Optimize subtyping and equation of GeneratorWitness

compiler/rustc_infer/src/infer/equate.rs

@@ -110,6 +110,24 @@ impl<'tcx> TypeRelation<'tcx> for Equate<'_, '_, 'tcx> {
                         .obligations,
                 );
             }
+            (&ty::GeneratorWitness(a_types), &ty::GeneratorWitness(b_types)) => {
+                let a_types = infcx.tcx.anonymize_bound_vars(a_types);
+                let b_types = infcx.tcx.anonymize_bound_vars(b_types);
+                if a_types.bound_vars() == b_types.bound_vars() {
+                    let (a_types, b_types) = infcx.replace_bound_vars_with_placeholders(
+                        a_types.map_bound(|a_types| (a_types, b_types.skip_binder())),
+                    );
+                    for (a, b) in std::iter::zip(a_types, b_types) {
+                        self.relate(a, b)?;
+                    }
+                } else {
+                    self.fields.infcx.super_combine_tys(
+                        self,
+                        infcx.tcx.mk_generator_witness(a_types),
+                        infcx.tcx.mk_generator_witness(b_types),
+                    )?;
+                }
+            }
 
             _ => {
                 self.fields.infcx.super_combine_tys(self, a, b)?;

compiler/rustc_infer/src/infer/sub.rs

@@ -164,6 +164,25 @@ impl<'tcx> TypeRelation<'tcx> for Sub<'_, '_, 'tcx> {
                 );
                 Ok(ga)
             }
+            (&ty::GeneratorWitness(a_types), &ty::GeneratorWitness(b_types)) => {
+                let a_types = infcx.tcx.anonymize_bound_vars(a_types);
+                let b_types = infcx.tcx.anonymize_bound_vars(b_types);
+                if a_types.bound_vars() == b_types.bound_vars() {
+                    let (a_types, b_types) = infcx.replace_bound_vars_with_placeholders(
+                        a_types.map_bound(|a_types| (a_types, b_types.skip_binder())),
+                    );
+                    for (a, b) in std::iter::zip(a_types, b_types) {
+                        self.relate(a, b)?;
+                    }
+                } else {
+                    self.fields.infcx.super_combine_tys(
+                        self,
+                        infcx.tcx.mk_generator_witness(a_types),
+                        infcx.tcx.mk_generator_witness(b_types),
+                    )?;
+                }
+                Ok(a)
+            }
 
             _ => {
                 self.fields.infcx.super_combine_tys(self, a, b)?;

src/test/ui/higher-rank-trait-bounds/issue-95034.rs

@@ -1,23 +1,5 @@
-// known-bug: #95034
-// failure-status: 101
+// check-pass
 // compile-flags: --edition=2021 --crate-type=lib
-// rustc-env:RUST_BACKTRACE=0
-
-// normalize-stderr-test "thread 'rustc' panicked.*" -> "thread 'rustc' panicked"
-// normalize-stderr-test "note:.*RUST_BACKTRACE=1.*\n" -> ""
-// normalize-stderr-test "\nerror: internal compiler error.*\n\n" -> ""
-// normalize-stderr-test "note:.*unexpectedly panicked.*\n\n" -> ""
-// normalize-stderr-test "note: we would appreciate a bug report.*\n\n" -> ""
-// normalize-stderr-test "note: compiler flags.*\n\n" -> ""
-// normalize-stderr-test "note: rustc.*running on.*\n\n" -> ""
-// normalize-stderr-test "query stack during panic:\n" -> ""
-// normalize-stderr-test "we're just showing a limited slice of the query stack\n" -> ""
-// normalize-stderr-test "end of query stack\n" -> ""
-// normalize-stderr-test "#.*\n" -> ""
-
-// This should not ICE.
-
-// Refer to the issue for more minimized versions.
 
 use std::{
     future::Future,