diff options
| -rw-r--r-- | crates/hir-ty/src/chalk_ext.rs | 2 | ||||
| -rw-r--r-- | crates/hir-ty/src/lower.rs | 18 | ||||
| -rw-r--r-- | crates/hir-ty/src/tests/regression.rs | 12 |
3 files changed, 27 insertions, 5 deletions
diff --git a/crates/hir-ty/src/chalk_ext.rs b/crates/hir-ty/src/chalk_ext.rs index 4a5533c6487..ed97bd2da4f 100644 --- a/crates/hir-ty/src/chalk_ext.rs +++ b/crates/hir-ty/src/chalk_ext.rs @@ -166,6 +166,8 @@ impl TyExt for Ty { let trait_ref = match self.kind(Interner) { // The principal trait bound should be the first element of the bounds. This is an // invariant ensured by `TyLoweringContext::lower_dyn_trait()`. + // FIXME: dyn types may not have principal trait and we don't want to return auto trait + // here. TyKind::Dyn(dyn_ty) => dyn_ty.bounds.skip_binders().interned().get(0).and_then(|b| { match b.skip_binders() { WhereClause::Implemented(trait_ref) => Some(trait_ref), diff --git a/crates/hir-ty/src/lower.rs b/crates/hir-ty/src/lower.rs index 532544fee59..e28c87dfa46 100644 --- a/crates/hir-ty/src/lower.rs +++ b/crates/hir-ty/src/lower.rs @@ -981,10 +981,11 @@ impl<'a> TyLoweringContext<'a> { fn lower_dyn_trait(&self, bounds: &[Interned<TypeBound>]) -> Ty { let self_ty = TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(Interner); - // INVARIANT: The principal trait bound must come first. Others may be in any order but - // should be in the same order for the same set but possibly different order of bounds in - // the input. - // This invariant is used by `TyExt::dyn_trait()` and chalk. + // INVARIANT: The principal trait bound, if present, must come first. Others may be in any + // order but should be in the same order for the same set but possibly different order of + // bounds in the input. + // INVARIANT: If this function returns `DynTy`, there should be at least one trait bound. + // These invariants are utilized by `TyExt::dyn_trait()` and chalk. let bounds = self.with_shifted_in(DebruijnIndex::ONE, |ctx| { let mut bounds: Vec<_> = bounds .iter() @@ -1035,6 +1036,12 @@ impl<'a> TyLoweringContext<'a> { return None; } + if bounds.first().and_then(|b| b.trait_id()).is_none() { + // When there's no trait bound, that's an error. This happens when the trait refs + // are unresolved. + return None; + } + // As multiple occurrences of the same auto traits *are* permitted, we dedulicate the // bounds. We shouldn't have repeated elements besides auto traits at this point. bounds.dedup(); @@ -1046,7 +1053,8 @@ impl<'a> TyLoweringContext<'a> { let bounds = crate::make_single_type_binders(bounds); TyKind::Dyn(DynTy { bounds, lifetime: static_lifetime() }).intern(Interner) } else { - // FIXME: report error (additional non-auto traits or associated type rebound) + // FIXME: report error + // (additional non-auto traits, associated type rebound, or no resolved trait) TyKind::Error.intern(Interner) } } diff --git a/crates/hir-ty/src/tests/regression.rs b/crates/hir-ty/src/tests/regression.rs index 23e51a9c16a..47cc3341e70 100644 --- a/crates/hir-ty/src/tests/regression.rs +++ b/crates/hir-ty/src/tests/regression.rs @@ -1691,3 +1691,15 @@ fn macrostmts() -> u8 { "#, ); } + +#[test] +fn dyn_with_unresolved_trait() { + check_types( + r#" +fn foo(a: &dyn DoesNotExist) { + a.bar(); + //^&{unknown} +} + "#, + ); +} |