[semantic-sil] ObjC metatypes as metatypes are trivial. Only once converted to objects do they have @owned ownership.

This commit cleans up a few places in bridging code, where we were treating
metatypes as if they had non-invalid cleanups.

rdar://29791263

Author: gottesmm

lib/SILGen/SILGenApply.cpp

@@ -925,11 +925,11 @@ class SILGenApply : public Lowering::ExprVisitor<SILGenApply> {
         objcMetaType = CanExistentialMetatypeType::get(type,
                                                   MetatypeRepresentation::ObjC);
       }
-      selfMetaObjC = ManagedValue(
-                       SGF.B.emitThickToObjCMetatype(
-                         loc, selfMeta.getValue(),
-                         SGF.SGM.getLoweredType(objcMetaType)),
-                       selfMeta.getCleanup());
+      // ObjC metatypes are trivial and thus do not have a cleanup. Only if we
+      // convert them to an object do they become non-trivial.
+      assert(!selfMeta.hasCleanup());
+      selfMetaObjC = ManagedValue::forUnmanaged(SGF.B.emitThickToObjCMetatype(
+          loc, selfMeta.getValue(), SGF.SGM.getLoweredType(objcMetaType)));
     }
 
     // Allocate the object.

lib/SILGen/SILGenBridging.cpp

@@ -457,7 +457,11 @@ static ManagedValue emitNativeToCBridgedNonoptionalValue(SILGenFunction &gen,
     if (bridgedMetaTy->getRepresentation() == MetatypeRepresentation::ObjC) {
       SILValue native = gen.B.emitThickToObjCMetatype(loc, v.getValue(),
                            SILType::getPrimitiveObjectType(loweredBridgedTy));
-      return ManagedValue(native, v.getCleanup());
+      // *NOTE*: ObjCMetatypes are trivial types. They only gain ARC semantics
+      // when they are converted to an object via objc_metatype_to_object.
+      assert(!v.hasCleanup() &&
+             "Metatypes are trivial and thus should not have cleanups");
+      return ManagedValue::forUnmanaged(native);
     }
   }
 
@@ -710,7 +714,11 @@ static ManagedValue emitCBridgedToNativeValue(SILGenFunction &gen,
     if (bridgedMetaTy->getRepresentation() == MetatypeRepresentation::ObjC) {
       SILValue native = gen.B.emitObjCToThickMetatype(loc, v.getValue(),
                                         gen.getLoweredType(loweredNativeTy));
-      return ManagedValue(native, v.getCleanup());
+      // *NOTE*: ObjCMetatypes are trivial types. They only gain ARC semantics
+      // when they are converted to an object via objc_metatype_to_object.
+      assert(!v.hasCleanup() && "Metatypes are trivial and should not have "
+                                "cleanups");
+      return ManagedValue::forUnmanaged(native);
     }
   }