#include <metal_stdlib>
using namespace metal;

#define TINT_ISOLATE_UB(VOLATILE_NAME) \
  volatile bool VOLATILE_NAME = true; \
  if (VOLATILE_NAME)

void f() {
  {
    int must_not_collide = 0;
    TINT_ISOLATE_UB(tint_volatile_true) while(true) {
      break;
    }
  }
  int must_not_collide = 0;
}