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

Remove PredicateKind and instead only use Binder<PredicateAtom>

Originally brought up in #76814 (comment)

r? `@lcnr`

Author: bors

compiler/rustc_infer/src/infer/canonical/query_response.rs

@@ -530,19 +530,18 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
 
             let atom = match k1.unpack() {
                 GenericArgKind::Lifetime(r1) => {
-                    ty::PredicateAtom::RegionOutlives(ty::OutlivesPredicate(r1, r2))
+                    ty::PredicateKind::RegionOutlives(ty::OutlivesPredicate(r1, r2))
                 }
                 GenericArgKind::Type(t1) => {
-                    ty::PredicateAtom::TypeOutlives(ty::OutlivesPredicate(t1, r2))
+                    ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(t1, r2))
                 }
                 GenericArgKind::Const(..) => {
                     // Consts cannot outlive one another, so we don't expect to
                     // encounter this branch.
                     span_bug!(cause.span, "unexpected const outlives {:?}", constraint);
                 }
             };
-            let predicate =
-                predicate.rebind(atom).potentially_quantified(self.tcx, ty::PredicateKind::ForAll);
+            let predicate = predicate.rebind(atom).to_predicate(self.tcx);
 
             Obligation::new(cause.clone(), param_env, predicate)
         })
@@ -664,7 +663,7 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for QueryTypeRelatingDelegate<'_, 'tcx> {
         self.obligations.push(Obligation {
             cause: self.cause.clone(),
             param_env: self.param_env,
-            predicate: ty::PredicateAtom::RegionOutlives(ty::OutlivesPredicate(sup, sub))
+            predicate: ty::PredicateKind::RegionOutlives(ty::OutlivesPredicate(sup, sub))
                 .to_predicate(self.infcx.tcx),
             recursion_depth: 0,
         });

compiler/rustc_infer/src/infer/combine.rs

@@ -358,7 +358,7 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
             self.obligations.push(Obligation::new(
                 self.trace.cause.clone(),
                 self.param_env,
-                ty::PredicateAtom::WellFormed(b_ty.into()).to_predicate(self.infcx.tcx),
+                ty::PredicateKind::WellFormed(b_ty.into()).to_predicate(self.infcx.tcx),
             ));
         }
 
@@ -451,9 +451,9 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
         b: &'tcx ty::Const<'tcx>,
     ) {
         let predicate = if a_is_expected {
-            ty::PredicateAtom::ConstEquate(a, b)
+            ty::PredicateKind::ConstEquate(a, b)
         } else {
-            ty::PredicateAtom::ConstEquate(b, a)
+            ty::PredicateKind::ConstEquate(b, a)
         };
         self.obligations.push(Obligation::new(
             self.trace.cause.clone(),