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Auto merge of #13742 - lowr:fix/assoc-type-shorthand-with-gats, r=flodiebold
fix: only shift `BoundVar`s that come from outside lowering context
Fixes #13734
There are some free functions `TyLoweringContext` methods call, which do not know anything about current binders in scope. We need to shift in the `BoundVar`s in substitutions that we get from them (#4952), but not those we get from `TyLoweringContext` methods.
| -rw-r--r-- | crates/hir-ty/src/lower.rs | 42 | ||||
| -rw-r--r-- | crates/hir-ty/src/tests/regression.rs | 21 | ||||
| -rw-r--r-- | crates/hir/src/semantics.rs | 2 | ||||
| -rw-r--r-- | crates/hir/src/source_analyzer.rs | 2 |
4 files changed, 46 insertions, 21 deletions
diff --git a/crates/hir-ty/src/lower.rs b/crates/hir-ty/src/lower.rs index baf9842d5f..e8466a7eda 100644 --- a/crates/hir-ty/src/lower.rs +++ b/crates/hir-ty/src/lower.rs @@ -603,9 +603,8 @@ impl<'a> TyLoweringContext<'a> { } fn select_associated_type(&self, res: Option<TypeNs>, segment: PathSegment<'_>) -> Ty { - let (def, res) = match (self.resolver.generic_def(), res) { - (Some(def), Some(res)) => (def, res), - _ => return TyKind::Error.intern(Interner), + let Some((def, res)) = self.resolver.generic_def().zip(res) else { + return TyKind::Error.intern(Interner); }; let ty = named_associated_type_shorthand_candidates( self.db, @@ -617,6 +616,21 @@ impl<'a> TyLoweringContext<'a> { return None; } + let parent_subst = t.substitution.clone(); + let parent_subst = match self.type_param_mode { + ParamLoweringMode::Placeholder => { + // if we're lowering to placeholders, we have to put them in now. + let generics = generics(self.db.upcast(), def); + let s = generics.placeholder_subst(self.db); + s.apply(parent_subst, Interner) + } + ParamLoweringMode::Variable => { + // We need to shift in the bound vars, since + // `named_associated_type_shorthand_candidates` does not do that. + parent_subst.shifted_in_from(Interner, self.in_binders) + } + }; + // FIXME: `substs_from_path_segment()` pushes `TyKind::Error` for every parent // generic params. It's inefficient to splice the `Substitution`s, so we may want // that method to optionally take parent `Substitution` as we already know them at @@ -632,22 +646,9 @@ impl<'a> TyLoweringContext<'a> { let substs = Substitution::from_iter( Interner, - substs.iter(Interner).take(len_self).chain(t.substitution.iter(Interner)), + substs.iter(Interner).take(len_self).chain(parent_subst.iter(Interner)), ); - let substs = match self.type_param_mode { - ParamLoweringMode::Placeholder => { - // if we're lowering to placeholders, we have to put - // them in now - let generics = generics(self.db.upcast(), def); - let s = generics.placeholder_subst(self.db); - s.apply(substs, Interner) - } - ParamLoweringMode::Variable => substs, - }; - // We need to shift in the bound vars, since - // associated_type_shorthand_candidates does not do that - let substs = substs.shifted_in_from(Interner, self.in_binders); Some( TyKind::Alias(AliasTy::Projection(ProjectionTy { associated_ty_id: to_assoc_type_id(associated_ty), @@ -1190,9 +1191,9 @@ pub fn associated_type_shorthand_candidates<R>( db: &dyn HirDatabase, def: GenericDefId, res: TypeNs, - cb: impl FnMut(&Name, &TraitRef, TypeAliasId) -> Option<R>, + mut cb: impl FnMut(&Name, TypeAliasId) -> Option<R>, ) -> Option<R> { - named_associated_type_shorthand_candidates(db, def, res, None, cb) + named_associated_type_shorthand_candidates(db, def, res, None, |name, _, id| cb(name, id)) } fn named_associated_type_shorthand_candidates<R>( @@ -1202,6 +1203,9 @@ fn named_associated_type_shorthand_candidates<R>( def: GenericDefId, res: TypeNs, assoc_name: Option<Name>, + // Do NOT let `cb` touch `TraitRef` outside of `TyLoweringContext`. Its substitution contains + // free `BoundVar`s that need to be shifted and only `TyLoweringContext` knows how to do that + // properly (see `TyLoweringContext::select_associated_type()`). mut cb: impl FnMut(&Name, &TraitRef, TypeAliasId) -> Option<R>, ) -> Option<R> { let mut search = |t| { diff --git a/crates/hir-ty/src/tests/regression.rs b/crates/hir-ty/src/tests/regression.rs index 4e46397459..de6ae7fff8 100644 --- a/crates/hir-ty/src/tests/regression.rs +++ b/crates/hir-ty/src/tests/regression.rs @@ -1723,3 +1723,24 @@ fn bar() -> ControlFlow<(), ()> { "#, ); } + +#[test] +fn assoc_type_shorthand_with_gats_in_binders() { + // c.f. test `issue_4885()` + check_no_mismatches( + r#" +trait Gats { + type Assoc<T>; +} +trait Foo<T> {} + +struct Bar<'a, B: Gats, A> { + field: &'a dyn Foo<B::Assoc<A>>, +} + +fn foo(b: Bar) { + let _ = b.field; +} +"#, + ); +} diff --git a/crates/hir/src/semantics.rs b/crates/hir/src/semantics.rs index 2e1f88ba09..f887c75984 100644 --- a/crates/hir/src/semantics.rs +++ b/crates/hir/src/semantics.rs @@ -1600,7 +1600,7 @@ impl<'a> SemanticsScope<'a> { self.db, def, resolution.in_type_ns()?, - |name, _, id| cb(name, id.into()), + |name, id| cb(name, id.into()), ) } } diff --git a/crates/hir/src/source_analyzer.rs b/crates/hir/src/source_analyzer.rs index 91ea1c24d1..38950b12a1 100644 --- a/crates/hir/src/source_analyzer.rs +++ b/crates/hir/src/source_analyzer.rs @@ -967,7 +967,7 @@ fn resolve_hir_path_( db, def, res.in_type_ns()?, - |name, _, id| (name == unresolved.name).then(|| id), + |name, id| (name == unresolved.name).then(|| id), ) }) .map(TypeAlias::from) |