Auto merge of #133522 - estebank:dont-suggest-unstable-trait, r=compiler-errors

Don't suggest restricting bound with unstable traits on stable and mention it's unstable on nightly

On nightly, we mention the trait is unstable

```
error[E0277]: the trait bound `T: Unstable` is not satisfied
  --> $DIR/unstable-trait-suggestion.rs:13:9
   |
LL |     foo(t)
   |     --- ^ the trait `Unstable` is not implemented for `T`
   |     |
   |     required by a bound introduced by this call
   |
note: required by a bound in `foo`
  --> $DIR/unstable-trait-suggestion.rs:9:11
   |
LL | fn foo<T: Unstable>(_: T) {}
   |           ^^^^^^^^ required by this bound in `foo`
help: consider restricting type parameter `T` but it is an `unstable` trait
   |
LL | pub fn demo<T: Unstable>(t: T) {
   |              ++++++++++
```

On stable, we don't suggest the trait at all

```
error[E0277]: the trait bound `T: Unstable` is not satisfied
  --> $DIR/unstable-trait-suggestion.rs:13:9
   |
LL |     foo(t)
   |     --- ^ the trait `Unstable` is not implemented for `T`
   |     |
   |     required by a bound introduced by this call
   |
note: required by a bound in `foo`
  --> $DIR/unstable-trait-suggestion.rs:9:11
   |
LL | fn foo<T: Unstable>(_: T) {}
   |           ^^^^^^^^ required by this bound in `foo`
```

Fix #133511.

Author: bors

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -1450,6 +1450,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                         ty::Param(param_ty) => Ok((
                             generics.type_param(param_ty, tcx),
                             predicate.trait_ref.print_trait_sugared().to_string(),
+                            Some(predicate.trait_ref.def_id),
                         )),
                         _ => Err(()),
                     }
@@ -1463,9 +1464,9 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 tcx,
                 hir_generics,
                 err,
-                predicates
-                    .iter()
-                    .map(|(param, constraint)| (param.name.as_str(), &**constraint, None)),
+                predicates.iter().map(|(param, constraint, def_id)| {
+                    (param.name.as_str(), &**constraint, *def_id)
+                }),
                 None,
             );
         }

compiler/rustc_const_eval/src/check_consts/ops.rs

@@ -140,7 +140,7 @@ impl<'tcx> NonConstOp<'tcx> for FnCallNonConst<'tcx> {
                             err,
                             param_ty.name.as_str(),
                             &constraint,
-                            None,
+                            Some(trait_ref.def_id),
                             None,
                         );
                     }