[move-only] Ban @objc enum being marked as move only.

rdar://106340608

Author: gottesmm

include/swift/AST/DiagnosticsSema.def

@@ -6797,6 +6797,8 @@ ERROR(moveonly_cast,none,
       "move-only types cannot be conditionally cast", ())
 ERROR(moveonly_failable_init,none,
       "move-only types cannot have failable initializers yet", ())
+ERROR(moveonly_objc_enum_banned, none,
+      "@objc enums cannot be marked as move-only", ())
 
 //------------------------------------------------------------------------------
 // MARK: Type inference from default expressions

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -2547,6 +2547,13 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
       }
     }
 
+    // -----
+    // NonCopyableChecks
+    //
+
+    if (ED->isObjC() && ED->isMoveOnly()) {
+      ED->diagnose(diag::moveonly_objc_enum_banned);
+    }
     // FIXME(kavon): see if these can be integrated into other parts of Sema
     diagnoseCopyableTypeContainingMoveOnlyType(ED);
     diagnoseIncompatibleProtocolsForMoveOnlyType(ED);

test/Sema/moveonly_objc_enum.swift

@@ -0,0 +1,15 @@
+// RUN: %target-typecheck-verify-swift -enable-experimental-move-only
+
+// Validate that we can't mark an objc enum as move only.
+
+@_moveOnly
+@objc enum Foo : Int { // expected-error {{@objc enums cannot be marked as move-only}}
+  case X, Y, Z
+  deinit {} // objc enums cannot have deinits
+}
+
+@_moveOnly
+@objc enum Foo2 : Int { // expected-error {{@objc enums cannot be marked as move-only}}
+  case X, Y, Z
+}
+