Auto merge of #106395 - compiler-errors:rework-predicates, r=eholk

Rework some `predicates_of`/`{Generic,Instantiated}Predicates` code

1. Make `instantiate_own` return an iterator, since it's a bit more efficient and easier to work with
2. Remove `bound_{explicit,}_predicates_of` -- these `bound_` methods in particular were a bit awkward to work with since `ty::GenericPredicates` *already* acts kinda like an `EarlyBinder` with its own `instantiate_*` methods, and had only a few call sites anyways.
3. Implement `IntoIterator` for `InstantiatedPredicates`, since it's *very* commonly being `zip`'d together.

1 files changed, 2 insertions, 3 deletions

diff --git a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
index a41d10f1043..d4ac461690c 100644
--- a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
@@ -185,9 +185,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         })?);
 
         if let ty::Alias(ty::Projection, ..) = placeholder_self_ty.kind() {
-            let predicates = tcx.predicates_of(def_id).instantiate_own(tcx, substs).predicates;
-            debug!(?predicates, "projection predicates");
-            for predicate in predicates {
+            let predicates = tcx.predicates_of(def_id).instantiate_own(tcx, substs);
+            for (predicate, _) in predicates {
                 let normalized = normalize_with_depth_to(
                     self,
                     obligation.param_env,