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Add guard checking for associated types before computing intercrate ambiguity of projections. Bless test with more specific notes on the ambiguity cause.

This commit is contained in:
Gavin Gray 2023-11-14 13:55:59 +01:00
parent 60d99ab883
commit caae1e08ec
2 changed files with 9 additions and 1 deletions
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8
compiler/rustc_trait_selection/src/traits/coherence.rs
View File

@ -20,6 +20,7 @@ use crate::traits::{
};
use rustc_data_structures::fx::FxIndexSet;
use rustc_errors::Diagnostic;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::{DefId, LOCAL_CRATE};
use rustc_infer::infer::{DefineOpaqueTypes, InferCtxt, TyCtxtInferExt};
use rustc_infer::traits::{util, TraitEngine};
@ -1002,7 +1003,12 @@ impl<'a, 'tcx> ProofTreeVisitor<'tcx> for AmbiguityCausesVisitor<'a> {
// and then prove the resulting predicate as a nested goal.
let trait_ref = match predicate.kind().no_bound_vars() {
Some(ty::PredicateKind::Clause(ty::ClauseKind::Trait(tr))) => tr.trait_ref,
Some(ty::PredicateKind::Clause(ty::ClauseKind::Projection(proj))) => {
Some(ty::PredicateKind::Clause(ty::ClauseKind::Projection(proj)))
if matches!(
infcx.tcx.def_kind(proj.projection_ty.def_id),
DefKind::AssocTy | DefKind::AssocConst
) =>
{
proj.projection_ty.trait_ref(infcx.tcx)
}
_ => return ControlFlow::Continue(()),

2
tests/ui/impl-trait/auto-trait-coherence.next.stderr
View File

@ -6,6 +6,8 @@ LL | impl<T: Send> AnotherTrait for T {}
...
LL | impl AnotherTrait for D<OpaqueType> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `D<OpaqueType>`
|
= note: upstream crates may add a new impl of trait `std::marker::Send` for type `OpaqueType` in future versions
error: aborting due to previous error