Implemented more sane checks for breaking trait items. Fixes rust-lan…

…g#20.

src/semcheck/changes.rs

@@ -322,6 +322,38 @@ impl<'tcx> Change<'tcx> {
  self.changes.push((type_, span));
  }
 
+ /// Check whether a trait item contains breaking changes preventing further analysis of it's
+ /// child items.
+ fn trait_item_breaking(&self) -> bool {
+ for change in &self.changes {
+ match change.0 {
+ ItemMadePrivate |
+ KindDifference |
+ RegionParameterRemoved |
+ TypeParameterRemoved { .. } |
+ VariantAdded |
+ VariantRemoved |
+ VariantFieldAdded { .. } |
+ VariantFieldRemoved { .. } |
+ VariantStyleChanged { .. } |
+ TypeChanged { .. } |
+ FnConstChanged { now_const: false } |
+ MethodSelfChanged { now_self: false } |
+ Unknown => return true,
+ RegionParameterAdded |
+ MethodSelfChanged { now_self: true } |
+ TraitItemAdded { .. } |
+ TraitItemRemoved { .. } |
+ ItemMadePublic |
+ TypeParameterAdded { .. } |
+ TraitUnsafetyChanged { .. } |
+ FnConstChanged { now_const: true } => (),
+ }
+ }
+
+ false
+ }
+
  /// Get the change's category.
  fn to_category(&self) -> ChangeCategory {
  self.max.clone()
@@ -464,7 +496,16 @@ impl<'tcx> ChangeSet<'tcx> {
  // we only care about items that were present in both versions.
  self.changes
  .get(&old)
- .map(|changes| changes.to_category() == Breaking)
+ .map(|change| change.to_category() == Breaking)
+ .unwrap_or(false)
+ }
+
+ /// Check whether a trait item contains breaking changes preventing further analysis of it's
+ /// child items.
+ pub fn trait_item_breaking(&self, old: DefId) -> bool {
+ self.changes
+ .get(&old)
+ .map(|change| change.trait_item_breaking())
  .unwrap_or(false)
  }
 

src/semcheck/traverse.rs

@@ -543,7 +543,7 @@ fn diff_types<'a, 'tcx>(changes: &mut ChangeSet<'tcx>,
 
  if changes.item_breaking(old_def_id) ||
  id_mapping.get_trait_def(&old_def_id)
- .map_or(false, |did| changes.item_breaking(did)) {
+ .map_or(false, |did| changes.trait_item_breaking(did)) {
  return;
  }
 

tests/cases/traits/stdout

@@ -36,6 +36,14 @@ note: added defaulted item to trait (technically breaking)
 10 | | }
  | |_____^
 
+warning: breaking changes in `test7`
+ --> $REPO_PATH/tests/cases/traits/new.rs:11:5
+ |
+11 | fn test7() -> u16;
+ | ^^^^^^^^^^^^^^^^^^
+ |
+ = warning: type error: expected u8, found u16 (breaking)
+
 warning: breaking changes in `test8`
  --> $REPO_PATH/tests/cases/traits/new.rs:12:5
  |