struct(v) => v.fields.iter()
                         .map(|f| f.value)
                         .collect(),
                     Literal::Enum(_) => Vec::new(),
                     Literal::Union(v) => v.values.clone(),
                     _ => unreachable!()
                 };
                 ( expressions, "literal" )
             },
             Expression::Select(expr) =>
                 // Select expression uses the polymorphic variables of the
                 // struct it is accessing, so get the subject expression.
+                (
                     vec![expr.subject],
                     "selected field"
                 ),
             _ => unreachable!(),
         };
         // - check return type with itself
         if let Some((poly_idx, section_a, section_b)) = has_poly_mismatch(
             &poly_data.returned, &poly_data.returned
         ) {
             return construct_main_error(ctx, poly_data, poly_idx, expr)
                 .with_info_at_span(
                     &ctx.module().source, expr.full_span(), format!(
                         "The {} inferred the conflicting types '{}' and '{}'",
                         expr_return_name,
                         InferenceType::partial_display_name(&ctx.heap, section_a),
                         InferenceType::partial_display_name(&ctx.heap, section_b)
+                    )
                 );
+        }
         // - check arguments with each other argument and with return type
         for (arg_a_idx, arg_a) in poly_data.embedded.iter().enumerate() {
             for (arg_b_idx, arg_b) in poly_data.embedded.iter().enumerate() {
                 if arg_b_idx > arg_a_idx {
                     break;
+                }
                 if let Some((poly_idx, section_a, section_b)) = has_poly_mismatch(&arg_a, &arg_b) {
                     let error = construct_main_error(ctx, poly_data, poly_idx, expr);
                     if arg_a_idx == arg_b_idx {
                         // Same argument
                         let arg = &ctx.heap[expr_args[arg_a_idx]];
                         return error.with_info_at_span(
                             &ctx.module().source, arg.full_span(), format!(
                                 "This argument inferred the conflicting types '{}' and '{}'",
                                 InferenceType::partial_display_name(&ctx.heap, section_a),
                                 InferenceType::partial_display_name(&ctx.heap, section_b)
+                            )
                         );
                     } else {
                         let arg_a = &ctx.heap[expr_args[arg_a_idx]];
                         let arg_b = &ctx.heap[expr_args[arg_b_idx]];
                         return error.with_info_at_span(
                             &ctx.module().source, arg_a.full_span(), format!(
                                 "This argument inferred it to '{}'",
                                 InferenceType::partial_display_name(&ctx.heap, section_a)
+                            )
                         ).with_info_at_span(
                             &ctx.module().source, arg_b.full_span(), format!(
                                 "While this argument inferred it to '{}'",
                                 InferenceType::partial_display_name(&ctx.heap, section_b)
+                            )
+                        )
+                    }
+                }
+            }
             // Check with return type
             if let Some((poly_idx, section_arg, section_ret)) = has_poly_mismatch(arg_a, &poly_data.returned) {
                 let arg = &ctx.heap[expr_args[arg_a_idx]];
                 return construct_main_error(ctx, poly_data, poly_idx, expr)
                     .with_info_at_span(
                         &ctx.module().source, arg.full_span(), format!(
                             "This argument inferred it to '{}'",
                             InferenceType::partial_display_name(&ctx.heap, section_arg)
+                        )
+                    )
                     .with_info_at_span(
                         &ctx.module().source, expr.full_span(), format!(
                             "While the {} inferred it to '{}'",
                             expr_return_name,
                             InferenceType::partial_display_name(&ctx.heap, section_ret)
+                        )
                     );
+            }
+        }
         // Now check against the explicitly specified polymorphic variables (if
         // any).
         for (arg_idx, arg) in poly_data.embedded.iter().enumerate() {
             if let Some((poly_idx, poly_section, arg_section)) = has_explicit_poly_mismatch(&poly_data.poly_vars, arg) {
                 let arg = &ctx.heap[expr_args[arg_idx]];
                 return construct_main_error(ctx, poly_data, poly_idx, expr)
                     .with_info_at_span(
                         &ctx.module().source, arg.full_span(), format!(
                             "The polymorphic variable has type '{}' (which might have been partially inferred) while the argument inferred it to '{}'",
                             InferenceType::partial_display_name(&ctx.heap, poly_section),
                             InferenceType::partial_display_name(&ctx.heap, arg_section)
+                        )
                     );
+            }
+        }
         if let Some((poly_idx, poly_section, ret_section)) = has_explicit_poly_mismatch(&poly_data.poly_vars, &poly_data.returned) {
             return construct_main_error(ctx, poly_data, poly_idx, expr)
                 .with_info_at_span(
                     &ctx.module().source, expr.full_span(), format!(
                         "The polymorphic variable has type '{}' (which might have been partially inferred) while the {} inferred it to '{}'",
                         InferenceType::partial_display_name(&ctx.heap, poly_section),
                         expr_return_name,
                         InferenceType::partial_display_name(&ctx.heap, ret_section)
+                    )
+                )
+        }
         unreachable!("construct_poly_arg_error without actual error found?")
+    }
+}
 #[cfg(test)]
 mod tests {
     use super::*;
     use crate::protocol::arena::Id;
     use InferenceTypePart as ITP;
     use InferenceType as IT;
     #[test]
     fn test_single_part_inference() {
         // lhs argument inferred from rhs
         let pairs = [
             (ITP::NumberLike, ITP::UInt8),
             (ITP::IntegerLike, ITP::SInt32),
             (ITP::Unknown, ITP::UInt64),
             (ITP::Unknown, ITP::Bool)
         ];
         for (lhs, rhs) in pairs.iter() {
             // Using infer-both
             let mut lhs_type = IT::new(false, false, vec![lhs.clone()]);
             let mut rhs_type = IT::new(false, true, vec![rhs.clone()]);
             let result = unsafe{ IT::infer_subtrees_for_both_types(
                 &mut lhs_type, 0, &mut rhs_type, 0
             ) };
             assert_eq!(DualInferenceResult::First, result);
             assert_eq!(lhs_type.parts, rhs_type.parts);
             // Using infer-single
             let mut lhs_type = IT::new(false, false, vec![lhs.clone()]);
             let rhs_type = IT::new(false, true, vec![rhs.clone()]);
             let result = IT::infer_subtree_for_single_type(
                 &mut lhs_type, 0, &rhs_type.parts, 0, false
             );
             assert_eq!(SingleInferenceResult::Modified, result);
             assert_eq!(lhs_type.parts, rhs_type.parts);
+        }
+    }
     #[test]
     fn test_multi_part_inference() {
         let pairs = [
             (vec![ITP::ArrayLike, ITP::NumberLike], vec![ITP::Slice, ITP::SInt8]),
             (vec![ITP::Unknown], vec![ITP::Input, ITP::Array, ITP::String, ITP::Character]),
             (vec![ITP::PortLike, ITP::SInt32], vec![ITP::Input, ITP::SInt32]),
             (vec![ITP::Unknown], vec![ITP::Output, ITP::SInt32]),
+            (
                 vec![ITP::Instance(Id::new(0), 2), ITP::Input, ITP::Unknown, ITP::Output, ITP::Unknown],
                 vec![ITP::Instance(Id::new(0), 2), ITP::Input, ITP::Array, ITP::SInt32, ITP::Output, ITP::SInt32]
+            )
         ];
         for (lhs, rhs) in pairs.iter() {
             let mut lhs_type = IT::new(false, false, lhs.clone());
             let mut rhs_type = IT::new(false, true, rhs.clone());
             let result = unsafe{ IT::infer_subtrees_for_both_types(
                 &mut lhs_type, 0, &mut rhs_type, 0
             ) };
             assert_eq!(DualInferenceResult::First, result);
             assert_eq!(lhs_type.parts, rhs_type.parts);
             let mut lhs_type = IT::new(false, false, lhs.clone());
             let rhs_type = IT::new(false, true, rhs.clone());
             let result = IT::infer_subtree_for_single_type(
                 &mut lhs_type, 0, &rhs_type.parts, 0, false
             );
             assert_eq!(SingleInferenceResult::Modified, result);
             assert_eq!(lhs_type.parts, rhs_type.parts)
+        }
+    }
+}
@@ \ No newline at end of file @@

src/protocol/tests/eval_operators.rs

➞

Show inline comments

 use super::*;
 #[test]
 fn test_assignment_operators() {
     fn construct_source(value_type: &str, value_initial: &str, value_op: &str) -> String {
         return format!(
             "func foo() -> {} {{
                 {} value = {};
                 value {};
                 return value;
             }}",
             value_type, value_type, value_initial, value_op
         );
+    }
     fn perform_test(name: &str, source: String, expected_value: Value) {
         Tester::new_single_source_expect_ok(name, source)
             .for_function("foo", move |f| {
                 f.call_ok(Some(expected_value));
             });
+    }
     perform_test(
         "set",
         construct_source("u32", "1", "= 5"),
         Value::UInt32(5)
     );
     perform_test(
         "multiplied",
         construct_source("u32", "2", "*= 4"),
         Value::UInt32(8)
     );
     perform_test(
         "divided",
         construct_source("u32", "8", "/= 4"),
         Value::UInt32(2)
     );
     perform_test(
         "remained",
         construct_source("u32", "8", "%= 3"),
         Value::UInt32(2)
     );
     perform_test(
         "added",
         construct_source("u32", "2", "+= 4"),
         Value::UInt32(6)
     );
     perform_test(
         "subtracted",
         construct_source("u32", "6", "-= 4"),
         Value::UInt32(2)
     );
     perform_test(
         "shifted left",
         construct_source("u32", "2", "<<= 2"),
         Value::UInt32(8)
     );
     perform_test(
         "shifted right",
         construct_source("u32", "8", ">>= 2"),
         Value::UInt32(2)
     );
     perform_test(
         "bitwise and",
         construct_source("u32", "15", "&= 35"),
         Value::UInt32(3)
     );
     perform_test(
         "bitwise xor",
         construct_source("u32", "3", "^= 7"),
         Value::UInt32(4)
     );
     perform_test(
         "bitwise or",
         construct_source("u32", "12", "|= 3"),
         Value::UInt32(15)
     );
+}
 #[test]
 fn test_binary_integer_operators() {
     fn construct_source(value_type: &str, code: &str) -> String {
         format!("
         func foo() -> {} {{
             {}
         }}
         ", value_type, code)
+    }
     fn perform_test(test_name: &str, value_type: &str, code: &str, expected_value: Value) {
         Tester::new_single_source_expect_ok(test_name, construct_source(value_type, code))
             .for_function("foo", move |f| {
                 f.call_ok(Some(expected_value));
             });
+    }
     perform_test(
         "bitwise_or", "u16",
         "auto a = 3; return a | 4;", Value::UInt16(7)
     );
     perform_test(
         "bitwise_xor", "u16",
         "auto a = 3; return a ^ 7;", Value::UInt16(4)
     );
     perform_test(
         "bitwise and", "u16",
         "auto a = 0b110011; return a & 0b011110;", Value::UInt16(0b010010)
     );
     perform_test(
         "shift left", "u16",
         "auto a = 0x0F; return a << 4;", Value::UInt16(0xF0)
     );
     perform_test(
         "shift right", "u64",
         "auto a = 0xF0; return a >> 4;", Value::UInt64(0x0F)
     );
     perform_test(
         "add", "u32",
         "auto a = 5; return a + 5;", Value::UInt32(10)
     );
     perform_test(
         "subtract", "u32",
         "auto a = 3; return a - 3;", Value::UInt32(0)
     );
     perform_test(
         "multiply", "u8",
         "auto a = 2 * 2; return a * 2 * 2;", Value::UInt8(16)
     );
     perform_test(
         "divide", "u8",
         "auto a = 32 / 2; return a / 2 / 2;", Value::UInt8(4)
     );
     perform_test(
         "remainder", "u16",
         "auto a = 29; return a % 3;", Value::UInt16(2)
     );
+}
 #[test]
-fn test_tuple_operators() {
+fn test_tuple_comparison_operators() {
     Tester::new_single_source_expect_ok("tuple equality", "
     func test_func() -> bool {
         auto a1 = (8, 16, 32);
         (u8, u16, u32) a2 = (8, 16, 32);
         auto b1 = ();
         () b2 = ();
         return a1 == a2 && a2 == (8, 16, 32) && b1 == b2 && b2 == ();
+    }
     ").for_function("test_func", |f| { f
         .call_ok(Some(Value::Bool(true)));
     });
     Tester::new_single_source_expect_ok("tuple inequality", "
     func test_func() -> bool {
         auto a = (8, 16, 32);
         (u8, u16, u32) a_same = (8, 16, 32);
         auto a_diff = (0b111, 0b1111, 0b11111);
         auto b = ();
         return
             !(a != a_same) &&
             a != a_diff &&
             a != (8, 16, 320) &&
             !(b != ());
+    }
     ").for_function("test_func", |f| { f
         .call_ok(Some(Value::Bool(true)));
     });
+}
 #[test]
 fn test_tuple_select_operator() {
     Tester::new_single_source_expect_ok("tuple member assignment", "
     func test() -> bool {
         auto tuple = (0, 1, 0, 1);
         tuple.0 = cast<u8>(1);
         tuple.1 = cast<u16>(2);
         tuple.2 = cast<u32>(3);
         tuple.3 = cast<u64>(4);
         return cast(tuple.0) + cast(tuple.1) + tuple.2 + cast(tuple.3) == 10;
+    }
     ").for_function("test", |f| { f
         .for_variable("tuple", |v| { v.assert_concrete_type("(u8,u16,u32,u64)"); })
         .call_ok(Some(Value::Bool(true)));
     });
     Tester::new_single_source_expect_ok("tuple polymorph member access", "
     func sum_variant_a<A,B,C,D>((A,B,C,D) v) -> C {
         return cast(v.0) + cast(v.1) + v.2 + cast(v.3);
+    }
     func sum_variant_b<A,B,C,D>((A,B,C,D) i) -> B {
         (A,B,C,D) c = (0,0,0,0);
         c.0 = i.0; c.1 = i.1; c.2 = i.2; c.3 = i.3;
         return cast(c.0) + c.1 + cast(c.2) + cast(c.3);
+    }
     func test() -> bool {
         (u8,u16,u32,u64) tuple = (1, 2, 3, 4);
         return sum_variant_a(tuple) == 10 && sum_variant_b(tuple) == 10;
+    }
     ").for_function("test", |f| { f
         .call_ok(Some(Value::Bool(true)));
     });
+}
 #[test]
 fn test_string_operators() {
     Tester::new_single_source_expect_ok("string concatenation", "
 func create_concatenated(string left, string right) -> string {
     return left @ \", but also \" @ right;
+}
 func perform_concatenate(string left, string right) -> string {
     left @= \", but also \";
     left @= right;
     return left;
+}
 func foo() -> bool {
     auto left = \"Darth Vader\";
     auto right = \"Anakin Skywalker\";
     auto res1 = create_concatenated(left, right);
     auto res2 = perform_concatenate(left, right);
     auto expected = \"Darth Vader, but also Anakin Skywalker\";
     return
         res1 == expected &&
         res2 == \"Darth Vader, but also Anakin Skywalker\" &&
         res1 != \"This kind of thing\" && res2 != \"Another likewise kind of thing\";
+}
     ").for_function("foo", |f| { f
         .call_ok(Some(Value::Bool(true)));
     });
+}
@@ \ No newline at end of file @@

src/protocol/tests/parser_inference.rs

➞

Show inline comments

 /// parser_inference.rs
 ///
 /// Simple tests for the type inferences
 use super::*;
 #[test]
 fn test_integer_inference() {
     Tester::new_single_source_expect_ok(
         "by arguments",
+        "
         func call(u8 b, u16 s, u32 i, u64 l) -> u32 {
             auto b2 = b;
             auto s2 = s;
             auto i2 = i;
             auto l2 = l;
             return i2;
+        }
+        "
     ).for_function("call", |f| { f
         .for_variable("b2", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("u8");
         })
         .for_variable("s2", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("u16");
         })
         .for_variable("i2", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("u32");
         })
         .for_variable("l2", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("u64");
         });
     });
     Tester::new_single_source_expect_ok(
         "by assignment",
+        "
         func call() -> u32 {
             u8 b1 = 0; u16 s1 = 0; u32 i1 = 0; u64 l1 = 0;
             auto b2 = b1;
             auto s2 = s1;
             auto i2 = i1;
             auto l2 = l1;
             return 0;
         }"
     ).for_function("call", |f| { f
         .for_variable("b2", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("u8");
         })
         .for_variable("s2", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("u16");
         })
         .for_variable("i2", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("u32");
         })
         .for_variable("l2", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("u64");
         });
     });
+}
 #[test]
 fn test_binary_expr_inference() {
     Tester::new_single_source_expect_ok(
         "compatible types",
         "func call() -> s32 {
             s8 b0 = 0;
             s8 b1 = 1;
             s16 s0 = 0;
             s16 s1 = 1;
             s32 i0 = 0;
             s32 i1 = 1;
             s64 l0 = 0;
             s64 l1 = 1;
             auto b = b0 + b1;
             auto s = s0 + s1;
             auto i = i0 + i1;
             auto l = l0 + l1;
             return i;
         }"
     ).for_function("call", |f| { f
         .for_expression_by_source(
             "b0 + b1", "+",
             |e| { e.assert_concrete_type("s8"); }
+        )
         .for_expression_by_source(
             "s0 + s1", "+",
             |e| { e.assert_concrete_type("s16"); }
+        )
         .for_expression_by_source(
             "i0 + i1", "+",
             |e| { e.assert_concrete_type("s32"); }
+        )
         .for_expression_by_source(
             "l0 + l1", "+",
             |e| { e.assert_concrete_type("s64"); }
         );
     });
     Tester::new_single_source_expect_err(
         "incompatible types",
         "func call() -> s32 {
             s8 b = 0;
             s64 l = 1;
             auto r = b + l;
             return 0;
         }"
     ).error(|e| { e
         .assert_ctx_has(0, "b + l")
         .assert_msg_has(0, "cannot apply")
         .assert_occurs_at(0, "+")
         .assert_msg_has(1, "has type 's8'")
         .assert_msg_has(2, "has type 's64'");
     });
+}
 #[test]
 fn test_tuple_inference() {
     Tester::new_single_source_expect_ok(
         "from tuple to variable",
+        "
         func test() -> u32 {
             (u8,u16,u32,u64) tuple = (1, 2, 3, 4);
             auto a = tuple.0;
             auto b = tuple.1;
             auto c = tuple.2;
             auto d = tuple.3;
             return cast(a) + cast(b) + c + cast(d);
+        }
+        "
     ).for_function("test", |f| { f
         .for_variable("a", |v| { v.assert_concrete_type("u8"); })
         .for_variable("b", |v| { v.assert_concrete_type("u16"); })
         .for_variable("c", |v| { v.assert_concrete_type("u32"); })
         .for_variable("d", |v| { v.assert_concrete_type("u64"); })
         .call_ok(Some(Value::UInt32(10)));
     });
     Tester::new_single_source_expect_ok(
         "from variable to tuple",
+        "
         func test() -> u32 {
             auto tuple = (1, 2, 3, 4);
             u8  a = tuple.0;
             u16 b = tuple.1;
             u32 c = tuple.2;
             u64 d = tuple.3;
             return cast(a) + cast(b) + c + cast(d);
+        }
+        "
     ).for_function("test", |f| { f
         .for_variable("tuple", |v| { v.assert_concrete_type("(u8,u16,u32,u64)"); })
         .call_ok(Some(Value::UInt32(10)));
     });
+}
 #[test]
 fn test_struct_inference() {
     Tester::new_single_source_expect_ok(
         "by function calls",
+        "
         struct Pair<T1, T2>{ T1 first, T2 second }
         func construct<T1, T2>(T1 first, T2 second) -> Pair<T1, T2> {
             return Pair{ first: first, second: second };
+        }
         func fix_t1<T2>(Pair<s8, T2> arg) -> s32 { return 0; }
         func fix_t2<T1>(Pair<T1, s32> arg) -> s32 { return 0; }
         func test() -> s32 {
             auto first = 0;
             auto second = 1;
             auto pair = construct(first, second);
             fix_t1(pair);
             fix_t2(pair);
             return 0;
+        }
+        "
     ).for_function("test", |f| { f
         .for_variable("first", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("s8");
         })
         .for_variable("second", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("s32");
         })
         .for_variable("pair", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("Pair<s8,s32>");
         });
     });
     Tester::new_single_source_expect_ok(
         "by field access",
+        "
         struct Pair<T1, T2>{ T1 first, T2 second }
         func construct<T1, T2>(T1 first, T2 second) -> Pair<T1, T2> {
             return Pair{ first: first, second: second };
+        }
         func test() -> s32 {
             auto first = 0;
             auto second = 1;
             auto pair = construct(first, second);
             s8 assign_first = 0;
             s64 assign_second = 1;
             pair.first = assign_first;
             pair.second = assign_second;
             return 0;
+        }
+        "
     ).for_function("test", |f| { f
         .for_variable("first", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("s8");
         })
         .for_variable("second", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("s64");
         })
         .for_variable("pair", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("Pair<s8,s64>");
         });
     });
     Tester::new_single_source_expect_ok(
         "by nested field access",
+        "
         struct Node<T1, T2>{ T1 l, T2 r }
         func construct<T1, T2>(T1 l, T2 r) -> Node<T1, T2> {
             return Node{ l: l, r: r };
+        }
         func fix_poly<T>(Node<T, T> a) -> s32 { return 0; }
         func test() -> s32 {
             s8 assigned = 0;
             auto thing = construct(assigned, construct(0, 1));
             fix_poly(thing.r);
             thing.r.r = assigned;
             return 0;
+        }
         ",
     ).for_function("test", |f| { f
         .for_variable("thing", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("Node<s8,Node<s8,s8>>");
         });
     });
+}
 #[test]
 fn test_enum_inference() {
     Tester::new_single_source_expect_ok(
         "no polymorphic vars",
+        "
         enum Choice { A, B }
         func test_instances() -> s32 {
             auto foo = Choice::A;
             auto bar = Choice::B;
             return 0;
+        }
+        "
     ).for_function("test_instances", |f| { f
         .for_variable("foo", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("Choice");
         })
         .for_variable("bar", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("Choice");
         });
     });
     Tester::new_single_source_expect_ok(
         "one polymorphic var",
+        "
         enum Choice<T>{
             A,
             B,
+        }
         func fix_as_s8(Choice<s8> arg) -> s32 { return 0; }
         func fix_as_s32(Choice<s32> arg) -> s32 { return 0; }
         func test_instances() -> s32 {
             auto choice_s8 = Choice::A;
             auto choice_s32_1 = Choice::B;
             Choice<auto> choice_s32_2 = Choice::B;
             fix_as_s8(choice_s8);
             fix_as_s32(choice_s32_1);
             return fix_as_s32(choice_s32_2);
+        }
+        "
     ).for_function("test_instances", |f| { f
         .for_variable("choice_s8", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("Choice<s8>");
         })
         .for_variable("choice_s32_1", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("Choice<s32>");
         })
         .for_variable("choice_s32_2", |v| { v
             .assert_parser_type("Choice<auto>")
             .assert_concrete_type("Choice<s32>");
         });
     });
     Tester::new_single_source_expect_ok(
         "two polymorphic vars",
+        "
         enum Choice<T1, T2>{ A, B, }
         func fix_t1<T>(Choice<s8, T> arg) -> s32 { return 0; }
         func fix_t2<T>(Choice<T, s32> arg) -> s32 { return 0; }
         func test_instances() -> s32 {
             Choice<s8, auto> choice1 = Choice::A;
             Choice<auto, s32> choice2 = Choice::A;
             Choice<auto, auto> choice3 = Choice::B;
             auto choice4 = Choice::B;
             fix_t1(choice1); fix_t1(choice2); fix_t1(choice3); fix_t1(choice4);
             fix_t2(choice1); fix_t2(choice2); fix_t2(choice3); fix_t2(choice4);
             return 0;
+        }
+        "
     ).for_function("test_instances", |f| { f
         .for_variable("choice1", |v| { v
             .assert_parser_type("Choice<s8,auto>")
             .assert_concrete_type("Choice<s8,s32>");
         })
         .for_variable("choice2", |v| { v
             .assert_parser_type("Choice<auto,s32>")
             .assert_concrete_type("Choice<s8,s32>");
         })
         .for_variable("choice3", |v| { v
             .assert_parser_type("Choice<auto,auto>")
             .assert_concrete_type("Choice<s8,s32>");
         })
         .for_variable("choice4", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("Choice<s8,s32>");
         });
     });
+}
 #[test]
 fn test_failed_variable_inference() {
     Tester::new_single_source_expect_err(
         "variable assignment mismatch",
+        "
         func call() -> u32 {
             u16 val16 = 0;
             u32 val32 = 0;
             auto a = val16;
             a = val32;
             return 0;
+        }
+        "
     ).error(|e| { e
         .assert_num(2)
         .assert_msg_has(0, "type 'u16'")
         .assert_msg_has(1, "type 'u32'");
     });
+}
 #[test]
 fn test_failed_polymorph_inference() {
     Tester::new_single_source_expect_err(
         "function call inference mismatch",
+        "
         func poly<T>(T a, T b) -> s32 { return 0; }
         func call() -> s32 {
             s8 first_arg = 5;
             s64 second_arg = 2;
             return poly(first_arg, second_arg);
+        }
+        "
     ).error(|e| { e
         .assert_num(3)
         .assert_ctx_has(0, "poly(first_arg, second_arg)")
         .assert_occurs_at(0, "poly")
         .assert_msg_has(0, "Conflicting type for polymorphic variable 'T'")
         .assert_occurs_at(1, "second_arg")
         .assert_msg_has(1, "inferred it to 's64'")
         .assert_occurs_at(2, "first_arg")
         .assert_msg_has(2, "inferred it to 's8'");
     });
     Tester::new_single_source_expect_err(
         "struct literal inference mismatch",
+        "
         struct Pair<T>{ T first, T second }
         func call() -> s32 {
             s8 first_arg = 5;
             s64 second_arg = 2;
             auto pair = Pair{ first: first_arg, second: second_arg };
             return 3;
+        }
+        "
     ).error(|e| { e
         .assert_num(3)
         .assert_ctx_has(0, "Pair{ first: first_arg, second: second_arg }")
         .assert_occurs_at(0, "Pair{")
         .assert_msg_has(0, "Conflicting type for polymorphic variable 'T'")
         .assert_occurs_at(1, "second_arg")
         .assert_msg_has(1, "inferred it to 's64'")
         .assert_occurs_at(2, "first_arg")
         .assert_msg_has(2, "inferred it to 's8'");
     });
     // Cannot really test literal inference error, but this comes close
     Tester::new_single_source_expect_err(
         "enum literal inference mismatch",
+        "
         enum Uninteresting<T>{ Variant }
         func fix_t<T>(Uninteresting<T> arg) -> s32 { return 0; }
         func call() -> s32 {
             auto a = Uninteresting::Variant;
             fix_t<s8>(a);
             fix_t<s32>(a);
             return 4;
+        }
+        "
     ).error(|e| { e
         .assert_num(2)
         .assert_msg_has(0, "type 'Uninteresting<s8>'")
         .assert_msg_has(1, "type 'Uninteresting<s32>'");
     });
     Tester::new_single_source_expect_err(
         "field access inference mismatch",
+        "
         struct Holder<Shazam>{ Shazam a }
         func call() -> s32 {
             s8 to_hold = 0;
             auto holder = Holder{ a: to_hold };
             return holder.a;
+        }
+        "
     ).error(|e| { e
         .assert_num(3)
         .assert_ctx_has(0, "holder.a")
         .assert_occurs_at(0, "holder.a")
         .assert_msg_has(0, "Conflicting type for polymorphic variable 'Shazam'")
         .assert_msg_has(1, "inferred it to 's8'")
         .assert_msg_has(2, "inferred it to 's32'");
     });
     // Silly regression test
     Tester::new_single_source_expect_err(
         "nested field access inference mismatch",
+        "
         struct Node<T1, T2>{ T1 l, T2 r }
         func construct<T1, T2>(T1 l, T2 r) -> Node<T1, T2> { return Node{ l: l, r: r }; }
         func fix_poly<T>(Node<T, T> a) -> s32 { return 0; }
         func test() -> s32 {
             s8 assigned = 0;
             s64 another = 1;
             auto thing = construct(assigned, construct(another, 1));
             fix_poly(thing.r);
             thing.r.r = assigned;
             return 0;
+        }
         ",
     );
+}
 #[test]
 fn test_explicit_polymorph_argument() {
     // Failed because array was put at same type depth as u32. So interpreted
     // as a function with two polymorphic arguments
     Tester::new_single_source_expect_ok("explicit with array", "
     func foo<T>(T a, T b) -> T {
         return a @ b;
+    }
     func test() -> u32 {
         return foo<u32[]>({1}, {2})[1];
     }").for_function("test", |f| { f
         .call_ok(Some(Value::UInt32(2)));
     });
     Tester::new_single_source_expect_err("multi-explicit with array", "
     func foo<A, B, C>(A a, B b) -> C {
         return (a @ b)[1];
+    }
     func test() -> u32 {
         return foo<u32[], u32[], u32, u32>({1}, {2});
     }").error(|e| { e
         .assert_num(1)
         .assert_occurs_at(0, "foo<u32")
         .assert_msg_has(0, "expected 3")
         .assert_msg_has(0, "4 were provided");
     });
     // Failed because type inferencer did not construct polymorph errors by
     // considering that argument/return types failed against explicitly
     // specified polymorphic arguments
     Tester::new_single_source_expect_err("explicit polymorph argument mismatch", "
     func foo<T>(T a, T b) -> T { return a + b; }
     struct Bar<A, B>{A a, B b}
     func test() -> u32 {
         return foo<Bar<u32, u64>[]>(5, 6);
     }").error(|e| { e
         .assert_num(2)
         .assert_occurs_at(0, "foo<Bar")
         .assert_msg_has(0, "'T' of 'foo'")
         .assert_occurs_at(1, "5, ")
         .assert_msg_has(1, "has type 'Bar<u32, u64>[]")
         .assert_msg_has(1, "inferred it to 'integerlike'");
     });
     // Similar to above, now for return type
     Tester::new_single_source_expect_err("explicit polymorph return mismatch", "
     func foo<T>(T a, T b) -> T { return a + b; }
     func test() -> u32 {
         return foo<u64>(5, 6);
     }").error(|e| { e
         .assert_num(2)
         .assert_occurs_at(0, "foo<u64")
         .assert_msg_has(0, "'T' of 'foo'")
         .assert_occurs_at(1, "foo<u64")
         .assert_msg_has(1, "has type 'u64'")
         .assert_msg_has(1, "return type inferred it to 'u32'");
     });
+}
@@ \ No newline at end of file @@

src/protocol/tests/parser_validation.rs

➞

Show inline comments

 /// parser_validation.rs
 ///
 /// Simple tests for the validation phase
 use super::*;
 #[test]
 fn test_correct_struct_instance() {
     Tester::new_single_source_expect_ok(
         "single field",
+        "
         struct Foo { s32 a }
         func bar(s32 arg) -> Foo { return Foo{ a: arg }; }
+        "
     );
     Tester::new_single_source_expect_ok(
         "multiple fields",
+        "
         struct Foo { s32 a, s32 b }
         func bar(s32 arg) -> Foo { return Foo{ a: arg, b: arg }; }
+        "
     );
     Tester::new_single_source_expect_ok(
         "single field, explicit polymorph",
+        "
         struct Foo<T>{ T field }
         func bar(s32 arg) -> Foo<s32> { return Foo<s32>{ field: arg }; }
+        "
     );
     Tester::new_single_source_expect_ok(
         "single field, implicit polymorph",
+        "
         struct Foo<T>{ T field }
         func bar(s32 arg) -> s32 {
             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 }
         func bar(s32 arg) -> s32 {
             auto qux = Pair<s32, s32>{ 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 }
         func bar(s32 arg) -> s32 {
             auto wup = Pair{ first: arg, second: arg };
             return arg;
+        }
+        "
     );
     Tester::new_single_source_expect_ok(
         "multiple fields, different explicit polymorph",
+        "
         struct Pair<T1, T2>{ T1 first, T2 second }
         func bar(s32 arg1, s8 arg2) -> s32 {
             auto shoo = Pair<s32, s8>{ 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 }
         func bar(s32 arg1, s8 arg2) -> s32 {
             auto shrubbery = Pair{ first: arg1, second: arg2 };
             return arg1;
+        }
+        "
     );
+}
 #[test]
 fn test_incorrect_struct_instance() {
     Tester::new_single_source_expect_err(
         "reused field in definition",
         "struct Foo{ s32 a, s8 a }"
     ).error(|e| { e
         .assert_num(2)
         .assert_occurs_at(0, "a }")
         .assert_msg_has(0, "defined more than once")
         .assert_occurs_at(1, "a, ")
         .assert_msg_has(1, "other struct field");
     });
     Tester::new_single_source_expect_err(
         "reused field in instance",
+        "
         struct Foo{ s32 a, s32 b }
         func bar() -> s32 {
             auto foo = Foo{ a: 5, a: 3 };
             return 0;
+        }
+        "
     ).error(|e| { e
         .assert_occurs_at(0, "a: 3")
         .assert_msg_has(0, "field is specified more than once");
     });
     Tester::new_single_source_expect_err(
         "missing field",
+        "
         struct Foo { s32 a, s32 b }
         func bar() -> s32 {
             auto foo = Foo{ a: 2 };
             return 0;
+        }
+        "
     ).error(|e| { e
         .assert_occurs_at(0, "Foo{")
         .assert_msg_has(0, "'b' is missing");
     });
     Tester::new_single_source_expect_err(
         "missing fields",
+        "
         struct Foo { s32 a, s32 b, s32 c }
         func bar() -> s32 {
             auto foo = Foo{ a: 2 };
             return 0;
+        }
+        "
     ).error(|e| { e
         .assert_occurs_at(0, "Foo{")
         .assert_msg_has(0, "[b, c] are missing");
     });
+}
 #[test]
 fn test_correct_enum_instance() {
     Tester::new_single_source_expect_ok(
         "single variant",
+        "
         enum Foo { A }
         func bar() -> Foo { return Foo::A; }
+        "
     );
     Tester::new_single_source_expect_ok(
         "multiple variants",
+        "
         enum Foo { A=15, B = 0xF }
         func bar() -> Foo { auto a = Foo::A; return Foo::B; }
+        "
     );
     Tester::new_single_source_expect_ok(
         "explicit single polymorph",
+        "
         enum Foo<T>{ A }
         func bar() -> Foo<s32> { return Foo::A; }
+        "
     );
     Tester::new_single_source_expect_ok(
         "explicit multi-polymorph",
+        "
         enum Foo<A, B>{ A, B }
         func bar() -> Foo<s8, s32> { return Foo::B; }
+        "
     );
+}
 #[test]
 fn test_incorrect_enum_instance() {
     Tester::new_single_source_expect_err(
         "variant name reuse",
+        "
         enum Foo { A, A }
         func bar() -> Foo { return Foo::A; }
+        "
     ).error(|e| { e
         .assert_num(2)
         .assert_occurs_at(0, "A }")
         .assert_msg_has(0, "defined more than once")
         .assert_occurs_at(1, "A, ")
         .assert_msg_has(1, "other enum variant is defined here");
     });
     Tester::new_single_source_expect_err(
         "undefined variant",
+        "
         enum Foo { A }
         func bar() -> Foo { return Foo::B; }
+        "
     ).error(|e| { e
         .assert_num(1)
         .assert_msg_has(0, "variant 'B' does not exist on the enum 'Foo'");
     });
+}
 #[test]
 fn test_correct_union_instance() {
     Tester::new_single_source_expect_ok(
         "single tag",
+        "
         union Foo { A }
         func bar() -> Foo { return Foo::A; }
+        "
     );
     Tester::new_single_source_expect_ok(
         "multiple tags",
+        "
         union Foo { A, B }
         func bar() -> Foo { return Foo::B; }
+        "
     );
     Tester::new_single_source_expect_ok(
         "single embedded",
+        "
         union Foo { A(s32) }
         func bar() -> Foo { return Foo::A(5); }
+        "
     );
     Tester::new_single_source_expect_ok(
         "multiple embedded",
+        "
         union Foo { A(s32), B(s8) }
         func bar() -> Foo { return Foo::B(2); }
+        "
     );
     Tester::new_single_source_expect_ok(
         "multiple values in embedded",
+        "
         union Foo { A(s32, s8) }
         func bar() -> Foo { return Foo::A(0, 2); }
+        "
     );
     Tester::new_single_source_expect_ok(
         "mixed tag/embedded",
+        "
         union OptionInt { None, Some(s32) }
         func bar() -> OptionInt { return OptionInt::Some(3); }
+        "
     );
     Tester::new_single_source_expect_ok(
         "single polymorphic var",
+        "
         union Option<T> { None, Some(T) }
         func bar() -> Option<s32> { return Option::Some(3); }"
     );
     Tester::new_single_source_expect_ok(
         "multiple polymorphic vars",
+        "
         union Result<T, E> { Ok(T), Err(E), }
         func bar() -> Result<s32, s8> { return Result::Ok(3); }
+        "
     );
     Tester::new_single_source_expect_ok(
         "multiple polymorphic in one variant",
+        "
         union MaybePair<T1, T2>{ None, Some(T1, T2) }
         func bar() -> MaybePair<s8, s32> { return MaybePair::Some(1, 2); }
+        "
     );
+}
 #[test]
 fn test_incorrect_union_instance() {
     Tester::new_single_source_expect_err(
         "tag-variant name reuse",
+        "
         union Foo{ A, A }
+        "
     ).error(|e| { e
         .assert_num(2)
         .assert_occurs_at(0, "A }")
         .assert_msg_has(0, "union variant is defined more than once")
         .assert_occurs_at(1, "A, ")
         .assert_msg_has(1, "other union variant");
     });
     Tester::new_single_source_expect_err(
         "embedded-variant name reuse",
+        "
         union Foo{ A(s32), A(s8) }
+        "
     ).error(|e| { e
         .assert_num(2)
         .assert_occurs_at(0, "A(s8)")
         .assert_msg_has(0, "union variant is defined more than once")
         .assert_occurs_at(1, "A(s32)")
         .assert_msg_has(1, "other union variant");
     });
     Tester::new_single_source_expect_err(
         "undefined variant",
+        "
         union Silly{ Thing(s8) }
         func bar() -> Silly { return Silly::Undefined(5); }
+        "
     ).error(|e| { e
         .assert_msg_has(0, "variant 'Undefined' does not exist on the union 'Silly'");
     });
     Tester::new_single_source_expect_err(
         "using tag instead of embedded",
+        "
         union Foo{ A(s32) }
         func bar() -> Foo { return Foo::A; }
+        "
     ).error(|e| { e
         .assert_msg_has(0, "variant 'A' of union 'Foo' expects 1 embedded values, but 0 were");
     });
     Tester::new_single_source_expect_err(
         "using embedded instead of tag",
+        "
         union Foo{ A }
         func bar() -> Foo { return Foo::A(3); }
+        "
     ).error(|e| { e
         .assert_msg_has(0, "The variant 'A' of union 'Foo' expects 0");
     });
     Tester::new_single_source_expect_err(
         "wrong embedded value",
+        "
         union Foo{ A(s32) }
         func bar() -> Foo { return Foo::A(false); }
+        "
     ).error(|e| { e
         .assert_occurs_at(0, "Foo::A")
         .assert_msg_has(0, "failed to fully resolve")
         .assert_occurs_at(1, "false")
         .assert_msg_has(1, "has been resolved to 's32'")
         .assert_msg_has(1, "has been resolved to 'bool'");
     });
+}
 #[test]
 fn test_correct_tuple_members() {
     // Tuples with zero members
     Tester::new_single_source_expect_ok(
         "single zero-tuple",
         "struct Foo{ () bar }"
     ).for_struct("Foo", |s| { s
         .for_field("bar", |f| { f.assert_parser_type("()"); })
         .assert_size_alignment("Foo", 0, 1);
     });
     Tester::new_single_source_expect_ok(
         "triple zero-tuple",
         "struct Foo{ () bar, () baz, () qux }"
     ).for_struct("Foo", |s| { s
         .assert_size_alignment("Foo", 0, 1);
     });
     // Tuples with one member (which are elided, because due to ambiguity
     // between a one-tuple literal and a parenthesized expression, we're not
     // going to be able to construct one-tuples).
     Tester::new_single_source_expect_ok(
         "single elided one-tuple",
         "struct Foo{ (u32) bar }"
     ).for_struct("Foo", |s| { s
         .for_field("bar", |f| { f.assert_parser_type("u32"); })
         .assert_size_alignment("Foo", 4, 4);
     });
     Tester::new_single_source_expect_ok(
         "triple elided one-tuple",
         "struct Foo{ (u8) bar, (u16) baz, (u32) qux }"
     ).for_struct("Foo", |s| { s
         .assert_size_alignment("Foo", 8, 4);
     });
     // Tuples with three members
     Tester::new_single_source_expect_ok(
         "single three-tuple",
         "struct Foo{ (u8, u16, u32) bar }"
     ).for_struct("Foo", |s| { s
         .for_field("bar", |f| { f.assert_parser_type("(u8,u16,u32)"); })
         .assert_size_alignment("Foo", 8, 4);
     });
     Tester::new_single_source_expect_ok(
         "double three-tuple",
         "struct Foo{ (u8,u16,u32,) bar, (s8,s16,s32,) baz }"
     ).for_struct("Foo", |s| { s
         .for_field("bar", |f| { f.assert_parser_type("(u8,u16,u32)"); })
         .for_field("baz", |f| { f.assert_parser_type("(s8,s16,s32)"); })
         .assert_size_alignment("Foo", 16, 4);
     });
+}
 #[test]
 fn test_incorrect_tuple_member() {
     // Test not really necessary, but hey, what's a test between friends
     Tester::new_single_source_expect_err(
         "unknown tuple member",
         "struct Foo{ (u32, u32, u32, YouThirstySchmoo) field }"
     ).error(|e| { e
         .assert_num(1)
         .assert_msg_has(0, "unknown type")
         .assert_occurs_at(0, "YouThirstySchmoo");
     });
+}
 #[test]
 fn test_correct_tuple_polymorph_args() {
     Tester::new_single_source_expect_ok(
         "single tuple arg",
+        "
         union Option<T>{ Some(T), None }
         func thing() -> u32 {
             auto a = Option<()>::None;
             auto b = Option<(u32, u64)>::None;
             auto c = Option<(Option<(u8, s8)>, Option<(s8, u8)>)>::None;
             return 0;
+        }
+        "
     ).for_union("Option", |u| { u
         .assert_has_monomorph("Option<()>")
         .assert_has_monomorph("Option<(u32,u64)>")
         .assert_has_monomorph("Option<(Option<(u8,s8)>,Option<(s8,u8)>)>")
         .assert_size_alignment("Option<()>", 1, 1, 0, 0)
         .assert_size_alignment("Option<(u32,u64)>", 24, 8, 0, 0) // (u32, u64) becomes size 16, alignment 8. Hence union tag is aligned to 8
         .assert_size_alignment("Option<(Option<(u8,s8)>,Option<(s8,u8)>)>", 7, 1, 0, 0); // inner unions are size 3, alignment 1. Two of those with a tag is size 7
     });
+}
 #[test]
 fn test_incorrect_tuple_polymorph_args() {
     // Do some mismatching brackets. I don't know what else to test
     Tester::new_single_source_expect_err(
         "mismatch angle bracket",
+        "
         union Option<T>{ Some(T), None }
         func f() -> u32 {
             auto a = Option<(u32>)::None;
             return 0;
         }"
     ).error(|e| { e
         .assert_num(2)
         .assert_msg_has(0, "closing '>'").assert_occurs_at(0, ">)::None")
         .assert_msg_has(1, "match this '('").assert_occurs_at(1, "(u32>");
     });
     Tester::new_single_source_expect_err(
         "wrongly placed angle",
+        "
         union O<T>{ S(T), N }
         func f() -> u32 {
             auto a = O<(<u32>)>::None;
             return 0;
+        }
+        "
     ).error(|e| { e
         .assert_num(1)
         .assert_msg_has(0, "expected typename")
         .assert_occurs_at(0, "<u32");
     });
+}
 #[test]
 fn test_incorrect_tuple_member_access() {
     Tester::new_single_source_expect_err(
         "zero-tuple",
         "func foo() -> () { () a = (); auto b = a.0; return a; }"
     ).error(|e| { e
         .assert_num(1)
         .assert_msg_has(0, "out of bounds")
         .assert_occurs_at(0, "a.0");
     });
     // Make the type checker do some shenanigans before we can decide the tuple
     // type.
     Tester::new_single_source_expect_err(
         "sized tuple",
+        "
         func determinator<A,B>((A,B,A) v) -> B { return v.1; }
         func tester() -> u64 {
             auto v = (0,1,2);
             u32 a_u32 = 5;
             v.2 = a_u32;
             v.8 = 5;
             return determinator(v);
+        }
+        "
     ).error(|e| { e
         .assert_num(1)
         .assert_msg_has(0, "out of bounds")
         .assert_occurs_at(0, "v.8");
     });
+}
 #[test]
 fn test_polymorph_array_types() {
     Tester::new_single_source_expect_ok(
         "array of polymorph in struct",
+        "
         struct Foo<T> { T[] hello }
         struct Bar { Foo<u32>[] world }
+        "
     ).for_struct("Bar", |s| { s
         .for_field("world", |f| { f.assert_parser_type("Foo<u32>[]"); });
     });
     Tester::new_single_source_expect_ok(
         "array of port in struct",
+        "
         struct Bar { in<u32>[] inputs }
+        "
     ).for_struct("Bar", |s| { s
         .for_field("inputs", |f| { f.assert_parser_type("in<u32>[]"); });
     });
+}
@@ \ No newline at end of file @@

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