ObjFW  Diff

    objc_enumeration_mutation_handler_t _Nullable handler);
extern id _Nullable objc_constructInstance(Class _Nullable class_,
    void *_Nullable bytes);
extern void *_Nullable objc_destructInstance(id _Nullable object);
extern void *_Null_unspecified objc_autoreleasePoolPush(void);
extern void objc_autoreleasePoolPop(void *_Null_unspecified pool);
extern id _Nullable _objc_rootAutorelease(id _Nullable object);
extern void objc_setTaggedPointerSecret(uintptr_t secret);
extern int objc_registerTaggedPointerClass(Class _Nonnull class);
extern Class _Nullable object_getTaggedPointerClass(id _Nonnull object);
extern uintptr_t object_getTaggedPointerValue(id _Nonnull object);
extern id _Nullable objc_createTaggedPointer(int class, uintptr_t value);

/*
 * Used by the compiler, but can also be called manually.