You're right. Just compiled the following program with clang from Xcode 14 (Apple clang version 14.0.0 (clang-1400.0.29.102)) without issue.

  #include <stdio.h>
  
  struct foo {
   uintptr_t p __attribute__((xnu_usage_semantics("pointer")));
  };
  
  int main() {
   struct foo f = { 100 };
  
   printf("%lu\n", f.p);
   return 0;
  }

Doesn't seem -Wxnu-typed-allocators (which I forgot to mention above) is present in my version. Didn't test the others.

I also just realized that the latest tagged release of https://github.com/apple-oss-distributions/clang is 800.0.38, my clang is reporting 1400.0.29.102. Is Apple no longer releasing the source for their compilers?