bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Auto merge of #138249 - compiler-errors:auto-self, r=lcnr

Browse source 
Do not register `Self: AutoTrait` when confirming auto trait (in old solver)

Every built-in auto impl for a trait goal like `Ty: Auto` immediately registers another obligation of `Ty: Auto` as one of its nested obligations, leading to us stressing the cycle detection machinery a lot more than we need to. This is because all traits have a `Self: Trait` predicate.

To fix this, remove the call to `impl_or_trait_obligations` in `vtable_auto_impl`, since auto traits do not have where clauses.

r? lcnr
This commit is contained in:
bors 2025-03-13 05:37:55 +00:00
commit 961351c76c
3 changed files with 4 additions and 43 deletions
Download patch file Download diff file Expand all files Collapse all files

16
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
View file

@ -463,18 +463,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let cause = obligation.derived_cause(ObligationCauseCode::BuiltinDerived);
assert_eq!(obligation.predicate.polarity(), ty::PredicatePolarity::Positive);
let trait_ref =
self.infcx.enter_forall_and_leak_universe(obligation.predicate).trait_ref;
let trait_obligations = self.impl_or_trait_obligations(
&cause,
obligation.recursion_depth + 1,
obligation.param_env,
trait_def_id,
trait_ref.args,
obligation.predicate,
);
let mut obligations = self.collect_predicates_for_types(
let obligations = self.collect_predicates_for_types(
obligation.param_env,
cause,
obligation.recursion_depth + 1,
@ -482,10 +472,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
nested,
);
// Adds the predicates from the trait. Note that this contains a `Self: Trait`
// predicate as usual. It won't have any effect since auto traits are coinductive.
obligations.extend(trait_obligations);
debug!(?obligations, "vtable_auto_impl");
obligations