2 files changed, 30 insertions, 0 deletions
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 17647d13f99..62a22708210 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -1207,6 +1207,18 @@ impl<'tcx> ToPredicate<'tcx, PolyTraitPredicate<'tcx>> for Binder<'tcx, TraitRef
     }
 }
 
+impl<'tcx> ToPredicate<'tcx, PolyTraitPredicate<'tcx>> for TraitRef<'tcx> {
+    fn to_predicate(self, tcx: TyCtxt<'tcx>) -> PolyTraitPredicate<'tcx> {
+        ty::Binder::dummy(self).to_predicate(tcx)
+    }
+}
+
+impl<'tcx> ToPredicate<'tcx, PolyTraitPredicate<'tcx>> for TraitPredicate<'tcx> {
+    fn to_predicate(self, _tcx: TyCtxt<'tcx>) -> PolyTraitPredicate<'tcx> {
+        ty::Binder::dummy(self)
+    }
+}
+
 impl<'tcx> ToPredicate<'tcx> for PolyTraitPredicate<'tcx> {
     fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
         self.map_bound(|p| PredicateKind::Clause(Clause::Trait(p))).to_predicate(tcx)
@@ -1231,6 +1243,12 @@ impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
     }
 }
 
+impl<'tcx> ToPredicate<'tcx> for TraitPredicate<'tcx> {
+    fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
+        PredicateKind::Clause(Clause::Trait(self)).to_predicate(tcx)
+    }
+}
+
 impl<'tcx> Predicate<'tcx> {
     pub fn to_opt_poly_trait_pred(self) -> Option<PolyTraitPredicate<'tcx>> {
         let predicate = self.kind();
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index 32809783c29..1849a66fa8f 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -871,6 +871,18 @@ impl<'tcx> TraitRef<'tcx> {
         )
     }
 
+    /// Converts this trait ref to a trait predicate with a given `constness` and a positive polarity.
+    #[inline]
+    pub fn with_constness(self, constness: ty::BoundConstness) -> ty::TraitPredicate<'tcx> {
+        ty::TraitPredicate { trait_ref: self, constness, polarity: ty::ImplPolarity::Positive }
+    }
+
+    /// Converts this trait ref to a trait predicate without `const` and a positive polarity.
+    #[inline]
+    pub fn without_const(self) -> ty::TraitPredicate<'tcx> {
+        self.with_constness(ty::BoundConstness::NotConst)
+    }
+
     #[inline]
     pub fn self_ty(&self) -> Ty<'tcx> {
         self.substs.type_at(0)