Rollup merge of #135697 - compiler-errors:poly-trait-ref, r=lqd

Get rid of `ToPolyTraitRef`

It's generally a footgun, since it throws away `PredicatePolarity`.

This PR doesn't attempt to fix any related bugs having to do with binders or polarity; it just tries to pass through `TraitPredicate`s around instead of `TraitRef`s. There should be basically no functional changes.

2 files changed, 1 insertions, 12 deletions

diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index d2875fb3794..ca70ae794c5 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -79,8 +79,7 @@ pub use self::predicate::{
     PolyExistentialPredicate, PolyExistentialProjection, PolyExistentialTraitRef,
     PolyProjectionPredicate, PolyRegionOutlivesPredicate, PolySubtypePredicate, PolyTraitPredicate,
     PolyTraitRef, PolyTypeOutlivesPredicate, Predicate, PredicateKind, ProjectionPredicate,
-    RegionOutlivesPredicate, SubtypePredicate, ToPolyTraitRef, TraitPredicate, TraitRef,
-    TypeOutlivesPredicate,
+    RegionOutlivesPredicate, SubtypePredicate, TraitPredicate, TraitRef, TypeOutlivesPredicate,
 };
 pub use self::region::{
     BoundRegion, BoundRegionKind, EarlyParamRegion, LateParamRegion, LateParamRegionKind, Region,
diff --git a/compiler/rustc_middle/src/ty/predicate.rs b/compiler/rustc_middle/src/ty/predicate.rs
index 32d6455e825..584cac22ae8 100644
--- a/compiler/rustc_middle/src/ty/predicate.rs
+++ b/compiler/rustc_middle/src/ty/predicate.rs
@@ -476,16 +476,6 @@ impl<'tcx> Clause<'tcx> {
     }
 }
 
-pub trait ToPolyTraitRef<'tcx> {
-    fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
-}
-
-impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
-    fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
-        self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
-    }
-}
-
 impl<'tcx> UpcastFrom<TyCtxt<'tcx>, PredicateKind<'tcx>> for Predicate<'tcx> {
     fn upcast_from(from: PredicateKind<'tcx>, tcx: TyCtxt<'tcx>) -> Self {
         ty::Binder::dummy(from).upcast(tcx)