CSY/reowolf Changeset - fb68b70351ce · Centrum Wiskunde & Informatica (CWI)

Changeset - fb68b70351ce

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MH - 4 years ago 2021-05-24 14:13:53
contact@maxhenger.nl

WIP on evaluating casts

3 files changed with 138 insertions and 30 deletions:

src/protocol/eval/executor.rs

src/protocol/eval/value.rs

src/protocol/parser/pass_typing.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
+}
 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),
         };
         Frame{
             definition: definition_id,
             monomorph_idx,
             position: first_statement.upcast(),
             expr_stack: VecDeque::with_capacity(128),
             expr_values: VecDeque::with_capacity(128),
+        }
+    }
     /// 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) => {
                 todo!("implement binding expression");
             },
             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);
+                        }
+                    }
+                }
             },
             Expression::Cast(_) => {
                 todo!("casting expression");
             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>;
 pub enum EvalContinuation {
     Stepping,
     Inconsistent,
     Terminal,
     SyncBlockStart,
     SyncBlockEnd,
     NewComponent(DefinitionId, i32, ValueGroup),
     BlockFires(Value),
     BlockGet(Value),
     Put(Value, Value),
+}
 // 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?
         debug_assert!((monomorph_idx as usize) < _types.get_base_definition(&def).unwrap().definition.procedure_monomorphs().len());
         prompt.frames.push(Frame::new(heap, def, monomorph_idx));
         args.into_store(&mut prompt.store);
         prompt
+    }
     pub(crate) fn step(&mut self, types: &TypeTable, heap: &Heap, modules: &[Module], ctx: &mut EvalContext) -> 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::Terminal);
+        }
         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) => {
                             todo!("Binding expression");
                         },
                         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, subject_heap_pos) = 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 = subject.as_array();
                                     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)), subject_heap_pos)
                                 },
                                 _ => {
                                     // 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 = subject.as_array();
                                     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), subject_heap_pos)
                                 },
                             };
                             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)
                             let array_heap_pos = deref_subject.as_array();
                             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(Value::Array(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_expression_data(&cur_frame.definition, 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();
                                     (None, Value::Ref(ValueId::Heap(subject_heap_pos, field_idx)))
                                 },
                                 _ => {
                                     let subject_heap_pos = subject.as_struct();
                                     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_expression_data(&cur_frame.definition, 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)
+                                }
                             };
                             cur_frame.expr_values.push_back(value);
                         },
                         Expression::Cast(_) => {
                             todo!("casting expression evaluation");
                         Expression::Cast(expr) => {
                             let mono_data = types.get_procedure_expression_data(&cur_frame.definition, 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.
+                        }
                         Expression::Call(expr) => {
                             // 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_expression_data(&cur_frame.definition, cur_frame.monomorph_idx);
                             let call_data = &mono_data.expr_data[expr.unique_id_in_definition as usize];
                             // Push the new frame
                             self.frames.push(Frame::new(heap, expr.definition, call_data.field_or_monomorph_idx));
                             self.store.cur_stack_boundary = new_stack_boundary;
                             // 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()];
                             cur_frame.expr_values.push_back(Value::Ref(ValueId::Stack(variable.unique_id_in_scope as StackPos)));
+                        }
+                    }
+                }
+            }
+        }
         debug_log!("Frame [{:?}] at {:?}, stack size = {}", cur_frame.definition, cur_frame.position, self.store.stack.len());
         if debug_enabled!() {
             debug_log!("Stack:");
             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) => {
                 // Reserve space on stack, but also make sure excess stack space
                 // is cleared
                 self.store.clear_stack(stmt.first_unique_id_in_scope as usize);
                 self.store.reserve_stack(stmt.next_unique_id_in_scope as usize);
                 cur_frame.position = stmt.statements[0];
                 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;
                     },
                     LocalStatement::Channel(stmt) => {
                         let [from_value, to_value] = ctx.new_channel();
                         self.store.write(ValueId::Stack(heap[stmt.from].unique_id_in_scope as u32), from_value);
                         self.store.write(ValueId::Stack(heap[stmt.to].unique_id_in_scope as u32), to_value);
                         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().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().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::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);
                 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::Terminal);
+                }
                 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();

src/protocol/eval/value.rs

➞

Show inline comments

 use super::store::*;
 use crate::PortId;
 use crate::protocol::ast::{
     AssignmentOperator,
     BinaryOperator,
     UnaryOperator,
     ConcreteType,
     ConcreteTypePart,
 };
 pub type StackPos = u32;
 pub type HeapPos = u32;
 #[derive(Debug, Copy, Clone)]
 pub enum ValueId {
     Stack(StackPos), // place on stack
     Heap(HeapPos, u32), // allocated region + values within that region
+}
 /// Represents a value stored on the stack or on the heap. Some values contain
 /// a `HeapPos`, implying that they're stored in the store's `Heap`. Clearing
 /// a `Value` with a `HeapPos` from a stack must also clear the associated
 /// region from the `Heap`.
 #[derive(Debug, Clone)]
 pub enum Value {
     // Special types, never encountered during evaluation if the compiler works correctly
     Unassigned,                 // Marker when variables are first declared, immediately followed by assignment
     PrevStackBoundary(isize),   // Marker for stack frame beginning, so we can pop stack values
     Ref(ValueId),               // Reference to a value, used by expressions producing references
     // Builtin types
     Input(PortId),
     Output(PortId),
     Message(HeapPos),
     Null,
     Bool(bool),
     Char(char),
     String(HeapPos),
     UInt8(u8),
     UInt16(u16),
     UInt32(u32),
     UInt64(u64),
     SInt8(i8),
     SInt16(i16),
     SInt32(i32),
     SInt64(i64),
     Array(HeapPos),
     // Instances of user-defined types
     Enum(i64),
     Union(i64, HeapPos),
     Struct(HeapPos),
+}
 macro_rules! impl_union_unpack_as_value {
     ($func_name:ident, $variant_name:path, $return_type:ty) => {
         impl Value {
             pub(crate) fn $func_name(&self) -> $return_type {
                 match self {
                     $variant_name(v) => *v,
                     _ => panic!(concat!("called ", stringify!($func_name()), " on {:?}"), self),
+                }
+            }
+        }
+    }
+}
 impl_union_unpack_as_value!(as_stack_boundary, Value::PrevStackBoundary, isize);
 impl_union_unpack_as_value!(as_ref,     Value::Ref,     ValueId);
 impl_union_unpack_as_value!(as_input,   Value::Input,   PortId);
 impl_union_unpack_as_value!(as_output,  Value::Output,  PortId);
 impl_union_unpack_as_value!(as_message, Value::Message, HeapPos);
 impl_union_unpack_as_value!(as_bool,    Value::Bool,    bool);
 impl_union_unpack_as_value!(as_char,    Value::Char,    char);
 impl_union_unpack_as_value!(as_string,  Value::String,  HeapPos);
 impl_union_unpack_as_value!(as_uint8,   Value::UInt8,   u8);
 impl_union_unpack_as_value!(as_uint16,  Value::UInt16,  u16);
 impl_union_unpack_as_value!(as_uint32,  Value::UInt32,  u32);
 impl_union_unpack_as_value!(as_uint64,  Value::UInt64,  u64);
 impl_union_unpack_as_value!(as_sint8,   Value::SInt8,   i8);
 impl_union_unpack_as_value!(as_sint16,  Value::SInt16,  i16);
 impl_union_unpack_as_value!(as_sint32,  Value::SInt32,  i32);
 impl_union_unpack_as_value!(as_sint64,  Value::SInt64,  i64);
 impl_union_unpack_as_value!(as_array,   Value::Array,   HeapPos);
 impl_union_unpack_as_value!(as_enum,    Value::Enum,    i64);
 impl_union_unpack_as_value!(as_struct,  Value::Struct,  HeapPos);
 impl Value {
     pub(crate) fn as_union(&self) -> (i64, HeapPos) {
         match self {
             Value::Union(tag, v) => (*tag, *v),
             _ => panic!("called as_union on {:?}", self),
+        }
+    }
     pub(crate) fn is_integer(&self) -> bool {
         match self {
             Value::UInt8(_) | Value::UInt16(_) | Value::UInt32(_) | Value::UInt64(_) |
             Value::SInt8(_) | Value::SInt16(_) | Value::SInt32(_) | Value::SInt64(_) => true,
             _ => false
+        }
+    }
     pub(crate) fn is_unsigned_integer(&self) -> bool {
         match self {
             Value::UInt8(_) | Value::UInt16(_) | Value::UInt32(_) | Value::UInt64(_) => true,
             _ => false
+        }
+    }
     pub(crate) fn is_signed_integer(&self) -> bool {
         match self {
             Value::SInt8(_) | Value::SInt16(_) | Value::SInt32(_) | Value::SInt64(_) => true,
             _ => false
+        }
+    }
     pub(crate) fn as_unsigned_integer(&self) -> u64 {
         match self {
             Value::UInt8(v)  => *v as u64,
             Value::UInt16(v) => *v as u64,
             Value::UInt32(v) => *v as u64,
             Value::UInt64(v) => *v as u64,
             _ => unreachable!("called as_unsigned_integer on {:?}", self),
+        }
+    }
     pub(crate) fn as_signed_integer(&self) -> i64 {
         match self {
             Value::SInt8(v)  => *v as i64,
             Value::SInt16(v) => *v as i64,
             Value::SInt32(v) => *v as i64,
             Value::SInt64(v) => *v as i64,
             _ => unreachable!("called as_signed_integer on {:?}", self)
+        }
+    }
     /// Returns the heap position associated with the value. If the value
     /// doesn't store anything in the heap then we return `None`.
     pub(crate) fn get_heap_pos(&self) -> Option<HeapPos> {
         match self {
             Value::Message(v) => Some(*v),
             Value::Array(v) => Some(*v),
             Value::Union(_, v) => Some(*v),
             Value::Struct(v) => Some(*v),
             _ => None
+        }
+    }
+}
 /// When providing arguments to a new component, or when transferring values
 /// from one component's store to a newly instantiated component, one has to
 /// transfer stack and heap values. This `ValueGroup` represents such a
 /// temporary group of values with potential heap allocations.
 ///
 /// Constructing such a ValueGroup manually requires some extra care to make
 /// sure all elements of `values` point to valid elements of `regions`.
 ///
 /// Again: this is a temporary thing, hopefully removed once we move to a
 /// bytecode interpreter.
 pub struct ValueGroup {
     pub(crate) values: Vec<Value>,
     pub(crate) regions: Vec<Vec<Value>>
+}
 impl ValueGroup {
     pub(crate) fn new_stack(values: Vec<Value>) -> Self {
         debug_assert!(values.iter().all(|v| v.get_heap_pos().is_none()));
         Self{
             values,
             regions: Vec::new(),
+        }
+    }
     pub(crate) fn from_store(store: &Store, values: &[Value]) -> Self {
         let mut group = ValueGroup{
             values: Vec::with_capacity(values.len()),
             regions: Vec::with_capacity(values.len()), // estimation
         };
         for value in values {
             let transferred = group.retrieve_value(value, store);
             group.values.push(transferred);
+        }
         group
+    }
     /// Transfers a provided value from a store into a local value with its
     /// heap allocations (if any) stored in the ValueGroup. Calling this
     /// function will not store the returned value in the `values` member.
     fn retrieve_value(&mut self, value: &Value, from_store: &Store) -> Value {
         if let Some(heap_pos) = value.get_heap_pos() {
             // Value points to a heap allocation, so transfer the heap values
             // internally.
             let from_region = &from_store.heap_regions[heap_pos as usize].values;
             let mut new_region = Vec::with_capacity(from_region.len());
             for value in from_region {
                 let transferred = self.retrieve_value(value, from_store);
                 new_region.push(transferred);
+            }
             // Region is constructed, store internally and return the new value.
                     *lhs_heap_pos = rhs_heap_pos;
+                }
                 Value::Struct(v) => { to_dealloc = Some(*v); *v = rhs.as_struct(); },
                 _ => unreachable!("apply_assignment_operator {:?} on lhs {:?} and rhs {:?}", op, lhs, rhs),
+            }
         },
         AO::Multiplied =>   { apply_int_op!(lhs, *=,  op, rhs) },
         AO::Divided =>      { apply_int_op!(lhs, /=,  op, rhs) },
         AO::Remained =>     { apply_int_op!(lhs, %=,  op, rhs) },
         AO::Added =>        { apply_int_op!(lhs, +=,  op, rhs) },
         AO::Subtracted =>   { apply_int_op!(lhs, -=,  op, rhs) },
         AO::ShiftedLeft =>  { apply_int_op!(lhs, <<=, op, rhs) },
         AO::ShiftedRight => { apply_int_op!(lhs, >>=, op, rhs) },
         AO::BitwiseAnded => { apply_int_op!(lhs, &=,  op, rhs) },
         AO::BitwiseXored => { apply_int_op!(lhs, ^=,  op, rhs) },
         AO::BitwiseOred =>  { apply_int_op!(lhs, |=,  op, rhs) },
+    }
     if let Some(heap_pos) = to_dealloc {
         store.drop_heap_pos(heap_pos);
+    }
+}
 pub(crate) fn apply_binary_operator(store: &mut Store, lhs: &Value, op: BinaryOperator, rhs: &Value) -> Value {
     use BinaryOperator as BO;
     macro_rules! apply_int_op_and_return_self {
         ($lhs:ident, $operator_tokens:tt, $operator:ident, $rhs:ident) => {
             return match $lhs {
                 Value::UInt8(v)  => { Value::UInt8( *v $operator_tokens $rhs.as_uint8() ) },
                 Value::UInt16(v) => { Value::UInt16(*v $operator_tokens $rhs.as_uint16()) },
                 Value::UInt32(v) => { Value::UInt32(*v $operator_tokens $rhs.as_uint32()) },
                 Value::UInt64(v) => { Value::UInt64(*v $operator_tokens $rhs.as_uint64()) },
                 Value::SInt8(v)  => { Value::SInt8( *v $operator_tokens $rhs.as_sint8() ) },
                 Value::SInt16(v) => { Value::SInt16(*v $operator_tokens $rhs.as_sint16()) },
                 Value::SInt32(v) => { Value::SInt32(*v $operator_tokens $rhs.as_sint32()) },
                 Value::SInt64(v) => { Value::SInt64(*v $operator_tokens $rhs.as_sint64()) },
                 _ => unreachable!("apply_binary_operator {:?} on lhs {:?} and rhs {:?}", $operator, $lhs, $rhs)
             };
+        }
+    }
     macro_rules! apply_int_op_and_return_bool {
         ($lhs:ident, $operator_tokens:tt, $operator:ident, $rhs:ident) => {
             return match $lhs {
                 Value::UInt8(v)  => { Value::Bool(*v $operator_tokens $rhs.as_uint8() ) },
                 Value::UInt16(v) => { Value::Bool(*v $operator_tokens $rhs.as_uint16()) },
                 Value::UInt32(v) => { Value::Bool(*v $operator_tokens $rhs.as_uint32()) },
                 Value::UInt64(v) => { Value::Bool(*v $operator_tokens $rhs.as_uint64()) },
                 Value::SInt8(v)  => { Value::Bool(*v $operator_tokens $rhs.as_sint8() ) },
                 Value::SInt16(v) => { Value::Bool(*v $operator_tokens $rhs.as_sint16()) },
                 Value::SInt32(v) => { Value::Bool(*v $operator_tokens $rhs.as_sint32()) },
                 Value::SInt64(v) => { Value::Bool(*v $operator_tokens $rhs.as_sint64()) },
                 _ => unreachable!("apply_binary_operator {:?} on lhs {:?} and rhs {:?}", $operator, $lhs, $rhs)
             };
+        }
+    }
     // We need to handle concatenate in a special way because it needs the store
     // mutably.
     if op == BO::Concatenate {
         let target_heap_pos = store.alloc_heap();
         let lhs_heap_pos;
         let rhs_heap_pos;
         let lhs = store.maybe_read_ref(lhs);
         let rhs = store.maybe_read_ref(rhs);
         enum ValueKind { Message, String, Array }
         let value_kind;
         match lhs {
             Value::Message(lhs_pos) => {
                 lhs_heap_pos = *lhs_pos;
                 rhs_heap_pos = rhs.as_message();
                 value_kind = ValueKind::Message;
             },
             Value::String(lhs_pos) => {
                 lhs_heap_pos = *lhs_pos;
                 rhs_heap_pos = rhs.as_string();
                 value_kind = ValueKind::String;
             },
             Value::Array(lhs_pos) => {
                 lhs_heap_pos = *lhs_pos;
                 rhs_heap_pos = rhs.as_array();
                 value_kind = ValueKind::Array;
             },
             _ => unreachable!("apply_binary_operator {:?} on lhs {:?} and rhs {:?}", op, lhs, rhs)
+        }
         let lhs_heap_pos = lhs_heap_pos as usize;
         let rhs_heap_pos = rhs_heap_pos as usize;
         // TODO: I hate this, but fine...
         let mut concatenated = Vec::new();
         let lhs_len = store.heap_regions[lhs_heap_pos].values.len();
         let rhs_len = store.heap_regions[rhs_heap_pos].values.len();
         concatenated.reserve(lhs_len + rhs_len);
         for idx in 0..lhs_len {
             concatenated.push(store.clone_value(store.heap_regions[lhs_heap_pos].values[idx].clone()));
+        }
         for idx in 0..rhs_len {
             concatenated.push(store.clone_value(store.heap_regions[rhs_heap_pos].values[idx].clone()));
+        }
         store.heap_regions[target_heap_pos as usize].values = concatenated;
         return match value_kind{
             ValueKind::Message => Value::Message(target_heap_pos),
             ValueKind::String => Value::String(target_heap_pos),
             ValueKind::Array => Value::Array(target_heap_pos),
         };
+    }
     // If any of the values are references, retrieve the thing they're referring
     // to.
     let lhs = store.maybe_read_ref(lhs);
     let rhs = store.maybe_read_ref(rhs);
     match op {
         BO::Concatenate => unreachable!(),
         BO::LogicalOr => {
             return Value::Bool(lhs.as_bool() || rhs.as_bool());
         },
         BO::LogicalAnd => {
             return Value::Bool(lhs.as_bool() && rhs.as_bool());
         },
         BO::BitwiseOr        => { apply_int_op_and_return_self!(lhs, |,  op, rhs); },
         BO::BitwiseXor       => { apply_int_op_and_return_self!(lhs, ^,  op, rhs); },
         BO::BitwiseAnd       => { apply_int_op_and_return_self!(lhs, &,  op, rhs); },
         BO::Equality         => { Value::Bool(apply_equality_operator(store, lhs, rhs)) },
         BO::Inequality       => { Value::Bool(apply_inequality_operator(store, lhs, rhs)) },
         BO::LessThan         => { apply_int_op_and_return_bool!(lhs, <,  op, rhs); },
         BO::GreaterThan      => { apply_int_op_and_return_bool!(lhs, >,  op, rhs); },
         BO::LessThanEqual    => { apply_int_op_and_return_bool!(lhs, <=, op, rhs); },
         BO::GreaterThanEqual => { apply_int_op_and_return_bool!(lhs, >=, op, rhs); },
         BO::ShiftLeft        => { apply_int_op_and_return_self!(lhs, <<, op, rhs); },
         BO::ShiftRight       => { apply_int_op_and_return_self!(lhs, >>, op, rhs); },
         BO::Add              => { apply_int_op_and_return_self!(lhs, +,  op, rhs); },
         BO::Subtract         => { apply_int_op_and_return_self!(lhs, -,  op, rhs); },
         BO::Multiply         => { apply_int_op_and_return_self!(lhs, *,  op, rhs); },
         BO::Divide           => { apply_int_op_and_return_self!(lhs, /,  op, rhs); },
         BO::Remainder        => { apply_int_op_and_return_self!(lhs, %,  op, rhs); }
+    }
+}
 pub(crate) fn apply_unary_operator(store: &mut Store, op: UnaryOperator, value: &Value) -> Value {
     use UnaryOperator as UO;
     macro_rules! apply_int_expr_and_return {
         ($value:ident, $apply:tt, $op:ident) => {
             return match $value {
                 Value::UInt8(v)  => Value::UInt8($apply *v),
                 Value::UInt16(v) => Value::UInt16($apply *v),
                 Value::UInt32(v) => Value::UInt32($apply *v),
                 Value::UInt64(v) => Value::UInt64($apply *v),
                 Value::SInt8(v)  => Value::SInt8($apply *v),
                 Value::SInt16(v) => Value::SInt16($apply *v),
                 Value::SInt32(v) => Value::SInt32($apply *v),
                 Value::SInt64(v) => Value::SInt64($apply *v),
                 _ => unreachable!("apply_unary_operator {:?} on value {:?}", $op, $value),
             };
+        }
+    }
     // If the value is a reference, retrieve the thing it is referring to
     let value = store.maybe_read_ref(value);
     match op {
         UO::Positive => {
             debug_assert!(value.is_integer());
             return value.clone();
         },
         UO::Negative => {
             // TODO: Error on negating unsigned integers
             return match value {
                 Value::SInt8(v) => Value::SInt8(-*v),
                 Value::SInt16(v) => Value::SInt16(-*v),
                 Value::SInt32(v) => Value::SInt32(-*v),
                 Value::SInt64(v) => Value::SInt64(-*v),
                 _ => unreachable!("apply_unary_operator {:?} on value {:?}", op, value),
+            }
         },
         UO::BitwiseNot => { apply_int_expr_and_return!(value, !, op)},
         UO::LogicalNot => { return Value::Bool(!value.as_bool()); },
         UO::PreIncrement => { todo!("implement") },
         UO::PreDecrement => { todo!("implement") },
         UO::PostIncrement => { todo!("implement") },
         UO::PostDecrement => { todo!("implement") },
+    }
+}
 pub(crate) fn apply_casting(store: &mut Store, output_type: &ConcreteType, subject: &Value) -> Value {
     // To simplify the casting logic: if the output type is not a simple
     // integer/boolean/character, then the type checker made sure that the two
     // types must be equal, hence we can do a simple clone.
     use ConcreteTypePart as CTP;
     let part = &output_type.parts[0];
     if output_type.parts.len() > 1 || (
         part != CTP::Bool &&
         part != CTP::Character &&
         part != CTP::UInt8 && part != CTP::UInt16 && part != CTP::UInt32 && part != CTP::UInt64 &&
         part != CTP::SInt8 && part != CTP::SInt16 && part != CTP::SInt32 && part != CTP::SInt64
     ) {
         // Complex thingamajig
         return store.clone_value(subject.clone());
+    }
     macro_rules! unchecked_cast {
         ($input: expr, $output_part: expr) => {
             match $output_part {
                 CTP::Bool => Value::Bool($input as bool),
                 CTP::Character => Value::Char($input as char),
                 CTP::UInt8 => Value::UInt8($input as u8),
                 CTP::UInt16 => Value::UInt16($input as u16),
                 CTP::UInt32 => Value::UInt32($input as u32),
                 CTP::UInt64 => Value::UInt64($input as u64),
                 CTP::SInt8 => Value::SInt8($input as i8),
                 CTP::SInt16 => Value::SInt16($input as i16),
                 CTP::SInt32 => Value::SInt32($input as i32),
                 CTP::SInt64 => Value::SInt64($input as i64),
                 _ => unreachable!()
+            }
+        }
     };
     // If here, then the types might still be equal, but at least we're dealing
     // with a simple integer/boolean/character input and output type.
     let subject = store.maybe_read_ref(subject);
     match subject {
         Value::Bool(val) => unchecked_cast!(*val, part),
         Value::Char(val) => unchecked_cast!(*val, part),
         Value::UInt8(val) => {},
         Value::UInt16(val) => {},
         Value::UInt32(val) => {},
         Value::UInt64(val) => {},
         Value::SInt8(val) => {},
         Value::SInt16(val) => {},
         Value::SInt32(val) => {},
         Value::SInt64(val) => {},
+    }
+}
 pub(crate) fn apply_equality_operator(store: &Store, lhs: &Value, rhs: &Value) -> bool {
     let lhs = store.maybe_read_ref(lhs);
     let rhs = store.maybe_read_ref(rhs);
     fn eval_equality_heap(store: &Store, lhs_pos: HeapPos, rhs_pos: HeapPos) -> bool {
         let lhs_vals = &store.heap_regions[lhs_pos as usize].values;
         let rhs_vals = &store.heap_regions[rhs_pos as usize].values;
         let lhs_len = lhs_vals.len();
         if lhs_len != rhs_vals.len() {
             return false;
+        }
         for idx in 0..lhs_len {
             let lhs_val = &lhs_vals[idx];
             let rhs_val = &rhs_vals[idx];
             if !apply_equality_operator(store, lhs_val, rhs_val) {
                 return false;
+            }
+        }
         return true;
+    }
     match lhs {
         Value::Input(v) => *v == rhs.as_input(),
         Value::Output(v) => *v == rhs.as_output(),
         Value::Message(lhs_pos) => eval_equality_heap(store, *lhs_pos, rhs.as_message()),
         Value::Null => todo!("remove null"),
         Value::Bool(v) => *v == rhs.as_bool(),
         Value::Char(v) => *v == rhs.as_char(),
         Value::String(lhs_pos) => eval_equality_heap(store, *lhs_pos, rhs.as_string()),
         Value::UInt8(v) => *v == rhs.as_uint8(),
         Value::UInt16(v) => *v == rhs.as_uint16(),
         Value::UInt32(v) => *v == rhs.as_uint32(),
         Value::UInt64(v) => *v == rhs.as_uint64(),
         Value::SInt8(v) => *v == rhs.as_sint8(),
         Value::SInt16(v) => *v == rhs.as_sint16(),
         Value::SInt32(v) => *v == rhs.as_sint32(),
         Value::SInt64(v) => *v == rhs.as_sint64(),
         Value::Array(lhs_pos) => eval_equality_heap(store, *lhs_pos, rhs.as_array()),
         Value::Enum(v) => *v == rhs.as_enum(),
         Value::Union(lhs_tag, lhs_pos) => {
             let (rhs_tag, rhs_pos) = rhs.as_union();
             if *lhs_tag != rhs_tag {
                 return false;
+            }
             eval_equality_heap(store, *lhs_pos, rhs_pos)
         },
         Value::Struct(lhs_pos) => eval_equality_heap(store, *lhs_pos, rhs.as_struct()),
         _ => unreachable!("apply_equality_operator to lhs {:?}", lhs),
+    }
+}
 pub(crate) fn apply_inequality_operator(store: &Store, lhs: &Value, rhs: &Value) -> bool {
     let lhs = store.maybe_read_ref(lhs);
     let rhs = store.maybe_read_ref(rhs);
     fn eval_inequality_heap(store: &Store, lhs_pos: HeapPos, rhs_pos: HeapPos) -> bool {
         let lhs_vals = &store.heap_regions[lhs_pos as usize].values;
         let rhs_vals = &store.heap_regions[rhs_pos as usize].values;
         let lhs_len = lhs_vals.len();
         if lhs_len != rhs_vals.len() {
             return true;
+        }
         for idx in 0..lhs_len {
             let lhs_val = &lhs_vals[idx];
             let rhs_val = &rhs_vals[idx];
             if apply_inequality_operator(store, lhs_val, rhs_val) {
                 return true;
+            }
+        }
         return false;
+    }
     match lhs {
         Value::Input(v) => *v != rhs.as_input(),
         Value::Output(v) => *v != rhs.as_output(),
         Value::Message(lhs_pos) => eval_inequality_heap(store, *lhs_pos, rhs.as_message()),
         Value::Null => todo!("remove null"),
         Value::Bool(v) => *v != rhs.as_bool(),
         Value::Char(v) => *v != rhs.as_char(),
         Value::String(lhs_pos) => eval_inequality_heap(store, *lhs_pos, rhs.as_string()),
         Value::UInt8(v) => *v != rhs.as_uint8(),
         Value::UInt16(v) => *v != rhs.as_uint16(),
         Value::UInt32(v) => *v != rhs.as_uint32(),
         Value::UInt64(v) => *v != rhs.as_uint64(),
         Value::SInt8(v) => *v != rhs.as_sint8(),
         Value::SInt16(v) => *v != rhs.as_sint16(),
         Value::SInt32(v) => *v != rhs.as_sint32(),
         Value::SInt64(v) => *v != rhs.as_sint64(),
         Value::Enum(v) => *v != rhs.as_enum(),
         Value::Union(lhs_tag, lhs_pos) => {
             let (rhs_tag, rhs_pos) = rhs.as_union();
             if *lhs_tag != rhs_tag {
                 return true;
+            }
             eval_inequality_heap(store, *lhs_pos, rhs_pos)
         },
         Value::String(lhs_pos) => eval_inequality_heap(store, *lhs_pos, rhs.as_struct()),
         _ => unreachable!("apply_inequality_operator to lhs {:?}", lhs)
+    }
+}
@@ \ 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 casee we return an
+/// determined), or we have incomplete types. In the latter case we return an
 /// error.
 ///
 /// Inference may be applied on non-polymorphic procedures and on polymorphic
 /// procedures. When dealing with a non-polymorphic procedure we apply the type
 /// resolver and annotate the AST with the `ConcreteType`s. When dealing with
 /// polymorphic procedures we will only annotate the AST once, preserving
 /// references to polymorphic variables. Any later pass will perform just the
 /// type checking.
 ///
 /// TODO: Needs a thorough rewrite:
 ///  0. polymorph_progress is intentionally broken at the moment.
 ///  1. For polymorphic type inference we need to have an extra datastructure
 ///     for progressing the polymorphic variables and mapping them back to each
 ///     signature type that uses that polymorphic type. The two types of markers
 ///     became somewhat of a mess.
 ///  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, then to apply forced constraints (arg
 ///     to a fires() call must be port-like), only then to start progressing the
 ///     types.
 ///     Furthermore, queueing of expressions can be more intelligent, currently
 ///     every child/parent of an expression is inferred again when queued. Hence
 ///     we need to queue only specific children/parents of expressions.
 ///     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`).
 ///  5. Implement implicit and explicit casting.
 ///  6. Investigate different ways of performing the type-on-type inference,
 ///     maybe there is a better way then flattened trees + markers?
 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,
     Visitor2,
     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; 1] = [ InferenceTypePart::String ];
 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,
     // 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_msg_array_or_slice(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::Array | ITP::Slice | 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_msg_array_or_slice()) ||
         (*self == ITP::PortLike && arg.is_concrete_port())
+    }
     /// 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 | ITP::String => {
                 -1
             },
             ITP::Marker(_) |
             ITP::ArrayLike | ITP::Message | ITP::Array | ITP::Slice |
             ITP::PortLike | ITP::Input | ITP::Output => {
                 // One subtype, so do not modify depth
             },
             ITP::Instance(_, num_args) => {
                 (*num_args as i32) - 1
+            }
+        }
+    }
+}
 impl From<ConcreteTypePart> for InferenceTypePart {
     fn from(v: ConcreteTypePart) -> InferenceTypePart {
         use ConcreteTypePart as CTP;
         use InferenceTypePart as ITP;
         match v {
             CTP::Void => ITP::Void,
             CTP::Message => ITP::Message,
             CTP::Bool => ITP::Bool,
             CTP::UInt8 => ITP::UInt8,
             CTP::UInt16 => ITP::UInt16,
             CTP::UInt32 => ITP::UInt32,
             CTP::UInt64 => ITP::UInt64,
             CTP::SInt8 => ITP::SInt8,
             CTP::SInt16 => ITP::SInt16,
             CTP::SInt32 => ITP::SInt32,
@@ @@ -1224,461 +1213,469 @@ impl Visitor2 for PassTyping { @@
+    }
     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) => {
                 // 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());
         let var_data = self.var_types.get_mut(var_expr.declaration.as_ref().unwrap()).unwrap();
         var_data.used_at.push(upcast_id);
         self.progress_variable_expr(ctx, id)
+    }
+}
 impl PassTyping {
     fn temp_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() {
             let next_expr_idx = self.expr_queued.pop_front().unwrap();
             self.progress_expr(ctx, next_expr_idx)?;
+        }
         // Helper for transferring polymorphic variables to concrete types and
         // checking if they're completely specified
         fn poly_inference_to_concrete_type(
             ctx: &Ctx, expr_id: ExpressionId, inference: &Vec<InferenceType>
         ) -> Result<Vec<ConcreteType>, ParseError> {
             let mut concrete = Vec::with_capacity(inference.len());
             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.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)
+                        )
                     ));
+                }
                 let mut concrete_type = ConcreteType::default();
                 poly_type.write_concrete_type(&mut concrete_type);
                 concrete.push(concrete_type);
+            }
             Ok(concrete)
+        }
         // 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() {
+        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 {
                 // Auto-infer numberlike/integerlike types to a regular int
                 if expr_type.parts.len() == 1 && expr_type.parts[0] == InferenceTypePart::IntegerLike {
                     expr_type.parts[0] = InferenceTypePart::SInt32;
                     self.expr_queued.push_back(infer_expr_idx as i32);
                 } else {
                     let expr = &ctx.heap[infer_expr.expr_id];
                     return Err(ParseError::new_error_at_span(
                         &ctx.module.source, expr.span(), format!(
                             "could not fully infer the type of this expression (got '{}')",
                             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];
             if extra_data.poly_vars.is_empty() { continue; }
             // 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) => {
                     if expr.method != Method::UserFunction && expr.method != Method::UserComponent {
                         // Builtin function
                         continue;
+                    }
                     let definition_id = expr.definition;
                     let poly_types = poly_inference_to_concrete_type(ctx, extra_data.expr_id, &extra_data.poly_vars)?;
                     match ctx.types.get_procedure_monomorph_index(&definition_id, &poly_types) {
                         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, Some(poly_types.clone()));
                             infer_expr.field_or_monomorph_idx = reserved_idx;
                             queue.push(ResolveQueueElement{
                                 root_id: ctx.heap[definition_id].defined_in(),
                                 definition_id,
                                 monomorph_types: poly_types,
                                 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 poly_types = poly_inference_to_concrete_type(ctx, extra_data.expr_id, &extra_data.poly_vars)?;
                     let mono_index = ctx.types.add_data_monomorph(&definition_id, poly_types);
                     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]);
+                }
+            }
+        }
         // If we did any implicit type forcing, then our queue isn't empty
         // anymore
         while !self.expr_queued.is_empty() {
             let expr_idx = self.expr_queued.pop_back().unwrap();
             self.progress_expr(ctx, expr_idx)?;
+        }
         // Every expression checked, and new monomorphs are queued. Transfer the
         // expression information to the type table.
         let definition_id = match &self.definition_type {
             DefinitionType::Component(id) => id.upcast(),
             DefinitionType::Function(id) => id.upcast(),
         };
         let target = ctx.types.get_procedure_expression_data_mut(&definition_id, self.reserved_idx);
         debug_assert!(target.poly_args == self.poly_vars);
         debug_assert!(target.expr_data.is_empty()); // makes sure we never queue something twice
         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) => {
                 unimplemented!("progress binding expression");
             },
             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.temp_get_display_name(ctx, arg1_expr_id));
         debug_log!("   - Arg2 type: {}", self.temp_get_display_name(ctx, arg2_expr_id));
         debug_log!("   - Expr type: {}", self.temp_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::Multiplied | AO::Divided | AO::Added | AO::Subtracted =>
                 self.apply_forced_constraint(ctx, arg1_expr_id, &NUMBERLIKE_TEMPLATE)?,
             AO::Remained | AO::ShiftedLeft | AO::ShiftedRight |
             AO::BitwiseAnded | AO::BitwiseXored | AO::BitwiseOred =>
                 self.apply_forced_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_assert!(if progress_forced { progress_arg2 } else { true });
         debug_log!(" * After:");
         debug_log!("   - Arg1 type [{}]: {}", progress_forced || progress_arg1, self.temp_get_display_name(ctx, arg1_expr_id));
         debug_log!("   - Arg2 type [{}]: {}", progress_arg2, self.temp_get_display_name(ctx, arg2_expr_id));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.temp_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_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.temp_get_display_name(ctx, arg1_expr_id));
         debug_log!("   - Arg2 type: {}", self.temp_get_display_name(ctx, arg2_expr_id));
         debug_log!("   - Expr type: {}", self.temp_get_display_name(ctx, upcast_id));
         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.temp_get_display_name(ctx, arg1_expr_id));
         debug_log!("   - Arg2 type [{}]: {}", progress_arg2, self.temp_get_display_name(ctx, arg2_expr_id));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.temp_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.temp_get_display_name(ctx, arg1_id));
         debug_log!("   - Arg2 type: {}", self.temp_get_display_name(ctx, arg2_id));
         debug_log!("   - Expr type: {}", self.temp_get_display_name(ctx, upcast_id));
         let (progress_expr, progress_arg1, progress_arg2) = match expr.operation {
             BO::Concatenate => {
                 // Arguments may be arrays/slices, output is always an array
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &ARRAY_TEMPLATE)?;
                 let progress_arg1 = self.apply_forced_constraint(ctx, arg1_id, &ARRAYLIKE_TEMPLATE)?;
                 let progress_arg2 = self.apply_forced_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::LogicalOr | 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, 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
@@ @@ -2113,395 +2110,447 @@ impl PassTyping { @@
                     );
                     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.temp_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_forced_constraint(ctx, upcast_id, &ARRAY_TEMPLATE)?;
                 if !expr_elements.is_empty() {
                     let first_arg_id = expr_elements[0];
                     let (inner_expr_progress, arg_progress) = self.apply_equal2_constraint(
                         ctx, upcast_id, upcast_id, 1, first_arg_id, 0
                     )?;
                     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.temp_get_display_name(ctx, upcast_id));
                 progress_expr
             },
         };
         debug_log!(" * After:");
         debug_log!("   - Expr type: {}", self.temp_get_display_name(ctx, upcast_id));
         // TODO: FIX!!!!
         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;
         // The cast expression acts like a blocker for two-way inference. The
         // only thing we can do is wait until both the input and the output
         // TODO: Continue here
         // 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_forced_constraint(ctx, upcast_id, &infer_type.parts)?;
         if expr_progress {
             self.queue_expr_parent(ctx, upcast_id);
+        }
         // Check if the two types are compatible
         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
             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
         };
         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.span, "invalid casting operation"
             ).with_info_at_span(
                 &ctx.module.source, subject_expr.span(), format!(
                     "cannot cast this 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.temp_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.temp_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.temp_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) {
                     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];

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