[NCGenerics] handle ReferenceStorageType queries

Author: kavon

lib/AST/Type.cpp

@@ -182,6 +182,9 @@ static CanType preprocessTypeForInvertibleQuery(GenericEnvironment *env,
                                                 Type orig) {
   Type type = orig;
 
+  // Strip off any StorageType wrapper.
+  type = type->getReferenceStorageReferent();
+
   // Always strip off SILMoveOnlyWrapper.
   if (auto wrapper = type->getAs<SILMoveOnlyWrappedType>())
     type = wrapper->getInnerType();

test/ModuleInterface/Inputs/Swiftskell.swift

@@ -109,3 +109,8 @@ public func isJust<A: ~Copyable>(_ m: borrowing Maybe<A>) -> Bool {
 public func isNothing<A: ~Copyable>(_ m: borrowing Maybe<A>) -> Bool {
   return !isJust(m)
 }
+
+public struct UnownedRef<Instance: AnyObject> {
+  @usableFromInline
+  internal unowned(unsafe) var _value: Instance
+}