Auto merge of #133527 - matthiaskrgr:rollup-kyre1df, r=matthiaskrgr

Rollup of 6 pull requests

Successful merges:

 - #132979 (use `--exact` on `--skip` to avoid unintended substring matches)
 - #133248 (CI: split x86_64-msvc-ext job)
 - #133449 (std: expose `const_io_error!` as `const_error!`)
 - #133453 (Commit license-metadata.json to git and check it's correct in CI)
 - #133457 (miri: implement `TlsFree`)
 - #133493 (do not constrain infer vars in `find_best_leaf_obligation`)

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 13 insertions, 4 deletions

diff --git a/compiler/rustc_trait_selection/src/solve/fulfill.rs b/compiler/rustc_trait_selection/src/solve/fulfill.rs
index 311dc214de6..0f90c45d032 100644
--- a/compiler/rustc_trait_selection/src/solve/fulfill.rs
+++ b/compiler/rustc_trait_selection/src/solve/fulfill.rs
@@ -346,12 +346,21 @@ fn find_best_leaf_obligation<'tcx>(
     consider_ambiguities: bool,
 ) -> PredicateObligation<'tcx> {
     let obligation = infcx.resolve_vars_if_possible(obligation.clone());
+    // FIXME: we use a probe here as the `BestObligation` visitor does not
+    // check whether it uses candidates which get shadowed by where-bounds.
+    //
+    // We should probably fix the visitor to not do so instead, as this also
+    // means the leaf obligation may be incorrect.
     infcx
-        .visit_proof_tree(obligation.clone().into(), &mut BestObligation {
-            obligation: obligation.clone(),
-            consider_ambiguities,
+        .fudge_inference_if_ok(|| {
+            infcx
+                .visit_proof_tree(obligation.clone().into(), &mut BestObligation {
+                    obligation: obligation.clone(),
+                    consider_ambiguities,
+                })
+                .break_value()
+                .ok_or(())
         })
-        .break_value()
         .unwrap_or(obligation)
 }