Auto merge of #80679 - jackh726:predicate-kind-take2, r=lcnr

Remove PredicateKind and instead only use Binder<PredicateAtom>

Originally brought up in https://github.com/rust-lang/rust/pull/76814#discussion_r546858171

r? `@lcnr`

3 files changed, 10 insertions, 10 deletions

diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 4e393df81fd..8cdb33ea317 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -1550,13 +1550,13 @@ declare_lint_pass!(
 impl<'tcx> LateLintPass<'tcx> for TrivialConstraints {
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'tcx>) {
         use rustc_middle::ty::fold::TypeFoldable;
-        use rustc_middle::ty::PredicateAtom::*;
+        use rustc_middle::ty::PredicateKind::*;
 
         if cx.tcx.features().trivial_bounds {
             let def_id = cx.tcx.hir().local_def_id(item.hir_id);
             let predicates = cx.tcx.predicates_of(def_id);
             for &(predicate, span) in predicates.predicates {
-                let predicate_kind_name = match predicate.skip_binders() {
+                let predicate_kind_name = match predicate.kind().skip_binder() {
                     Trait(..) => "Trait",
                     TypeOutlives(..) |
                     RegionOutlives(..) => "Lifetime",
@@ -1936,8 +1936,8 @@ impl ExplicitOutlivesRequirements {
     ) -> Vec<ty::Region<'tcx>> {
         inferred_outlives
             .iter()
-            .filter_map(|(pred, _)| match pred.skip_binders() {
-                ty::PredicateAtom::RegionOutlives(ty::OutlivesPredicate(a, b)) => match a {
+            .filter_map(|(pred, _)| match pred.kind().skip_binder() {
+                ty::PredicateKind::RegionOutlives(ty::OutlivesPredicate(a, b)) => match a {
                     ty::ReEarlyBound(ebr) if ebr.index == index => Some(b),
                     _ => None,
                 },
@@ -1952,8 +1952,8 @@ impl ExplicitOutlivesRequirements {
     ) -> Vec<ty::Region<'tcx>> {
         inferred_outlives
             .iter()
-            .filter_map(|(pred, _)| match pred.skip_binders() {
-                ty::PredicateAtom::TypeOutlives(ty::OutlivesPredicate(a, b)) => {
+            .filter_map(|(pred, _)| match pred.kind().skip_binder() {
+                ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(a, b)) => {
                     a.is_param(index).then_some(b)
                 }
                 _ => None,
diff --git a/compiler/rustc_lint/src/traits.rs b/compiler/rustc_lint/src/traits.rs
index d4f79036e5a..b031c1108c6 100644
--- a/compiler/rustc_lint/src/traits.rs
+++ b/compiler/rustc_lint/src/traits.rs
@@ -45,12 +45,12 @@ declare_lint_pass!(
 
 impl<'tcx> LateLintPass<'tcx> for DropTraitConstraints {
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'tcx>) {
-        use rustc_middle::ty::PredicateAtom::*;
+        use rustc_middle::ty::PredicateKind::*;
 
         let def_id = cx.tcx.hir().local_def_id(item.hir_id);
         let predicates = cx.tcx.explicit_predicates_of(def_id);
         for &(predicate, span) in predicates.predicates {
-            let trait_predicate = match predicate.skip_binders() {
+            let trait_predicate = match predicate.kind().skip_binder() {
                 Trait(trait_predicate, _constness) => trait_predicate,
                 _ => continue,
             };
diff --git a/compiler/rustc_lint/src/unused.rs b/compiler/rustc_lint/src/unused.rs
index bc7363a69a6..c1a3eecbbc7 100644
--- a/compiler/rustc_lint/src/unused.rs
+++ b/compiler/rustc_lint/src/unused.rs
@@ -202,8 +202,8 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
                     let mut has_emitted = false;
                     for &(predicate, _) in cx.tcx.explicit_item_bounds(def) {
                         // We only look at the `DefId`, so it is safe to skip the binder here.
-                        if let ty::PredicateAtom::Trait(ref poly_trait_predicate, _) =
-                            predicate.skip_binders()
+                        if let ty::PredicateKind::Trait(ref poly_trait_predicate, _) =
+                            predicate.kind().skip_binder()
                         {
                             let def_id = poly_trait_predicate.trait_ref.def_id;
                             let descr_pre =