not knowing about opaque types is worse than not knowing about regions, make sure we don't accidentally mark something as ok-modulo-regions if there are opaque types involved

Author: oli-obk

compiler/rustc_middle/src/traits/select.rs

@@ -174,12 +174,12 @@ pub enum SelectionCandidate<'tcx> {
 pub enum EvaluationResult {
     /// Evaluation successful.
     EvaluatedToOk,
+    /// Evaluation successful, but there were unevaluated region obligations.
+    EvaluatedToOkModuloRegions,
     /// Evaluation successful, but need to rerun because opaque types got
     /// hidden types assigned without it being known whether the opaque types
     /// are within their defining scope
     EvaluatedToOkModuloOpaqueTypes,
-    /// Evaluation successful, but there were unevaluated region obligations.
-    EvaluatedToOkModuloRegions,
     /// Evaluation is known to be ambiguous -- it *might* hold for some
     /// assignment of inference variables, but it might not.
     ///