Rollup merge of rust-lang#103488 - oli-obk:impl_trait_for_tait, r=lcnr

Allow opaque types in trait impl headers and rely on coherence to reject unsound cases

r? ````@lcnr````

fixes rust-lang#99840

clippy_utils/src/qualify_min_const_fn.rs

@@ -37,6 +37,7 @@ pub fn is_min_const_fn<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>, msrv: Option<
                 ty::PredicateKind::ClosureKind(..) => panic!("closure kind predicate on function: {predicate:#?}"),
                 ty::PredicateKind::Subtype(_) => panic!("subtype predicate on function: {predicate:#?}"),
                 ty::PredicateKind::Coerce(_) => panic!("coerce predicate on function: {predicate:#?}"),
+                ty::PredicateKind::Ambiguous => panic!("ambiguous predicate on function: {predicate:#?}"),
             }
         }
         match predicates.parent {