Define opaque types everywhere in confirmation.

Confirmation is only applied to things that selection already considered equal.
If an opaque type were to be compared with another type, we'd already have errored out in selection.

Author: oli-obk

compiler/rustc_trait_selection/src/traits/select/confirmation.rs

@@ -197,7 +197,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         obligations.extend(
             self.infcx
                 .at(&obligation.cause, obligation.param_env)
-                .eq(DefineOpaqueTypes::No, placeholder_trait_predicate, candidate)
+                .eq(DefineOpaqueTypes::Yes, placeholder_trait_predicate, candidate)
                 .map(|InferOk { obligations, .. }| obligations)
                 .map_err(|_| Unimplemented)?,
         );
@@ -568,7 +568,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         nested.extend(
             self.infcx
                 .at(&obligation.cause, obligation.param_env)
-                .eq(DefineOpaqueTypes::No, trait_predicate.trait_ref, upcast_trait_ref)
+                .eq(DefineOpaqueTypes::Yes, trait_predicate.trait_ref, upcast_trait_ref)
                 .map(|InferOk { obligations, .. }| obligations)
                 .map_err(|_| Unimplemented)?,
         );
@@ -1195,7 +1195,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 let InferOk { mut obligations, .. } = self
                     .infcx
                     .at(&obligation.cause, obligation.param_env)
-                    .sup(DefineOpaqueTypes::No, target, source_trait)
+                    .sup(DefineOpaqueTypes::Yes, target, source_trait)
                     .map_err(|_| Unimplemented)?;
 
                 // Register one obligation for 'a: 'b.
@@ -1263,7 +1263,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 let InferOk { obligations, .. } = self
                     .infcx
                     .at(&obligation.cause, obligation.param_env)
-                    .eq(DefineOpaqueTypes::No, b, a)
+                    .eq(DefineOpaqueTypes::Yes, b, a)
                     .map_err(|_| Unimplemented)?;
 
                 ImplSource::Builtin(BuiltinImplSource::Misc, obligations)
@@ -1311,7 +1311,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 let InferOk { obligations, .. } = self
                     .infcx
                     .at(&obligation.cause, obligation.param_env)
-                    .eq(DefineOpaqueTypes::No, target, new_struct)
+                    .eq(DefineOpaqueTypes::Yes, target, new_struct)
                     .map_err(|_| Unimplemented)?;
                 nested.extend(obligations);
 
@@ -1344,7 +1344,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 let InferOk { mut obligations, .. } = self
                     .infcx
                     .at(&obligation.cause, obligation.param_env)
-                    .eq(DefineOpaqueTypes::No, target, new_tuple)
+                    .eq(DefineOpaqueTypes::Yes, target, new_tuple)
                     .map_err(|_| Unimplemented)?;
 
                 // Add a nested `T: Unsize<U>` predicate.