Auto merge of #112938 - compiler-errors:clause-3, r=oli-obk

Migrate `TyCtxt::predicates_of` and `ParamEnv::caller_bounds` to `Clause`

The last big change in the series.

I will follow-up with additional filed issues once this PR lands:
- [ ] Investigate making `TypeFoldable<TyCtxt<'tcx>> for ty::Clause<'tcx>` implementation less weird: https://github.com/rust-lang/rust/blob/2efe09170530fa18e42ff05b8d9dd23f00b5c430/compiler/rustc_middle/src/ty/structural_impls.rs#L672
- [ ] Clean up the elaborator since it should only be emitting child clauses, not predicates
- [ ] Rename identifiers like `pred` and `predicates` to `clause` if they're actually clauses around the codebase
- [ ] Validate that all of the `ToPredicate` impls are acutally still needed, or prune them if they're not

r? `@ghost` until the other branch lands

1 files changed, 4 insertions, 4 deletions

diff --git a/compiler/rustc_mir_transform/src/function_item_references.rs b/compiler/rustc_mir_transform/src/function_item_references.rs
index 502f367dcb6..0b41e57be3b 100644
--- a/compiler/rustc_mir_transform/src/function_item_references.rs
+++ b/compiler/rustc_mir_transform/src/function_item_references.rs
@@ -2,7 +2,7 @@ use itertools::Itertools;
 use rustc_hir::def_id::DefId;
 use rustc_middle::mir::visit::Visitor;
 use rustc_middle::mir::*;
-use rustc_middle::ty::{self, EarlyBinder, PredicateKind, SubstsRef, Ty, TyCtxt};
+use rustc_middle::ty::{self, EarlyBinder, SubstsRef, Ty, TyCtxt};
 use rustc_session::lint::builtin::FUNCTION_ITEM_REFERENCES;
 use rustc_span::{symbol::sym, Span};
 use rustc_target::spec::abi::Abi;
@@ -74,7 +74,7 @@ impl<'tcx> FunctionItemRefChecker<'_, 'tcx> {
         let param_env = self.tcx.param_env(def_id);
         let bounds = param_env.caller_bounds();
         for bound in bounds {
-            if let Some(bound_ty) = self.is_pointer_trait(&bound.kind().skip_binder()) {
+            if let Some(bound_ty) = self.is_pointer_trait(bound) {
                 // Get the argument types as they appear in the function signature.
                 let arg_defs = self.tcx.fn_sig(def_id).subst_identity().skip_binder().inputs();
                 for (arg_num, arg_def) in arg_defs.iter().enumerate() {
@@ -104,8 +104,8 @@ impl<'tcx> FunctionItemRefChecker<'_, 'tcx> {
     }
 
     /// If the given predicate is the trait `fmt::Pointer`, returns the bound parameter type.
-    fn is_pointer_trait(&self, bound: &PredicateKind<'tcx>) -> Option<Ty<'tcx>> {
-        if let ty::PredicateKind::Clause(ty::ClauseKind::Trait(predicate)) = bound {
+    fn is_pointer_trait(&self, bound: ty::Clause<'tcx>) -> Option<Ty<'tcx>> {
+        if let ty::ClauseKind::Trait(predicate) = bound.kind().skip_binder() {
             self.tcx
                 .is_diagnostic_item(sym::Pointer, predicate.def_id())
                 .then(|| predicate.trait_ref.self_ty())