Auto merge of #118120 - compiler-errors:closure-kind, r=lcnr

Remove `PredicateKind::ClosureKind`

We don't need the `ClosureKind` predicate kind -- instead, `Fn`-family trait goals are left as ambiguous, and we only need to make progress on `FnOnce` projection goals for inference purposes.

This is similar to how we do confirmation of `Fn`-family trait and projection goals in the new trait solver, which also doesn't use the `ClosureKind` predicate.

Some hacky logic is added in the second commit so that we can keep the error messages the same.

3 files changed, 0 insertions, 12 deletions

diff --git a/compiler/rustc_middle/src/ty/flags.rs b/compiler/rustc_middle/src/ty/flags.rs
index 4d7b12662c6..cd9b429ec56 100644
--- a/compiler/rustc_middle/src/ty/flags.rs
+++ b/compiler/rustc_middle/src/ty/flags.rs
@@ -263,9 +263,6 @@ impl FlagComputation {
                 self.add_args(slice::from_ref(&arg));
             }
             ty::PredicateKind::ObjectSafe(_def_id) => {}
-            ty::PredicateKind::ClosureKind(_def_id, args, _kind) => {
-                self.add_args(args);
-            }
             ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(uv)) => {
                 self.add_const(uv);
             }
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 1d7abcf53ea..56739ce96c3 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -548,7 +548,6 @@ impl<'tcx> Predicate<'tcx> {
             | PredicateKind::Clause(ClauseKind::ConstArgHasType(..))
             | PredicateKind::AliasRelate(..)
             | PredicateKind::ObjectSafe(_)
-            | PredicateKind::ClosureKind(_, _, _)
             | PredicateKind::Subtype(_)
             | PredicateKind::Coerce(_)
             | PredicateKind::Clause(ClauseKind::ConstEvaluatable(_))
@@ -1276,7 +1275,6 @@ impl<'tcx> Predicate<'tcx> {
             | PredicateKind::Clause(ClauseKind::RegionOutlives(..))
             | PredicateKind::Clause(ClauseKind::WellFormed(..))
             | PredicateKind::ObjectSafe(..)
-            | PredicateKind::ClosureKind(..)
             | PredicateKind::Clause(ClauseKind::TypeOutlives(..))
             | PredicateKind::Clause(ClauseKind::ConstEvaluatable(..))
             | PredicateKind::ConstEquate(..)
@@ -1296,7 +1294,6 @@ impl<'tcx> Predicate<'tcx> {
             | PredicateKind::Clause(ClauseKind::RegionOutlives(..))
             | PredicateKind::Clause(ClauseKind::WellFormed(..))
             | PredicateKind::ObjectSafe(..)
-            | PredicateKind::ClosureKind(..)
             | PredicateKind::Clause(ClauseKind::TypeOutlives(..))
             | PredicateKind::Clause(ClauseKind::ConstEvaluatable(..))
             | PredicateKind::ConstEquate(..)
@@ -1317,7 +1314,6 @@ impl<'tcx> Predicate<'tcx> {
             | PredicateKind::Clause(ClauseKind::RegionOutlives(..))
             | PredicateKind::Clause(ClauseKind::WellFormed(..))
             | PredicateKind::ObjectSafe(..)
-            | PredicateKind::ClosureKind(..)
             | PredicateKind::Clause(ClauseKind::ConstEvaluatable(..))
             | PredicateKind::ConstEquate(..)
             | PredicateKind::Ambiguous => None,
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index a58362950ff..25a151443d5 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -2781,11 +2781,6 @@ define_print! {
             ty::PredicateKind::ObjectSafe(trait_def_id) => {
                 p!("the trait `", print_def_path(trait_def_id, &[]), "` is object-safe")
             }
-            ty::PredicateKind::ClosureKind(closure_def_id, _closure_args, kind) => p!(
-                "the closure `",
-                print_value_path(closure_def_id, &[]),
-                write("` implements the trait `{}`", kind)
-            ),
             ty::PredicateKind::ConstEquate(c1, c2) => {
                 p!("the constant `", print(c1), "` equals `", print(c2), "`")
             }