Don't select infer -> dyn Trait

2023-07-31 15:53:31 +00:00
parent abd3637e42
commit d21a335e8f
3 changed files with 23 additions and 1 deletions
--- a/compiler/rustc_trait_selection/src/solve/eval_ctxt/select.rs
+++ b/compiler/rustc_trait_selection/src/solve/eval_ctxt/select.rs
@@ -235,7 +235,10 @@ fn rematch_unsize<'tcx>(
        goal.param_env,
        &mut nested,
    );
+
    match (a_ty.kind(), b_ty.kind()) {
+        // Don't try to coerce `?0` to `dyn Trait`
+        (ty::Infer(ty::TyVar(_)), _) | (_, ty::Infer(ty::TyVar(_))) => Ok(None),
        // Stall any ambiguous upcasting goals, since we can't rematch those
        (ty::Dynamic(_, _, ty::Dyn), ty::Dynamic(_, _, ty::Dyn)) => match certainty {
            Certainty::Yes => Ok(Some(ImplSource::Builtin(source, nested))),