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Fast path for stalled obligations on self ty

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This commit is contained in:
Michael Goulet
2025-05-28 11:14:43 +00:00
parent 2398bd60ef
commit 3418d5db3a
3 changed files with 13 additions and 6 deletions
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2
compiler/rustc_infer/src/infer/opaque_types/table.rs
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@@ -53,7 +53,7 @@ impl<'tcx> OpaqueTypeStorage<'tcx> {
assert!(entry.is_some());
}
pub(crate) fn is_empty(&self) -> bool {
pub fn is_empty(&self) -> bool {
let OpaqueTypeStorage { opaque_types, duplicate_entries } = self;
opaque_types.is_empty() && duplicate_entries.is_empty()
}

10
compiler/rustc_trait_selection/src/solve/delegate.rs
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@@ -64,6 +64,16 @@ impl<'tcx> rustc_next_trait_solver::delegate::SolverDelegate for SolverDelegate<
span: Span,
) -> Option<Certainty> {
if let Some(trait_pred) = goal.predicate.as_trait_clause() {
if self.shallow_resolve(trait_pred.self_ty().skip_binder()).is_ty_var()
// We don't do this fast path when opaques are defined since we may
// eventually use opaques to incompletely guide inference via ty var
// self types.
// FIXME: Properly consider opaques here.
&& self.inner.borrow_mut().opaque_types().is_empty()
{
return Some(Certainty::AMBIGUOUS);
}
if trait_pred.polarity() == ty::PredicatePolarity::Positive {
match self.0.tcx.as_lang_item(trait_pred.def_id()) {
Some(LangItem::Sized)

7
tests/ui/traits/next-solver/coherence/coherence-fulfill-overflow.stderr
View File

@@ -1,13 +1,10 @@
error[E0119]: conflicting implementations of trait `Trait` for type `W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<_>>>>>>>>>>>>>>>>>>>>>`
error[E0119]: conflicting implementations of trait `Trait` for type `W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<_>>>>>>>>>>>>>>>>>>>>>>>`
--> $DIR/coherence-fulfill-overflow.rs:12:1
|
LL | impl<T: ?Sized + TwoW> Trait for W<T> {}
| ------------------------------------- first implementation here
LL | impl<T: ?Sized + TwoW> Trait for T {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<_>>>>>>>>>>>>>>>>>>>>>`
|
= note: overflow evaluating the requirement `W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<_>>>>>>>>>>>>>>>>>>>>>: TwoW`
= help: consider increasing the recursion limit by adding a `#![recursion_limit = "20"]` attribute to your crate (`coherence_fulfill_overflow`)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<_>>>>>>>>>>>>>>>>>>>>>>>`
error: aborting due to 1 previous error