Auto merge of #115960 - GuillaumeGomez:rollup-8tky3qu, r=GuillaumeGomez

Rollup of 6 pull requests

Successful merges:

 - #112725 (rustdoc-search: add support for type parameters)
 - #114941 (Don't resolve generic impls that may be shadowed by dyn built-in impls)
 - #115625 (Explain HRTB + infer limitations of old solver)
 - #115839 (Bump libc to 0.2.148)
 - #115924 (Don't complain on a single non-exhaustive 1-ZST)
 - #115946 (panic when encountering an illegal cpumask in thread::available_parallelism)

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

1 files changed, 24 insertions, 1 deletions

diff --git a/compiler/rustc_ty_utils/src/instance.rs b/compiler/rustc_ty_utils/src/instance.rs
index da2958bf56e..91f1c21310e 100644
--- a/compiler/rustc_ty_utils/src/instance.rs
+++ b/compiler/rustc_ty_utils/src/instance.rs
@@ -141,11 +141,34 @@ fn resolve_associated_item<'tcx>(
                     false
                 }
             };
-
             if !eligible {
                 return Ok(None);
             }
 
+            // HACK: We may have overlapping `dyn Trait` built-in impls and
+            // user-provided blanket impls. Detect that case here, and return
+            // ambiguity.
+            //
+            // This should not affect totally monomorphized contexts, only
+            // resolve calls that happen polymorphically, such as the mir-inliner
+            // and const-prop (and also some lints).
+            let self_ty = rcvr_args.type_at(0);
+            if !self_ty.is_known_rigid() {
+                let predicates = tcx
+                    .predicates_of(impl_data.impl_def_id)
+                    .instantiate(tcx, impl_data.args)
+                    .predicates;
+                let sized_def_id = tcx.lang_items().sized_trait();
+                // If we find a `Self: Sized` bound on the item, then we know
+                // that `dyn Trait` can certainly never apply here.
+                if !predicates.into_iter().filter_map(ty::Clause::as_trait_clause).any(|clause| {
+                    Some(clause.def_id()) == sized_def_id
+                        && clause.skip_binder().self_ty() == self_ty
+                }) {
+                    return Ok(None);
+                }
+            }
+
             // Any final impl is required to define all associated items.
             if !leaf_def.item.defaultness(tcx).has_value() {
                 let guard = tcx.sess.delay_span_bug(