Merge pull request #20309 from compnerd/BO

Runtime: add UnknownObject on non-ObjC builds

Author: compnerd

include/swift/Runtime/BuiltinTypes.def

@@ -55,9 +55,7 @@ BUILTIN_POINTER_TYPE(Bb, "Builtin.BridgeObject")
 BUILTIN_POINTER_TYPE(Bp, "Builtin.RawPointer")
 BUILTIN_TYPE(BB, "Builtin.UnsafeValueBuffer")
 
-#if SWIFT_OBJC_INTEROP
 BUILTIN_POINTER_TYPE(BO, "Builtin.UnknownObject")
-#endif
 
 // Int8 vector types
 BUILTIN_VECTOR_TYPE(Bi8_, Int8, 2)

stdlib/public/runtime/KnownMetadata.cpp

@@ -101,6 +101,8 @@ namespace pointer_types {
 
     /// The basic value-witness table for ObjC object pointers.
     using BO = ObjCRetainableBox;
+#else
+    using BO = UnknownObjectRetainableBox;
 #endif
 
   }