CSY/reowolf Changeset - 2df3ee19d578 · Centrum Wiskunde & Informatica (CWI)

Changeset - 2df3ee19d578

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MH - 4 years ago 2021-12-16 11:34:22
contact@maxhenger.nl

Remove more hot-loop allocations

3 files changed with 101 insertions and 58 deletions:

src/collections/scoped_buffer.rs

src/protocol/parser/pass_typing.rs

src/protocol/parser/pass_validation_linking.rs

0 comments (0 inline, 0 general)

src/collections/scoped_buffer.rs

➞

Show inline comments

 /// scoped_buffer.rs
 ///
 /// Solves the common pattern where we are performing some kind of recursive
 /// pattern while using a temporary buffer. At the start, or during the
 /// procedure, we push stuff into the buffer. At the end we take out what we
 /// have put in.
 ///
 /// It is unsafe because we're using pointers to circumvent borrowing rules in
 /// the name of code cleanliness. The correctness of use is checked in debug
 /// mode.
+/// mode at runtime.
 use std::iter::FromIterator;
 pub(crate) struct ScopedBuffer<T: Sized> {
     pub inner: Vec<T>,
 macro_rules! hide {
     ($v:block) => {
         #[cfg(debug_assertions)] $v
     };
     ($v:expr) => {
         #[cfg(debug_assertions)] $v
     };
+}
 /// A section of the buffer. Keeps track of where we started the section. When
 /// done with the section one must call `into_vec` or `forget` to remove the
 /// section from the underlying buffer. This will also be done upon dropping the
 /// ScopedSection in case errors are being handled.
 pub(crate) struct ScopedSection<T: Sized> {
     inner: *mut Vec<T>,
     start_size: u32,
     #[cfg(debug_assertions)] cur_size: u32,
 pub(crate) struct ScopedBuffer<T: Sized> {
     pub inner: Vec<T>,
+}
 impl<T: Sized> ScopedBuffer<T> {
     pub(crate) fn with_capacity(capacity: usize) -> Self {
         Self { inner: Vec::with_capacity(capacity) }
         Self {
             inner: Vec::with_capacity(capacity),
+        }
+    }
     pub(crate) fn start_section(&mut self) -> ScopedSection<T> {
         let start_size = self.inner.len() as u32;
         ScopedSection {
             inner: &mut self.inner,
             start_size,
             #[cfg(debug_assertions)] cur_size: start_size
+            #[cfg(debug_assertions)] cur_size: start_size,
+        }
+    }
+}
 impl<T: Clone> ScopedBuffer<T> {
     pub(crate) fn start_section_initialized(&mut self, initialize_with: &[T]) -> ScopedSection<T> {
         let start_size = self.inner.len() as u32;
         let _data_size = initialize_with.len() as u32;
         self.inner.extend_from_slice(initialize_with);
         ScopedSection{
             inner: &mut self.inner,
             start_size,
             #[cfg(debug_assertions)] cur_size: start_size + _data_size,
+        }
+    }
+}
 #[cfg(debug_assertions)]
 impl<T: Sized> Drop for ScopedBuffer<T> {
     fn drop(&mut self) {
         // Make sure that everyone cleaned up the buffer neatly
         debug_assert!(self.inner.is_empty(), "dropped non-empty scoped buffer");
+    }
+}
 /// A section of the buffer. Keeps track of where we started the section. When
 /// done with the section one must call `into_vec` or `forget` to remove the
 /// section from the underlying buffer. This will also be done upon dropping the
 /// ScopedSection in case errors are being handled.
 pub(crate) struct ScopedSection<T: Sized> {
     inner: *mut Vec<T>,
     start_size: u32,
     #[cfg(debug_assertions)] cur_size: u32,
+}
 impl<T: Sized> ScopedSection<T> {
     #[inline]
     pub(crate) fn push(&mut self, value: T) {
         let vec = unsafe{&mut *self.inner};
         #[cfg(debug_assertions)] debug_assert_eq!(vec.len(), self.cur_size as usize, "trying to push onto section, but size is larger than expected");
         hide!(debug_assert_eq!(
             vec.len(), self.cur_size as usize,
             "trying to push onto section, but size is larger than expected"
         ));
         vec.push(value);
-        #[cfg(debug_assertions)] { self.cur_size += 1; }
+        hide!(self.cur_size += 1);
+    }
     #[inline]
     pub(crate) fn len(&self) -> usize {
         let vec = unsafe{&mut *self.inner};
         #[cfg(debug_assertions)] debug_assert_eq!(vec.len(), self.cur_size as usize, "trying to get section length, but size is larger than expected");
         hide!(debug_assert_eq!(
             vec.len(), self.cur_size as usize,
             "trying to get section length, but size is larger than expected"
         ));
         return vec.len() - self.start_size as usize;
+    }
     #[inline]
     #[allow(unused_mut)] // used in debug mode
     pub(crate) fn forget(mut self) {
         let vec = unsafe{&mut *self.inner};
-        #[cfg(debug_assertions)] {
+        hide!({
             debug_assert_eq!(
                 vec.len(), self.cur_size as usize,
                 "trying to forget section, but size is larger than expected"
             );
             self.cur_size = self.start_size;
+        }
+        });
         vec.truncate(self.start_size as usize);
+    }
     #[inline]
     #[allow(unused_mut)] // used in debug mode
     pub(crate) fn into_vec(mut self) -> Vec<T> {
         let vec = unsafe{&mut *self.inner};
-        #[cfg(debug_assertions)]  {
+        hide!({
             debug_assert_eq!(
                 vec.len(), self.cur_size as usize,
                 "trying to turn section into vec, but size is larger than expected"
             );
             self.cur_size = self.start_size;
+        }
+        });
         let section = Vec::from_iter(vec.drain(self.start_size as usize..));
         section
+    }
+}
 impl<T: Copy> ScopedSection<T> {
     pub(crate) fn iter_copied(&self) -> ScopedIter<T> {
         return ScopedIter{
             inner: self.inner,
             cur_index: self.start_size,
             last_index: unsafe{ (*self.inner).len() as u32 },
+        }
+    }
+}
-impl<T: Sized> std::ops::Index<usize> for ScopedSection<T> {
 impl<T> std::ops::Index<usize> for ScopedSection<T> {
     type Output = T;
-    fn index(&self, idx: usize) -> &Self::Output {
+    fn index(&self, index: usize) -> &Self::Output {
         let vec = unsafe{&*self.inner};
         return &vec[self.start_size as usize + idx]
         return &vec[self.start_size as usize + index]
+    }
+}
 impl<T> std::ops::IndexMut<usize> for ScopedSection<T> {
     fn index_mut(&mut self, index: usize) -> &mut Self::Output {
         let vec = unsafe{&mut *self.inner};
         return &mut vec[self.start_size as usize + index]
+    }
+}
 #[cfg(debug_assertions)]
 impl<T: Sized> Drop for ScopedSection<T> {
     fn drop(&mut self) {
         let vec = unsafe{&mut *self.inner};
-        #[cfg(debug_assertions)] debug_assert_eq!(vec.len(), self.cur_size as usize);
+        hide!(debug_assert_eq!(vec.len(), self.cur_size as usize));
         vec.truncate(self.start_size as usize);
+    }
+}
 /// Small utility for iterating over a section of the buffer. Same conditions as
 /// the buffer apply: each time we retrieve an element the buffer must have the
 /// same size as the moment of creation.
 pub(crate) struct ScopedIter<T: Copy> {
     inner: *mut Vec<T>,
     cur_index: u32,
     last_index: u32,
+}
 impl<T: Copy> Iterator for ScopedIter<T> {
     type Item = T;
     fn next(&mut self) -> Option<Self::Item> {
         hide!(debug_assert_eq!(self.last_index as usize, unsafe { (*self.inner).len() }));
         if self.cur_index >= self.last_index {
             return None;
+        }
         let vec = unsafe{ &*self.inner };
         let index = self.cur_index as usize;
         self.cur_index += 1;
         return Some(vec[index]);
+    }
+}
@@ \ No newline at end of file @@

src/protocol/parser/pass_typing.rs

➞

Show inline comments

 /// pass_typing
 ///
 /// Performs type inference and type checking. Type inference is implemented by
 /// applying constraints on (sub)trees of types. During this process the
 /// resolver takes the `ParserType` structs (the representation of the types
 /// written by the programmer), converts them to `InferenceType` structs (the
 /// temporary data structure used during type inference) and attempts to arrive
 /// at `ConcreteType` structs (the representation of a fully checked and
 /// validated type).
 ///
 /// The resolver will visit every statement and expression relevant to the
 /// procedure and insert and determine its initial type based on context (e.g. a
 /// return statement's expression must match the function's return type, an
 /// if statement's test expression must evaluate to a boolean). When all are
 /// visited we attempt to make progress in evaluating the types. Whenever a type
 /// is progressed we queue the related expressions for further type progression.
 /// Once no more expressions are in the queue the algorithm is finished. At this
 /// point either all types are inferred (or can be trivially implicitly
 /// determined), or we have incomplete types. In the latter case we return an
 /// error.
 ///
 /// TODO: Needs a thorough rewrite:
 ///  0. polymorph_progress is intentionally broken at the moment. Make it work
 ///     again and use a normal VecSomething.
 ///  1. The foundation for doing all of the work with predetermined indices
 ///     instead of with HashMaps is there, but it is not really used because of
 ///     time constraints. When time is available, rewrite the system such that
 ///     AST IDs are not needed, and only indices into arrays are used.
 ///  2. We're doing a lot of extra work. It seems better to apply the initial
 ///     type based on expression parents, and immediately apply forced
 ///     constraints (arg to a fires() call must be port-like). All of the \
 ///     progress_xxx calls should then only be concerned with "transmitting"
 ///     type inference across their parent/child expressions.
 ///  3. Remove the `msg` type?
 ///  4. Disallow certain types in certain operations (e.g. `Void`).
 macro_rules! debug_log_enabled {
     () => { false };
+}
 macro_rules! debug_log {
     ($format:literal) => {
         enabled_debug_print!(false, "types", $format);
     };
     ($format:literal, $($args:expr),*) => {
         enabled_debug_print!(false, "types", $format, $($args),*);
     };
+}
 use std::collections::{HashMap, HashSet};
 use crate::collections::{ScopedBuffer, DequeSet};
+use crate::collections::{ScopedBuffer, ScopedSection, 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::{
     BUFFER_INIT_CAPACITY,
     Ctx,
     Visitor,
     VisitorResult
 };
 const VOID_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::Void ];
 const MESSAGE_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::Message, InferenceTypePart::UInt8 ];
 const BOOL_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::Bool ];
 const CHARACTER_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::Character ];
 const STRING_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::String, InferenceTypePart::Character ];
 const NUMBERLIKE_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::NumberLike ];
 const INTEGERLIKE_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::IntegerLike ];
 const ARRAY_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::Array, InferenceTypePart::Unknown ];
 const SLICE_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::Slice, InferenceTypePart::Unknown ];
 const ARRAYLIKE_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::ArrayLike, InferenceTypePart::Unknown ];
 /// TODO: @performance Turn into PartialOrd+Ord to simplify checks
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub(crate) enum InferenceTypePart {
     // When we infer types of AST elements that support polymorphic arguments,
     // then we might have the case that multiple embedded types depend on the
     // polymorphic type (e.g. func bla(T a, T[] b) -> T[][]). If we can infer
     // the type in one place (e.g. argument a), then we may propagate this
     // information to other types (e.g. argument b and the return type). For
     // this reason we place markers in the `InferenceType` instances such that
     // we know which part of the type was originally a polymorphic argument.
     Marker(u32),
     // Completely unknown type, needs to be inferred
     Unknown,
     // Partially known type, may be inferred to to be the appropriate related
     // type.
     // IndexLike,      // index into array/slice
     NumberLike,     // any kind of integer/float
     IntegerLike,    // any kind of integer
     ArrayLike,      // array or slice. Note that this must have a subtype
     PortLike,       // input or output port
     // Special types that cannot be instantiated by the user
     Void, // For builtin functions that do not return anything
     // Concrete types without subtypes
     Bool,
     UInt8,
     UInt16,
     UInt32,
     UInt64,
     SInt8,
     SInt16,
     SInt32,
     SInt64,
     Character,
     String,
     // One subtype
     Message,
     Array,
     Slice,
     Input,
     Output,
     // Tuple with any number of subtypes (for practical reasons 1 element is impossible)
     Tuple(u32),
     // A user-defined type with any number of subtypes
     Instance(DefinitionId, u32)
+}
 impl InferenceTypePart {
     fn is_marker(&self) -> bool {
         match self {
             InferenceTypePart::Marker(_) => true,
             _ => false,
+        }
+    }
     /// Checks if the type is concrete, markers are interpreted as concrete
     /// types.
     fn is_concrete(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::Unknown | ITP::NumberLike |
             ITP::IntegerLike | ITP::ArrayLike | ITP::PortLike => false,
             _ => true
+        }
+    }
     fn is_concrete_number(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::UInt8 | ITP::UInt16 | ITP::UInt32 | ITP::UInt64 |
             ITP::SInt8 | ITP::SInt16 | ITP::SInt32 | ITP::SInt64 => true,
             _ => false,
+        }
+    }
     fn is_concrete_integer(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::UInt8 | ITP::UInt16 | ITP::UInt32 | ITP::UInt64 |
             ITP::SInt8 | ITP::SInt16 | ITP::SInt32 | ITP::SInt64 => true,
             _ => false,
+        }
+    }
     fn is_concrete_arraylike(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::Array | ITP::Slice | ITP::String | ITP::Message => true,
             _ => false,
+        }
+    }
     fn is_concrete_port(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::Input | ITP::Output => true,
             _ => false,
+        }
+    }
     /// Checks if a part is less specific than the argument. Only checks for
     /// single-part inference (i.e. not the replacement of an `Unknown` variant
     /// with the argument)
     fn may_be_inferred_from(&self, arg: &InferenceTypePart) -> bool {
         use InferenceTypePart as ITP;
         (*self == ITP::IntegerLike && arg.is_concrete_integer()) ||
         (*self == ITP::NumberLike && (arg.is_concrete_number() || *arg == ITP::IntegerLike)) ||
         (*self == ITP::ArrayLike && arg.is_concrete_arraylike()) ||
         (*self == ITP::PortLike && arg.is_concrete_port())
+    }
     /// Checks if a part is more specific
     /// Returns the change in "iteration depth" when traversing this particular
     /// part. The iteration depth is used to traverse the tree in a linear
     /// fashion. It is basically `number_of_subtypes - 1`
     fn depth_change(&self) -> i32 {
         use InferenceTypePart as ITP;
         match &self {
             ITP::Unknown | ITP::NumberLike | ITP::IntegerLike |
             ITP::Void | ITP::Bool |
             ITP::UInt8 | ITP::UInt16 | ITP::UInt32 | ITP::UInt64 |
             ITP::SInt8 | ITP::SInt16 | ITP::SInt32 | ITP::SInt64 |
             ITP::Character => {
                 -1
             },
             ITP::Marker(_) |
             ITP::ArrayLike | ITP::Message | ITP::Array | ITP::Slice |
             ITP::PortLike | ITP::Input | ITP::Output | ITP::String => {
                 // One subtype, so do not modify depth
             },
             ITP::Tuple(num) | ITP::Instance(_, num) => {
                 (*num as i32) - 1
+            }
+        }
+    }
+}
 #[derive(Debug, Clone)]
 struct InferenceType {
     has_marker: bool,
     is_done: bool,
     parts: Vec<InferenceTypePart>,
+}
 impl InferenceType {
     /// Generates a new InferenceType. The two boolean flags will be checked in
     /// debug mode.
     fn new(has_marker: bool, is_done: bool, parts: Vec<InferenceTypePart>) -> Self {
         if cfg!(debug_assertions) {
             debug_assert!(!parts.is_empty());
             let parts_body_marker = parts.iter().any(|v| v.is_marker());
             debug_assert_eq!(has_marker, parts_body_marker);
             let parts_done = parts.iter().all(|v| v.is_concrete());
             debug_assert_eq!(is_done, parts_done, "{:?}", parts);
+        }
         Self{ has_marker, is_done, parts }
+    }
     /// Replaces a type subtree with the provided subtree. The caller must make
     /// sure the the replacement is a well formed type subtree.
     fn replace_subtree(&mut self, start_idx: usize, with: &[InferenceTypePart]) {
         let end_idx = Self::find_subtree_end_idx(&self.parts, start_idx);
         debug_assert_eq!(with.len(), Self::find_subtree_end_idx(with, 0));
         self.parts.splice(start_idx..end_idx, with.iter().cloned());
         self.recompute_is_done();
+    }
     // TODO: @performance, might all be done inline in the type inference methods
     fn recompute_is_done(&mut self) {
         self.is_done = self.parts.iter().all(|v| v.is_concrete());
+    }
     /// Seeks a body marker starting at the specified position. If a marker is
     /// found then its value and the index of the type subtree that follows it
     /// is returned.
     fn find_marker(&self, mut start_idx: usize) -> Option<(u32, usize)> {
         while start_idx < self.parts.len() {
             if let InferenceTypePart::Marker(marker) = &self.parts[start_idx] {
                 return Some((*marker, start_idx + 1))
+            }
             start_idx += 1;
+        }
         None
+    }
     /// Returns an iterator over all body markers and the partial type tree that
     /// follows those markers. If it is a problem that `InferenceType` is
     /// borrowed by the iterator, then use `find_body_marker`.
     fn marker_iter(&self) -> InferenceTypeMarkerIter {
         InferenceTypeMarkerIter::new(&self.parts)
+    }
     /// Given that the `parts` are a depth-first serialized tree of types, this
     /// function finds the subtree anchored at a specific node. The returned
     /// index is exclusive.
     fn find_subtree_end_idx(parts: &[InferenceTypePart], start_idx: usize) -> usize {
         let mut depth = 1;
         let mut idx = start_idx;
         while idx < parts.len() {
             depth += parts[idx].depth_change();
             if depth == 0 {
                 return idx + 1;
+            }
             idx += 1;
+        }
         // If here, then the inference type is malformed
         unreachable!("Malformed type: {:?}", parts);
+    }
     /// Call that attempts to infer the part at `to_infer.parts[to_infer_idx]`
     /// using the subtree at `template.parts[template_idx]`. Will return
     /// `Some(depth_change_due_to_traversal)` if type inference has been
     /// applied. In this case the indices will also be modified to point to the
     /// next part in both templates. If type inference has not (or: could not)
     /// be applied then `None` will be returned. Note that this might mean that
     /// the types are incompatible.
     ///
     /// As this is a helper functions, some assumptions: the parts are not
     /// exactly equal, and neither of them contains a marker. Also: only the
     /// `to_infer` parts are checked for inference. It might be that this
     /// function returns `None`, but that that `template` is still compatible
     /// with `to_infer`, e.g. when `template` has an `Unknown` part.
     fn infer_part_for_single_type(
         to_infer: &mut InferenceType, to_infer_idx: &mut usize,
         template_parts: &[InferenceTypePart], template_idx: &mut usize,
     ) -> Option<i32> {
         use InferenceTypePart as ITP;
         let to_infer_part = &to_infer.parts[*to_infer_idx];
         let template_part = &template_parts[*template_idx];
         // Check for programmer mistakes
         debug_assert_ne!(to_infer_part, template_part);
         debug_assert!(!to_infer_part.is_marker(), "marker encountered in 'infer part'");
         debug_assert!(!template_part.is_marker(), "marker encountered in 'template part'");
         // Inference of a somewhat-specified type
         if to_infer_part.may_be_inferred_from(template_part) {
             let depth_change = to_infer_part.depth_change();
             debug_assert_eq!(depth_change, template_part.depth_change());
             to_infer.parts[*to_infer_idx] = template_part.clone();
             *to_infer_idx += 1;
             *template_idx += 1;
             return Some(depth_change);
+        }
         // Inference of a completely unknown type
         if *to_infer_part == ITP::Unknown {
             // template part is different, so cannot be unknown, hence copy the
             // entire subtree. Make sure not to copy markers.
             let template_end_idx = Self::find_subtree_end_idx(template_parts, *template_idx);
             to_infer.parts[*to_infer_idx] = template_parts[*template_idx].clone(); // first element
             *to_infer_idx += 1;
             for template_idx in *template_idx + 1..template_end_idx {
                 let template_part = &template_parts[template_idx];
                 if !template_part.is_marker() {
                     to_infer.parts.insert(*to_infer_idx, template_part.clone());
                     *to_infer_idx += 1;
+                }
+            }
             *template_idx = template_end_idx;
             // Note: by definition the LHS was Unknown and the RHS traversed a
             // full subtree.
             return Some(-1);
+        }
         None
+    }
     /// Call that checks if the `to_check` part is compatible with the `infer`
     /// part. This is essentially a copy of `infer_part_for_single_type`, but
     /// without actually copying the type parts.
     fn check_part_for_single_type(
         to_check_parts: &[InferenceTypePart], to_check_idx: &mut usize,
         template_parts: &[InferenceTypePart], template_idx: &mut usize
     ) -> Option<i32> {
         use InferenceTypePart as ITP;
         let to_check_part = &to_check_parts[*to_check_idx];
         let template_part = &template_parts[*template_idx];
         // Checking programmer errors
         debug_assert_ne!(to_check_part, template_part);
         debug_assert!(!to_check_part.is_marker(), "marker encountered in 'to_check part'");
         debug_assert!(!template_part.is_marker(), "marker encountered in 'template part'");
         if to_check_part.may_be_inferred_from(template_part) {
             let depth_change = to_check_part.depth_change();
             debug_assert_eq!(depth_change, template_part.depth_change());
             *to_check_idx += 1;
             *template_idx += 1;
             return Some(depth_change);
+        }
         if *to_check_part == ITP::Unknown {
             *to_check_idx += 1;
             *template_idx = Self::find_subtree_end_idx(template_parts, *template_idx);
             // By definition LHS and RHS had depth change of -1
             return Some(-1);
+        }
         None
+    }
     /// Attempts to infer types between two `InferenceType` instances. This
     /// function is unsafe as it accepts pointers to work around Rust's
     /// borrowing rules. The caller must ensure that the pointers are distinct.
     unsafe fn infer_subtrees_for_both_types(
         type_a: *mut InferenceType, start_idx_a: usize,
         type_b: *mut InferenceType, start_idx_b: usize
     ) -> DualInferenceResult {
         debug_assert!(!std::ptr::eq(type_a, type_b), "encountered pointers to the same inference type");
         let type_a = &mut *type_a;
         let type_b = &mut *type_b;
         let mut modified_a = false;
         let mut modified_b = false;
         let mut idx_a = start_idx_a;
         let mut idx_b = start_idx_b;
         let mut depth = 1;
         while depth > 0 {
             // Advance indices if we encounter markers or equal parts
             let part_a = &type_a.parts[idx_a];
             let part_b = &type_b.parts[idx_b];
             if part_a == part_b {
                 let depth_change = part_a.depth_change();
                 depth += depth_change;
                 debug_assert_eq!(depth_change, part_b.depth_change());
                 idx_a += 1;
                 idx_b += 1;
                 continue;
+            }
             if part_a.is_marker() { idx_a += 1; continue; }
             if part_b.is_marker() { idx_b += 1; continue; }
             // Types are not equal and are both not markers
             if let Some(depth_change) = Self::infer_part_for_single_type(type_a, &mut idx_a, &type_b.parts, &mut idx_b) {
                 depth += depth_change;
                 modified_a = true;
                 continue;
+            }
             if let Some(depth_change) = Self::infer_part_for_single_type(type_b, &mut idx_b, &type_a.parts, &mut idx_a) {
                 depth += depth_change;
                 modified_b = true;
                 continue;
+            }
             // Types can not be inferred in any way: types must be incompatible
             return DualInferenceResult::Incompatible;
+        }
         if modified_a { type_a.recompute_is_done(); }
         if modified_b { type_b.recompute_is_done(); }
         // If here then we completely inferred the subtrees.
         match (modified_a, modified_b) {
             (false, false) => DualInferenceResult::Neither,
             (false, true) => DualInferenceResult::Second,
             (true, false) => DualInferenceResult::First,
             (true, true) => DualInferenceResult::Both
+        }
+    }
     /// Attempts to infer the first subtree based on the template. Like
     /// `infer_subtrees_for_both_types`, but now only applying inference to
     /// `to_infer` based on the type information in `template`.
     ///
     /// The `forced_template` flag controls whether `to_infer` is considered
     /// valid if it is more specific then the template. When `forced_template`
     /// is false, then as long as the `to_infer` and `template` types are
     /// compatible the inference will succeed. If `forced_template` is true,
     /// then `to_infer` MUST be less specific than `template` (e.g.
     /// `IntegerLike` is less specific than `UInt32`)
     fn infer_subtree_for_single_type(
         to_infer: &mut InferenceType, mut to_infer_idx: usize,
         template: &[InferenceTypePart], mut template_idx: usize,
         forced_template: bool,
     ) -> SingleInferenceResult {
         let mut modified = false;
         let mut depth = 1;
         while depth > 0 {
             let to_infer_part = &to_infer.parts[to_infer_idx];
             let template_part = &template[template_idx];
             if to_infer_part == template_part {
                 let depth_change = to_infer_part.depth_change();
                 depth += depth_change;
                 debug_assert_eq!(depth_change, template_part.depth_change());
                 to_infer_idx += 1;
                 template_idx += 1;
                 continue;
+            }
             if to_infer_part.is_marker() { to_infer_idx += 1; continue; }
             if template_part.is_marker() { template_idx += 1; continue; }
             // Types are not equal and not markers. So check if we can infer
             // anything
             if let Some(depth_change) = Self::infer_part_for_single_type(
                 to_infer, &mut to_infer_idx, template, &mut template_idx
             ) {
                 depth += depth_change;
                 modified = true;
                 continue;
+            }
             if !forced_template {
                 // We cannot infer anything, but the template may still be
                 // compatible with the type we're inferring
                 if let Some(depth_change) = Self::check_part_for_single_type(
                     template, &mut template_idx, &to_infer.parts, &mut to_infer_idx
                 ) {
                     depth += depth_change;
                     continue;
+                }
+            }
             return SingleInferenceResult::Incompatible
+        }
         if modified {
             to_infer.recompute_is_done();
             return SingleInferenceResult::Modified;
         } else {
             return SingleInferenceResult::Unmodified;
+        }
+    }
     /// Checks if both types are compatible, doesn't perform any inference
     fn check_subtrees(
         type_parts_a: &[InferenceTypePart], start_idx_a: usize,
         type_parts_b: &[InferenceTypePart], start_idx_b: usize
     ) -> bool {
         let mut depth = 1;
         let mut idx_a = start_idx_a;
         let mut idx_b = start_idx_b;
         while depth > 0 {
             let part_a = &type_parts_a[idx_a];
             let part_b = &type_parts_b[idx_b];
             if part_a == part_b {
                 let depth_change = part_a.depth_change();
                 depth += depth_change;
                 debug_assert_eq!(depth_change, part_b.depth_change());
                 idx_a += 1;
                 idx_b += 1;
                 continue;
+            }
             if part_a.is_marker() { idx_a += 1; continue; }
             if part_b.is_marker() { idx_b += 1; continue; }
             if let Some(depth_change) = Self::check_part_for_single_type(
                 type_parts_a, &mut idx_a, type_parts_b, &mut idx_b
             ) {
                 depth += depth_change;
                 continue;
+            }
             if let Some(depth_change) = Self::check_part_for_single_type(
                 type_parts_b, &mut idx_b, type_parts_a, &mut idx_a
             ) {
                 depth += depth_change;
                 continue;
+            }
             return false;
+        }
         true
+    }
     /// Performs the conversion of the inference type into a concrete type.
     /// By calling this function you must make sure that no unspecified types
     /// (e.g. Unknown or IntegerLike) exist in the type. Will not clear or check
     /// if the supplied `ConcreteType` is empty, will simply append to the parts
     /// vector.
     fn write_concrete_type(&self, concrete_type: &mut ConcreteType) {
         use InferenceTypePart as ITP;
         use ConcreteTypePart as CTP;
         // Make sure inference type is specified but concrete type is not yet specified
         debug_assert!(!self.parts.is_empty());
         concrete_type.parts.reserve(self.parts.len());
         let mut idx = 0;
         while idx < self.parts.len() {
             let part = &self.parts[idx];
             let converted_part = match part {
                 ITP::Marker(_) => {
                     // Markers are removed when writing to the concrete type.
                     idx += 1;
                     continue;
                 },
                 ITP::Unknown | ITP::NumberLike |
                 ITP::IntegerLike | ITP::ArrayLike | ITP::PortLike => {
                     // Should not happen if type inferencing works correctly: we
                     // should have returned a programmer-readable error or have
                     // inferred all types.
                     unreachable!("attempted to convert inference type part {:?} into concrete type", part);
                 },
                 ITP::Void => CTP::Void,
                 ITP::Message => CTP::Message,
                 ITP::Bool => CTP::Bool,
                 ITP::UInt8 => CTP::UInt8,
                 ITP::UInt16 => CTP::UInt16,
                 ITP::UInt32 => CTP::UInt32,
                 ITP::UInt64 => CTP::UInt64,
                 ITP::SInt8 => CTP::SInt8,
                 ITP::SInt16 => CTP::SInt16,
                 ITP::SInt32 => CTP::SInt32,
                 ITP::SInt64 => CTP::SInt64,
                 ITP::Character => CTP::Character,
                 ITP::String => {
                     // Inferred type has a 'char' subtype to simplify array
                     // checking, we remove it here.
                     debug_assert_eq!(self.parts[idx + 1], InferenceTypePart::Character);
                     idx += 1;
                     CTP::String
                 },
                 ITP::Array => CTP::Array,
                 ITP::Slice => CTP::Slice,
                 ITP::Input => CTP::Input,
                 ITP::Output => CTP::Output,
                 ITP::Tuple(num) => CTP::Tuple(*num),
                 ITP::Instance(id, num) => CTP::Instance(*id, *num),
             };
             concrete_type.parts.push(converted_part);
             idx += 1;
+        }
+    }
     /// Writes a human-readable version of the type to a string. This is used
     /// to display error messages
     fn write_display_name(
         buffer: &mut String, heap: &Heap, parts: &[InferenceTypePart], mut idx: usize
     ) -> usize {
         use InferenceTypePart as ITP;
         match &parts[idx] {
             ITP::Marker(_marker_idx) => {
                 if debug_log_enabled!() {
                     buffer.push_str(&format!("{{Marker:{}}}", *_marker_idx));
+                }
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
             },
             ITP::Unknown => buffer.push_str("?"),
             ITP::NumberLike => buffer.push_str("numberlike"),
             ITP::IntegerLike => buffer.push_str("integerlike"),
             ITP::ArrayLike => {
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push_str("[?]");
             },
             ITP::PortLike => {
                 buffer.push_str("portlike<");
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push('>');
+            }
             ITP::Void => buffer.push_str("void"),
             ITP::Bool => buffer.push_str(KW_TYPE_BOOL_STR),
             ITP::UInt8 => buffer.push_str(KW_TYPE_UINT8_STR),
             ITP::UInt16 => buffer.push_str(KW_TYPE_UINT16_STR),
             ITP::UInt32 => buffer.push_str(KW_TYPE_UINT32_STR),
             ITP::UInt64 => buffer.push_str(KW_TYPE_UINT64_STR),
             ITP::SInt8 => buffer.push_str(KW_TYPE_SINT8_STR),
             ITP::SInt16 => buffer.push_str(KW_TYPE_SINT16_STR),
             ITP::SInt32 => buffer.push_str(KW_TYPE_SINT32_STR),
             ITP::SInt64 => buffer.push_str(KW_TYPE_SINT64_STR),
             ITP::Character => buffer.push_str(KW_TYPE_CHAR_STR),
             ITP::String => {
                 buffer.push_str(KW_TYPE_STRING_STR);
                 idx += 1; // skip the 'char' subtype
             },
             ITP::Message => {
                 buffer.push_str(KW_TYPE_MESSAGE_STR);
                 buffer.push('<');
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push('>');
             },
             ITP::Array => {
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push_str("[]");
             },
             ITP::Slice => {
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push_str("[..]");
             },
             ITP::Input => {
                 buffer.push_str(KW_TYPE_IN_PORT_STR);
                 buffer.push('<');
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push('>');
             },
             ITP::Output => {
                 buffer.push_str(KW_TYPE_OUT_PORT_STR);
                 buffer.push('<');
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push('>');
             },
             ITP::Tuple(num_sub) => {
                 buffer.push('(');
                 if *num_sub > 0 {
                     idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                     for _sub_idx in 1..*num_sub {
                         buffer.push_str(", ");
                         idx = Self::write_display_name(buffer, heap, parts, idx + 1);
+                    }
+                }
                 buffer.push(')');
+            }
             ITP::Instance(definition_id, num_sub) => {
                 let definition = &heap[*definition_id];
                 buffer.push_str(definition.identifier().value.as_str());
                 if *num_sub > 0 {
                     buffer.push('<');
                     idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                     for _sub_idx in 1..*num_sub {
                         buffer.push_str(", ");
                         idx = Self::write_display_name(buffer, heap, parts, idx + 1);
+                    }
                     buffer.push('>');
+                }
             },
+        }
         idx
+    }
     /// Returns the display name of a (part of) the type tree. Will allocate a
     /// string.
     fn partial_display_name(heap: &Heap, parts: &[InferenceTypePart]) -> String {
         let mut buffer = String::with_capacity(parts.len() * 6);
         Self::write_display_name(&mut buffer, heap, parts, 0);
         buffer
+    }
     /// Returns the display name of the full type tree. Will allocate a string.
     fn display_name(&self, heap: &Heap) -> String {
         Self::partial_display_name(heap, &self.parts)
+    }
+}
 impl Default for InferenceType {
     fn default() -> Self {
         Self{
             has_marker: false,
             is_done: false,
             parts: Vec::new(),
+        }
+    }
+}
 /// Iterator over the subtrees that follow a marker in an `InferenceType`
 /// instance. Returns immutable slices over the internal parts
 struct InferenceTypeMarkerIter<'a> {
     parts: &'a [InferenceTypePart],
     idx: usize,
+}
 impl<'a> InferenceTypeMarkerIter<'a> {
     fn new(parts: &'a [InferenceTypePart]) -> Self {
         Self{ parts, idx: 0 }
+    }
+}
 impl<'a> Iterator for InferenceTypeMarkerIter<'a> {
     type Item = (u32, &'a [InferenceTypePart]);
     fn next(&mut self) -> Option<Self::Item> {
         // Iterate until we find a marker
         while self.idx < self.parts.len() {
             if let InferenceTypePart::Marker(marker) = self.parts[self.idx] {
                 // Found a marker, find the subtree end
                 let start_idx = self.idx + 1;
                 let end_idx = InferenceType::find_subtree_end_idx(self.parts, start_idx);
                 // Modify internal index, then return items
                 self.idx = end_idx;
                 return Some((marker, &self.parts[start_idx..end_idx]));
+            }
             self.idx += 1;
+        }
         None
+    }
+}
 #[derive(Debug, PartialEq, Eq)]
 enum DualInferenceResult {
     Neither,        // neither argument is clarified
     First,          // first argument is clarified using the second one
     Second,         // second argument is clarified using the first one
     Both,           // both arguments are clarified
     Incompatible,   // types are incompatible: programmer error
+}
 impl DualInferenceResult {
     fn modified_lhs(&self) -> bool {
         match self {
             DualInferenceResult::First | DualInferenceResult::Both => true,
             _ => false
+        }
+    }
     fn modified_rhs(&self) -> bool {
         match self {
             DualInferenceResult::Second | DualInferenceResult::Both => true,
             _ => false
+        }
+    }
+}
 #[derive(Debug, PartialEq, Eq)]
 enum SingleInferenceResult {
     Unmodified,
     Modified,
     Incompatible
+}
 enum DefinitionType{
     Component(ComponentDefinitionId),
     Function(FunctionDefinitionId),
+}
 impl DefinitionType {
     fn definition_id(&self) -> DefinitionId {
         match self {
             DefinitionType::Component(v) => v.upcast(),
             DefinitionType::Function(v) => v.upcast(),
+        }
+    }
+}
 pub(crate) struct ResolveQueueElement {
     // Note that using the `definition_id` and the `monomorph_idx` one may
     // query the type table for the full procedure type, thereby retrieving
     // the polymorphic arguments to the procedure.
     pub(crate) root_id: RootId,
     pub(crate) definition_id: DefinitionId,
     pub(crate) reserved_monomorph_idx: i32,
+}
 pub(crate) type ResolveQueue = Vec<ResolveQueueElement>;
 #[derive(Clone)]
 struct InferenceExpression {
     expr_type: InferenceType,       // result type from expression
     expr_id: ExpressionId,          // expression that is evaluated
     field_or_monomorph_idx: i32,    // index of field, of index of monomorph array in type table
     extra_data_idx: i32,            // index of extra data needed for inference
+}
 impl Default for InferenceExpression {
     fn default() -> Self {
         Self{
             expr_type: InferenceType::default(),
             expr_id: ExpressionId::new_invalid(),
             field_or_monomorph_idx: -1,
             extra_data_idx: -1,
+        }
+    }
+}
 /// This particular visitor will recurse depth-first into the AST and ensures
 /// that all expressions have the appropriate types.
 pub(crate) struct PassTyping {
     // Current definition we're typechecking.
     reserved_idx: i32,
     definition_type: DefinitionType,
     poly_vars: Vec<ConcreteType>,
-    // Buffers for iteration over substatements and subexpressions
+    // Buffers for iteration over various types
     var_buffer: ScopedBuffer<VariableId>,
     expr_buffer: ScopedBuffer<ExpressionId>,
     stmt_buffer: ScopedBuffer<StatementId>,
     bool_buffer: ScopedBuffer<bool>,
     // Mapping from parser type to inferred type. We attempt to continue to
     // specify these types until we're stuck or we've fully determined the type.
     var_types: HashMap<VariableId, VarData>,            // types of variables
     expr_types: Vec<InferenceExpression>,                     // will be transferred to type table at end
     extra_data: Vec<ExtraData>,       // data for polymorph inference
     // Keeping track of which expressions need to be reinferred because the
     // expressions they're linked to made progression on an associated type
     expr_queued: DequeSet<i32>,
+}
 // TODO: @Rename, this is used for a lot of type inferencing. It seems like
 //  there is a different underlying architecture waiting to surface.
 struct ExtraData {
     expr_id: ExpressionId, // the expression with which this data is associated
     definition_id: DefinitionId, // the definition, only used for user feedback
     /// Progression of polymorphic variables (if any)
     poly_vars: Vec<InferenceType>,
     /// Progression of types of call arguments or struct members
     embedded: Vec<InferenceType>,
     returned: InferenceType,
+}
 impl Default for ExtraData {
     fn default() -> Self {
         Self{
             expr_id: ExpressionId::new_invalid(),
             definition_id: DefinitionId::new_invalid(),
             poly_vars: Vec::new(),
             embedded: Vec::new(),
             returned: InferenceType::default(),
+        }
+    }
+}
 struct VarData {
     /// Type of the variable
     var_type: InferenceType,
     /// VariableExpressions that use the variable
     used_at: Vec<ExpressionId>,
     /// For channel statements we link to the other variable such that when one
     /// channel's interior type is resolved, we can also resolve the other one.
     linked_var: Option<VariableId>,
+}
 impl VarData {
     fn new_channel(var_type: InferenceType, other_port: VariableId) -> Self {
         Self{ var_type, used_at: Vec::new(), linked_var: Some(other_port) }
+    }
     fn new_local(var_type: InferenceType) -> Self {
         Self{ var_type, used_at: Vec::new(), linked_var: None }
+    }
+}
 impl PassTyping {
     pub(crate) fn new() -> Self {
         PassTyping {
             reserved_idx: -1,
             definition_type: DefinitionType::Function(FunctionDefinitionId::new_invalid()),
             poly_vars: Vec::new(),
             var_buffer: ScopedBuffer::with_capacity(BUFFER_INIT_CAPACITY),
             expr_buffer: ScopedBuffer::with_capacity(BUFFER_INIT_CAPACITY),
             stmt_buffer: ScopedBuffer::with_capacity(BUFFER_INIT_CAPACITY),
             bool_buffer: ScopedBuffer::with_capacity(16),
             var_types: HashMap::new(),
             expr_types: Vec::new(),
             extra_data: Vec::new(),
             expr_queued: DequeSet::new(),
+        }
+    }
     pub(crate) fn queue_module_definitions(ctx: &mut Ctx, queue: &mut ResolveQueue) {
         debug_assert_eq!(ctx.module().phase, ModuleCompilationPhase::ValidatedAndLinked);
         let root_id = ctx.module().root_id;
         let root = &ctx.heap.protocol_descriptions[root_id];
         for definition_id in &root.definitions {
             let definition = &ctx.heap[*definition_id];
             let first_concrete_part = match definition {
                 Definition::Function(definition) => {
                     if definition.poly_vars.is_empty() {
                         Some(ConcreteTypePart::Function(*definition_id, 0))
                     } else {
                         None
+                    }
+                }
                 Definition::Component(definition) => {
                     if definition.poly_vars.is_empty() {
                         Some(ConcreteTypePart::Component(*definition_id, 0))
                     } else {
                         None
+                    }
                 },
                 Definition::Enum(_) | Definition::Struct(_) | Definition::Union(_) => None,
             };
             if let Some(first_concrete_part) = first_concrete_part {
                 let concrete_type = ConcreteType{ parts: vec![first_concrete_part] };
                 let reserved_idx = ctx.types.reserve_procedure_monomorph_index(definition_id, concrete_type);
                 queue.push(ResolveQueueElement{
                     root_id,
                     definition_id: *definition_id,
                     reserved_monomorph_idx: reserved_idx,
                 })
+            }
+        }
+    }
     pub(crate) fn handle_module_definition(
         &mut self, ctx: &mut Ctx, queue: &mut ResolveQueue, element: ResolveQueueElement
     ) -> VisitorResult {
         self.reset();
         debug_assert_eq!(ctx.module().root_id, element.root_id);
         debug_assert!(self.poly_vars.is_empty());
         // Prepare for visiting the definition
         self.reserved_idx = element.reserved_monomorph_idx;
         let proc_base = ctx.types.get_base_definition(&element.definition_id).unwrap();
         if proc_base.is_polymorph {
             let monomorph = ctx.types.get_monomorph(element.reserved_monomorph_idx);
             for poly_arg in monomorph.concrete_type.embedded_iter(0) {
                 self.poly_vars.push(ConcreteType{ parts: Vec::from(poly_arg) });
+            }
+        }
         // Visit the definition, setting up the type resolving process, then
         // (attempt to) resolve all types
         self.visit_definition(ctx, element.definition_id)?;
         self.resolve_types(ctx, queue)?;
         Ok(())
+    }
     fn reset(&mut self) {
         self.reserved_idx = -1;
         self.definition_type = DefinitionType::Function(FunctionDefinitionId::new_invalid());
         self.poly_vars.clear();
         self.var_types.clear();
         self.expr_types.clear();
         self.extra_data.clear();
         self.expr_queued.clear();
+    }
+}
 impl Visitor for PassTyping {
     // Definitions
     fn visit_component_definition(&mut self, ctx: &mut Ctx, id: ComponentDefinitionId) -> VisitorResult {
         self.definition_type = DefinitionType::Component(id);
         let comp_def = &ctx.heap[id];
         debug_assert_eq!(comp_def.poly_vars.len(), self.poly_vars.len(), "component polyvars do not match imposed polyvars");
         debug_log!("{}", "-".repeat(50));
         debug_log!("Visiting component '{}': {}", comp_def.identifier.value.as_str(), id.0.index);
         debug_log!("{}", "-".repeat(50));
         // Reserve data for expression types
         debug_assert!(self.expr_types.is_empty());
         self.expr_types.resize(comp_def.num_expressions_in_body as usize, Default::default());
         // Visit parameters
         let section = self.var_buffer.start_section_initialized(comp_def.parameters.as_slice());
         for param_id in section.iter_copied() {
             let param = &ctx.heap[param_id];
             let var_type = self.determine_inference_type_from_parser_type_elements(&param.parser_type.elements, true);
             debug_assert!(var_type.is_done, "expected component arguments to be concrete types");
             self.var_types.insert(param_id, VarData::new_local(var_type));
+        }
         section.forget();
         // Visit the body and all of its expressions
         let body_stmt_id = ctx.heap[id].body;
         self.visit_block_stmt(ctx, body_stmt_id)
+    }
     fn visit_function_definition(&mut self, ctx: &mut Ctx, id: FunctionDefinitionId) -> VisitorResult {
         self.definition_type = DefinitionType::Function(id);
         let func_def = &ctx.heap[id];
         debug_assert_eq!(func_def.poly_vars.len(), self.poly_vars.len(), "function polyvars do not match imposed polyvars");
         debug_log!("{}", "-".repeat(50));
         debug_log!("Visiting function '{}': {}", func_def.identifier.value.as_str(), id.0.index);
         if debug_log_enabled!() {
             debug_log!("Polymorphic variables:");
             for (_idx, poly_var) in self.poly_vars.iter().enumerate() {
                 let mut infer_type_parts = Vec::new();
                 Self::determine_inference_type_from_concrete_type(
                     &mut infer_type_parts, &poly_var.parts
                 );
                 let _infer_type = InferenceType::new(false, true, infer_type_parts);
                 debug_log!(" - [{:03}] {:?}", _idx, _infer_type.display_name(&ctx.heap));
+            }
+        }
         debug_log!("{}", "-".repeat(50));
         // Reserve data for expression types
         debug_assert!(self.expr_types.is_empty());
         self.expr_types.resize(func_def.num_expressions_in_body as usize, Default::default());
         // Visit parameters
         let section = self.var_buffer.start_section_initialized(func_def.parameters.as_slice());
         for param_id in section.iter_copied() {
             let param = &ctx.heap[param_id];
             let var_type = self.determine_inference_type_from_parser_type_elements(&param.parser_type.elements, true);
             debug_assert!(var_type.is_done, "expected function arguments to be concrete types");
             self.var_types.insert(param_id, VarData::new_local(var_type));
+        }
         section.forget();
         // Visit all of the expressions within the body
         let body_stmt_id = ctx.heap[id].body;
         self.visit_block_stmt(ctx, body_stmt_id)
+    }
     // Statements
     fn visit_block_stmt(&mut self, ctx: &mut Ctx, id: BlockStatementId) -> VisitorResult {
         // Transfer statements for traversal
         let block = &ctx.heap[id];
         let section = self.stmt_buffer.start_section_initialized(block.statements.as_slice());
         for stmt_id in section.iter_copied() {
             self.visit_stmt(ctx, stmt_id)?;
+        }
         section.forget();
         Ok(())
+    }
     fn visit_local_memory_stmt(&mut self, ctx: &mut Ctx, id: MemoryStatementId) -> VisitorResult {
         let memory_stmt = &ctx.heap[id];
         let local = &ctx.heap[memory_stmt.variable];
         let var_type = self.determine_inference_type_from_parser_type_elements(&local.parser_type.elements, true);
         self.var_types.insert(memory_stmt.variable, VarData::new_local(var_type));
         Ok(())
+    }
     fn visit_local_channel_stmt(&mut self, ctx: &mut Ctx, id: ChannelStatementId) -> VisitorResult {
         let channel_stmt = &ctx.heap[id];
         let from_local = &ctx.heap[channel_stmt.from];
         let from_var_type = self.determine_inference_type_from_parser_type_elements(&from_local.parser_type.elements, true);
         self.var_types.insert(from_local.this, VarData::new_channel(from_var_type, channel_stmt.to));
         let to_local = &ctx.heap[channel_stmt.to];
         let to_var_type = self.determine_inference_type_from_parser_type_elements(&to_local.parser_type.elements, true);
         self.var_types.insert(to_local.this, VarData::new_channel(to_var_type, channel_stmt.from));
         Ok(())
+    }
     fn visit_labeled_stmt(&mut self, ctx: &mut Ctx, id: LabeledStatementId) -> VisitorResult {
         let labeled_stmt = &ctx.heap[id];
         let substmt_id = labeled_stmt.body;
         self.visit_stmt(ctx, substmt_id)
+    }
     fn visit_if_stmt(&mut self, ctx: &mut Ctx, id: IfStatementId) -> VisitorResult {
         let if_stmt = &ctx.heap[id];
         let true_body_id = if_stmt.true_body;
         let false_body_id = if_stmt.false_body;
         let test_expr_id = if_stmt.test;
         self.visit_expr(ctx, test_expr_id)?;
         self.visit_block_stmt(ctx, true_body_id)?;
         if let Some(false_body_id) = false_body_id {
             self.visit_block_stmt(ctx, false_body_id)?;
+        }
         Ok(())
+    }
     fn visit_while_stmt(&mut self, ctx: &mut Ctx, id: WhileStatementId) -> VisitorResult {
         let while_stmt = &ctx.heap[id];
         let body_id = while_stmt.body;
         let test_expr_id = while_stmt.test;
         self.visit_expr(ctx, test_expr_id)?;
         self.visit_block_stmt(ctx, body_id)?;
         Ok(())
+    }
     fn visit_synchronous_stmt(&mut self, ctx: &mut Ctx, id: SynchronousStatementId) -> VisitorResult {
         let sync_stmt = &ctx.heap[id];
         let body_id = sync_stmt.body;
         self.visit_block_stmt(ctx, body_id)
+    }
     fn visit_fork_stmt(&mut self, ctx: &mut Ctx, id: ForkStatementId) -> VisitorResult {
         let fork_stmt = &ctx.heap[id];
         let left_body_id = fork_stmt.left_body;
         let right_body_id = fork_stmt.right_body;
         self.visit_block_stmt(ctx, left_body_id)?;
         if let Some(right_body_id) = right_body_id {
             self.visit_block_stmt(ctx, right_body_id)?;
+        }
         Ok(())
+    }
     fn visit_return_stmt(&mut self, ctx: &mut Ctx, id: ReturnStatementId) -> VisitorResult {
         let return_stmt = &ctx.heap[id];
         debug_assert_eq!(return_stmt.expressions.len(), 1);
         let expr_id = return_stmt.expressions[0];
         self.visit_expr(ctx, expr_id)
+    }
     fn visit_new_stmt(&mut self, ctx: &mut Ctx, id: NewStatementId) -> VisitorResult {
         let new_stmt = &ctx.heap[id];
         let call_expr_id = new_stmt.expression;
         self.visit_call_expr(ctx, call_expr_id)
+    }
     fn visit_expr_stmt(&mut self, ctx: &mut Ctx, id: ExpressionStatementId) -> VisitorResult {
         let expr_stmt = &ctx.heap[id];
         let subexpr_id = expr_stmt.expression;
         self.visit_expr(ctx, subexpr_id)
+    }
     // Expressions
     fn visit_assignment_expr(&mut self, ctx: &mut Ctx, id: AssignmentExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let assign_expr = &ctx.heap[id];
         let left_expr_id = assign_expr.left;
         let right_expr_id = assign_expr.right;
         self.visit_expr(ctx, left_expr_id)?;
         self.visit_expr(ctx, right_expr_id)?;
         self.progress_assignment_expr(ctx, id)
+    }
     fn visit_binding_expr(&mut self, ctx: &mut Ctx, id: BindingExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let binding_expr = &ctx.heap[id];
         let bound_to_id = binding_expr.bound_to;
         let bound_from_id = binding_expr.bound_from;
         self.visit_expr(ctx, bound_to_id)?;
         self.visit_expr(ctx, bound_from_id)?;
         self.progress_binding_expr(ctx, id)
+    }
     fn visit_conditional_expr(&mut self, ctx: &mut Ctx, id: ConditionalExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let conditional_expr = &ctx.heap[id];
         let test_expr_id = conditional_expr.test;
         let true_expr_id = conditional_expr.true_expression;
         let false_expr_id = conditional_expr.false_expression;
         self.visit_expr(ctx, test_expr_id)?;
         self.visit_expr(ctx, true_expr_id)?;
         self.visit_expr(ctx, false_expr_id)?;
         self.progress_conditional_expr(ctx, id)
+    }
     fn visit_binary_expr(&mut self, ctx: &mut Ctx, id: BinaryExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let binary_expr = &ctx.heap[id];
         let lhs_expr_id = binary_expr.left;
         let rhs_expr_id = binary_expr.right;
         self.visit_expr(ctx, lhs_expr_id)?;
         self.visit_expr(ctx, rhs_expr_id)?;
         self.progress_binary_expr(ctx, id)
+    }
     fn visit_unary_expr(&mut self, ctx: &mut Ctx, id: UnaryExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let unary_expr = &ctx.heap[id];
         let arg_expr_id = unary_expr.expression;
         self.visit_expr(ctx, arg_expr_id)?;
         self.progress_unary_expr(ctx, id)
+    }
     fn visit_indexing_expr(&mut self, ctx: &mut Ctx, id: IndexingExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let indexing_expr = &ctx.heap[id];
         let subject_expr_id = indexing_expr.subject;
         let index_expr_id = indexing_expr.index;
         self.visit_expr(ctx, subject_expr_id)?;
         self.visit_expr(ctx, index_expr_id)?;
         self.progress_indexing_expr(ctx, id)
+    }
     fn visit_slicing_expr(&mut self, ctx: &mut Ctx, id: SlicingExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let slicing_expr = &ctx.heap[id];
         let subject_expr_id = slicing_expr.subject;
         let from_expr_id = slicing_expr.from_index;
         let to_expr_id = slicing_expr.to_index;
         self.visit_expr(ctx, subject_expr_id)?;
         self.visit_expr(ctx, from_expr_id)?;
         self.visit_expr(ctx, to_expr_id)?;
         self.progress_slicing_expr(ctx, id)
+    }
     fn visit_select_expr(&mut self, ctx: &mut Ctx, id: SelectExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let select_expr = &ctx.heap[id];
         let subject_expr_id = select_expr.subject;
         self.visit_expr(ctx, subject_expr_id)?;
         self.progress_select_expr(ctx, id)
+    }
     fn visit_literal_expr(&mut self, ctx: &mut Ctx, id: LiteralExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let literal_expr = &ctx.heap[id];
         match &literal_expr.value {
             Literal::Null | Literal::False | Literal::True |
             Literal::Integer(_) | Literal::Character(_) | Literal::String(_) => {
                 // No subexpressions
             },
             Literal::Struct(literal) => {
                 let mut expr_ids = self.expr_buffer.start_section();
                 for field in &literal.fields {
                     expr_ids.push(field.value);
+                }
                 self.insert_initial_struct_polymorph_data(ctx, id);
                 for expr_id in expr_ids.iter_copied() {
                     self.visit_expr(ctx, expr_id)?;
+                }
                 expr_ids.forget();
             },
             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
                 let expr_ids = self.expr_buffer.start_section_initialized(literal.values.as_slice());
                 self.insert_initial_union_polymorph_data(ctx, id);
                 for expr_id in expr_ids.iter_copied() {
                     self.visit_expr(ctx, expr_id)?;
+                }
                 expr_ids.forget();
             },
             Literal::Array(expressions) | Literal::Tuple(expressions) => {
                 let expr_ids = self.expr_buffer.start_section_initialized(expressions.as_slice());
                 for expr_id in expr_ids.iter_copied() {
                     self.visit_expr(ctx, expr_id)?;
+                }
                 expr_ids.forget();
+            }
+        }
         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
         let expr_ids = self.expr_buffer.start_section_initialized(call_expr.arguments.as_slice());
         for arg_expr_id in expr_ids.iter_copied() {
             self.visit_expr(ctx, arg_expr_id)?;
+        }
         expr_ids.forget();
         self.progress_call_expr(ctx, id)
+    }
     fn visit_variable_expr(&mut self, ctx: &mut Ctx, id: VariableExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let var_expr = &ctx.heap[id];
         debug_assert!(var_expr.declaration.is_some());
         // Not pretty: if a binding expression, then this is the first time we
         // encounter the variable, so we still need to insert the variable data.
         let declaration = &ctx.heap[var_expr.declaration.unwrap()];
         if !self.var_types.contains_key(&declaration.this)  {
             debug_assert!(declaration.kind == VariableKind::Binding);
             let var_type = self.determine_inference_type_from_parser_type_elements(
                 &declaration.parser_type.elements, true
             );
             self.var_types.insert(declaration.this, VarData{
                 var_type,
                 used_at: vec![upcast_id],
                 linked_var: None
             });
         } else {
             let var_data = self.var_types.get_mut(&declaration.this).unwrap();
             var_data.used_at.push(upcast_id);
+        }
         self.progress_variable_expr(ctx, id)
+    }
+}
 impl PassTyping {
     #[allow(dead_code)] // used when debug flag at the top of this file is true.
     fn debug_get_display_name(&self, ctx: &Ctx, expr_id: ExpressionId) -> String {
         let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition();
         let expr_type = &self.expr_types[expr_idx as usize].expr_type;
         expr_type.display_name(&ctx.heap)
+    }
     fn resolve_types(&mut self, ctx: &mut Ctx, queue: &mut ResolveQueue) -> Result<(), ParseError> {
         // Keep inferring until we can no longer make any progress
         while !self.expr_queued.is_empty() {
             // Make as much progress as possible without forced integer
             // inference.
             while !self.expr_queued.is_empty() {
                 let next_expr_idx = self.expr_queued.pop_front().unwrap();
                 self.progress_expr(ctx, next_expr_idx)?;
+            }
             // Nothing is queued anymore. However we might have integer literals
             // whose type cannot be inferred. For convenience's sake we'll
             // infer these to be s32.
             for (infer_expr_idx, infer_expr) in self.expr_types.iter_mut().enumerate() {
                 let expr_type = &mut infer_expr.expr_type;
                 if !expr_type.is_done && expr_type.parts.len() == 1 && expr_type.parts[0] == InferenceTypePart::IntegerLike {
                     // Force integer type to s32
                     println!("DEBUG: Autoinferring (idx {}) {}", infer_expr.expr_id.index, String::from_utf8_lossy(ctx.module().source.section_at_span(ctx.heap[infer_expr.expr_id].full_span())));
                     expr_type.parts[0] = InferenceTypePart::SInt32;
                     expr_type.is_done = true;
                     // Requeue expression (and its parent, if it exists)
                     self.expr_queued.push_back(infer_expr_idx as i32);
                     if let Some(parent_expr) = ctx.heap[infer_expr.expr_id].parent_expr_id() {
                         let parent_idx = ctx.heap[parent_expr].get_unique_id_in_definition();
                         self.expr_queued.push_back(parent_idx);
+                    }
+                }
+            }
+        }
         // Helper for transferring polymorphic variables to concrete types and
         // checking if they're completely specified
         fn inference_type_to_concrete_type(
             ctx: &Ctx, expr_id: ExpressionId, inference: &Vec<InferenceType>,
             first_concrete_part: ConcreteTypePart,
         ) -> Result<ConcreteType, ParseError> {
             // Prepare storage vector
             let mut num_inference_parts = 0;
             for inference_type in inference {
                 num_inference_parts += inference_type.parts.len();
+            }
             let mut concrete_type = ConcreteType{
                 parts: Vec::with_capacity(1 + num_inference_parts),
             };
             concrete_type.parts.push(first_concrete_part);
             // Go through all polymorphic arguments and add them to the concrete
             // types.
             for (poly_idx, poly_type) in inference.iter().enumerate() {
                 if !poly_type.is_done {
                     let expr = &ctx.heap[expr_id];
                     let definition = match expr {
                         Expression::Call(expr) => expr.definition,
                         Expression::Literal(expr) => match &expr.value {
                             Literal::Enum(lit) => lit.definition,
                             Literal::Union(lit) => lit.definition,
                             Literal::Struct(lit) => lit.definition,
                             _ => unreachable!()
                         },
                         _ => unreachable!(),
                     };
                     let poly_vars = ctx.heap[definition].poly_vars();
                     return Err(ParseError::new_error_at_span(
                         &ctx.module().source, expr.operation_span(), format!(
                             "could not fully infer the type of polymorphic variable '{}' of this expression (got '{}')",
                             poly_vars[poly_idx].value.as_str(), poly_type.display_name(&ctx.heap)
+                        )
                     ));
+                }
                 poly_type.write_concrete_type(&mut concrete_type);
+            }
             Ok(concrete_type)
+        }
         // Inference is now done. But we may still have uninferred types. So we
         // check for these.
         for infer_expr in self.expr_types.iter_mut() {
             if !infer_expr.expr_type.is_done {
                 let expr = &ctx.heap[infer_expr.expr_id];
                 return Err(ParseError::new_error_at_span(
                     &ctx.module().source, expr.full_span(), format!(
                         "could not fully infer the type of this expression (got '{}')",
                         infer_expr.expr_type.display_name(&ctx.heap)
+                    )
                 ));
+            }
             // Expression is fine, check if any extra data is attached
             if infer_expr.extra_data_idx < 0 { continue; }
             // Extra data is attached, perform typechecking and transfer
             // resolved information to the expression
             let extra_data = &self.extra_data[infer_expr.extra_data_idx as usize];
             // Note that only call and literal expressions need full inference.
             // Select expressions also use `extra_data`, but only for temporary
             // storage of the struct type whose field it is selecting.
             match &ctx.heap[extra_data.expr_id] {
                 Expression::Call(expr) => {
                     // Check if it is not a builtin function. If not, then
                     // construct the first part of the concrete type.
                     let first_concrete_part = if expr.method == Method::UserFunction {
                         ConcreteTypePart::Function(expr.definition, extra_data.poly_vars.len() as u32)
                     } else if expr.method == Method::UserComponent {
                         ConcreteTypePart::Component(expr.definition, extra_data.poly_vars.len() as u32)
                     } else {
                         // Builtin function
                         continue;
                     };
                     let definition_id = expr.definition;
                     let concrete_type = inference_type_to_concrete_type(
                         ctx, extra_data.expr_id, &extra_data.poly_vars, first_concrete_part
                     )?;
                     match ctx.types.get_procedure_monomorph_index(&definition_id, &concrete_type.parts) {
                         Some(reserved_idx) => {
                             // Already typechecked, or already put into the resolve queue
                             infer_expr.field_or_monomorph_idx = reserved_idx;
                         },
                         None => {
                             // Not typechecked yet, so add an entry in the queue
                             let reserved_idx = ctx.types.reserve_procedure_monomorph_index(&definition_id, concrete_type);
                             infer_expr.field_or_monomorph_idx = reserved_idx;
                             queue.push(ResolveQueueElement {
                                 root_id: ctx.heap[definition_id].defined_in(),
                                 definition_id,
                                 reserved_monomorph_idx: reserved_idx,
                             });
+                        }
+                    }
                 },
                 Expression::Literal(expr) => {
                     let definition_id = match &expr.value {
                         Literal::Enum(lit) => lit.definition,
                         Literal::Union(lit) => lit.definition,
                         Literal::Struct(lit) => lit.definition,
                         _ => unreachable!(),
                     };
                     let first_concrete_part = ConcreteTypePart::Instance(definition_id, extra_data.poly_vars.len() as u32);
                     let concrete_type = inference_type_to_concrete_type(
                         ctx, extra_data.expr_id, &extra_data.poly_vars, first_concrete_part
                     )?;
                     let mono_index = ctx.types.add_data_monomorph(ctx.modules, ctx.heap, ctx.arch, definition_id, concrete_type)?;
                     infer_expr.field_or_monomorph_idx = mono_index;
                 },
                 Expression::Select(_) => {
                     debug_assert!(infer_expr.field_or_monomorph_idx >= 0);
                 },
                 _ => {
                     unreachable!("handling extra data for expression {:?}", &ctx.heap[extra_data.expr_id]);
+                }
+            }
+        }
         // Every expression checked, and new monomorphs are queued. Transfer the
         // expression information to the type table.
         let procedure_arguments = match &self.definition_type {
             DefinitionType::Component(id) => {
                 let definition = &ctx.heap[*id];
                 &definition.parameters
             },
             DefinitionType::Function(id) => {
                 let definition = &ctx.heap[*id];
                 &definition.parameters
             },
         };
         let target = ctx.types.get_procedure_monomorph_mut(self.reserved_idx);
         debug_assert!(target.arg_types.is_empty()); // makes sure we never queue a procedure's type inferencing twice
         debug_assert!(target.expr_data.is_empty());
         // - Write the arguments to the procedure
         target.arg_types.reserve(procedure_arguments.len());
         for argument_id in procedure_arguments {
             let mut concrete = ConcreteType::default();
             let argument_type = self.var_types.get(argument_id).unwrap();
             argument_type.var_type.write_concrete_type(&mut concrete);
             target.arg_types.push(concrete);
+        }
         // - Write the expression data
         target.expr_data.reserve(self.expr_types.len());
         for infer_expr in self.expr_types.iter() {
             let mut concrete = ConcreteType::default();
             infer_expr.expr_type.write_concrete_type(&mut concrete);
             target.expr_data.push(MonomorphExpression{
                 expr_type: concrete,
                 field_or_monomorph_idx: infer_expr.field_or_monomorph_idx
             });
+        }
         Ok(())
+    }
     fn progress_expr(&mut self, ctx: &mut Ctx, idx: i32) -> Result<(), ParseError> {
         let id = self.expr_types[idx as usize].expr_id;
         match &ctx.heap[id] {
             Expression::Assignment(expr) => {
                 let id = expr.this;
                 self.progress_assignment_expr(ctx, id)
             },
             Expression::Binding(expr) => {
                 let id = expr.this;
                 self.progress_binding_expr(ctx, id)
             },
             Expression::Conditional(expr) => {
                 let id = expr.this;
                 self.progress_conditional_expr(ctx, id)
             },
             Expression::Binary(expr) => {
                 let id = expr.this;
                 self.progress_binary_expr(ctx, id)
             },
             Expression::Unary(expr) => {
                 let id = expr.this;
                 self.progress_unary_expr(ctx, id)
             },
             Expression::Indexing(expr) => {
                 let id = expr.this;
                 self.progress_indexing_expr(ctx, id)
             },
             Expression::Slicing(expr) => {
                 let id = expr.this;
                 self.progress_slicing_expr(ctx, id)
             },
             Expression::Select(expr) => {
                 let id = expr.this;
                 self.progress_select_expr(ctx, id)
             },
             Expression::Literal(expr) => {
                 let id = expr.this;
                 self.progress_literal_expr(ctx, id)
             },
             Expression::Cast(expr) => {
                 let id = expr.this;
                 self.progress_cast_expr(ctx, id)
             },
             Expression::Call(expr) => {
                 let id = expr.this;
                 self.progress_call_expr(ctx, id)
             },
             Expression::Variable(expr) => {
                 let id = expr.this;
                 self.progress_variable_expr(ctx, id)
+            }
+        }
+    }
     fn progress_assignment_expr(&mut self, ctx: &mut Ctx, id: AssignmentExpressionId) -> Result<(), ParseError> {
         use AssignmentOperator as AO;
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let arg1_expr_id = expr.left;
         let arg2_expr_id = expr.right;
         debug_log!("Assignment expr '{:?}': {}", expr.operation, upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Arg1 type: {}", self.debug_get_display_name(ctx, arg1_expr_id));
         debug_log!("   - Arg2 type: {}", self.debug_get_display_name(ctx, arg2_expr_id));
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         // Assignment does not return anything (it operates like a statement)
         let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &VOID_TEMPLATE)?;
         // Apply forced constraint to LHS value
         let progress_forced = match expr.operation {
             AO::Set =>
                 false,
             AO::Concatenated =>
                 self.apply_template_constraint(ctx, arg1_expr_id, &ARRAYLIKE_TEMPLATE)?,
             AO::Multiplied | AO::Divided | AO::Added | AO::Subtracted =>
                 self.apply_template_constraint(ctx, arg1_expr_id, &NUMBERLIKE_TEMPLATE)?,
             AO::Remained | AO::ShiftedLeft | AO::ShiftedRight |
             AO::BitwiseAnded | AO::BitwiseXored | AO::BitwiseOred =>
                 self.apply_template_constraint(ctx, arg1_expr_id, &INTEGERLIKE_TEMPLATE)?,
         };
         let (progress_arg1, progress_arg2) = self.apply_equal2_constraint(
             ctx, upcast_id, arg1_expr_id, 0, arg2_expr_id, 0
         )?;
         debug_log!(" * After:");
         debug_log!("   - Arg1 type [{}]: {}", progress_forced || progress_arg1, self.debug_get_display_name(ctx, arg1_expr_id));
         debug_log!("   - Arg2 type [{}]: {}", progress_arg2, self.debug_get_display_name(ctx, arg2_expr_id));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_forced || progress_arg1 { self.queue_expr(ctx, arg1_expr_id); }
         if progress_arg2 { self.queue_expr(ctx, arg2_expr_id); }
         Ok(())
+    }
     fn progress_binding_expr(&mut self, ctx: &mut Ctx, id: BindingExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let binding_expr = &ctx.heap[id];
         let bound_from_id = binding_expr.bound_from;
         let bound_to_id = binding_expr.bound_to;
         // Output is always a boolean. The two arguments should be of equal
         // type.
         let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
         let (progress_from, progress_to) = self.apply_equal2_constraint(ctx, upcast_id, bound_from_id, 0, bound_to_id, 0)?;
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_from { self.queue_expr(ctx, bound_from_id); }
         if progress_to { self.queue_expr(ctx, bound_to_id); }
         Ok(())
+    }
     fn progress_conditional_expr(&mut self, ctx: &mut Ctx, id: ConditionalExpressionId) -> Result<(), ParseError> {
         // Note: test expression type is already enforced
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let arg1_expr_id = expr.true_expression;
         let arg2_expr_id = expr.false_expression;
         debug_log!("Conditional expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Arg1 type: {}", self.debug_get_display_name(ctx, arg1_expr_id));
         debug_log!("   - Arg2 type: {}", self.debug_get_display_name(ctx, arg2_expr_id));
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         // I keep confusing myself: this applies equality of types between the
         // condition branches' types, and the result from the conditional
         // expression, because the result from the conditional is one of the
         // branches.
         let (progress_expr, progress_arg1, progress_arg2) = self.apply_equal3_constraint(
             ctx, upcast_id, arg1_expr_id, arg2_expr_id, 0
         )?;
         debug_log!(" * After:");
         debug_log!("   - Arg1 type [{}]: {}", progress_arg1, self.debug_get_display_name(ctx, arg1_expr_id));
         debug_log!("   - Arg2 type [{}]: {}", progress_arg2, self.debug_get_display_name(ctx, arg2_expr_id));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_arg1 { self.queue_expr(ctx, arg1_expr_id); }
         if progress_arg2 { self.queue_expr(ctx, arg2_expr_id); }
         Ok(())
+    }
     fn progress_binary_expr(&mut self, ctx: &mut Ctx, id: BinaryExpressionId) -> Result<(), ParseError> {
         // Note: our expression type might be fixed by our parent, but we still
         // need to make sure it matches the type associated with our operation.
         use BinaryOperator as BO;
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let arg1_id = expr.left;
         let arg2_id = expr.right;
         debug_log!("Binary expr '{:?}': {}", expr.operation, upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Arg1 type: {}", self.debug_get_display_name(ctx, arg1_id));
         debug_log!("   - Arg2 type: {}", self.debug_get_display_name(ctx, arg2_id));
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         let (progress_expr, progress_arg1, progress_arg2) = match expr.operation {
             BO::Concatenate => {
                 // Two cases: if one of the arguments or the output type is a
                 // string, then all must be strings. Otherwise the arguments
                 // must be arraylike and the output will be a array.
                 let (expr_is_str, expr_is_not_str) = self.type_is_certainly_or_certainly_not_string(ctx, upcast_id);
                 let (arg1_is_str, arg1_is_not_str) = self.type_is_certainly_or_certainly_not_string(ctx, arg1_id);
                 let (arg2_is_str, arg2_is_not_str) = self.type_is_certainly_or_certainly_not_string(ctx, arg2_id);
                 let someone_is_str = expr_is_str || arg1_is_str || arg2_is_str;
                 let someone_is_not_str = expr_is_not_str || arg1_is_not_str || arg2_is_not_str;
                 // Note: this statement is an expression returning the progression bools
                 if someone_is_str {
                     // One of the arguments is a string, then all must be strings
                     self.apply_equal3_constraint(ctx, upcast_id, arg1_id, arg2_id, 0)?
                 } else {
                     let progress_expr = if someone_is_not_str {
                         // Output must be a normal array
                         self.apply_template_constraint(ctx, upcast_id, &ARRAY_TEMPLATE)?
                     } else {
                         // Output may still be anything
                         self.apply_template_constraint(ctx, upcast_id, &ARRAYLIKE_TEMPLATE)?
                     };
                     let progress_arg1 = self.apply_template_constraint(ctx, arg1_id, &ARRAYLIKE_TEMPLATE)?;
                     let progress_arg2 = self.apply_template_constraint(ctx, arg2_id, &ARRAYLIKE_TEMPLATE)?;
                     // If they're all arraylike, then we want the subtype to match
                     let (subtype_expr, subtype_arg1, subtype_arg2) =
                         self.apply_equal3_constraint(ctx, upcast_id, arg1_id, arg2_id, 1)?;
                     (progress_expr || subtype_expr, progress_arg1 || subtype_arg1, progress_arg2 || subtype_arg2)
+                }
             },
             BO::LogicalAnd => {
                 // Forced boolean on all
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let progress_arg1 = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let progress_arg2 = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 (progress_expr, progress_arg1, progress_arg2)
             },
             BO::LogicalOr => {
                 // Forced boolean on all
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let progress_arg1 = self.apply_forced_constraint(ctx, arg1_id, &BOOL_TEMPLATE)?;
                 let progress_arg2 = self.apply_forced_constraint(ctx, arg2_id, &BOOL_TEMPLATE)?;
                 (progress_expr, progress_arg1, progress_arg2)
             },
             BO::BitwiseOr | BO::BitwiseXor | BO::BitwiseAnd | BO::Remainder | BO::ShiftLeft | BO::ShiftRight => {
                 // All equal of integer type
                 let progress_base = self.apply_template_constraint(ctx, upcast_id, &INTEGERLIKE_TEMPLATE)?;
                 let (progress_expr, progress_arg1, progress_arg2) =
                     self.apply_equal3_constraint(ctx, upcast_id, arg1_id, arg2_id, 0)?;
                 (progress_base || progress_expr, progress_base || progress_arg1, progress_base || progress_arg2)
             },
             BO::Equality | BO::Inequality => {
                 // Equal2 on args, forced boolean output
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let (progress_arg1, progress_arg2) =
                     self.apply_equal2_constraint(ctx, upcast_id, arg1_id, 0, arg2_id, 0)?;
                 (progress_expr, progress_arg1, progress_arg2)
             },
             BO::LessThan | BO::GreaterThan | BO::LessThanEqual | BO::GreaterThanEqual => {
                 // Equal2 on args with numberlike type, forced boolean output
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let progress_arg_base = self.apply_template_constraint(ctx, arg1_id, &NUMBERLIKE_TEMPLATE)?;
                 let (progress_arg1, progress_arg2) =
                     self.apply_equal2_constraint(ctx, upcast_id, arg1_id, 0, arg2_id, 0)?;
                 (progress_expr, progress_arg_base || progress_arg1, progress_arg_base || progress_arg2)
             },
             BO::Add | BO::Subtract | BO::Multiply | BO::Divide => {
                 // All equal of number type
                 let progress_base = self.apply_template_constraint(ctx, upcast_id, &NUMBERLIKE_TEMPLATE)?;
                 let (progress_expr, progress_arg1, progress_arg2) =
                     self.apply_equal3_constraint(ctx, upcast_id, arg1_id, arg2_id, 0)?;
                 (progress_base || progress_expr, progress_base || progress_arg1, progress_base || progress_arg2)
             },
         };
         debug_log!(" * After:");
         debug_log!("   - Arg1 type [{}]: {}", progress_arg1, self.debug_get_display_name(ctx, arg1_id));
         debug_log!("   - Arg2 type [{}]: {}", progress_arg2, self.debug_get_display_name(ctx, arg2_id));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_arg1 { self.queue_expr(ctx, arg1_id); }
         if progress_arg2 { self.queue_expr(ctx, arg2_id); }
         Ok(())
+    }
     fn progress_unary_expr(&mut self, ctx: &mut Ctx, id: UnaryExpressionId) -> Result<(), ParseError> {
         use UnaryOperator as UO;
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let arg_id = expr.expression;
         debug_log!("Unary expr '{:?}': {}", expr.operation, upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Arg  type: {}", self.debug_get_display_name(ctx, arg_id));
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         let (progress_expr, progress_arg) = match expr.operation {
             UO::Positive | UO::Negative => {
                 // Equal types of numeric class
                 let progress_base = self.apply_template_constraint(ctx, upcast_id, &NUMBERLIKE_TEMPLATE)?;
                 let (progress_expr, progress_arg) =
                     self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 0, arg_id, 0)?;
                 (progress_base || progress_expr, progress_base || progress_arg)
             },
             UO::BitwiseNot => {
                 // Equal types of integer class
                 let progress_base = self.apply_template_constraint(ctx, upcast_id, &INTEGERLIKE_TEMPLATE)?;
                 let (progress_expr, progress_arg) =
                     self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 0, arg_id, 0)?;
                 (progress_base || progress_expr, progress_base || progress_arg)
             },
             UO::LogicalNot => {
                 // Both bools
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let progress_arg = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 (progress_expr, progress_arg)
+            }
         };
         debug_log!(" * After:");
         debug_log!("   - Arg  type [{}]: {}", progress_arg, self.debug_get_display_name(ctx, arg_id));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_arg { self.queue_expr(ctx, arg_id); }
         Ok(())
+    }
     fn progress_indexing_expr(&mut self, ctx: &mut Ctx, id: IndexingExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let subject_id = expr.subject;
         let index_id = expr.index;
         debug_log!("Indexing expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Subject type: {}", self.debug_get_display_name(ctx, subject_id));
         debug_log!("   - Index   type: {}", self.debug_get_display_name(ctx, index_id));
         debug_log!("   - Expr    type: {}", self.debug_get_display_name(ctx, upcast_id));
         // Make sure subject is arraylike and index is integerlike
         let progress_subject_base = self.apply_template_constraint(ctx, subject_id, &ARRAYLIKE_TEMPLATE)?;
         let progress_index = self.apply_template_constraint(ctx, index_id, &INTEGERLIKE_TEMPLATE)?;
         // Make sure if output is of T then subject is Array<T>
         let (progress_expr, progress_subject) =
             self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 0, subject_id, 1)?;
         debug_log!(" * After:");
         debug_log!("   - Subject type [{}]: {}", progress_subject_base || progress_subject, self.debug_get_display_name(ctx, subject_id));
         debug_log!("   - Index   type [{}]: {}", progress_index, self.debug_get_display_name(ctx, index_id));
         debug_log!("   - Expr    type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_subject_base || progress_subject { self.queue_expr(ctx, subject_id); }
         if progress_index { self.queue_expr(ctx, index_id); }
         Ok(())
+    }
     fn progress_slicing_expr(&mut self, ctx: &mut Ctx, id: SlicingExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let subject_id = expr.subject;
         let from_id = expr.from_index;
         let to_id = expr.to_index;
         debug_log!("Slicing expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Subject type: {}", self.debug_get_display_name(ctx, subject_id));
         debug_log!("   - FromIdx type: {}", self.debug_get_display_name(ctx, from_id));
         debug_log!("   - ToIdx   type: {}", self.debug_get_display_name(ctx, to_id));
         debug_log!("   - Expr    type: {}", self.debug_get_display_name(ctx, upcast_id));
         // Make sure subject is arraylike and indices are of equal integerlike
         let progress_subject_base = self.apply_template_constraint(ctx, subject_id, &ARRAYLIKE_TEMPLATE)?;
         let progress_idx_base = self.apply_template_constraint(ctx, from_id, &INTEGERLIKE_TEMPLATE)?;
         let (progress_from, progress_to) = self.apply_equal2_constraint(ctx, upcast_id, from_id, 0, to_id, 0)?;
         let (progress_expr, progress_subject) = match self.type_is_certainly_or_certainly_not_string(ctx, subject_id) {
             (true, _) => {
                 // Certainly a string
                 (self.apply_forced_constraint(ctx, upcast_id, &STRING_TEMPLATE)?, false)
             },
             (_, true) => {
                 // Certainly not a string
                 let progress_expr_base = self.apply_template_constraint(ctx, upcast_id, &SLICE_TEMPLATE)?;
                 let (progress_expr, progress_subject) =
                     self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 1, subject_id, 1)?;
                 (progress_expr_base || progress_expr, progress_subject)
             },
             _ => {
                 // Could be anything, at least attempt to progress subtype
                 let progress_expr_base = self.apply_template_constraint(ctx, upcast_id, &ARRAYLIKE_TEMPLATE)?;
                 let (progress_expr, progress_subject) =
                     self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 1, subject_id, 1)?;
                 (progress_expr_base || progress_expr, progress_subject)
+            }
         };
         debug_log!(" * After:");
         debug_log!("   - Subject type [{}]: {}", progress_subject_base || progress_subject, self.debug_get_display_name(ctx, subject_id));
         debug_log!("   - FromIdx type [{}]: {}", progress_idx_base || progress_from, self.debug_get_display_name(ctx, from_id));
         debug_log!("   - ToIdx   type [{}]: {}", progress_idx_base || progress_to, self.debug_get_display_name(ctx, to_id));
         debug_log!("   - Expr    type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_subject_base || progress_subject { self.queue_expr(ctx, subject_id); }
         if progress_idx_base || progress_from { self.queue_expr(ctx, from_id); }
         if progress_idx_base || progress_to { self.queue_expr(ctx, to_id); }
         Ok(())
+    }
     fn progress_select_expr(&mut self, ctx: &mut Ctx, id: SelectExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         debug_log!("Select expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Subject type: {}", self.debug_get_display_name(ctx, ctx.heap[id].subject));
         debug_log!("   - Expr    type: {}", self.debug_get_display_name(ctx, upcast_id));
         let subject_id = ctx.heap[id].subject;
         let subject_expr_idx = ctx.heap[subject_id].get_unique_id_in_definition();
         let select_expr = &ctx.heap[id];
         let expr_idx = select_expr.unique_id_in_definition;
         let infer_expr = &self.expr_types[expr_idx as usize];
         let extra_idx = infer_expr.extra_data_idx;
         fn try_get_definition_id_from_inference_type<'a>(types: &'a TypeTable, infer_type: &InferenceType) -> Result<Option<&'a DefinedType>, ()> {
             for part in &infer_type.parts {
                 if part.is_marker() || !part.is_concrete() {
                     continue;
+                }
                 // Part is concrete, check if it is an instance of something
                 if let InferenceTypePart::Instance(definition_id, _num_sub) = part {
                     // Lookup type definition and ensure the specified field
                     // name exists on the struct
                     let definition = types.get_base_definition(definition_id);
                     debug_assert!(definition.is_some());
                     let definition = definition.unwrap();
                     return Ok(Some(definition))
                 } else {
                     // Expected an instance of something
                     return Err(())
+                }
+            }
             // Nothing is concrete yet
             Ok(None)
+        }
         fn try_get_tuple_size_from_inference_type(infer_type: &InferenceType) -> Result<Option<u32>, ()> {
             for part in &infer_type.parts {
                 if part.is_marker() || !part.is_concrete() {
                     continue;
+                }
                 if let InferenceTypePart::Tuple(size) = part {
                     return Ok(Some(*size));
                 } else {
                     // Expected a tuple
                     return Err(());
+                }
+            }
             // Type is not "defined enough" yet
             Ok(None)
+        }
         let (progress_subject, progress_expr) = match &select_expr.kind {
             SelectKind::StructField(field_name) => {
                 // Handle select of a struct's field
                 if infer_expr.field_or_monomorph_idx < 0 {
                     // We don't know the field or the definition it is pointing to yet
                     // Not yet known, check if we can determine it
                     let subject_type = &self.expr_types[subject_expr_idx as usize].expr_type;
                     let type_def = try_get_definition_id_from_inference_type(&ctx.types, subject_type);
                     match type_def {
                         Ok(Some(type_def)) => {
                             // Subject type is known, check if it is a
                             // struct and the field exists on the struct
                             let struct_def = if let DefinedTypeVariant::Struct(struct_def) = &type_def.definition {
                                 struct_def
                             } else {
                                 return Err(ParseError::new_error_at_span(
                                     &ctx.module().source, field_name.span, format!(
                                         "Can only apply field access to structs, got a subject of type '{}'",
                                         subject_type.display_name(&ctx.heap)
+                                    )
                                 ));
                             };
                             let mut struct_def_id = None;
                             for (field_def_idx, field_def) in struct_def.fields.iter().enumerate() {
                                 if field_def.identifier == *field_name {
                                     // Set field definition and index
                                     let infer_expr = &mut self.expr_types[expr_idx as usize];
                                     infer_expr.field_or_monomorph_idx = field_def_idx as i32;
                                     struct_def_id = Some(type_def.ast_definition);
                                     break;
+                                }
+                            }
                             if struct_def_id.is_none() {
                                 let ast_struct_def = ctx.heap[type_def.ast_definition].as_struct();
                                 return Err(ParseError::new_error_at_span(
                                     &ctx.module().source, field_name.span, format!(
                                         "this field does not exist on the struct '{}'",
                                         ast_struct_def.identifier.value.as_str()
+                                    )
                                 ))
+                            }
                             // Encountered definition and field index for the
                             // first time
                             self.insert_initial_select_polymorph_data(ctx, id, struct_def_id.unwrap());
                         },
                         Ok(None) => {
                             // Type of subject is not yet known, so we
                             // cannot make any progress yet
                             return Ok(())
                         },
                         Err(()) => {
                             return Err(ParseError::new_error_at_span(
                                 &ctx.module().source, field_name.span, format!(
                                     "Can only apply field access to structs, got a subject of type '{}'",
                                     subject_type.display_name(&ctx.heap)
+                                )
                             ));
+                        }
+                    }
+                }
                 // If here then field index is known, and the referenced struct type
                 // information is inserted into `extra_data`. Check to see if we can
                 // do some mutual inference.
                 let poly_data = &mut self.extra_data[extra_idx as usize];
                 let mut poly_progress = HashSet::new(); // TODO: @Performance
                 // Apply to struct's type
                 let signature_type: *mut _ = &mut poly_data.embedded[0];
                 let subject_type: *mut _ = &mut self.expr_types[subject_expr_idx as usize].expr_type;
                 let (_, progress_subject) = Self::apply_equal2_signature_constraint(
                     ctx, upcast_id, Some(subject_id), poly_data, &mut poly_progress,
                     signature_type, 0, subject_type, 0
                 )?;
                 if progress_subject {
                     self.expr_queued.push_back(subject_expr_idx);
+                }
                 // Apply to field's type
                 let signature_type: *mut _ = &mut poly_data.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let (_, progress_expr) = Self::apply_equal2_signature_constraint(
                     ctx, upcast_id, None, poly_data, &mut poly_progress,
                     signature_type, 0, expr_type, 0
                 )?;
                 if progress_expr {
                     if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
                         let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
                         self.expr_queued.push_back(parent_idx);
+                    }
+                }
                 // Reapply progress in polymorphic variables to struct's type
                 let signature_type: *mut _ = &mut poly_data.embedded[0];
                 let subject_type: *mut _ = &mut self.expr_types[subject_expr_idx as usize].expr_type;
                 let progress_subject = Self::apply_equal2_polyvar_constraint(
                     poly_data, &poly_progress, signature_type, subject_type
                 );
                 let signature_type: *mut _ = &mut poly_data.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let progress_expr = Self::apply_equal2_polyvar_constraint(
                     poly_data, &poly_progress, signature_type, expr_type
                 );
                 (progress_subject, progress_expr)
             },
             SelectKind::TupleMember(member_index) => {
                 let member_index = *member_index;
                 if infer_expr.field_or_monomorph_idx < 0 {
                     // We don't know what kind of tuple we're accessing yet
                     let subject_type = &self.expr_types[subject_expr_idx as usize].expr_type;
                     let tuple_size = try_get_tuple_size_from_inference_type(subject_type);
                     match tuple_size {
                         Ok(Some(enum_size)) => {
                             // Make sure we don't access an element outside of
                             // the tuple's bounds
                             if member_index >= enum_size as u64 {
                                 return Err(ParseError::new_error_at_span(
                                     &ctx.module().source, select_expr.full_span, format!(
                                         "element index {} is out of bounds, tuple has {} elements",
                                         member_index, enum_size
+                                    )
                                 ));
+                            }
                             // Within bounds, so set the index (such that we
                             // will not perform this lookup again)
                             let infer_expr = &mut self.expr_types[expr_idx as usize];
                             infer_expr.field_or_monomorph_idx = member_index as i32;
                         },
                         Ok(None) => {
                             // Nothing is known about the tuple yet
                             return Ok(());
                         },
                         Err(()) => {
                             return Err(ParseError::new_error_at_span(
                                 &ctx.module().source, select_expr.full_span, format!(
                                     "Can only apply tuple element selection to tuples, got a subject of type '{}'",
                                     subject_type.display_name(&ctx.heap)
+                                )
                             ));
+                        }
+                    }
+                }
                 // If here then we know which member we're accessing. So seek
                 // that member in the subject type and apply inference.
                 let subject_type = &self.expr_types[subject_expr_idx as usize].expr_type;
                 let mut member_start_idx = 1;
                 for _ in 0..member_index {
                     member_start_idx = InferenceType::find_subtree_end_idx(&subject_type.parts, member_start_idx);
+                }
                 let (progress_expr, progress_subject) = self.apply_equal2_constraint(
                     ctx, upcast_id, upcast_id, 0, subject_id, member_start_idx
                 )?;
                 (progress_subject, progress_expr)
             },
         };
         if progress_subject { self.queue_expr(ctx, subject_id); }
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         debug_log!(" * After:");
         debug_log!("   - Subject type [{}]: {}", progress_subject, self.debug_get_display_name(ctx, subject_id));
         debug_log!("   - Expr    type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         Ok(())
+    }
     fn progress_literal_expr(&mut self, ctx: &mut Ctx, id: LiteralExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let expr_idx = expr.unique_id_in_definition;
         let extra_idx = self.expr_types[expr_idx as usize].extra_data_idx;
         debug_log!("Literal expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         let progress_expr = match &expr.value {
             Literal::Null => {
                 self.apply_template_constraint(ctx, upcast_id, &MESSAGE_TEMPLATE)?
             },
             Literal::Integer(_) => {
                 self.apply_template_constraint(ctx, upcast_id, &INTEGERLIKE_TEMPLATE)?
             },
             Literal::True | Literal::False => {
                 self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?
             },
             Literal::Character(_) => {
                 self.apply_forced_constraint(ctx, upcast_id, &CHARACTER_TEMPLATE)?
             },
             Literal::String(_) => {
                 self.apply_forced_constraint(ctx, upcast_id, &STRING_TEMPLATE)?
             },
             Literal::Struct(data) => {
                 let extra = &mut self.extra_data[extra_idx as usize];
                 for _poly in &extra.poly_vars {
                     debug_log!(" * Poly: {}", _poly.display_name(&ctx.heap));
+                }
                 let mut poly_progress = HashSet::new();
                 debug_assert_eq!(extra.embedded.len(), data.fields.len());
                 debug_log!(" * During (inferring types from fields and struct type):");
                 // Mutually infer field signature/expression types
                 for (field_idx, field) in data.fields.iter().enumerate() {
                     let field_expr_id = field.value;
                     let field_expr_idx = ctx.heap[field_expr_id].get_unique_id_in_definition();
                     let signature_type: *mut _ = &mut extra.embedded[field_idx];
                     let field_type: *mut _ = &mut self.expr_types[field_expr_idx as usize].expr_type;
                     let (_, progress_arg) = Self::apply_equal2_signature_constraint(
                         ctx, upcast_id, Some(field_expr_id), extra, &mut poly_progress,
                         signature_type, 0, field_type, 0
                     )?;
                     debug_log!(
                         "   - Field {} type | sig: {}, field: {}", field_idx,
                         unsafe{&*signature_type}.display_name(&ctx.heap),
                         unsafe{&*field_type}.display_name(&ctx.heap)
                     );
                     if progress_arg {
                         self.expr_queued.push_back(field_expr_idx);
+                    }
+                }
                 debug_log!("   - Field poly progress | {:?}", poly_progress);
                 // Same for the type of the struct itself
                 let signature_type: *mut _ = &mut extra.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let (_, progress_expr) = Self::apply_equal2_signature_constraint(
                     ctx, upcast_id, None, extra, &mut poly_progress,
                     signature_type, 0, expr_type, 0
                 )?;
                 debug_log!(
                     "   - Ret type | sig: {}, expr: {}",
                     unsafe{&*signature_type}.display_name(&ctx.heap),
                     unsafe{&*expr_type}.display_name(&ctx.heap)
                 );
                 debug_log!("   - Ret poly progress | {:?}", poly_progress);
                 if progress_expr {
                     // TODO: @cleanup, cannot call utility self.queue_parent thingo
                     if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
                         let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
                         self.expr_queued.push_back(parent_idx);
+                    }
+                }
                 // Check which expressions use the polymorphic arguments. If the
                 // polymorphic variables have been progressed then we try to
                 // progress them inside the expression as well.
                 debug_log!(" * During (reinferring from progressed polyvars):");
                 // For all field expressions
                 for field_idx in 0..extra.embedded.len() {
                     // Note: fields in extra.embedded are in the same order as
                     // they are specified in the literal. Whereas
                     // `data.fields[...].field_idx` points to the field in the
                     // struct definition.
                     let signature_type: *mut _ = &mut extra.embedded[field_idx];
                     let field_expr_id = data.fields[field_idx].value;
                     let field_expr_idx = ctx.heap[field_expr_id].get_unique_id_in_definition();
                     let field_type: *mut _ = &mut self.expr_types[field_expr_idx as usize].expr_type;
                     let progress_arg = Self::apply_equal2_polyvar_constraint(
                         extra, &poly_progress, signature_type, field_type
                     );
                     debug_log!(
                         "   - Field {} type | sig: {}, field: {}", field_idx,
                         unsafe{&*signature_type}.display_name(&ctx.heap),
                         unsafe{&*field_type}.display_name(&ctx.heap)
                     );
                     if progress_arg {
                         self.expr_queued.push_back(field_expr_idx);
+                    }
+                }
                 // For the return type
                 let signature_type: *mut _ = &mut extra.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let progress_expr = Self::apply_equal2_polyvar_constraint(
                     extra, &poly_progress, signature_type, expr_type
                 );
                 progress_expr
             },
             Literal::Enum(_) => {
                 let extra = &mut self.extra_data[extra_idx as usize];
                 for _poly in &extra.poly_vars {
                     debug_log!(" * Poly: {}", _poly.display_name(&ctx.heap));
+                }
                 let mut poly_progress = HashSet::new();
                 debug_log!(" * During (inferring types from return type)");
                 let signature_type: *mut _ = &mut extra.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let (_, progress_expr) = Self::apply_equal2_signature_constraint(
                     ctx, upcast_id, None, extra, &mut poly_progress,
                     signature_type, 0, expr_type, 0
                 )?;
                 debug_log!(
                     "   - Ret type | sig: {}, expr: {}",
                     unsafe{&*signature_type}.display_name(&ctx.heap),
                     unsafe{&*expr_type}.display_name(&ctx.heap)
                 );
                 if progress_expr {
                     // TODO: @cleanup
                     if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
                         let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
                         self.expr_queued.push_back(parent_idx);
+                    }
+                }
                 debug_log!(" * During (reinferring from progress polyvars):");
                 let progress_expr = Self::apply_equal2_polyvar_constraint(
                     extra, &poly_progress, signature_type, expr_type
                 );
                 progress_expr
             },
             Literal::Union(data) => {
                 let extra = &mut self.extra_data[extra_idx as usize];
                 for _poly in &extra.poly_vars {
                     debug_log!(" * Poly: {}", _poly.display_name(&ctx.heap));
+                }
                 let mut poly_progress = HashSet::new();
                 debug_assert_eq!(extra.embedded.len(), data.values.len());
                 debug_log!(" * During (inferring types from variant values and union type):");
                 // Mutually infer union variant values
                 for (value_idx, value_expr_id) in data.values.iter().enumerate() {
                     let value_expr_id = *value_expr_id;
                     let value_expr_idx = ctx.heap[value_expr_id].get_unique_id_in_definition();
                     let signature_type: *mut _ = &mut extra.embedded[value_idx];
                     let value_type: *mut _ = &mut self.expr_types[value_expr_idx as usize].expr_type;
                     let (_, progress_arg) = Self::apply_equal2_signature_constraint(
                         ctx, upcast_id, Some(value_expr_id), extra, &mut poly_progress,
                         signature_type, 0, value_type, 0
                     )?;
                     debug_log!(
                         "   - Value {} type | sig: {}, field: {}", value_idx,
                         unsafe{&*signature_type}.display_name(&ctx.heap),
                         unsafe{&*value_type}.display_name(&ctx.heap)
                     );
                     if progress_arg {
                         self.expr_queued.push_back(value_expr_idx);
+                    }
+                }
                 debug_log!("   - Field poly progress | {:?}", poly_progress);
                 // Infer type of union itself
                 let signature_type: *mut _ = &mut extra.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let (_, progress_expr) = Self::apply_equal2_signature_constraint(
                     ctx, upcast_id, None, extra, &mut poly_progress,
                     signature_type, 0, expr_type, 0
                 )?;
                 debug_log!(
                     "   - Ret type | sig: {}, expr: {}",
                     unsafe{&*signature_type}.display_name(&ctx.heap),
                     unsafe{&*expr_type}.display_name(&ctx.heap)
                 );
                 debug_log!("   - Ret poly progress | {:?}", poly_progress);
                 if progress_expr {
                     // TODO: @cleanup, borrowing rules
                     if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
                         let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
                         self.expr_queued.push_back(parent_idx);
+                    }
+                }
                 debug_log!(" * During (reinferring from progress polyvars):");
                 // For all embedded values of the union variant
                 for value_idx in 0..extra.embedded.len() {
                     let signature_type: *mut _ = &mut extra.embedded[value_idx];
                     let value_expr_id = data.values[value_idx];
                     let value_expr_idx = ctx.heap[value_expr_id].get_unique_id_in_definition();
                     let value_type: *mut _ = &mut self.expr_types[value_expr_idx as usize].expr_type;
                     let progress_arg = Self::apply_equal2_polyvar_constraint(
                         extra, &poly_progress, signature_type, value_type
                     );
                     debug_log!(
                         "   - Value {} type | sig: {}, value: {}", value_idx,
                         unsafe{&*signature_type}.display_name(&ctx.heap),
                         unsafe{&*value_type}.display_name(&ctx.heap)
                     );
                     if progress_arg {
                         self.expr_queued.push_back(value_expr_idx);
+                    }
+                }
                 // And for the union type itself
                 let signature_type: *mut _ = &mut extra.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let progress_expr = Self::apply_equal2_polyvar_constraint(
                     extra, &poly_progress, signature_type, expr_type
                 );
                 progress_expr
             },
             Literal::Array(data) => {
                 // TODO: Continue here with performance improvements by reducing allocations
                 let expr_elements = data.clone(); // TODO: @performance
                 let expr_elements = self.expr_buffer.start_section_initialized(data.as_slice());
                 debug_log!("Array expr ({} elements): {}", expr_elements.len(), upcast_id.index);
                 debug_log!(" * Before:");
                 debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
                 // All elements should have an equal type
                 let progress = self.apply_equal_n_constraint(ctx, upcast_id, &expr_elements)?;
                 for (progress_arg, arg_id) in progress.iter().zip(expr_elements.iter()) {
                     if *progress_arg {
                         self.queue_expr(ctx, *arg_id);
                 let mut bool_buffer = self.bool_buffer.start_section();
                 self.apply_equal_n_constraint(ctx, upcast_id, &expr_elements, &mut bool_buffer)?;
                 for (progress_arg, arg_id) in bool_buffer.iter_copied().zip(expr_elements.iter_copied()) {
                     if progress_arg {
                         self.queue_expr(ctx, arg_id);
+                    }
+                }
                 // And the output should be an array of the element types
                 let mut progress_expr = self.apply_template_constraint(ctx, upcast_id, &ARRAY_TEMPLATE)?;
-                if !expr_elements.is_empty() {
+                if expr_elements.len() != 0 {
                     let first_arg_id = expr_elements[0];
                     let (inner_expr_progress, arg_progress) = self.apply_equal2_constraint(
                         ctx, upcast_id, upcast_id, 1, first_arg_id, 0
                     )?;
                     progress_expr = progress_expr || inner_expr_progress;
                     // Note that if the array type progressed the type of the arguments,
                     // then we should enqueue this progression function again
                     // TODO: @fix Make apply_equal_n accept a start idx as well
                     if arg_progress { self.queue_expr(ctx, upcast_id); }
+                }
                 debug_log!(" * After:");
                 debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
                 expr_elements.forget();
                 progress_expr
             },
             Literal::Tuple(data) => {
-                let expr_elements = data.clone(); // TODO: @performance
+                let expr_elements = self.expr_buffer.start_section_initialized(data.as_slice());
                 debug_log!("Tuple expr ({} elements): {}", expr_elements.len(), upcast_id.index);
                 debug_log!(" * Before:");
                 debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
                 // Initial tuple constraint
                 let num_members = expr_elements.len();
                 let mut initial_type = Vec::with_capacity(num_members + 1); // TODO: @performance
                 initial_type.push(InferenceTypePart::Tuple(num_members as u32));
                 for _ in 0..num_members {
                     initial_type.push(InferenceTypePart::Unknown);
+                }
                 let mut progress_expr = self.apply_template_constraint(ctx, upcast_id, &initial_type)?;
                 // The elements of the tuple can have any type, but they must
                 // end up as arguments to the output tuple type.
                 debug_log!(" * During (checking expressions constituting tuple):");
-                for (member_expr_index, member_expr_id) in expr_elements.iter().enumerate() {
+                for (member_expr_index, member_expr_id) in expr_elements.iter_copied().enumerate() {
                     // For the current expression index, (re)compute the
                     // position in the tuple type where the types should match.
                     let mut start_index = 1; // first element is Tuple type, second is the first child
                     for _ in 0..member_expr_index {
                         let tuple_expr_index = ctx.heap[id].unique_id_in_definition;
                         let tuple_type = &self.expr_types[tuple_expr_index as usize].expr_type;
                         start_index = InferenceType::find_subtree_end_idx(&tuple_type.parts, start_index);
                         debug_assert_ne!(start_index, tuple_type.parts.len()); // would imply less tuple type children than member expressions
+                    }
                     // Apply the constraint
                     let (member_progress_expr, member_progress) = self.apply_equal2_constraint(
-                        ctx, upcast_id, upcast_id, start_index, *member_expr_id, 0
                         ctx, upcast_id, upcast_id, start_index, member_expr_id, 0
                     )?;
                     debug_log!("   - Member {} type | {}", member_expr_index, self.debug_get_display_name(ctx, *member_expr_id));
                     progress_expr = progress_expr || member_progress_expr;
                     if member_progress {
-                        self.queue_expr(ctx, *member_expr_id);
                         self.queue_expr(ctx, member_expr_id);
+                    }
+                }
                 expr_elements.forget();
                 progress_expr
+            }
         };
         debug_log!(" * After:");
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         Ok(())
+    }
     fn progress_cast_expr(&mut self, ctx: &mut Ctx, id: CastExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let expr_idx = expr.unique_id_in_definition;
         debug_log!("Casting expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Expr type:    {}", self.debug_get_display_name(ctx, upcast_id));
         debug_log!("   - Subject type: {}", self.debug_get_display_name(ctx, expr.subject));
         // The cast expression might have its output type fixed by the
         // programmer, so apply that type to the output. Apart from that casting
         // acts like a blocker for two-way inference. So we'll just have to wait
         // until we know if the cast is valid.
         // TODO: Another thing that has to be updated the moment the type
         //  inferencer is fully index/job-based
         let infer_type = self.determine_inference_type_from_parser_type_elements(&expr.to_type.elements, true);
         let expr_progress = self.apply_template_constraint(ctx, upcast_id, &infer_type.parts)?;
         if expr_progress {
             self.queue_expr_parent(ctx, upcast_id);
+        }
         // Check if the two types are compatible
         debug_log!(" * After:");
         debug_log!("   - Expr type [{}]: {}", expr_progress, self.debug_get_display_name(ctx, upcast_id));
         debug_log!("   - Note that the subject type can never be inferred");
         debug_log!(" * Decision:");
         let subject_idx = ctx.heap[expr.subject].get_unique_id_in_definition();
         let expr_type = &self.expr_types[expr_idx as usize].expr_type;
         let subject_type = &self.expr_types[subject_idx as usize].expr_type;
         if !expr_type.is_done || !subject_type.is_done {
             // Not yet done
             debug_log!("   - Casting is valid: unknown as the types are not yet complete");
             return Ok(())
+        }
         // Valid casts: (bool, integer, character) can always be cast to one
         // another. A cast from a type to itself is also valid.
         fn is_bool_int_or_char(parts: &[InferenceTypePart]) -> bool {
             return parts.len() == 1 && (
                 parts[0] == InferenceTypePart::Bool ||
                 parts[0] == InferenceTypePart::Character ||
                 parts[0].is_concrete_integer()
             );
+        }
         let is_valid = if is_bool_int_or_char(&expr_type.parts) && is_bool_int_or_char(&subject_type.parts) {
             true
         } else if expr_type.parts == subject_type.parts {
             true
         } else {
             false
         };
         debug_log!("   - Casting is valid: {}", is_valid);
         if !is_valid {
             let cast_expr = &ctx.heap[id];
             let subject_expr = &ctx.heap[cast_expr.subject];
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, cast_expr.full_span, "invalid casting operation"
             ).with_info_at_span(
                 &ctx.module().source, subject_expr.full_span(), format!(
                     "cannot cast the argument type '{}' to the cast type '{}'",
                     subject_type.display_name(&ctx.heap),
                     expr_type.display_name(&ctx.heap)
+                )
             ));
+        }
         Ok(())
+    }
     // TODO: @cleanup, see how this can be cleaned up once I implement
     //  polymorphic struct/enum/union literals. These likely follow the same
     //  pattern as here.
     fn progress_call_expr(&mut self, ctx: &mut Ctx, id: CallExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let expr_idx = expr.unique_id_in_definition;
         let extra_idx = self.expr_types[expr_idx as usize].extra_data_idx;
         debug_log!("Call expr '{}': {}", ctx.heap[expr.definition].identifier().value.as_str(), upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         debug_log!(" * During (inferring types from arguments and return type):");
         let extra = &mut self.extra_data[extra_idx as usize];
         // Check if we can make progress using the arguments and/or return types
         // while keeping track of the polyvars we've extended
         let mut poly_progress = HashSet::new();
         debug_assert_eq!(extra.embedded.len(), expr.arguments.len());
         for (call_arg_idx, arg_id) in expr.arguments.clone().into_iter().enumerate() {
             let arg_expr_idx = ctx.heap[arg_id].get_unique_id_in_definition();
             let signature_type: *mut _ = &mut extra.embedded[call_arg_idx];
             let argument_type: *mut _ = &mut self.expr_types[arg_expr_idx as usize].expr_type;
             let (_, progress_arg) = Self::apply_equal2_signature_constraint(
                 ctx, upcast_id, Some(arg_id), extra, &mut poly_progress,
                 signature_type, 0, argument_type, 0
             )?;
             debug_log!(
                 "   - Arg {} type | sig: {}, arg: {}", call_arg_idx,
                 unsafe{&*signature_type}.display_name(&ctx.heap),
                 unsafe{&*argument_type}.display_name(&ctx.heap));
             if progress_arg {
                 // Progressed argument expression
                 self.expr_queued.push_back(arg_expr_idx);
+            }
+        }
         // Do the same for the return type
         let signature_type: *mut _ = &mut extra.returned;
         let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
         let (_, progress_expr) = Self::apply_equal2_signature_constraint(
             ctx, upcast_id, None, extra, &mut poly_progress,
             signature_type, 0, expr_type, 0
         )?;
         debug_log!(
             "   - Ret type | sig: {}, expr: {}",
             unsafe{&*signature_type}.display_name(&ctx.heap),
             unsafe{&*expr_type}.display_name(&ctx.heap)
         );
         if progress_expr {
             // TODO: @cleanup, cannot call utility self.queue_parent thingo
             if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
                 let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
                 self.expr_queued.push_back(parent_idx);
+            }
+        }
         // If we did not have an error in the polymorph inference above, then
         // reapplying the polymorph type to each argument type and the return
         // type should always succeed.
         debug_log!(" * During (reinferring from progressed polyvars):");
         for (_poly_idx, _poly_var) in extra.poly_vars.iter().enumerate() {
             debug_log!("   - Poly {} | sig: {}", _poly_idx, _poly_var.display_name(&ctx.heap));
+        }
         // TODO: @performance If the algorithm is changed to be more "on demand
         //  argument re-evaluation", instead of "all-argument re-evaluation",
         //  then this is no longer true
         for arg_idx in 0..extra.embedded.len() {
             let signature_type: *mut _ = &mut extra.embedded[arg_idx];
             let arg_expr_id = expr.arguments[arg_idx];
             let arg_expr_idx = ctx.heap[arg_expr_id].get_unique_id_in_definition();
             let arg_type: *mut _ = &mut self.expr_types[arg_expr_idx as usize].expr_type;
             let progress_arg = Self::apply_equal2_polyvar_constraint(
                 extra, &poly_progress,
                 signature_type, arg_type
             );
             debug_log!(
                 "   - Arg {} type | sig: {}, arg: {}", arg_idx,
                 unsafe{&*signature_type}.display_name(&ctx.heap),
                 unsafe{&*arg_type}.display_name(&ctx.heap)
             );
             if progress_arg {
                 self.expr_queued.push_back(arg_expr_idx);
+            }
+        }
         // Once more for the return type
         let signature_type: *mut _ = &mut extra.returned;
         let ret_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
         let progress_ret = Self::apply_equal2_polyvar_constraint(
             extra, &poly_progress, signature_type, ret_type
         );
         debug_log!(
             "   - Ret type | sig: {}, arg: {}",
             unsafe{&*signature_type}.display_name(&ctx.heap),
             unsafe{&*ret_type}.display_name(&ctx.heap)
         );
         if progress_ret {
             self.queue_expr_parent(ctx, upcast_id);
+        }
         debug_log!(" * After:");
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         Ok(())
+    }
     fn progress_variable_expr(&mut self, ctx: &mut Ctx, id: VariableExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let var_expr = &ctx.heap[id];
         let var_expr_idx = var_expr.unique_id_in_definition;
         let var_id = var_expr.declaration.unwrap();
         debug_log!("Variable expr '{}': {}", ctx.heap[var_id].identifier.value.as_str(), upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Var  type: {}", self.var_types.get(&var_id).unwrap().var_type.display_name(&ctx.heap));
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         // Retrieve shared variable type and expression type and apply inference
         let var_data = self.var_types.get_mut(&var_id).unwrap();
         let expr_type = &mut self.expr_types[var_expr_idx as usize].expr_type;
         let infer_res = unsafe{ InferenceType::infer_subtrees_for_both_types(
             &mut var_data.var_type as *mut _, 0, expr_type, 0
         ) };
         if infer_res == DualInferenceResult::Incompatible {
             let var_decl = &ctx.heap[var_id];
             return Err(ParseError::new_error_at_span(
                 &ctx.module().source, var_decl.identifier.span, format!(
                     "Conflicting types for this variable, previously assigned the type '{}'",
                     var_data.var_type.display_name(&ctx.heap)
+                )
             ).with_info_at_span(
                 &ctx.module().source, var_expr.identifier.span, format!(
                     "But inferred to have incompatible type '{}' here",
                     expr_type.display_name(&ctx.heap)
+                )
             ))
+        }
         let progress_var = infer_res.modified_lhs();
         let progress_expr = infer_res.modified_rhs();
         if progress_var {
             // Let other variable expressions using this type progress as well
             for other_expr in var_data.used_at.iter() {
                 if *other_expr != upcast_id {
                     let other_expr_idx = ctx.heap[*other_expr].get_unique_id_in_definition();
                     self.expr_queued.push_back(other_expr_idx);
+                }
+            }
             // Let a linked port know that our type has updated
             if let Some(linked_id) = var_data.linked_var {
                 // Only perform one-way inference to prevent updating our type,
                 // this would lead to an inconsistency in the type inference
                 // algorithm otherwise.
                 let var_type: *mut _ = &mut var_data.var_type;
                 let link_data = self.var_types.get_mut(&linked_id).unwrap();
                 debug_assert!(
                     unsafe{&*var_type}.parts[0] == InferenceTypePart::Input ||
                     unsafe{&*var_type}.parts[0] == InferenceTypePart::Output
                 );
                 debug_assert!(
                     link_data.var_type.parts[0] == InferenceTypePart::Input ||
                     link_data.var_type.parts[0] == InferenceTypePart::Output
                 );
                 match InferenceType::infer_subtree_for_single_type(&mut link_data.var_type, 1, &unsafe{&*var_type}.parts, 1, false) {
                     SingleInferenceResult::Modified => {
                         for other_expr in &link_data.used_at {
                             let other_expr_idx = ctx.heap[*other_expr].get_unique_id_in_definition();
                             self.expr_queued.push_back(other_expr_idx);
+                        }
                     },
                     SingleInferenceResult::Unmodified => {},
                     SingleInferenceResult::Incompatible => {
                         let var_data = self.var_types.get(&var_id).unwrap();
                         let link_data = self.var_types.get(&linked_id).unwrap();
                         let var_decl = &ctx.heap[var_id];
                         let link_decl = &ctx.heap[linked_id];
                         return Err(ParseError::new_error_at_span(
                             &ctx.module().source, var_decl.identifier.span, format!(
                                 "Conflicting types for this variable, assigned the type '{}'",
                                 var_data.var_type.display_name(&ctx.heap)
+                            )
                         ).with_info_at_span(
                             &ctx.module().source, link_decl.identifier.span, format!(
                                 "Because it is incompatible with this variable, assigned the type '{}'",
                                 link_data.var_type.display_name(&ctx.heap)
+                            )
                         ));
+                    }
+                }
+            }
+        }
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         debug_log!(" * After:");
         debug_log!("   - Var  type [{}]: {}", progress_var, self.var_types.get(&var_id).unwrap().var_type.display_name(&ctx.heap));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         Ok(())
+    }
     fn queue_expr_parent(&mut self, ctx: &Ctx, expr_id: ExpressionId) {
         if let ExpressionParent::Expression(parent_expr_id, _) = &ctx.heap[expr_id].parent() {
             let expr_idx = ctx.heap[*parent_expr_id].get_unique_id_in_definition();
             self.expr_queued.push_back(expr_idx);
+        }
+    }
     fn queue_expr(&mut self, ctx: &Ctx, expr_id: ExpressionId) {
         let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition();
         self.expr_queued.push_back(expr_idx);
+    }
     // first returned is certainly string, second is certainly not
     fn type_is_certainly_or_certainly_not_string(&self, ctx: &Ctx, expr_id: ExpressionId) -> (bool, bool) {
         let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition();
         let expr_type = &self.expr_types[expr_idx as usize].expr_type;
         if expr_type.is_done {
             if expr_type.parts[0] == InferenceTypePart::String {
                 return (true, false);
             } else {
                 return (false, true);
+            }
+        }
         (false, false)
+    }
     /// Applies a template type constraint: the type associated with the
     /// supplied expression will be molded into the provided `template`. But
     /// will be considered valid if the template could've been molded into the
     /// expression type as well. Hence the template may be fully specified (e.g.
     /// a bool) or contain "inference" variables (e.g. an array of T)
     fn apply_template_constraint(
         &mut self, ctx: &Ctx, expr_id: ExpressionId, template: &[InferenceTypePart]
     ) -> Result<bool, ParseError> {
         let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition(); // TODO: @Temp
         let expr_type = &mut self.expr_types[expr_idx as usize].expr_type;
         match InferenceType::infer_subtree_for_single_type(expr_type, 0, template, 0, false) {
             SingleInferenceResult::Modified => Ok(true),
             SingleInferenceResult::Unmodified => Ok(false),
             SingleInferenceResult::Incompatible => Err(
                 self.construct_template_type_error(ctx, expr_id, template)
+            )
+        }
+    }
     fn apply_template_constraint_to_types(
         to_infer: *mut InferenceType, to_infer_start_idx: usize,
         template: &[InferenceTypePart], template_start_idx: usize
     ) -> Result<bool, ()> {
         match InferenceType::infer_subtree_for_single_type(
             unsafe{ &mut *to_infer }, to_infer_start_idx,
             template, template_start_idx, false
         ) {
             SingleInferenceResult::Modified => Ok(true),
             SingleInferenceResult::Unmodified => Ok(false),
             SingleInferenceResult::Incompatible => Err(()),
+        }
+    }
     /// Applies a forced constraint: the supplied expression's type MUST be
     /// inferred from the template, the other way around is considered invalid.
     fn apply_forced_constraint(
         &mut self, ctx: &Ctx, expr_id: ExpressionId, template: &[InferenceTypePart]
     ) -> Result<bool, ParseError> {
         let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition();
         let expr_type = &mut self.expr_types[expr_idx as usize].expr_type;
         match InferenceType::infer_subtree_for_single_type(expr_type, 0, template, 0, true) {
             SingleInferenceResult::Modified => Ok(true),
             SingleInferenceResult::Unmodified => Ok(false),
             SingleInferenceResult::Incompatible => Err(
                 self.construct_template_type_error(ctx, expr_id, template)
+            )
+        }
+    }
     /// Applies a type constraint that expects the two provided types to be
     /// equal. We attempt to make progress in inferring the types. If the call
     /// is successful then the composition of all types are made equal.
     /// The "parent" `expr_id` is provided to construct errors.
     fn apply_equal2_constraint(
         &mut self, ctx: &Ctx, expr_id: ExpressionId,
         arg1_id: ExpressionId, arg1_start_idx: usize,
         arg2_id: ExpressionId, arg2_start_idx: usize
     ) -> Result<(bool, bool), ParseError> {
         let arg1_expr_idx = ctx.heap[arg1_id].get_unique_id_in_definition(); // TODO: @Temp
         let arg2_expr_idx = ctx.heap[arg2_id].get_unique_id_in_definition();
         let arg1_type: *mut _ = &mut self.expr_types[arg1_expr_idx as usize].expr_type;
         let arg2_type: *mut _ = &mut self.expr_types[arg2_expr_idx as usize].expr_type;
         let infer_res = unsafe{ InferenceType::infer_subtrees_for_both_types(
             arg1_type, arg1_start_idx,
             arg2_type, arg2_start_idx
         ) };
         if infer_res == DualInferenceResult::Incompatible {
             return Err(self.construct_arg_type_error(ctx, expr_id, arg1_id, arg2_id));
+        }
         Ok((infer_res.modified_lhs(), infer_res.modified_rhs()))
+    }
     /// Applies an equal2 constraint between a signature type (e.g. a function
     /// argument or struct field) and an expression whose type should match that
     /// expression. If we make progress on the signature, then we try to see if
     /// any of the embedded polymorphic types can be progressed.
     ///
     /// `outer_expr_id` is the main expression we're progressing (e.g. a
     /// function call), while `expr_id` is the embedded expression we're
     /// matching against the signature. `expression_type` and
     /// `expression_start_idx` belong to `expr_id`.
     fn apply_equal2_signature_constraint(
         ctx: &Ctx, outer_expr_id: ExpressionId, expr_id: Option<ExpressionId>,
         polymorph_data: &mut ExtraData, polymorph_progress: &mut HashSet<u32>,
         signature_type: *mut InferenceType, signature_start_idx: usize,
         expression_type: *mut InferenceType, expression_start_idx: usize
     ) -> Result<(bool, bool), ParseError> {
         // Safety: all pointers distinct
         // Infer the signature and expression type
         let infer_res = unsafe {
             InferenceType::infer_subtrees_for_both_types(
                 signature_type, signature_start_idx,
                 expression_type, expression_start_idx
+            )
         };
         if infer_res == DualInferenceResult::Incompatible {
             // TODO: Check if I still need to use this
             let outer_span = ctx.heap[outer_expr_id].full_span();
             let (span_name, span) = match expr_id {
                 Some(expr_id) => ("argument's", ctx.heap[expr_id].full_span()),
                 None => ("type's", outer_span)
             };
             let (signature_display_type, expression_display_type) = unsafe { (
                 (&*signature_type).display_name(&ctx.heap),
                 (&*expression_type).display_name(&ctx.heap)
             ) };
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, outer_span,
                 "failed to fully resolve the types of this expression"
             ).with_info_at_span(
                 &ctx.module().source, span, format!(
                     "because the {} signature has been resolved to '{}', but the expression has been resolved to '{}'",
                     span_name, signature_display_type, expression_display_type
+                )
             ));
+        }
         // Try to see if we can progress any of the polymorphic variables
         let progress_sig = infer_res.modified_lhs();
         let progress_expr = infer_res.modified_rhs();
         if progress_sig {
             let signature_type = unsafe{&mut *signature_type};
             debug_assert!(
                 signature_type.has_marker,
                 "made progress on signature type, but it doesn't have a marker"
             );
             for (poly_idx, poly_section) in signature_type.marker_iter() {
                 let polymorph_type = &mut polymorph_data.poly_vars[poly_idx as usize];
                 match Self::apply_template_constraint_to_types(
                     polymorph_type, 0, poly_section, 0
                 ) {
                     Ok(true) => { polymorph_progress.insert(poly_idx); },
                     Ok(false) => {},
                     Err(()) => { return Err(Self::construct_poly_arg_error(ctx, polymorph_data, outer_expr_id))}
+                }
+            }
+        }
         Ok((progress_sig, progress_expr))
+    }
     /// Applies equal2 constraints on the signature type for each of the
     /// polymorphic variables. If the signature type is progressed then we
     /// progress the expression type as well.
     ///
     /// This function assumes that the polymorphic variables have already been
     /// progressed as far as possible by calling
     /// `apply_equal2_signature_constraint`. As such, we expect to not encounter
     /// any errors.
     ///
     /// This function returns true if the expression's type has been progressed
     fn apply_equal2_polyvar_constraint(
         polymorph_data: &ExtraData, _polymorph_progress: &HashSet<u32>,
         signature_type: *mut InferenceType, expr_type: *mut InferenceType
     ) -> bool {
         // Safety: all pointers should be distinct
         //         polymorph_data containers may not be modified
         let signature_type = unsafe{&mut *signature_type};
         let expr_type = unsafe{&mut *expr_type};
         // Iterate through markers in signature type to try and make progress
         // on the polymorphic variable
         let mut seek_idx = 0;
         let mut modified_sig = false;
         while let Some((poly_idx, start_idx)) = signature_type.find_marker(seek_idx) {
             let end_idx = InferenceType::find_subtree_end_idx(&signature_type.parts, start_idx);
             // if polymorph_progress.contains(&poly_idx) {
                 // Need to match subtrees
                 let polymorph_type = &polymorph_data.poly_vars[poly_idx as usize];
                 let modified_at_marker = Self::apply_template_constraint_to_types(
                     signature_type, start_idx,
                     &polymorph_type.parts, 0
                 ).expect("no failure when applying polyvar constraints");
                 modified_sig = modified_sig || modified_at_marker;
             // }
             seek_idx = end_idx;
+        }
         // If we made any progress on the signature's type, then we also need to
         // apply it to the expression that is supposed to match the signature.
         if modified_sig {
             match InferenceType::infer_subtree_for_single_type(
                 expr_type, 0, &signature_type.parts, 0, true
             ) {
                 SingleInferenceResult::Modified => true,
                 SingleInferenceResult::Unmodified => false,
                 SingleInferenceResult::Incompatible =>
                     unreachable!("encountered failure while reapplying modified signature to expression after polyvar inference")
+            }
         } else {
             false
+        }
+    }
     /// Applies a type constraint that expects all three provided types to be
     /// equal. In case we can make progress in inferring the types then we
     /// attempt to do so. If the call is successful then the composition of all
     /// types is made equal.
     fn apply_equal3_constraint(
         &mut self, ctx: &Ctx, expr_id: ExpressionId,
         arg1_id: ExpressionId, arg2_id: ExpressionId,
         start_idx: usize
     ) -> Result<(bool, bool, bool), ParseError> {
         // Safety: all points are unique
         //         containers may not be modified
         let expr_expr_idx = ctx.heap[expr_id].get_unique_id_in_definition(); // TODO: @Temp
         let arg1_expr_idx = ctx.heap[arg1_id].get_unique_id_in_definition();
         let arg2_expr_idx = ctx.heap[arg2_id].get_unique_id_in_definition();
         let expr_type: *mut _ = &mut self.expr_types[expr_expr_idx as usize].expr_type;
         let arg1_type: *mut _ = &mut self.expr_types[arg1_expr_idx as usize].expr_type;
         let arg2_type: *mut _ = &mut self.expr_types[arg2_expr_idx as usize].expr_type;
         let expr_res = unsafe{
             InferenceType::infer_subtrees_for_both_types(expr_type, start_idx, arg1_type, start_idx)
         };
         if expr_res == DualInferenceResult::Incompatible {
             return Err(self.construct_expr_type_error(ctx, expr_id, arg1_id));
+        }
         let args_res = unsafe{
             InferenceType::infer_subtrees_for_both_types(arg1_type, start_idx, arg2_type, start_idx) };
         if args_res == DualInferenceResult::Incompatible {
             return Err(self.construct_arg_type_error(ctx, expr_id, arg1_id, arg2_id));
+        }
         // If all types are compatible, but the second call caused the arg1_type
         // to be expanded, then we must also assign this to expr_type.
         let mut progress_expr = expr_res.modified_lhs();
         let mut progress_arg1 = expr_res.modified_rhs();
         let progress_arg2 = args_res.modified_rhs();
         if args_res.modified_lhs() {
             unsafe {
                 let end_idx = InferenceType::find_subtree_end_idx(&(*arg2_type).parts, start_idx);
                 let subtree = &((*arg2_type).parts[start_idx..end_idx]);
                 (*expr_type).replace_subtree(start_idx, subtree);
+            }
             progress_expr = true;
             progress_arg1 = true;
+        }
         Ok((progress_expr, progress_arg1, progress_arg2))
+    }
     // TODO: @optimize Since we only deal with a single type this might be done
     //  a lot more efficiently, methinks (disregarding the allocations here)
     /// Applies equal constraint to N consecutive expressions. The returned
     /// `progress` vec will contain which expressions were progressed and will
     /// have length N
     // If you ever
     fn apply_equal_n_constraint(
         &mut self, ctx: &Ctx, expr_id: ExpressionId, args: &[ExpressionId],
     ) -> Result<Vec<bool>, ParseError> {
         &mut self, ctx: &Ctx, expr_id: ExpressionId,
         args: &ScopedSection<ExpressionId>, progress: &mut ScopedSection<bool>
     ) -> Result<(), ParseError> {
         // Early exit
         debug_assert_eq!(progress.len(), 0);
         match args.len() {
 => return Ok(vec!()),         // nothing to progress
 => return Ok(vec![false]),    // only one type, so nothing to infer
             _ => {}
 => {
                 // nothing to progress
                 return Ok(())
             },
 => {
                 // only one type, so nothing to infer
                 progress.push(false);
                 return Ok(())
             },
             n => {
                 for _ in 0..n {
                     progress.push(false);
+                }
+            }
+        }
         let mut progress = Vec::new(); // TODO: @Performance
         progress.resize(args.len(), false);
         // Do pairwise inference, keep track of the last entry we made progress
         // on. Once done we need to update everything to the most-inferred type.
         let mut arg_iter = args.iter();
         let mut last_arg_id = *arg_iter.next().unwrap();
         let mut arg_iter = args.iter_copied();
         let mut last_arg_id = arg_iter.next().unwrap();
         let mut last_lhs_progressed = 0;
         let mut lhs_arg_idx = 0;
         while let Some(next_arg_id) = arg_iter.next() {
             let last_expr_idx = ctx.heap[last_arg_id].get_unique_id_in_definition(); // TODO: @Temp
-            let next_expr_idx = ctx.heap[*next_arg_id].get_unique_id_in_definition();
             let next_expr_idx = ctx.heap[next_arg_id].get_unique_id_in_definition();
             let last_type: *mut _ = &mut self.expr_types[last_expr_idx as usize].expr_type;
             let next_type: *mut _ = &mut self.expr_types[next_expr_idx as usize].expr_type;
             let res = unsafe {
                 InferenceType::infer_subtrees_for_both_types(last_type, 0, next_type, 0)
             };
             if res == DualInferenceResult::Incompatible {
-                return Err(self.construct_arg_type_error(ctx, expr_id, last_arg_id, *next_arg_id));
                 return Err(self.construct_arg_type_error(ctx, expr_id, last_arg_id, next_arg_id));
+            }
             if res.modified_lhs() {
                 // We re-inferred something on the left hand side, so everything
                 // up until now should be re-inferred.
                 progress[lhs_arg_idx] = true;
                 last_lhs_progressed = lhs_arg_idx;
+            }
             progress[lhs_arg_idx + 1] = res.modified_rhs();
-            last_arg_id = *next_arg_id;
             last_arg_id = next_arg_id;
             lhs_arg_idx += 1;
+        }
         // Re-infer everything. Note that we do not need to re-infer the type
         // exactly at `last_lhs_progressed`, but only everything up to it.
-        let last_arg_expr_idx = ctx.heap[*args.last().unwrap()].get_unique_id_in_definition();
+        let last_arg_expr_idx = ctx.heap[last_arg_id].get_unique_id_in_definition();
         let last_type: *mut _ = &mut self.expr_types[last_arg_expr_idx as usize].expr_type;
         for arg_idx in 0..last_lhs_progressed {
             let other_arg_expr_idx = ctx.heap[args[arg_idx]].get_unique_id_in_definition();
             let arg_type: *mut _ = &mut self.expr_types[other_arg_expr_idx as usize].expr_type;
             unsafe{
                 (*arg_type).replace_subtree(0, &(*last_type).parts);
+            }
             progress[arg_idx] = true;
+        }
-        Ok(progress)
+        return Ok(());
+    }
     /// Determines the `InferenceType` for the expression based on the
     /// expression parent. Note that if the parent is another expression, we do
     /// not take special action, instead we let parent expressions fix the type
     /// of subexpressions before they have a chance to call this function.
     fn insert_initial_expr_inference_type(
         &mut self, ctx: &mut Ctx, expr_id: ExpressionId
     ) -> Result<(), ParseError> {
         use ExpressionParent as EP;
         use InferenceTypePart as ITP;
         let expr = &ctx.heap[expr_id];
         let inference_type = match expr.parent() {
             EP::None =>
                 // Should have been set by linker
                 unreachable!(),
             EP::ExpressionStmt(_) =>
                 // Determined during type inference
                 InferenceType::new(false, false, vec![ITP::Unknown]),
             EP::Expression(parent_id, idx_in_parent) => {
                 // If we are the test expression of a conditional expression,
                 // then we must resolve to a boolean
                 let is_conditional = if let Expression::Conditional(_) = &ctx.heap[*parent_id] {
                     true
                 } else {
                     false
                 };
                 if is_conditional && *idx_in_parent == 0 {
                     InferenceType::new(false, true, vec![ITP::Bool])
                 } else {
                     InferenceType::new(false, false, vec![ITP::Unknown])
+                }
             },
             EP::If(_) | EP::While(_) =>
                 // Must be a boolean
                 InferenceType::new(false, true, vec![ITP::Bool]),
             EP::Return(_) =>
                 // Must match the return type of the function
                 if let DefinitionType::Function(func_id) = self.definition_type {
                     debug_assert_eq!(ctx.heap[func_id].return_types.len(), 1);
                     let returned = &ctx.heap[func_id].return_types[0];
                     self.determine_inference_type_from_parser_type_elements(&returned.elements, true)
                 } else {
                     // Cannot happen: definition always set upon body traversal
                     // and "return" calls in components are illegal.
                     unreachable!();
                 },
             EP::New(_) =>
                 // Must be a component call, which we assign a "Void" return
                 // type
                 InferenceType::new(false, true, vec![ITP::Void]),
         };
         let infer_expr = &mut self.expr_types[expr.get_unique_id_in_definition() as usize];
         let needs_extra_data = match expr {
             Expression::Call(_) => true,
             Expression::Literal(expr) => match expr.value {
                 Literal::Enum(_) | Literal::Union(_) | Literal::Struct(_) => true,
                 _ => false,
             },
             Expression::Select(expr) => match expr.kind {
                 SelectKind::StructField(_) => true,
                 SelectKind::TupleMember(_) => false,
             },
             _ => false,
         };
         if infer_expr.expr_id.is_invalid() {
             // Nothing is set yet
             infer_expr.expr_type = inference_type;
             infer_expr.expr_id = expr_id;
             if needs_extra_data {
                 let extra_idx = self.extra_data.len() as i32;
                 self.extra_data.push(ExtraData::default());
                 infer_expr.extra_data_idx = extra_idx;
+            }
         } else {
             // We already have an entry
             debug_assert!(false, "does this ever happen?");
             if let SingleInferenceResult::Incompatible = InferenceType::infer_subtree_for_single_type(
                 &mut infer_expr.expr_type, 0, &inference_type.parts, 0, false
             ) {
                 return Err(self.construct_expr_type_error(ctx, expr_id, expr_id));
+            }
             debug_assert!((infer_expr.extra_data_idx != -1) == needs_extra_data);
+        }
         Ok(())
+    }
     fn insert_initial_call_polymorph_data(
         &mut self, ctx: &mut Ctx, call_id: CallExpressionId
     ) {
         // Note: the polymorph variables may be partially specified and may
         // contain references to the wrapping definition's (i.e. the proctype
         // we are currently visiting) polymorphic arguments.
         //
         // The arguments of the call may refer to polymorphic variables in the
         // definition of the function we're calling, not of the wrapping
         // definition. We insert markers in these inferred types to be able to
         // map them back and forth to the polymorphic arguments of the function
         // we are calling.
         let call = &ctx.heap[call_id];
         let extra_data_idx = self.expr_types[call.unique_id_in_definition as usize].extra_data_idx; // TODO: @Temp
         debug_assert!(extra_data_idx != -1, "insert initial call polymorph data, no preallocated ExtraData");
         // Handle the polymorphic arguments (if there are any)
         let num_poly_args = call.parser_type.elements[0].variant.num_embedded();
         let mut poly_args = Vec::with_capacity(num_poly_args);
         for embedded_elements in call.parser_type.iter_embedded(0) {
             poly_args.push(self.determine_inference_type_from_parser_type_elements(embedded_elements, true));
+        }
         // Handle the arguments and return types
         let definition = &ctx.heap[call.definition];
         let (parameters, returned) = match definition {
             Definition::Component(definition) => {
                 debug_assert_eq!(poly_args.len(), definition.poly_vars.len());
                 (&definition.parameters, None)
             },
             Definition::Function(definition) => {
                 debug_assert_eq!(poly_args.len(), definition.poly_vars.len());
                 (&definition.parameters, Some(&definition.return_types))
             },
             Definition::Struct(_) | Definition::Enum(_) | Definition::Union(_) => {
                 unreachable!("insert_initial_call_polymorph data for non-procedure type");
             },
         };
         let mut parameter_types = Vec::with_capacity(parameters.len());
         for parameter_id in parameters.clone().into_iter() { // TODO: @Performance @Now
             let param = &ctx.heap[parameter_id];
             parameter_types.push(self.determine_inference_type_from_parser_type_elements(&param.parser_type.elements, false));
+        }
         let return_type = match returned {
             None => {
                 // Component, so returns a "Void"
                 InferenceType::new(false, true, vec![InferenceTypePart::Void])
             },
             Some(returned) => {
                 debug_assert_eq!(returned.len(), 1); // TODO: @ReturnTypes
                 let returned = &returned[0];
                 self.determine_inference_type_from_parser_type_elements(&returned.elements, false)
+            }
         };
         self.extra_data[extra_data_idx as usize] = ExtraData{
             expr_id: call_id.upcast(),
             definition_id: call.definition,
             poly_vars: poly_args,
             embedded: parameter_types,
             returned: return_type
         };
+    }
     fn insert_initial_struct_polymorph_data(
         &mut self, ctx: &mut Ctx, lit_id: LiteralExpressionId,
     ) {
         use InferenceTypePart as ITP;
         let literal = &ctx.heap[lit_id];
         let extra_data_idx = self.expr_types[literal.unique_id_in_definition as usize].extra_data_idx; // TODO: @Temp
         debug_assert!(extra_data_idx != -1, "initial struct polymorph data, but no preallocated ExtraData");
         let literal = ctx.heap[lit_id].value.as_struct();
         // Handle polymorphic arguments
         let num_embedded = literal.parser_type.elements[0].variant.num_embedded();
         let mut total_num_poly_parts = 0;
         let mut poly_args = Vec::with_capacity(num_embedded);
         for embedded_elements in literal.parser_type.iter_embedded(0) {
             let poly_type = self.determine_inference_type_from_parser_type_elements(embedded_elements, true);
             total_num_poly_parts += poly_type.parts.len();
             poly_args.push(poly_type);
+        }
         // Handle parser types on struct definition
         let defined_type = ctx.types.get_base_definition(&literal.definition).unwrap();
         let struct_type = defined_type.definition.as_struct();
         debug_assert_eq!(poly_args.len(), defined_type.poly_vars.len());
         // Note: programmer is capable of specifying fields in a struct literal
         // in a different order than on the definition. We take the literal-
         // specified order to be leading.
         let mut embedded_types = Vec::with_capacity(struct_type.fields.len());
         for lit_field in literal.fields.iter() {
             let def_field = &struct_type.fields[lit_field.field_idx];
             let inference_type = self.determine_inference_type_from_parser_type_elements(&def_field.parser_type.elements, false);
             embedded_types.push(inference_type);
+        }
         // Return type is the struct type itself, with the appropriate
         // polymorphic variables. So:
         // - 1 part for definition
         // - N_poly_arg marker parts for each polymorphic argument
         // - all the parts for the currently known polymorphic arguments
         let parts_reserved = 1 + poly_args.len() + total_num_poly_parts;
         let mut parts = Vec::with_capacity(parts_reserved);
         parts.push(ITP::Instance(literal.definition, poly_args.len() as u32));
         let mut return_type_done = true;
         for (poly_var_idx, poly_var) in poly_args.iter().enumerate() {
             if !poly_var.is_done { return_type_done = false; }
             parts.push(ITP::Marker(poly_var_idx as u32));
             parts.extend(poly_var.parts.iter().cloned());
+        }
         debug_assert_eq!(parts.len(), parts_reserved);
         let return_type = InferenceType::new(!poly_args.is_empty(), return_type_done, parts);
         self.extra_data[extra_data_idx as usize] = ExtraData{
             expr_id: lit_id.upcast(),
             definition_id: literal.definition,
             poly_vars: poly_args,
             embedded: embedded_types,
             returned: return_type,
         };
+    }
     /// Inserts the extra polymorphic data struct for enum expressions. These
     /// can never be determined from the enum itself, but may be inferred from
     /// the use of the enum.
     fn insert_initial_enum_polymorph_data(
         &mut self, ctx: &Ctx, lit_id: LiteralExpressionId
     ) {
         use InferenceTypePart as ITP;
         let literal = &ctx.heap[lit_id];
         let extra_data_idx = self.expr_types[literal.unique_id_in_definition as usize].extra_data_idx; // TODO: @Temp
         debug_assert!(extra_data_idx != -1, "initial enum polymorph data, but no preallocated ExtraData");
         let literal = ctx.heap[lit_id].value.as_enum();
         // Handle polymorphic arguments to the enum
         let num_poly_args = literal.parser_type.elements[0].variant.num_embedded();
         let mut total_num_poly_parts = 0;
         let mut poly_args = Vec::with_capacity(num_poly_args);
         for embedded_elements in literal.parser_type.iter_embedded(0) {
             let poly_type = self.determine_inference_type_from_parser_type_elements(embedded_elements, true);
             total_num_poly_parts += poly_type.parts.len();
             poly_args.push(poly_type);
+        }
         // Handle enum type itself
         let parts_reserved = 1 + poly_args.len() + total_num_poly_parts;
         let mut parts = Vec::with_capacity(parts_reserved);
         parts.push(ITP::Instance(literal.definition, poly_args.len() as u32));
         let mut enum_type_done = true;
         for (poly_var_idx, poly_var) in poly_args.iter().enumerate() {
             if !poly_var.is_done { enum_type_done = false; }
             parts.push(ITP::Marker(poly_var_idx as u32));
             parts.extend(poly_var.parts.iter().cloned());
+        }
         debug_assert_eq!(parts.len(), parts_reserved);
         let enum_type = InferenceType::new(!poly_args.is_empty(), enum_type_done, parts);
         self.extra_data[extra_data_idx as usize] = ExtraData{
             expr_id: lit_id.upcast(),
             definition_id: literal.definition,
             poly_vars: poly_args,
             embedded: Vec::new(),
             returned: enum_type,
         };
+    }
     /// Inserts the extra polymorphic data struct for unions. The polymorphic
     /// arguments may be partially determined from embedded values in the union.
     fn insert_initial_union_polymorph_data(
         &mut self, ctx: &Ctx, lit_id: LiteralExpressionId
     ) {
         use InferenceTypePart as ITP;
         let literal = &ctx.heap[lit_id];
         let extra_data_idx = self.expr_types[literal.unique_id_in_definition as usize].extra_data_idx; // TODO: @Temp
         debug_assert!(extra_data_idx != -1, "initial union polymorph data, but no preallocated ExtraData");
         let literal = ctx.heap[lit_id].value.as_union();
         // Construct the polymorphic variables
         let num_poly_args = literal.parser_type.elements[0].variant.num_embedded();
         let mut total_num_poly_parts = 0;
         let mut poly_args = Vec::with_capacity(num_poly_args);
         for embedded_elements in literal.parser_type.iter_embedded(0) {
             let poly_type = self.determine_inference_type_from_parser_type_elements(embedded_elements, true);
             total_num_poly_parts += poly_type.parts.len();
             poly_args.push(poly_type);
+        }
         // Handle any of the embedded values in the variant, if specified
         let definition_id = literal.definition;
         let type_definition = ctx.types.get_base_definition(&definition_id).unwrap();
         let union_definition = type_definition.definition.as_union();
         debug_assert_eq!(poly_args.len(), type_definition.poly_vars.len());
         let variant_definition = &union_definition.variants[literal.variant_idx];
         debug_assert_eq!(variant_definition.embedded.len(), literal.values.len());
         let mut embedded = Vec::with_capacity(variant_definition.embedded.len());
         for embedded_parser_type in &variant_definition.embedded {
             let inference_type = self.determine_inference_type_from_parser_type_elements(&embedded_parser_type.elements, false);
             embedded.push(inference_type);
+        }
         // Handle the type of the union itself
         let parts_reserved = 1 + poly_args.len() + total_num_poly_parts;
         let mut parts = Vec::with_capacity(parts_reserved);
         parts.push(ITP::Instance(definition_id, poly_args.len() as u32));
         let mut union_type_done = true;
         for (poly_var_idx, poly_var) in poly_args.iter().enumerate() {
             if !poly_var.is_done { union_type_done = false; }
             parts.push(ITP::Marker(poly_var_idx as u32));
             parts.extend(poly_var.parts.iter().cloned());
+        }
         debug_assert_eq!(parts_reserved, parts.len());
         let union_type = InferenceType::new(!poly_args.is_empty(), union_type_done, parts);
         self.extra_data[extra_data_idx as usize] = ExtraData{
             expr_id: lit_id.upcast(),
             definition_id: literal.definition,
             poly_vars: poly_args,
             embedded,
             returned: union_type
         };
+    }
     /// Inserts the extra polymorphic data struct. Assumes that the select
     /// expression's referenced (definition_id, field_idx) has been resolved.
     fn insert_initial_select_polymorph_data(
         &mut self, ctx: &Ctx, select_id: SelectExpressionId, struct_def_id: DefinitionId
     ) {
         use InferenceTypePart as ITP;
         // Retrieve relevant data
         let expr = &ctx.heap[select_id];
         let expr_type = &self.expr_types[expr.unique_id_in_definition as usize];
         let field_idx = expr_type.field_or_monomorph_idx as usize;
         let extra_data_idx = expr_type.extra_data_idx; // TODO: @Temp
         debug_assert!(extra_data_idx != -1, "initial select polymorph data, but no preallocated ExtraData");
         let definition = ctx.heap[struct_def_id].as_struct();
         // Generate initial polyvar types and struct type
         // TODO: @Performance: we can immediately set the polyvars of the subject's struct type
         let num_poly_vars = definition.poly_vars.len();
         let mut poly_vars = Vec::with_capacity(num_poly_vars);
         let struct_parts_reserved = 1 + 2 * num_poly_vars;
         let mut struct_parts = Vec::with_capacity(struct_parts_reserved);
         struct_parts.push(ITP::Instance(struct_def_id, num_poly_vars as u32));
         for poly_idx in 0..num_poly_vars {
             poly_vars.push(InferenceType::new(true, false, vec![
                 ITP::Marker(poly_idx as u32), ITP::Unknown,
             ]));
             struct_parts.push(ITP::Marker(poly_idx as u32));
             struct_parts.push(ITP::Unknown);
+        }
         debug_assert_eq!(struct_parts.len(), struct_parts_reserved);
         // Generate initial field type
         let field_type = self.determine_inference_type_from_parser_type_elements(&definition.fields[field_idx].parser_type.elements, false);
         self.extra_data[extra_data_idx as usize] = ExtraData{
             expr_id: select_id.upcast(),
             definition_id: struct_def_id,
             poly_vars,
             embedded: vec![InferenceType::new(num_poly_vars != 0, num_poly_vars == 0, struct_parts)],
             returned: field_type
         };
+    }
     /// Determines the initial InferenceType from the provided ParserType. This
     /// may be called with two kinds of intentions:
     /// 1. To resolve a ParserType within the body of a function, or on
     ///     polymorphic arguments to calls/instantiations within that body. This
     ///     means that the polymorphic variables are known and can be replaced
     ///     with the monomorph we're instantiating.
     /// 2. To resolve a ParserType on a called function's definition or on
     ///     an instantiated datatype's members. This means that the polymorphic
     ///     arguments inside those ParserTypes refer to the polymorphic
     ///     variables in the called/instantiated type's definition.
     /// In the second case we place InferenceTypePart::Marker instances such
     /// that we can perform type inference on the polymorphic variables.
     fn determine_inference_type_from_parser_type_elements(
         &mut self, elements: &[ParserTypeElement],
         use_definitions_known_poly_args: bool
     ) -> InferenceType {
         use ParserTypeVariant as PTV;
         use InferenceTypePart as ITP;
         let mut infer_type = Vec::with_capacity(elements.len());
         let mut has_inferred = false;
         let mut has_markers = false;
         for element in elements {
             match &element.variant {
                 // Compiler-only types
                 PTV::Void => { infer_type.push(ITP::Void); },
                 PTV::InputOrOutput => { infer_type.push(ITP::PortLike); has_inferred = true },
                 PTV::ArrayLike => { infer_type.push(ITP::ArrayLike); has_inferred = true },
                 PTV::IntegerLike => { infer_type.push(ITP::IntegerLike); has_inferred = true },
                 // Builtins
                 PTV::Message => {
                     // TODO: @types Remove the Message -> Byte hack at some point...
                     infer_type.push(ITP::Message);
                     infer_type.push(ITP::UInt8);
                 },
                 PTV::Bool => { infer_type.push(ITP::Bool); },
                 PTV::UInt8 => { infer_type.push(ITP::UInt8); },
                 PTV::UInt16 => { infer_type.push(ITP::UInt16); },
                 PTV::UInt32 => { infer_type.push(ITP::UInt32); },
                 PTV::UInt64 => { infer_type.push(ITP::UInt64); },
                 PTV::SInt8 => { infer_type.push(ITP::SInt8); },
                 PTV::SInt16 => { infer_type.push(ITP::SInt16); },
                 PTV::SInt32 => { infer_type.push(ITP::SInt32); },
                 PTV::SInt64 => { infer_type.push(ITP::SInt64); },
                 PTV::Character => { infer_type.push(ITP::Character); },
                 PTV::String => {
                     infer_type.push(ITP::String);
                     infer_type.push(ITP::Character);
                 },
                 // Special markers
                 PTV::IntegerLiteral => { unreachable!("integer literal type on variable type"); },
                 PTV::Inferred => {
                     infer_type.push(ITP::Unknown);
                     has_inferred = true;
                 },
                 // With nested types
                 PTV::Array => { infer_type.push(ITP::Array); },
                 PTV::Input => { infer_type.push(ITP::Input); },
                 PTV::Output => { infer_type.push(ITP::Output); },
                 PTV::Tuple(num_embedded) => { infer_type.push(ITP::Tuple(*num_embedded)); },
                 PTV::PolymorphicArgument(belongs_to_definition, poly_arg_idx) => {
                     let poly_arg_idx = *poly_arg_idx;
                     if use_definitions_known_poly_args {
                         // Refers to polymorphic argument on procedure we're currently processing.
                         // This argument is already known.
                         debug_assert_eq!(*belongs_to_definition, self.definition_type.definition_id());
                         debug_assert!((poly_arg_idx as usize) < self.poly_vars.len());
                         Self::determine_inference_type_from_concrete_type(
                             &mut infer_type, &self.poly_vars[poly_arg_idx as usize].parts
                         );
                     } else {
                         // Polymorphic argument has to be inferred
                         has_markers = true;
                         has_inferred = true;
                         infer_type.push(ITP::Marker(poly_arg_idx));
                         infer_type.push(ITP::Unknown)
+                    }
                 },
                 PTV::Definition(definition_id, num_embedded) => {
                     infer_type.push(ITP::Instance(*definition_id, *num_embedded));
+                }
+            }
+        }
         InferenceType::new(has_markers, !has_inferred, infer_type)
+    }
     /// Determines the inference type from an already concrete type. Applies the
     /// various type "hacks" inside the type inferencer.
     fn determine_inference_type_from_concrete_type(parser_type: &mut Vec<InferenceTypePart>, concrete_type: &[ConcreteTypePart]) {
         use InferenceTypePart as ITP;
         use ConcreteTypePart as CTP;
         for concrete_part in concrete_type {
             match concrete_part {
                 CTP::Void => parser_type.push(ITP::Void),
                 CTP::Message => {
                     parser_type.push(ITP::Message);
                     parser_type.push(ITP::UInt8)
                 },
                 CTP::Bool => parser_type.push(ITP::Bool),
                 CTP::UInt8 => parser_type.push(ITP::UInt8),
                 CTP::UInt16 => parser_type.push(ITP::UInt16),
                 CTP::UInt32 => parser_type.push(ITP::UInt32),
                 CTP::UInt64 => parser_type.push(ITP::UInt64),
                 CTP::SInt8 => parser_type.push(ITP::SInt8),
                 CTP::SInt16 => parser_type.push(ITP::SInt16),
                 CTP::SInt32 => parser_type.push(ITP::SInt32),
                 CTP::SInt64 => parser_type.push(ITP::SInt64),
                 CTP::Character => parser_type.push(ITP::Character),
                 CTP::String => {
                     parser_type.push(ITP::String);
                     parser_type.push(ITP::Character)
                 },
                 CTP::Array => parser_type.push(ITP::Array),
                 CTP::Slice => parser_type.push(ITP::Slice),
                 CTP::Input => parser_type.push(ITP::Input),
                 CTP::Output => parser_type.push(ITP::Output),
                 CTP::Tuple(num) => parser_type.push(ITP::Tuple(*num)),
                 CTP::Instance(id, num) => parser_type.push(ITP::Instance(*id, *num)),
                 CTP::Function(_, _) => unreachable!("function type during concrete to inference type conversion"),
                 CTP::Component(_, _) => unreachable!("component type during concrete to inference type conversion"),
+            }
+        }
+    }
     /// Construct an error when an expression's type does not match. This
     /// happens if we infer the expression type from its arguments (e.g. the
     /// expression type of an addition operator is the type of the arguments)
     /// But the expression type was already set due to our parent (e.g. an
     /// "if statement" or a "logical not" always expecting a boolean)
     fn construct_expr_type_error(
         &self, ctx: &Ctx, expr_id: ExpressionId, arg_id: ExpressionId
     ) -> ParseError {
         // TODO: Expand and provide more meaningful information for humans
         let expr = &ctx.heap[expr_id];
         let arg_expr = &ctx.heap[arg_id];
         let expr_idx = expr.get_unique_id_in_definition();
         let arg_expr_idx = arg_expr.get_unique_id_in_definition();
         let expr_type = &self.expr_types[expr_idx as usize].expr_type;
         let arg_type = &self.expr_types[arg_expr_idx as usize].expr_type;
         return ParseError::new_error_at_span(
             &ctx.module().source, expr.operation_span(), format!(
                 "incompatible types: this expression expected a '{}'",
                 expr_type.display_name(&ctx.heap)
+            )
         ).with_info_at_span(
             &ctx.module().source, arg_expr.full_span(), format!(
                 "but this expression yields a '{}'",
                 arg_type.display_name(&ctx.heap)
+            )
+        )
+    }
     fn construct_arg_type_error(
         &self, ctx: &Ctx, expr_id: ExpressionId,
         arg1_id: ExpressionId, arg2_id: ExpressionId
     ) -> ParseError {
         let expr = &ctx.heap[expr_id];
         let arg1 = &ctx.heap[arg1_id];
         let arg2 = &ctx.heap[arg2_id];
         let arg1_idx = arg1.get_unique_id_in_definition();
         let arg1_type = &self.expr_types[arg1_idx as usize].expr_type;
         let arg2_idx = arg2.get_unique_id_in_definition();
         let arg2_type = &self.expr_types[arg2_idx as usize].expr_type;
         return ParseError::new_error_str_at_span(
             &ctx.module().source, expr.operation_span(),
             "incompatible types: cannot apply this expression"
         ).with_info_at_span(
             &ctx.module().source, arg1.full_span(), format!(
                 "Because this expression has type '{}'",
                 arg1_type.display_name(&ctx.heap)
+            )
         ).with_info_at_span(
             &ctx.module().source, arg2.full_span(), format!(
                 "But this expression has type '{}'",
                 arg2_type.display_name(&ctx.heap)
+            )
+        )
+    }
     fn construct_template_type_error(
         &self, ctx: &Ctx, expr_id: ExpressionId, template: &[InferenceTypePart]
     ) -> ParseError {
         let expr = &ctx.heap[expr_id];
         let expr_idx = expr.get_unique_id_in_definition();
         let expr_type = &self.expr_types[expr_idx as usize].expr_type;
         return ParseError::new_error_at_span(
             &ctx.module().source, expr.full_span(), format!(
                 "incompatible types: got a '{}' but expected a '{}'",
                 expr_type.display_name(&ctx.heap),
                 InferenceType::partial_display_name(&ctx.heap, template)
+            )
+        )
+    }
     /// Constructs a human interpretable error in the case that type inference
     /// on a polymorphic variable to a function call or literal construction
     /// failed. This may only be caused by a pair of inference types (which may
     /// come from arguments or the return type) having two different inferred
     /// values for that polymorphic variable.
     ///
     /// So we find this pair and construct the error using it.
     ///
     /// We assume that the expression is a function call or a struct literal,
     /// and that an actual error has occurred.
     fn construct_poly_arg_error(
         ctx: &Ctx, poly_data: &ExtraData, expr_id: ExpressionId
     ) -> ParseError {
         // Helper function to check for polymorph mismatch between two inference
         // types.
         fn has_poly_mismatch<'a>(type_a: &'a InferenceType, type_b: &'a InferenceType) -> Option<(u32, &'a [InferenceTypePart], &'a [InferenceTypePart])> {
             if !type_a.has_marker || !type_b.has_marker {
                 return None
+            }
             for (marker_a, section_a) in type_a.marker_iter() {
                 for (marker_b, section_b) in type_b.marker_iter() {
                     if marker_a != marker_b {
                         // Not the same polymorphic variable
                         continue;
+                    }
                     if !InferenceType::check_subtrees(section_a, 0, section_b, 0) {
                         // Not compatible
                         return Some((marker_a, section_a, section_b))
+                    }
+                }
+            }
             None
+        }
         // Helper function to check for polymorph mismatch between an inference
         // type and the polymorphic variables in the poly_data struct.
         fn has_explicit_poly_mismatch<'a>(
             poly_vars: &'a [InferenceType], arg: &'a InferenceType
         ) -> Option<(u32, &'a [InferenceTypePart], &'a [InferenceTypePart])> {
             for (marker, section) in arg.marker_iter() {
                 debug_assert!((marker as usize) < poly_vars.len());
                 let poly_section = &poly_vars[marker as usize].parts;
                 if !InferenceType::check_subtrees(poly_section, 0, section, 0) {
                     return Some((marker, poly_section, section))
+                }
+            }
             None
+        }
         // Helpers function to retrieve polyvar name and definition name
         fn get_poly_var_and_definition_name<'a>(ctx: &'a Ctx, poly_var_idx: u32, definition_id: DefinitionId) -> (&'a str, &'a str) {
             let definition = &ctx.heap[definition_id];
             let poly_var = definition.poly_vars()[poly_var_idx as usize].value.as_str();
             let func_name = definition.identifier().value.as_str();
             (poly_var, func_name)
+        }
         // Helper function to construct initial error
         fn construct_main_error(ctx: &Ctx, poly_data: &ExtraData, poly_var_idx: u32, expr: &Expression) -> ParseError {
             match expr {
                 Expression::Call(expr) => {
                     let (poly_var, func_name) = get_poly_var_and_definition_name(ctx, poly_var_idx, poly_data.definition_id);
                     return ParseError::new_error_at_span(
                         &ctx.module().source, expr.func_span, format!(
                             "Conflicting type for polymorphic variable '{}' of '{}'",
                             poly_var, func_name
+                        )
+                    )
                 },
                 Expression::Literal(expr) => {
                     let (poly_var, type_name) = get_poly_var_and_definition_name(ctx, poly_var_idx, poly_data.definition_id);
                     return ParseError::new_error_at_span(
                         &ctx.module().source, expr.span, format!(
                             "Conflicting type for polymorphic variable '{}' of instantiation of '{}'",
                             poly_var, type_name
+                        )
                     );
                 },
                 Expression::Select(expr) => {
                     let (poly_var, struct_name) = get_poly_var_and_definition_name(ctx, poly_var_idx, poly_data.definition_id);
                     let field_name = match &expr.kind {
                         SelectKind::StructField(v) => v,
                         SelectKind::TupleMember(_) => unreachable!(), // because we're constructing a polymorph error, and tuple access does not deal with polymorphs
                     };
                     return ParseError::new_error_at_span(
                         &ctx.module().source, expr.full_span, format!(
                             "Conflicting type for polymorphic variable '{}' while accessing field '{}' of '{}'",
                             poly_var, field_name.value.as_str(), struct_name
+                        )
+                    )
+                }
                 _ => unreachable!("called construct_poly_arg_error without an expected expression, got: {:?}", expr)
+            }
+        }
         // Actual checking
         let expr = &ctx.heap[expr_id];
         let (expr_args, expr_return_name) = match expr {
             Expression::Call(expr) =>
+                (
                     expr.arguments.clone(),
                     "return type"
                 ),
             Expression::Literal(expr) => {
                 let expressions = match &expr.value {
                     Literal::Struct(v) => v.fields.iter()
                         .map(|f| f.value)
                         .collect(),
                     Literal::Enum(_) => Vec::new(),
                     Literal::Union(v) => v.values.clone(),
                     _ => unreachable!()
                 };
                 ( expressions, "literal" )
             },
             Expression::Select(expr) =>
                 // Select expression uses the polymorphic variables of the
                 // struct it is accessing, so get the subject expression.
+                (
                     vec![expr.subject],
                     "selected field"
                 ),
             _ => unreachable!(),
         };
         // - check return type with itself
         if let Some((poly_idx, section_a, section_b)) = has_poly_mismatch(
             &poly_data.returned, &poly_data.returned
         ) {
             return construct_main_error(ctx, poly_data, poly_idx, expr)
                 .with_info_at_span(
                     &ctx.module().source, expr.full_span(), format!(
                         "The {} inferred the conflicting types '{}' and '{}'",
                         expr_return_name,
                         InferenceType::partial_display_name(&ctx.heap, section_a),
                         InferenceType::partial_display_name(&ctx.heap, section_b)
+                    )
                 );
+        }
         // - check arguments with each other argument and with return type
         for (arg_a_idx, arg_a) in poly_data.embedded.iter().enumerate() {
             for (arg_b_idx, arg_b) in poly_data.embedded.iter().enumerate() {
                 if arg_b_idx > arg_a_idx {
                     break;
+                }
                 if let Some((poly_idx, section_a, section_b)) = has_poly_mismatch(&arg_a, &arg_b) {
                     let error = construct_main_error(ctx, poly_data, poly_idx, expr);
                     if arg_a_idx == arg_b_idx {
                         // Same argument
                         let arg = &ctx.heap[expr_args[arg_a_idx]];
                         return error.with_info_at_span(
                             &ctx.module().source, arg.full_span(), format!(
                                 "This argument inferred the conflicting types '{}' and '{}'",
                                 InferenceType::partial_display_name(&ctx.heap, section_a),
                                 InferenceType::partial_display_name(&ctx.heap, section_b)
+                            )
                         );
                     } else {
                         let arg_a = &ctx.heap[expr_args[arg_a_idx]];
                         let arg_b = &ctx.heap[expr_args[arg_b_idx]];
                         return error.with_info_at_span(
                             &ctx.module().source, arg_a.full_span(), format!(
                                 "This argument inferred it to '{}'",
                                 InferenceType::partial_display_name(&ctx.heap, section_a)
+                            )
                         ).with_info_at_span(
                             &ctx.module().source, arg_b.full_span(), format!(
                                 "While this argument inferred it to '{}'",
                                 InferenceType::partial_display_name(&ctx.heap, section_b)
+                            )
+                        )
+                    }
+                }
+            }
             // Check with return type
             if let Some((poly_idx, section_arg, section_ret)) = has_poly_mismatch(arg_a, &poly_data.returned) {
                 let arg = &ctx.heap[expr_args[arg_a_idx]];
                 return construct_main_error(ctx, poly_data, poly_idx, expr)
                     .with_info_at_span(
                         &ctx.module().source, arg.full_span(), format!(
                             "This argument inferred it to '{}'",
                             InferenceType::partial_display_name(&ctx.heap, section_arg)
+                        )
+                    )
                     .with_info_at_span(
                         &ctx.module().source, expr.full_span(), format!(
                             "While the {} inferred it to '{}'",
                             expr_return_name,
                             InferenceType::partial_display_name(&ctx.heap, section_ret)
+                        )
                     );
+            }
+        }
         // Now check against the explicitly specified polymorphic variables (if
         // any).
         for (arg_idx, arg) in poly_data.embedded.iter().enumerate() {
             if let Some((poly_idx, poly_section, arg_section)) = has_explicit_poly_mismatch(&poly_data.poly_vars, arg) {
                 let arg = &ctx.heap[expr_args[arg_idx]];
                 return construct_main_error(ctx, poly_data, poly_idx, expr)
                     .with_info_at_span(
                         &ctx.module().source, arg.full_span(), format!(
                             "The polymorphic variable has type '{}' (which might have been partially inferred) while the argument inferred it to '{}'",
                             InferenceType::partial_display_name(&ctx.heap, poly_section),
                             InferenceType::partial_display_name(&ctx.heap, arg_section)
+                        )
                     );
+            }
+        }
         if let Some((poly_idx, poly_section, ret_section)) = has_explicit_poly_mismatch(&poly_data.poly_vars, &poly_data.returned) {
             return construct_main_error(ctx, poly_data, poly_idx, expr)
                 .with_info_at_span(
                     &ctx.module().source, expr.full_span(), format!(
                         "The polymorphic variable has type '{}' (which might have been partially inferred) while the {} inferred it to '{}'",
                         InferenceType::partial_display_name(&ctx.heap, poly_section),
                         expr_return_name,
                         InferenceType::partial_display_name(&ctx.heap, ret_section)
+                    )
+                )
+        }
         unreachable!("construct_poly_arg_error without actual error found?")
+    }
+}
 #[cfg(test)]
 mod tests {
     use super::*;
     use crate::protocol::arena::Id;
     use InferenceTypePart as ITP;
     use InferenceType as IT;
     #[test]
     fn test_single_part_inference() {
         // lhs argument inferred from rhs
         let pairs = [
             (ITP::NumberLike, ITP::UInt8),
             (ITP::IntegerLike, ITP::SInt32),
             (ITP::Unknown, ITP::UInt64),
             (ITP::Unknown, ITP::Bool)
         ];
         for (lhs, rhs) in pairs.iter() {
             // Using infer-both
             let mut lhs_type = IT::new(false, false, vec![lhs.clone()]);
             let mut rhs_type = IT::new(false, true, vec![rhs.clone()]);
             let result = unsafe{ IT::infer_subtrees_for_both_types(
                 &mut lhs_type, 0, &mut rhs_type, 0
             ) };
             assert_eq!(DualInferenceResult::First, result);
             assert_eq!(lhs_type.parts, rhs_type.parts);
             // Using infer-single
             let mut lhs_type = IT::new(false, false, vec![lhs.clone()]);
             let rhs_type = IT::new(false, true, vec![rhs.clone()]);
             let result = IT::infer_subtree_for_single_type(
                 &mut lhs_type, 0, &rhs_type.parts, 0, false
             );
             assert_eq!(SingleInferenceResult::Modified, result);
             assert_eq!(lhs_type.parts, rhs_type.parts);
+        }
+    }
     #[test]
     fn test_multi_part_inference() {
         let pairs = [
             (vec![ITP::ArrayLike, ITP::NumberLike], vec![ITP::Slice, ITP::SInt8]),
             (vec![ITP::Unknown], vec![ITP::Input, ITP::Array, ITP::String, ITP::Character]),
             (vec![ITP::PortLike, ITP::SInt32], vec![ITP::Input, ITP::SInt32]),
             (vec![ITP::Unknown], vec![ITP::Output, ITP::SInt32]),
+            (
                 vec![ITP::Instance(Id::new(0), 2), ITP::Input, ITP::Unknown, ITP::Output, ITP::Unknown],
                 vec![ITP::Instance(Id::new(0), 2), ITP::Input, ITP::Array, ITP::SInt32, ITP::Output, ITP::SInt32]
+            )
         ];
         for (lhs, rhs) in pairs.iter() {
             let mut lhs_type = IT::new(false, false, lhs.clone());
             let mut rhs_type = IT::new(false, true, rhs.clone());
             let result = unsafe{ IT::infer_subtrees_for_both_types(
                 &mut lhs_type, 0, &mut rhs_type, 0
             ) };
             assert_eq!(DualInferenceResult::First, result);
             assert_eq!(lhs_type.parts, rhs_type.parts);
             let mut lhs_type = IT::new(false, false, lhs.clone());
             let rhs_type = IT::new(false, true, rhs.clone());
             let result = IT::infer_subtree_for_single_type(
                 &mut lhs_type, 0, &rhs_type.parts, 0, false
             );
             assert_eq!(SingleInferenceResult::Modified, result);
             assert_eq!(lhs_type.parts, rhs_type.parts)
+        }
+    }
+}
@@ \ No newline at end of file @@

src/protocol/parser/pass_validation_linking.rs

➞

Show inline comments

 /*
  * pass_validation_linking.rs
+ *
  * The pass that will validate properties of the AST statements (one is not
  * allowed to nest synchronous statements, instantiating components occurs in
  * the right places, etc.) and expressions (assignments may not occur in
  * arbitrary expressions).
+ *
  * Furthermore, this pass will also perform "linking", in the sense of: some AST
  * nodes have something to do with one another, so we link them up in this pass
  * (e.g. setting the parents of expressions, linking the control flow statements
  * like `continue` and `break` up to the respective loop statement, etc.).
+ *
  * There are several "confusing" parts about this pass:
+ *
  * Setting expression parents: this is the simplest one. The pass struct acts
  * like a little state machine. When visiting an expression it will set the
  * "parent expression" field of the pass to itself, then visit its child. The
  * child will look at this "parent expression" field to determine its parent.
+ *
  * Setting the `next` statement: the AST is a tree, but during execution we walk
  * a linear path through all statements. So where appropriate a statement may
  * set the "previous statement" field of the pass to itself. When visiting the
  * subsequent statement it will check this "previous statement", and if set, it
  * will link this previous statement up to itself. Not every statement has a
  * previous statement. Hence there are two patterns that occur: assigning the
  * `next` value, then clearing the "previous statement" field. And assigning the
  * `next` value, and then putting the current statement's ID in the "previous
  * statement" field. Because it is so common, this file contain two macros that
  * perform that operation.
+ *
  * To make storing types for polymorphic procedures simpler and more efficient,
  * we assign to each expression in the procedure a unique ID. This is what the
  * "next expression index" field achieves. Each expression simply takes the
  * current value, and then increments this counter.
  */
 use crate::collections::{ScopedBuffer};
 use crate::protocol::ast::*;
 use crate::protocol::input_source::*;
 use crate::protocol::parser::symbol_table::*;
 use crate::protocol::parser::type_table::*;
 use super::visitor::{
     BUFFER_INIT_CAPACITY,
     Ctx,
     Visitor,
     VisitorResult
 };
 use crate::protocol::parser::ModuleCompilationPhase;
 #[derive(PartialEq, Eq)]
 enum DefinitionType {
     Primitive(ComponentDefinitionId),
     Composite(ComponentDefinitionId),
     Function(FunctionDefinitionId)
+}
 impl DefinitionType {
     fn is_primitive(&self) -> bool { if let Self::Primitive(_) = self { true } else { false } }
     fn is_composite(&self) -> bool { if let Self::Composite(_) = self { true } else { false } }
     fn is_function(&self) -> bool { if let Self::Function(_) = self { true } else { false } }
     fn definition_id(&self) -> DefinitionId {
         match self {
             DefinitionType::Primitive(v) => v.upcast(),
             DefinitionType::Composite(v) => v.upcast(),
             DefinitionType::Function(v) => v.upcast(),
+        }
+    }
+}
 /// This particular visitor will go through the entire AST in a recursive manner
 /// and check if all statements and expressions are legal (e.g. no "return"
 /// statements in component definitions), and will link certain AST nodes to
 /// their appropriate targets (e.g. goto statements, or function calls).
 ///
 /// This visitor will not perform control-flow analysis (e.g. making sure that
 /// each function actually returns) and will also not perform type checking. So
 /// the linking of function calls and component instantiations will be checked
 /// and linked to the appropriate definitions, but the return types and/or
 /// arguments will not be checked for validity.
 pub(crate) struct PassValidationLinking {
     // Traversal state, all valid IDs if inside a certain AST element. Otherwise
     // `id.is_invalid()` returns true.
     in_sync: SynchronousStatementId,
     in_while: WhileStatementId, // to resolve labeled continue/break
     in_test_expr: StatementId, // wrapping if/while stmt id
     in_binding_expr: BindingExpressionId, // to resolve variable expressions
     in_binding_expr_lhs: bool,
     // Traversal state, current scope (which can be used to find the parent
     // scope) and the definition variant we are considering.
     cur_scope: Scope,
     def_type: DefinitionType,
     // "Trailing" traversal state, set be child/prev stmt/expr used by next one
     prev_stmt: StatementId,
     expr_parent: ExpressionParent,
     // Set by parent to indicate that child expression must be assignable. The
     // child will throw an error if it is not assignable. The stored span is
     // used for the error's position
     must_be_assignable: Option<InputSpan>,
     // Keeping track of relative positions and unique IDs.
     relative_pos_in_block: u32, // of statements: to determine when variables are visible
     next_expr_index: i32, // to arrive at a unique ID for all expressions within a definition
     // Various temporary buffers for traversal. Essentially working around
     // Rust's borrowing rules since it cannot understand we're modifying AST
     // members but not the AST container.
     variable_buffer: ScopedBuffer<VariableId>,
     definition_buffer: ScopedBuffer<DefinitionId>,
     statement_buffer: ScopedBuffer<StatementId>,
     expression_buffer: ScopedBuffer<ExpressionId>,
+}
 impl PassValidationLinking {
     pub(crate) fn new() -> Self {
         Self{
             in_sync: SynchronousStatementId::new_invalid(),
             in_while: WhileStatementId::new_invalid(),
             in_test_expr: StatementId::new_invalid(),
             in_binding_expr: BindingExpressionId::new_invalid(),
             in_binding_expr_lhs: false,
             cur_scope: Scope::Definition(DefinitionId::new_invalid()),
             prev_stmt: StatementId::new_invalid(),
             expr_parent: ExpressionParent::None,
             def_type: DefinitionType::Function(FunctionDefinitionId::new_invalid()),
             must_be_assignable: None,
             relative_pos_in_block: 0,
             next_expr_index: 0,
             variable_buffer: ScopedBuffer::with_capacity(128),
             definition_buffer: ScopedBuffer::with_capacity(128),
             statement_buffer: ScopedBuffer::with_capacity(BUFFER_INIT_CAPACITY),
             expression_buffer: ScopedBuffer::with_capacity(BUFFER_INIT_CAPACITY),
+        }
+    }
     fn reset_state(&mut self) {
         self.in_sync = SynchronousStatementId::new_invalid();
         self.in_while = WhileStatementId::new_invalid();
         self.in_test_expr = StatementId::new_invalid();
         self.in_binding_expr = BindingExpressionId::new_invalid();
         self.in_binding_expr_lhs = false;
         self.cur_scope = Scope::Definition(DefinitionId::new_invalid());
         self.def_type = DefinitionType::Function(FunctionDefinitionId::new_invalid());
         self.prev_stmt = StatementId::new_invalid();
         self.expr_parent = ExpressionParent::None;
         self.must_be_assignable = None;
         self.relative_pos_in_block = 0;
         self.next_expr_index = 0
+    }
+}
 macro_rules! assign_then_erase_next_stmt {
     ($self:ident, $ctx:ident, $stmt_id:expr) => {
         if !$self.prev_stmt.is_invalid() {
             $ctx.heap[$self.prev_stmt].link_next($stmt_id);
             $self.prev_stmt = StatementId::new_invalid();
+        }
+    }
+}
 macro_rules! assign_and_replace_next_stmt {
     ($self:ident, $ctx:ident, $stmt_id:expr) => {
         if !$self.prev_stmt.is_invalid() {
             $ctx.heap[$self.prev_stmt].link_next($stmt_id);
+        }
         $self.prev_stmt = $stmt_id;
+    }
+}
 impl Visitor for PassValidationLinking {
     fn visit_module(&mut self, ctx: &mut Ctx) -> VisitorResult {
         debug_assert_eq!(ctx.module().phase, ModuleCompilationPhase::TypesAddedToTable);
         let root = &ctx.heap[ctx.module().root_id];
         let section = self.definition_buffer.start_section_initialized(&root.definitions);
         for definition_idx in 0..section.len() {
             let definition_id = section[definition_idx];
         for definition_id in section.iter_copied() {
             self.visit_definition(ctx, definition_id)?;
+        }
         section.forget();
         ctx.module_mut().phase = ModuleCompilationPhase::ValidatedAndLinked;
         Ok(())
+    }
     //--------------------------------------------------------------------------
     // Definition visitors
     //--------------------------------------------------------------------------
     fn visit_component_definition(&mut self, ctx: &mut Ctx, id: ComponentDefinitionId) -> VisitorResult {
         self.reset_state();
         self.def_type = match &ctx.heap[id].variant {
             ComponentVariant::Primitive => DefinitionType::Primitive(id),
             ComponentVariant::Composite => DefinitionType::Composite(id),
         };
         self.cur_scope = Scope::Definition(id.upcast());
         self.expr_parent = ExpressionParent::None;
         // Visit parameters and assign a unique scope ID
         let definition = &ctx.heap[id];
         let body_id = definition.body;
         let section = self.variable_buffer.start_section_initialized(&definition.parameters);
         for variable_idx in 0..section.len() {
             let variable_id = section[variable_idx];
             let variable = &mut ctx.heap[variable_id];
             variable.unique_id_in_scope = variable_idx as i32;
+        }
         section.forget();
         // Visit statements in component body
         self.visit_block_stmt(ctx, body_id)?;
         // Assign total number of expressions and assign an in-block unique ID
         // to each of the locals in the procedure.
         ctx.heap[id].num_expressions_in_body = self.next_expr_index;
         self.visit_definition_and_assign_local_ids(ctx, id.upcast());
         Ok(())
+    }
     fn visit_function_definition(&mut self, ctx: &mut Ctx, id: FunctionDefinitionId) -> VisitorResult {
         self.reset_state();
         // Set internal statement indices
         self.def_type = DefinitionType::Function(id);
         self.cur_scope = Scope::Definition(id.upcast());
         self.expr_parent = ExpressionParent::None;
         // Visit parameters and assign a unique scope ID
         let definition = &ctx.heap[id];
         let body_id = definition.body;
         let section = self.variable_buffer.start_section_initialized(&definition.parameters);
         for variable_idx in 0..section.len() {
             let variable_id = section[variable_idx];
             let variable = &mut ctx.heap[variable_id];
             variable.unique_id_in_scope = variable_idx as i32;
+        }
         section.forget();
         // Visit statements in function body
         self.visit_block_stmt(ctx, body_id)?;
         // Assign total number of expressions and assign an in-block unique ID
         // to each of the locals in the procedure.
         ctx.heap[id].num_expressions_in_body = self.next_expr_index;
         self.visit_definition_and_assign_local_ids(ctx, id.upcast());
         Ok(())
+    }
     //--------------------------------------------------------------------------
     // Statement visitors
     //--------------------------------------------------------------------------
     fn visit_block_stmt(&mut self, ctx: &mut Ctx, id: BlockStatementId) -> VisitorResult {
         self.visit_block_stmt_with_hint(ctx, id, None)
+    }
     fn visit_local_memory_stmt(&mut self, ctx: &mut Ctx, id: MemoryStatementId) -> VisitorResult {
         assign_and_replace_next_stmt!(self, ctx, id.upcast().upcast());
         Ok(())
+    }
     fn visit_local_channel_stmt(&mut self, ctx: &mut Ctx, id: ChannelStatementId) -> VisitorResult {
         assign_and_replace_next_stmt!(self, ctx, id.upcast().upcast());
         Ok(())
+    }
     fn visit_labeled_stmt(&mut self, ctx: &mut Ctx, id: LabeledStatementId) -> VisitorResult {
         let body_id = ctx.heap[id].body;
         self.visit_stmt(ctx, body_id)?;
         Ok(())
+    }
     fn visit_if_stmt(&mut self, ctx: &mut Ctx, id: IfStatementId) -> VisitorResult {
         let if_stmt = &ctx.heap[id];
         let end_if_id = if_stmt.end_if;
         let test_expr_id = if_stmt.test;
         let true_stmt_id = if_stmt.true_body;
         let false_stmt_id = if_stmt.false_body;
         // Visit test expression
         debug_assert_eq!(self.expr_parent, ExpressionParent::None);
         debug_assert!(self.in_test_expr.is_invalid());
         self.in_test_expr = id.upcast();
         self.expr_parent = ExpressionParent::If(id);
         self.visit_expr(ctx, test_expr_id)?;
         self.in_test_expr = StatementId::new_invalid();
         self.expr_parent = ExpressionParent::None;
         // Visit true and false branch. Executor chooses next statement based on
         // test expression, not on if-statement itself. Hence the if statement
         // does not have a static subsequent statement.
         assign_then_erase_next_stmt!(self, ctx, id.upcast());
         self.visit_block_stmt(ctx, true_stmt_id)?;
         assign_then_erase_next_stmt!(self, ctx, end_if_id.upcast());
         if let Some(false_id) = false_stmt_id {
             self.visit_block_stmt(ctx, false_id)?;
             assign_then_erase_next_stmt!(self, ctx, end_if_id.upcast());
+        }
         self.prev_stmt = end_if_id.upcast();
         Ok(())
+    }
     fn visit_while_stmt(&mut self, ctx: &mut Ctx, id: WhileStatementId) -> VisitorResult {
         let stmt = &ctx.heap[id];
         let end_while_id = stmt.end_while;
         let test_expr_id = stmt.test;
         let body_stmt_id = stmt.body;
         let old_while = self.in_while;
         self.in_while = id;
         // Visit test expression
         debug_assert_eq!(self.expr_parent, ExpressionParent::None);
         debug_assert!(self.in_test_expr.is_invalid());
         self.in_test_expr = id.upcast();
         self.expr_parent = ExpressionParent::While(id);
         self.visit_expr(ctx, test_expr_id)?;
         self.in_test_expr = StatementId::new_invalid();
         // Link up to body statement
         assign_then_erase_next_stmt!(self, ctx, id.upcast());
         self.expr_parent = ExpressionParent::None;
         self.visit_block_stmt(ctx, body_stmt_id)?;
         self.in_while = old_while;
         // Link final entry in while's block statement back to the while. The
         // executor will go to the end-while statement if the test expression
         // is false, so put that in as the new previous stmt
         assign_then_erase_next_stmt!(self, ctx, id.upcast());
         self.prev_stmt = end_while_id.upcast();
         Ok(())
+    }
     fn visit_break_stmt(&mut self, ctx: &mut Ctx, id: BreakStatementId) -> VisitorResult {
         // Resolve break target
         let target_end_while = {
             let stmt = &ctx.heap[id];
             let target_while_id = self.resolve_break_or_continue_target(ctx, stmt.span, &stmt.label)?;
             let target_while = &ctx.heap[target_while_id];
             debug_assert!(!target_while.end_while.is_invalid());
             target_while.end_while
         };
         assign_then_erase_next_stmt!(self, ctx, id.upcast());
         let stmt = &mut ctx.heap[id];
         stmt.target = Some(target_end_while);
         Ok(())
+    }
     fn visit_continue_stmt(&mut self, ctx: &mut Ctx, id: ContinueStatementId) -> VisitorResult {
         // Resolve continue target
         let target_while_id = {
             let stmt = &ctx.heap[id];
             self.resolve_break_or_continue_target(ctx, stmt.span, &stmt.label)?
         };
         assign_then_erase_next_stmt!(self, ctx, id.upcast());
         let stmt = &mut ctx.heap[id];
         stmt.target = Some(target_while_id);
         Ok(())
+    }
     fn visit_synchronous_stmt(&mut self, ctx: &mut Ctx, id: SynchronousStatementId) -> VisitorResult {
         // Check for validity of synchronous statement
         let sync_stmt = &ctx.heap[id];
         let end_sync_id = sync_stmt.end_sync;
         let cur_sync_span = sync_stmt.span;
         if !self.in_sync.is_invalid() {
             // Nested synchronous statement
             let old_sync_span = ctx.heap[self.in_sync].span;
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, cur_sync_span, "Illegal nested synchronous statement"
             ).with_info_str_at_span(
                 &ctx.module().source, old_sync_span, "It is nested in this synchronous statement"
             ));
+        }
         if !self.def_type.is_primitive() {
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, cur_sync_span,
                 "synchronous statements may only be used in primitive components"
             ));
+        }
         // Synchronous statement implicitly moves to its block
         assign_then_erase_next_stmt!(self, ctx, id.upcast());
         let sync_body = ctx.heap[id].body;
         debug_assert!(self.in_sync.is_invalid());
         self.in_sync = id;
         self.visit_block_stmt_with_hint(ctx, sync_body, Some(id))?;
         assign_and_replace_next_stmt!(self, ctx, end_sync_id.upcast());
         self.in_sync = SynchronousStatementId::new_invalid();
         Ok(())
+    }
     fn visit_fork_stmt(&mut self, ctx: &mut Ctx, id: ForkStatementId) -> VisitorResult {
         let fork_stmt = &ctx.heap[id];
         let end_fork_id = fork_stmt.end_fork;
         let left_body_id = fork_stmt.left_body;
         let right_body_id = fork_stmt.right_body;
         // Fork statements may only occur inside sync blocks
         if self.in_sync.is_invalid() {
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, fork_stmt.span,
                 "Forking may only occur inside sync blocks"
             ));
+        }
         // Visit the respective bodies. Like the if statement, a fork statement
         // does not have a single static subsequent statement. It forks and then
         // each fork has a different next statement.
         assign_then_erase_next_stmt!(self, ctx, id.upcast());
         self.visit_block_stmt(ctx, left_body_id)?;
         assign_then_erase_next_stmt!(self, ctx, end_fork_id.upcast());
         if let Some(right_body_id) = right_body_id {
             self.visit_block_stmt(ctx, right_body_id)?;
             assign_then_erase_next_stmt!(self, ctx, end_fork_id.upcast());
+        }
         self.prev_stmt = end_fork_id.upcast();
         Ok(())
+    }
     fn visit_return_stmt(&mut self, ctx: &mut Ctx, id: ReturnStatementId) -> VisitorResult {
         // Check if "return" occurs within a function
         let stmt = &ctx.heap[id];
         if !self.def_type.is_function() {
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, stmt.span,
                 "return statements may only appear in function bodies"
             ));
+        }
         // If here then we are within a function
         assign_then_erase_next_stmt!(self, ctx, id.upcast());
         debug_assert_eq!(self.expr_parent, ExpressionParent::None);
         debug_assert_eq!(ctx.heap[id].expressions.len(), 1);
         self.expr_parent = ExpressionParent::Return(id);
         self.visit_expr(ctx, ctx.heap[id].expressions[0])?;
         self.expr_parent = ExpressionParent::None;
         Ok(())
+    }
     fn visit_goto_stmt(&mut self, ctx: &mut Ctx, id: GotoStatementId) -> VisitorResult {
         let target_id = self.find_label(ctx, &ctx.heap[id].label)?;
         ctx.heap[id].target = Some(target_id);
         let target = &ctx.heap[target_id];
         if self.in_sync != target.in_sync {
             // We can only goto the current scope or outer scopes. Because
             // nested sync statements are not allowed we must be inside a sync
             // statement.
             debug_assert!(!self.in_sync.is_invalid());
             let goto_stmt = &ctx.heap[id];
             let sync_stmt = &ctx.heap[self.in_sync];
             return Err(
                 ParseError::new_error_str_at_span(&ctx.module().source, goto_stmt.span, "goto may not escape the surrounding synchronous block")
                 .with_info_str_at_span(&ctx.module().source, target.label.span, "this is the target of the goto statement")
                 .with_info_str_at_span(&ctx.module().source, sync_stmt.span, "which will jump past this statement")
             );
+        }
         assign_then_erase_next_stmt!(self, ctx, id.upcast());
         Ok(())
+    }
     fn visit_new_stmt(&mut self, ctx: &mut Ctx, id: NewStatementId) -> VisitorResult {
         // Make sure the new statement occurs inside a composite component
         if !self.def_type.is_composite() {
             let new_stmt = &ctx.heap[id];
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, new_stmt.span,
                 "instantiating components may only be done in composite components"
             ));
+        }
         // Recurse into call expression (which will check the expression parent
         // to ensure that the "new" statment instantiates a component)
         let call_expr_id = ctx.heap[id].expression;
         assign_and_replace_next_stmt!(self, ctx, id.upcast());
         debug_assert_eq!(self.expr_parent, ExpressionParent::None);
         self.expr_parent = ExpressionParent::New(id);
         self.visit_call_expr(ctx, call_expr_id)?;
         self.expr_parent = ExpressionParent::None;
         Ok(())
+    }
     fn visit_expr_stmt(&mut self, ctx: &mut Ctx, id: ExpressionStatementId) -> VisitorResult {
         let expr_id = ctx.heap[id].expression;
         assign_and_replace_next_stmt!(self, ctx, id.upcast());
         debug_assert_eq!(self.expr_parent, ExpressionParent::None);
         self.expr_parent = ExpressionParent::ExpressionStmt(id);
         self.visit_expr(ctx, expr_id)?;
         self.expr_parent = ExpressionParent::None;
         Ok(())
+    }
     //--------------------------------------------------------------------------
     // Expression visitors
     //--------------------------------------------------------------------------
     fn visit_assignment_expr(&mut self, ctx: &mut Ctx, id: AssignmentExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         let assignment_expr = &mut ctx.heap[id];
         // Although we call assignment an expression to simplify the compiler's
         // code (mainly typechecking), we disallow nested use in expressions
         match self.expr_parent {
             // Look at us: lying through our teeth while providing error messages.
             ExpressionParent::ExpressionStmt(_) => {},
             _ => {
                 let assignment_span = assignment_expr.full_span;
                 return Err(ParseError::new_error_str_at_span(
                     &ctx.module().source, assignment_span,
                     "assignments are statements, and cannot be used in expressions"
                 ))
             },
+        }
         let left_expr_id = assignment_expr.left;
         let right_expr_id = assignment_expr.right;
         let old_expr_parent = self.expr_parent;
         assignment_expr.parent = old_expr_parent;
         assignment_expr.unique_id_in_definition = self.next_expr_index;
         self.next_expr_index += 1;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
         self.must_be_assignable = Some(assignment_expr.operator_span);
         self.visit_expr(ctx, left_expr_id)?;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
         self.must_be_assignable = None;
         self.visit_expr(ctx, right_expr_id)?;
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_binding_expr(&mut self, ctx: &mut Ctx, id: BindingExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         // Check for valid context of binding expression
         if let Some(span) = self.must_be_assignable {
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, span, "cannot assign to the result from a binding expression"
             ));
+        }
         if self.in_test_expr.is_invalid() {
             let binding_expr = &ctx.heap[id];
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, binding_expr.full_span,
                 "binding expressions can only be used inside the testing expression of 'if' and 'while' statements"
             ));
+        }
         if !self.in_binding_expr.is_invalid() {
             let binding_expr = &ctx.heap[id];
             let previous_expr = &ctx.heap[self.in_binding_expr];
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, binding_expr.full_span,
                 "nested binding expressions are not allowed"
             ).with_info_str_at_span(
                 &ctx.module().source, previous_expr.operator_span,
                 "the outer binding expression is found here"
             ));
+        }
         let mut seeking_parent = self.expr_parent;
         loop {
             // Perform upward search to make sure only LogicalAnd is applied to
             // the binding expression
             let valid = match seeking_parent {
                 ExpressionParent::If(_) | ExpressionParent::While(_) => {
                     // Every parent expression (if any) were LogicalAnd.
                     break;
+                }
                 ExpressionParent::Expression(parent_id, _) => {
                     let parent_expr = &ctx.heap[parent_id];
                     match parent_expr {
                         Expression::Binary(parent_expr) => {
                             // Set new parent to continue the search. Otherwise
                             // halt and provide an error using the current
                             // parent.
                             if parent_expr.operation == BinaryOperator::LogicalAnd {
                                 seeking_parent = parent_expr.parent;
                                 true
                             } else {
                                 false
+                            }
                         },
                         _ => false,
+                    }
                 },
                 _ => unreachable!(), // nested under if/while, so always expressions as parents
             };
             if !valid {
                 let binding_expr = &ctx.heap[id];
                 let parent_expr = &ctx.heap[seeking_parent.as_expression()];
                 return Err(ParseError::new_error_str_at_span(
                     &ctx.module().source, binding_expr.full_span,
                     "only the logical-and operator (&&) may be applied to binding expressions"
                 ).with_info_str_at_span(
                     &ctx.module().source, parent_expr.operation_span(),
                     "this was the disallowed operation applied to the result from a binding expression"
                 ));
+            }
+        }
         // Perform all of the index/parent assignment magic
         let binding_expr = &mut ctx.heap[id];
         let old_expr_parent = self.expr_parent;
         binding_expr.parent = old_expr_parent;
         binding_expr.unique_id_in_definition = self.next_expr_index;
         self.next_expr_index += 1;
         self.in_binding_expr = id;
         // Perform preliminary check on children: binding expressions only make
         // sense if the left hand side is just a variable expression, or if it
         // is a literal of some sort. The typechecker will take care of the rest
         let bound_to_id = binding_expr.bound_to;
         let bound_from_id = binding_expr.bound_from;
         match &ctx.heap[bound_to_id] {
             // Variables may not be binding variables, and literals may
             // actually not contain binding variables. But in that case we just
             // perform an equality check.
             Expression::Variable(_) => {}
             Expression::Literal(_) => {},
             _ => {
                 let binding_expr = &ctx.heap[id];
                 return Err(ParseError::new_error_str_at_span(
                     &ctx.module().source, binding_expr.operator_span,
                     "the left hand side of a binding expression may only be a variable or a literal expression"
                 ));
             },
+        }
         // Visit the children themselves
         self.in_binding_expr_lhs = true;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
         self.visit_expr(ctx, bound_to_id)?;
         self.in_binding_expr_lhs = false;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
         self.visit_expr(ctx, bound_from_id)?;
         self.expr_parent = old_expr_parent;
         self.in_binding_expr = BindingExpressionId::new_invalid();
         Ok(())
+    }
     fn visit_conditional_expr(&mut self, ctx: &mut Ctx, id: ConditionalExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         let conditional_expr = &mut ctx.heap[id];
         if let Some(span) = self.must_be_assignable {
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, span, "cannot assign to the result from a conditional expression"
             ))
+        }
         let test_expr_id = conditional_expr.test;
         let true_expr_id = conditional_expr.true_expression;
         let false_expr_id = conditional_expr.false_expression;
         let old_expr_parent = self.expr_parent;
         conditional_expr.parent = old_expr_parent;
         conditional_expr.unique_id_in_definition = self.next_expr_index;
         self.next_expr_index += 1;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
         self.visit_expr(ctx, test_expr_id)?;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
         self.visit_expr(ctx, true_expr_id)?;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 2);
         self.visit_expr(ctx, false_expr_id)?;
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_binary_expr(&mut self, ctx: &mut Ctx, id: BinaryExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         let binary_expr = &mut ctx.heap[id];
         if let Some(span) = self.must_be_assignable {
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, span, "cannot assign to the result from a binary expression"
             ))
+        }
         let left_expr_id = binary_expr.left;
         let right_expr_id = binary_expr.right;
         let old_expr_parent = self.expr_parent;
         binary_expr.parent = old_expr_parent;
         binary_expr.unique_id_in_definition = self.next_expr_index;
         self.next_expr_index += 1;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
         self.visit_expr(ctx, left_expr_id)?;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
         self.visit_expr(ctx, right_expr_id)?;
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_unary_expr(&mut self, ctx: &mut Ctx, id: UnaryExpressionId) -> VisitorResult {
         let unary_expr = &mut ctx.heap[id];
         let expr_id = unary_expr.expression;
         if let Some(span) = self.must_be_assignable {
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, span, "cannot assign to the result from a unary expression"
             ))
+        }
         let old_expr_parent = self.expr_parent;
         unary_expr.parent = old_expr_parent;
         unary_expr.unique_id_in_definition = self.next_expr_index;
         self.next_expr_index += 1;
         self.expr_parent = ExpressionParent::Expression(id.upcast(), 0);
         self.visit_expr(ctx, expr_id)?;
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_indexing_expr(&mut self, ctx: &mut Ctx, id: IndexingExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         let indexing_expr = &mut ctx.heap[id];
         let subject_expr_id = indexing_expr.subject;
         let index_expr_id = indexing_expr.index;
         let old_expr_parent = self.expr_parent;
         indexing_expr.parent = old_expr_parent;
         indexing_expr.unique_id_in_definition = self.next_expr_index;
         self.next_expr_index += 1;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
         self.visit_expr(ctx, subject_expr_id)?;
         let old_assignable = self.must_be_assignable.take();
         self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
         self.visit_expr(ctx, index_expr_id)?;
         self.must_be_assignable = old_assignable;
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_slicing_expr(&mut self, ctx: &mut Ctx, id: SlicingExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         let slicing_expr = &mut ctx.heap[id];
         if let Some(span) = self.must_be_assignable {
             // TODO: @Slicing
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, span, "assignment to slices should be valid in the final language, but is currently not implemented"
             ));
+        }
         let subject_expr_id = slicing_expr.subject;
         let from_expr_id = slicing_expr.from_index;
         let to_expr_id = slicing_expr.to_index;
         let old_expr_parent = self.expr_parent;
         slicing_expr.parent = old_expr_parent;
         slicing_expr.unique_id_in_definition = self.next_expr_index;
         self.next_expr_index += 1;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
         self.visit_expr(ctx, subject_expr_id)?;
         let old_assignable = self.must_be_assignable.take();
         self.expr_parent = ExpressionParent::Expression(upcast_id, 1);
         self.visit_expr(ctx, from_expr_id)?;
         self.expr_parent = ExpressionParent::Expression(upcast_id, 2);
         self.visit_expr(ctx, to_expr_id)?;
         self.must_be_assignable = old_assignable;
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_select_expr(&mut self, ctx: &mut Ctx, id: SelectExpressionId) -> VisitorResult {
         let select_expr = &mut ctx.heap[id];
         let expr_id = select_expr.subject;
         let old_expr_parent = self.expr_parent;
         select_expr.parent = old_expr_parent;
         select_expr.unique_id_in_definition = self.next_expr_index;
         self.next_expr_index += 1;
         self.expr_parent = ExpressionParent::Expression(id.upcast(), 0);
         self.visit_expr(ctx, expr_id)?;
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_literal_expr(&mut self, ctx: &mut Ctx, id: LiteralExpressionId) -> VisitorResult {
         let literal_expr = &mut ctx.heap[id];
         let old_expr_parent = self.expr_parent;
         literal_expr.parent = old_expr_parent;
         literal_expr.unique_id_in_definition = self.next_expr_index;
         self.next_expr_index += 1;
         if let Some(span) = self.must_be_assignable {
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, span, "cannot assign to a literal expression"
             ))
+        }
         match &mut literal_expr.value {
             Literal::Null | Literal::True | Literal::False |
             Literal::Character(_) | Literal::String(_) | Literal::Integer(_) => {
                 // Just the parent has to be set, done above
             },
             Literal::Struct(literal) => {
                 let upcast_id = id.upcast();
                 // Retrieve type definition
                 let type_definition = ctx.types.get_base_definition(&literal.definition).unwrap();
                 let struct_definition = type_definition.definition.as_struct();
                 // Make sure all fields are specified, none are specified twice
                 // and all fields exist on the struct definition
                 let mut specified = Vec::new(); // TODO: @performance
                 specified.resize(struct_definition.fields.len(), false);
                 for field in &mut literal.fields {
                     // Find field in the struct definition
                     let field_idx = struct_definition.fields.iter().position(|v| v.identifier == field.identifier);
                     if field_idx.is_none() {
                         let field_span = field.identifier.span;
                         let literal = ctx.heap[id].value.as_struct();
                         let ast_definition = &ctx.heap[literal.definition];
                         return Err(ParseError::new_error_at_span(
                             &ctx.module().source, field_span, format!(
                                 "This field does not exist on the struct '{}'",
                                 ast_definition.identifier().value.as_str()
+                            )
                         ));
+                    }
                     field.field_idx = field_idx.unwrap();
                     // Check if specified more than once
                     if specified[field.field_idx] {
                         let field_span = field.identifier.span;
                         return Err(ParseError::new_error_str_at_span(
                             &ctx.module().source, field_span,
                             "This field is specified more than once"
                         ));
+                    }
                     specified[field.field_idx] = true;
+                }
                 if !specified.iter().all(|v| *v) {
                     // Some fields were not specified
                     let mut not_specified = String::new();
                     let mut num_not_specified = 0;
                     for (def_field_idx, is_specified) in specified.iter().enumerate() {
                         if !is_specified {
                             if !not_specified.is_empty() { not_specified.push_str(", ") }
                             let field_ident = &struct_definition.fields[def_field_idx].identifier;
                             not_specified.push_str(field_ident.value.as_str());
                             num_not_specified += 1;
+                        }
+                    }
                     debug_assert!(num_not_specified > 0);
                     let msg = if num_not_specified == 1 {
                         format!("not all fields are specified, '{}' is missing", not_specified)
                     } else {
                         format!("not all fields are specified, [{}] are missing", not_specified)
                     };
                     let literal_span = literal.parser_type.full_span;
                     return Err(ParseError::new_error_at_span(
                         &ctx.module().source, literal_span, msg
                     ));
+                }
                 // Need to traverse fields expressions in struct and evaluate
                 // the poly args
                 let mut expr_section = self.expression_buffer.start_section();
                 for field in &literal.fields {
                     expr_section.push(field.value);
+                }
                 for expr_idx in 0..expr_section.len() {
                     let expr_id = expr_section[expr_idx];
                     self.expr_parent = ExpressionParent::Expression(upcast_id, expr_idx as u32);
                     self.visit_expr(ctx, expr_id)?;
+                }
                 expr_section.forget();
             },
             Literal::Enum(literal) => {
                 // Make sure the variant exists
                 let type_definition = ctx.types.get_base_definition(&literal.definition).unwrap();
                 let enum_definition = type_definition.definition.as_enum();
                 let variant_idx = enum_definition.variants.iter().position(|v| {
                     v.identifier == literal.variant
                 });
                 if variant_idx.is_none() {
                     let literal = ctx.heap[id].value.as_enum();
                     let ast_definition = ctx.heap[literal.definition].as_enum();
                     return Err(ParseError::new_error_at_span(
                         &ctx.module().source, literal.parser_type.full_span, format!(
                             "the variant '{}' does not exist on the enum '{}'",
                             literal.variant.value.as_str(), ast_definition.identifier.value.as_str()
+                        )
                     ));
+                }
                 literal.variant_idx = variant_idx.unwrap();
             },
             Literal::Union(literal) => {
                 // Make sure the variant exists
                 let type_definition = ctx.types.get_base_definition(&literal.definition).unwrap();
                 let union_definition = type_definition.definition.as_union();
                 let variant_idx = union_definition.variants.iter().position(|v| {
                     v.identifier == literal.variant
                 });
                 if variant_idx.is_none() {
                     let literal = ctx.heap[id].value.as_union();
                     let ast_definition = ctx.heap[literal.definition].as_union();
                     return Err(ParseError::new_error_at_span(
                         &ctx.module().source, literal.parser_type.full_span, format!(
                             "the variant '{}' does not exist on the union '{}'",
                             literal.variant.value.as_str(), ast_definition.identifier.value.as_str()
+                        )
                     ));
+                }
                 literal.variant_idx = variant_idx.unwrap();
                 // Make sure the number of specified values matches the expected
                 // number of embedded values in the union variant.
                 let union_variant = &union_definition.variants[literal.variant_idx];
                 if union_variant.embedded.len() != literal.values.len() {
                     let literal = ctx.heap[id].value.as_union();
                     let ast_definition = ctx.heap[literal.definition].as_union();
                     return Err(ParseError::new_error_at_span(
                         &ctx.module().source, literal.parser_type.full_span, format!(
                             "The variant '{}' of union '{}' expects {} embedded values, but {} were specified",
                             literal.variant.value.as_str(), ast_definition.identifier.value.as_str(),
                             union_variant.embedded.len(), literal.values.len()
                         ),
                     ))
+                }
                 // Traverse embedded values of union (if any) and evaluate the
                 // polymorphic arguments
                 let upcast_id = id.upcast();
                 let mut expr_section = self.expression_buffer.start_section();
                 for value in &literal.values {
                     expr_section.push(*value);
+                }
                 for expr_idx in 0..expr_section.len() {
                     let expr_id = expr_section[expr_idx];
                     self.expr_parent = ExpressionParent::Expression(upcast_id, expr_idx as u32);
                     self.visit_expr(ctx, expr_id)?;
+                }
                 expr_section.forget();
             },
             Literal::Array(literal) | Literal::Tuple(literal) => {
                 // Visit all expressions in the array
                 let upcast_id = id.upcast();
                 let expr_section = self.expression_buffer.start_section_initialized(literal);
                 for expr_idx in 0..expr_section.len() {
                     let expr_id = expr_section[expr_idx];
                     self.expr_parent = ExpressionParent::Expression(upcast_id, expr_idx as u32);
                     self.visit_expr(ctx, expr_id)?;
+                }
                 expr_section.forget();
+            }
+        }
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_cast_expr(&mut self, ctx: &mut Ctx, id: CastExpressionId) -> VisitorResult {
         let cast_expr = &mut ctx.heap[id];
         if let Some(span) = self.must_be_assignable {
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, span, "cannot assign to the result from a cast expression"
             ))
+        }
         let upcast_id = id.upcast();
         let old_expr_parent = self.expr_parent;
         cast_expr.parent = old_expr_parent;
         cast_expr.unique_id_in_definition = self.next_expr_index;
         self.next_expr_index += 1;
         // Recurse into the thing that we're casting
         self.expr_parent = ExpressionParent::Expression(upcast_id, 0);
         let subject_id = cast_expr.subject;
         self.visit_expr(ctx, subject_id)?;
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_call_expr(&mut self, ctx: &mut Ctx, id: CallExpressionId) -> VisitorResult {
         let call_expr = &mut ctx.heap[id];
         if let Some(span) = self.must_be_assignable {
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, span, "cannot assign to the result from a call expression"
             ))
+        }
         // Check whether the method is allowed to be called within the code's
         // context (in sync, definition type, etc.)
         let mut expected_wrapping_new_stmt = false;
         match &mut call_expr.method {
             Method::Get => {
                 if !self.def_type.is_primitive() {
                     let call_span = call_expr.func_span;
                     return Err(ParseError::new_error_str_at_span(
                         &ctx.module().source, call_span,
                         "a call to 'get' may only occur in primitive component definitions"
                     ));
+                }
                 if self.in_sync.is_invalid() {
                     let call_span = call_expr.func_span;
                     return Err(ParseError::new_error_str_at_span(
                         &ctx.module().source, call_span,
                         "a call to 'get' may only occur inside synchronous blocks"
                     ));
+                }
             },
             Method::Put => {
                 if !self.def_type.is_primitive() {
                     let call_span = call_expr.func_span;
                     return Err(ParseError::new_error_str_at_span(
                         &ctx.module().source, call_span,
                         "a call to 'put' may only occur in primitive component definitions"
                     ));
+                }
                 if self.in_sync.is_invalid() {
                     let call_span = call_expr.func_span;
                     return Err(ParseError::new_error_str_at_span(
                         &ctx.module().source, call_span,
                         "a call to 'put' may only occur inside synchronous blocks"
                     ));
+                }
             },
             Method::Fires => {
                 if !self.def_type.is_primitive() {
                     let call_span = call_expr.func_span;
                     return Err(ParseError::new_error_str_at_span(
                         &ctx.module().source, call_span,
                         "a call to 'fires' may only occur in primitive component definitions"
                     ));
+                }
                 if self.in_sync.is_invalid() {
                     let call_span = call_expr.func_span;
                     return Err(ParseError::new_error_str_at_span(
                         &ctx.module().source, call_span,
                         "a call to 'fires' may only occur inside synchronous blocks"
                     ));
+                }
             },
             Method::Create => {},
             Method::Length => {},
             Method::Assert => {
                 if self.def_type.is_function() {
                     let call_span = call_expr.func_span;
                     return Err(ParseError::new_error_str_at_span(
                         &ctx.module().source, call_span,
                         "assert statement may only occur in components"
                     ));
+                }
                 if self.in_sync.is_invalid() {
                     let call_span = call_expr.func_span;
                     return Err(ParseError::new_error_str_at_span(
                         &ctx.module().source, call_span,
                         "assert statements may only occur inside synchronous blocks"
                     ));
+                }
             },
             Method::Print => {},
             Method::UserFunction => {},
             Method::UserComponent => {
                 expected_wrapping_new_stmt = true;
             },
+        }
         if expected_wrapping_new_stmt {
             if !self.expr_parent.is_new() {
                 let call_span = call_expr.func_span;
                 return Err(ParseError::new_error_str_at_span(
                     &ctx.module().source, call_span,
                     "cannot call a component, it can only be instantiated by using 'new'"
                 ));
+            }
         } else {
             if self.expr_parent.is_new() {
                 let call_span = call_expr.func_span;
                 return Err(ParseError::new_error_str_at_span(
                     &ctx.module().source, call_span,
                     "only components can be instantiated, this is a function"
                 ));
+            }
+        }
         // Check the number of arguments
         let call_definition = ctx.types.get_base_definition(&call_expr.definition).unwrap();
         let num_expected_args = match &call_definition.definition {
             DefinedTypeVariant::Function(definition) => definition.arguments.len(),
             DefinedTypeVariant::Component(definition) => definition.arguments.len(),
             v => unreachable!("encountered {} type in call expression", v.type_class()),
         };
         let num_provided_args = call_expr.arguments.len();
         if num_provided_args != num_expected_args {
             let argument_text = if num_expected_args == 1 { "argument" } else { "arguments" };
             let call_span = call_expr.full_span;
             return Err(ParseError::new_error_at_span(
                 &ctx.module().source, call_span, format!(
                     "expected {} {}, but {} were provided",
                     num_expected_args, argument_text, num_provided_args
+                )
             ));
+        }
         // Recurse into all of the arguments and set the expression's parent
         let upcast_id = id.upcast();
         let section = self.expression_buffer.start_section_initialized(&call_expr.arguments);
         let old_expr_parent = self.expr_parent;
         call_expr.parent = old_expr_parent;
         call_expr.unique_id_in_definition = self.next_expr_index;
         self.next_expr_index += 1;
         for arg_expr_idx in 0..section.len() {
             let arg_expr_id = section[arg_expr_idx];
             self.expr_parent = ExpressionParent::Expression(upcast_id, arg_expr_idx as u32);
             self.visit_expr(ctx, arg_expr_id)?;
+        }
         section.forget();
         self.expr_parent = old_expr_parent;
         Ok(())
+    }
     fn visit_variable_expr(&mut self, ctx: &mut Ctx, id: VariableExpressionId) -> VisitorResult {
         let var_expr = &ctx.heap[id];
         let (variable_id, is_binding_target) = match self.find_variable(ctx, self.relative_pos_in_block, &var_expr.identifier) {
             Ok(variable_id) => {
                 // Regular variable
                 (variable_id, false)
             },
             Err(()) => {
                 // Couldn't find variable, but if we're in a binding expression,
                 // then this may be the thing we're binding to.
                 if self.in_binding_expr.is_invalid() || !self.in_binding_expr_lhs {
                     return Err(ParseError::new_error_str_at_span(
                         &ctx.module().source, var_expr.identifier.span, "unresolved variable"
                     ));
+                }
                 // This is a binding variable, but it may only appear in very
                 // specific locations.
                 let is_valid_binding = match self.expr_parent {
                     ExpressionParent::Expression(expr_id, idx) => {
                         match &ctx.heap[expr_id] {
                             Expression::Binding(_binding_expr) => {
                                 // Nested binding is disallowed, and because of
                                 // the check above we know we're directly at the
                                 // LHS of the binding expression
                                 debug_assert_eq!(_binding_expr.this, self.in_binding_expr);
                                 debug_assert_eq!(idx, 0);
                                 true
+                            }
                             Expression::Literal(lit_expr) => {
                                 // Only struct, unions and arrays can have
                                 // subexpressions, so we're always fine
                                 if cfg!(debug_assertions) {
                                     match lit_expr.value {
                                         Literal::Struct(_) | Literal::Union(_) | Literal::Array(_) | Literal::Tuple(_) => {},
                                         _ => unreachable!(),
+                                    }
+                                }
                                 true
                             },
                             _ => false,
+                        }
                     },
                     _ => {
                         false
+                    }
                 };
                 if !is_valid_binding {
                     let binding_expr = &ctx.heap[self.in_binding_expr];
                     return Err(ParseError::new_error_str_at_span(
                         &ctx.module().source, var_expr.identifier.span,
                         "illegal location for binding variable: binding variables may only be nested under a binding expression, or a struct, union or array literal"
                     ).with_info_at_span(
                         &ctx.module().source, binding_expr.operator_span, format!(
                             "'{}' was interpreted as a binding variable because the variable is not declared and it is nested under this binding expression",
                             var_expr.identifier.value.as_str()
+                        )
                     ));
+                }
                 // By now we know that this is a valid binding expression. Given
                 // that a binding expression must be nested under an if/while
                 // statement, we now add the variable to the (implicit) block
                 // statement following the if/while statement.
                 let bound_identifier = var_expr.identifier.clone();
                 let bound_variable_id = ctx.heap.alloc_variable(|this| Variable{
                     this,
                     kind: VariableKind::Binding,
                     parser_type: ParserType{
                         elements: vec![ParserTypeElement{
                             element_span: bound_identifier.span,
                             variant: ParserTypeVariant::Inferred
                         }],
                         full_span: bound_identifier.span
                     },
                     identifier: bound_identifier,
                     relative_pos_in_block: 0,
                     unique_id_in_scope: -1,
                 });
                 let body_stmt_id = match &ctx.heap[self.in_test_expr] {
                     Statement::If(stmt) => stmt.true_body,
                     Statement::While(stmt) => stmt.body,
                     _ => unreachable!(),
                 };
                 let body_scope = Scope::Regular(body_stmt_id);
                 self.checked_at_single_scope_add_local(ctx, body_scope, 0, bound_variable_id)?;
                 (bound_variable_id, true)
+            }
         };
         let var_expr = &mut ctx.heap[id];
         var_expr.declaration = Some(variable_id);
         var_expr.used_as_binding_target = is_binding_target;
         var_expr.parent = self.expr_parent;
         var_expr.unique_id_in_definition = self.next_expr_index;
         self.next_expr_index += 1;
         Ok(())
+    }
+}
 impl PassValidationLinking {
     //--------------------------------------------------------------------------
     // Special traversal
     //--------------------------------------------------------------------------
     fn visit_block_stmt_with_hint(&mut self, ctx: &mut Ctx, id: BlockStatementId, hint: Option<SynchronousStatementId>) -> VisitorResult {
         // Set parent scope and relative position in the parent scope. Remember
         // these values to set them back to the old values when we're done with
         // the traversal of the block's statements.
         let old_scope = self.cur_scope.clone();
         let new_scope = match hint {
             Some(sync_id) => Scope::Synchronous((sync_id, id)),
             None => Scope::Regular(id),
         };
         match old_scope {
             Scope::Definition(_def_id) => {
                 // Don't do anything. Block is implicitly a child of a
                 // definition scope.
                 if cfg!(debug_assertions) {
                     match &ctx.heap[_def_id] {
                         Definition::Function(proc_def) => debug_assert_eq!(proc_def.body, id),
                         Definition::Component(proc_def) => debug_assert_eq!(proc_def.body, id),
                         _ => unreachable!(),
+                    }
+                }
             },
             Scope::Regular(block_id) | Scope::Synchronous((_, block_id)) => {
                 let parent_block = &mut ctx.heap[block_id];
                 parent_block.scope_node.nested.push(new_scope);
+            }
+        }
         self.cur_scope = new_scope;
         let body = &mut ctx.heap[id];
         body.scope_node.parent = old_scope;
         body.relative_pos_in_parent = self.relative_pos_in_block;
         let end_block_id = body.end_block;
         let old_relative_pos = self.relative_pos_in_block;
         // Copy statement IDs into buffer
         let statement_section = self.statement_buffer.start_section_initialized(&body.statements);
         // Perform the breadth-first pass. Its main purpose is to find labeled
         // statements such that we can find the `goto`-targets immediately when
         // performing the depth pass
         for stmt_idx in 0..statement_section.len() {
             self.relative_pos_in_block = stmt_idx as u32;
             self.visit_statement_for_locals_labels_and_in_sync(ctx, self.relative_pos_in_block, statement_section[stmt_idx])?;
+        }
         // Perform the depth-first traversal
         assign_and_replace_next_stmt!(self, ctx, id.upcast());
         for stmt_idx in 0..statement_section.len() {
             self.relative_pos_in_block = stmt_idx as u32;
             self.visit_stmt(ctx, statement_section[stmt_idx])?;
+        }
         assign_and_replace_next_stmt!(self, ctx, end_block_id.upcast());
         self.cur_scope = old_scope;
         self.relative_pos_in_block = old_relative_pos;
         statement_section.forget();
         Ok(())
+    }
     fn visit_statement_for_locals_labels_and_in_sync(&mut self, ctx: &mut Ctx, relative_pos: u32, id: StatementId) -> VisitorResult {
         let statement = &mut ctx.heap[id];
         match statement {
             Statement::Local(stmt) => {
                 match stmt {
                     LocalStatement::Memory(local) => {
                         let variable_id = local.variable;
                         self.checked_add_local(ctx, relative_pos, variable_id)?;
                     },
                     LocalStatement::Channel(local) => {
                         let from_id = local.from;
                         let to_id = local.to;
                         self.checked_add_local(ctx, relative_pos, from_id)?;
                         self.checked_add_local(ctx, relative_pos, to_id)?;
+                    }
+                }
+            }
             Statement::Labeled(stmt) => {
                 let stmt_id = stmt.this;
                 let body_id = stmt.body;
                 self.checked_add_label(ctx, relative_pos, self.in_sync, stmt_id)?;
                 self.visit_statement_for_locals_labels_and_in_sync(ctx, relative_pos, body_id)?;
             },
             Statement::While(stmt) => {
                 stmt.in_sync = self.in_sync;
             },
             _ => {},
+        }
         return Ok(())
+    }
     fn visit_definition_and_assign_local_ids(&mut self, ctx: &mut Ctx, definition_id: DefinitionId) {
         let mut var_counter = 0;
         // Set IDs on parameters
         let (param_section, body_id) = match &ctx.heap[definition_id] {
             Definition::Function(func_def) => (
                 self.variable_buffer.start_section_initialized(&func_def.parameters),
                 func_def.body
             ),
             Definition::Component(comp_def) => (
                 self.variable_buffer.start_section_initialized(&comp_def.parameters),
                 comp_def.body
             ),
             _ => unreachable!(),
         } ;
         for idx in 0..param_section.len() {
             let var_id = param_section[idx];
         for var_id in param_section.iter_copied() {
             let var = &mut ctx.heap[var_id];
             var.unique_id_in_scope = var_counter;
             var_counter += 1;
+        }
         param_section.forget();
         // Recurse into body
         self.visit_block_and_assign_local_ids(ctx, body_id, var_counter);
+    }
     fn visit_block_and_assign_local_ids(&mut self, ctx: &mut Ctx, block_id: BlockStatementId, mut var_counter: i32) {
         let block_stmt = &mut ctx.heap[block_id];
         block_stmt.first_unique_id_in_scope = var_counter;
         let var_section = self.variable_buffer.start_section_initialized(&block_stmt.locals);
         let mut scope_section = self.statement_buffer.start_section();
         for child_scope in &block_stmt.scope_node.nested {
             debug_assert!(child_scope.is_block(), "found a child scope that is not a block statement");
             scope_section.push(child_scope.to_block().upcast());
+        }
         let mut var_idx = 0;
         let mut scope_idx = 0;
         while var_idx < var_section.len() || scope_idx < scope_section.len() {
             let relative_var_pos = if var_idx < var_section.len() {
                 ctx.heap[var_section[var_idx]].relative_pos_in_block
             } else {
                 u32::MAX
             };
             let relative_scope_pos = if scope_idx < scope_section.len() {
                 ctx.heap[scope_section[scope_idx]].as_block().relative_pos_in_parent
             } else {
                 u32::MAX
             };
             debug_assert!(!(relative_var_pos == u32::MAX && relative_scope_pos == u32::MAX));
             // In certain cases the relative variable position is the same as
             // the scope position (insertion of binding variables). In that case
             // the variable should be treated first
             if relative_var_pos <= relative_scope_pos {
                 let var = &mut ctx.heap[var_section[var_idx]];
                 var.unique_id_in_scope = var_counter;
                 var_counter += 1;
                 var_idx += 1;
             } else {
                 // Boy oh boy
                 let block_id = ctx.heap[scope_section[scope_idx]].as_block().this;
                 self.visit_block_and_assign_local_ids(ctx, block_id, var_counter);
                 scope_idx += 1;
+            }
+        }
         var_section.forget();
         scope_section.forget();
         // Done assigning all IDs, assign the last ID to the block statement scope
         let block_stmt = &mut ctx.heap[block_id];
         block_stmt.next_unique_id_in_scope = var_counter;
+    }
     //--------------------------------------------------------------------------
     // Utilities
     //--------------------------------------------------------------------------
     /// Adds a local variable to the current scope. It will also annotate the
     /// `Local` in the AST with its relative position in the block.
     fn checked_add_local(&mut self, ctx: &mut Ctx, relative_pos: u32, id: VariableId) -> Result<(), ParseError> {
         debug_assert!(self.cur_scope.is_block());
         let local = &ctx.heap[id];
         let mut scope = &self.cur_scope;
         loop {
             // We immediately go to the parent scope. We check the current scope
             // in the call at the end. Likewise for checking the symbol table.
             let block = &ctx.heap[scope.to_block()];
             scope = &block.scope_node.parent;
             if let Scope::Definition(definition_id) = scope {
                 // At outer scope, check parameters of function/component
                 for parameter_id in ctx.heap[*definition_id].parameters() {
                     let parameter = &ctx.heap[*parameter_id];
                     if local.identifier == parameter.identifier {
                         return Err(
                             ParseError::new_error_str_at_span(
                                 &ctx.module().source, local.identifier.span, "Local variable name conflicts with parameter"
                             ).with_info_str_at_span(
                                 &ctx.module().source, parameter.identifier.span, "Parameter definition is found here"
+                            )
                         );
+                    }
+                }
                 // No collisions
                 break;
+            }
             // If here then the parent scope is a block scope
             let local_relative_pos = ctx.heap[scope.to_block()].relative_pos_in_parent;
             for other_local_id in &block.locals {
                 let other_local = &ctx.heap[*other_local_id];
                 // Position check in case another variable with the same name
                 // is defined in a higher-level scope, but later than the scope
                 // in which the current variable resides.
                 if local.this != *other_local_id &&
                     local_relative_pos >= other_local.relative_pos_in_block &&
                     local.identifier == other_local.identifier {
                     // Collision within this scope
                     return Err(
                         ParseError::new_error_str_at_span(
                             &ctx.module().source, local.identifier.span, "Local variable name conflicts with another variable"
                         ).with_info_str_at_span(
                             &ctx.module().source, other_local.identifier.span, "Previous variable is found here"
+                        )
                     );
+                }
+            }
+        }
         // No collisions in any of the parent scope, attempt to add to scope
         self.checked_at_single_scope_add_local(ctx, self.cur_scope, relative_pos, id)
+    }
     /// Adds a local variable to the specified scope. Will check the specified
     /// scope for variable conflicts and the symbol table for global conflicts.
     /// Will NOT check parent scopes of the specified scope.
     fn checked_at_single_scope_add_local(
         &mut self, ctx: &mut Ctx, scope: Scope, relative_pos: u32, id: VariableId
     ) -> Result<(), ParseError> {
         // Check the symbol table for conflicts
+        {
             let cur_scope = SymbolScope::Definition(self.def_type.definition_id());
             let ident = &ctx.heap[id].identifier;
             if let Some(symbol) = ctx.symbols.get_symbol_by_name(cur_scope, &ident.value.as_bytes()) {
                 return Err(ParseError::new_error_str_at_span(
                     &ctx.module().source, ident.span,
                     "local variable declaration conflicts with symbol"
                 ).with_info_str_at_span(
                     &ctx.module().source, symbol.variant.span_of_introduction(&ctx.heap), "the conflicting symbol is introduced here"
                 ));
+            }
+        }
         // Check the specified scope for conflicts
         let local = &ctx.heap[id];
         debug_assert!(scope.is_block());
         let block = &ctx.heap[scope.to_block()];
         for other_local_id in &block.locals {
             let other_local = &ctx.heap[*other_local_id];
             if local.this != other_local.this &&
                 relative_pos >= other_local.relative_pos_in_block &&
                 local.identifier == other_local.identifier {
                 // Collision
                 return Err(
                     ParseError::new_error_str_at_span(
                         &ctx.module().source, local.identifier.span, "Local variable name conflicts with another variable"
                     ).with_info_str_at_span(
                         &ctx.module().source, other_local.identifier.span, "Previous variable is found here"
+                    )
                 );
+            }
+        }
         // No collisions
         let block = &mut ctx.heap[scope.to_block()];
         block.locals.push(id);
         let local = &mut ctx.heap[id];
         local.relative_pos_in_block = relative_pos;
         Ok(())
+    }
     /// Finds a variable in the visitor's scope that must appear before the
     /// specified relative position within that block.
     fn find_variable(&self, ctx: &Ctx, mut relative_pos: u32, identifier: &Identifier) -> Result<VariableId, ()> {
         debug_assert!(self.cur_scope.is_block());
         // No need to use iterator over namespaces if here
         let mut scope = &self.cur_scope;
         loop {
             debug_assert!(scope.is_block());
             let block = &ctx.heap[scope.to_block()];
             for local_id in &block.locals {
                 let local = &ctx.heap[*local_id];
                 if local.relative_pos_in_block <= relative_pos && identifier == &local.identifier {
                     return Ok(*local_id);
+                }
+            }
             scope = &block.scope_node.parent;
             if !scope.is_block() {
                 // Definition scope, need to check arguments to definition
                 match scope {
                     Scope::Definition(definition_id) => {
                         let definition = &ctx.heap[*definition_id];
                         for parameter_id in definition.parameters() {
                             let parameter = &ctx.heap[*parameter_id];
                             if identifier == &parameter.identifier {
                                 return Ok(*parameter_id);
+                            }
+                        }
                     },
                     _ => unreachable!(),
+                }
                 // Variable could not be found
                 return Err(())
             } else {
                 relative_pos = block.relative_pos_in_parent;
+            }
+        }
+    }
     /// Adds a particular label to the current scope. Will return an error if
     /// there is another label with the same name visible in the current scope.
     fn checked_add_label(&mut self, ctx: &mut Ctx, relative_pos: u32, in_sync: SynchronousStatementId, id: LabeledStatementId) -> Result<(), ParseError> {
         debug_assert!(self.cur_scope.is_block());
         // Make sure label is not defined within the current scope or any of the
         // parent scope.
         let label = &mut ctx.heap[id];
         label.relative_pos_in_block = relative_pos;
         label.in_sync = in_sync;
         let label = &ctx.heap[id];
         let mut scope = &self.cur_scope;
         loop {
             debug_assert!(scope.is_block(), "scope is not a block");
             let block = &ctx.heap[scope.to_block()];
             for other_label_id in &block.labels {
                 let other_label = &ctx.heap[*other_label_id];
                 if other_label.label == label.label {
                     // Collision
                     return Err(ParseError::new_error_str_at_span(
                         &ctx.module().source, label.label.span, "label name is used more than once"
                     ).with_info_str_at_span(
                         &ctx.module().source, other_label.label.span, "the other label is found here"
                     ));
+                }
+            }
             scope = &block.scope_node.parent;
             if !scope.is_block() {
                 break;
+            }
+        }
         // No collisions
         let block = &mut ctx.heap[self.cur_scope.to_block()];
         block.labels.push(id);
         Ok(())
+    }
     /// Finds a particular labeled statement by its identifier. Once found it
     /// will make sure that the target label does not skip over any variable
     /// declarations within the scope in which the label was found.
     fn find_label(&self, ctx: &Ctx, identifier: &Identifier) -> Result<LabeledStatementId, ParseError> {
         debug_assert!(self.cur_scope.is_block());
         let mut scope = &self.cur_scope;
         loop {
             debug_assert!(scope.is_block(), "scope is not a block");
             let relative_scope_pos = ctx.heap[scope.to_block()].relative_pos_in_parent;
             let block = &ctx.heap[scope.to_block()];
             for label_id in &block.labels {
                 let label = &ctx.heap[*label_id];
                 if label.label == *identifier {
                     for local_id in &block.locals {
                         // TODO: Better to do this in control flow analysis, it
                         //  is legal to skip over a variable declaration if it
                         //  is not actually being used. I might be missing
                         //  something here when laying out the bytecode...
                         let local = &ctx.heap[*local_id];
                         if local.relative_pos_in_block > relative_scope_pos && local.relative_pos_in_block < label.relative_pos_in_block {
                             return Err(
                                 ParseError::new_error_str_at_span(&ctx.module().source, identifier.span, "this target label skips over a variable declaration")
                                 .with_info_str_at_span(&ctx.module().source, label.label.span, "because it jumps to this label")
                                 .with_info_str_at_span(&ctx.module().source, local.identifier.span, "which skips over this variable")
                             );
+                        }
+                    }
                     return Ok(*label_id);
+                }
+            }
             scope = &block.scope_node.parent;
             if !scope.is_block() {
                 return Err(ParseError::new_error_str_at_span(
                     &ctx.module().source, identifier.span, "could not find this label"
                 ));
+            }
+        }
+    }
     /// This function will check if the provided while statement ID has a block
     /// statement that is one of our current parents.
     fn has_parent_while_scope(&self, ctx: &Ctx, id: WhileStatementId) -> bool {
         let mut scope = &self.cur_scope;
         let while_stmt = &ctx.heap[id];
         loop {
             debug_assert!(scope.is_block());
             let block = scope.to_block();
             if while_stmt.body == block {
                 return true;
+            }
             let block = &ctx.heap[block];
             scope = &block.scope_node.parent;
             if !scope.is_block() {
                 return false;
+            }
+        }
+    }
     /// This function should be called while dealing with break/continue
     /// statements. It will try to find the targeted while statement, using the
     /// target label if provided. If a valid target is found then the loop's
     /// ID will be returned, otherwise a parsing error is constructed.
     /// The provided input position should be the position of the break/continue
     /// statement.
     fn resolve_break_or_continue_target(&self, ctx: &Ctx, span: InputSpan, label: &Option<Identifier>) -> Result<WhileStatementId, ParseError> {
         let target = match label {
             Some(label) => {
                 let target_id = self.find_label(ctx, label)?;
                 // Make sure break target is a while statement
                 let target = &ctx.heap[target_id];
                 if let Statement::While(target_stmt) = &ctx.heap[target.body] {
                     // Even though we have a target while statement, the break might not be
                     // present underneath this particular labeled while statement
                     if !self.has_parent_while_scope(ctx, target_stmt.this) {
                         return Err(ParseError::new_error_str_at_span(
                             &ctx.module().source, label.span, "break statement is not nested under the target label's while statement"
                         ).with_info_str_at_span(
                             &ctx.module().source, target.label.span, "the targeted label is found here"
                         ));
+                    }
                     target_stmt.this
                 } else {
                     return Err(ParseError::new_error_str_at_span(
                         &ctx.module().source, label.span, "incorrect break target label, it must target a while loop"
                     ).with_info_str_at_span(
                         &ctx.module().source, target.label.span, "The targeted label is found here"
                     ));
+                }
             },
             None => {
                 // Use the enclosing while statement, the break must be
                 // nested within that while statement
                 if self.in_while.is_invalid() {
                     return Err(ParseError::new_error_str_at_span(
                         &ctx.module().source, span, "Break statement is not nested under a while loop"
                     ));
+                }
                 self.in_while
+            }
         };
         // We have a valid target for the break statement. But we need to
         // make sure we will not break out of a synchronous block
+        {
             let target_while = &ctx.heap[target];
             if target_while.in_sync != self.in_sync {
                 // Break is nested under while statement, so can only escape a
                 // sync block if the sync is nested inside the while statement.
                 debug_assert!(!self.in_sync.is_invalid());
                 let sync_stmt = &ctx.heap[self.in_sync];
                 return Err(
                     ParseError::new_error_str_at_span(&ctx.module().source, span, "break may not escape the surrounding synchronous block")
                         .with_info_str_at_span(&ctx.module().source, target_while.span, "the break escapes out of this loop")
                         .with_info_str_at_span(&ctx.module().source, sync_stmt.span, "And would therefore escape this synchronous block")
                 );
+            }
+        }
         Ok(target)
+    }
+}
@@ \ No newline at end of file @@

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