clang c89 ptr to int -Weverything

ptrtoint_inttoptr.c

#include <assert.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void ptrtointtoptr(void);

static void memset_16aligned(void * ptr, char byte, size_t size_bytes, uint16_t alignment) {
    assert((size_bytes & (alignment-1)) == 0);
    assert(((uintptr_t)ptr & (alignment-1)) == 0);
    memset(ptr, byte, size_bytes);
}
void ptrtointtoptr(void) {
  const uint16_t alignment = 16;
  const uint16_t align_min_1 = alignment - 1;
  void * mem = malloc(1024+align_min_1);
  void *ptr = (void *)((((uint64_t)mem)+align_min_1) & ~(uint64_t)align_min_1);
  printf("0x%08" PRIXPTR ", 0x%08" PRIXPTR "\n", (uintptr_t)mem, (uintptr_t)ptr);
  memset_16aligned(ptr, 0, 1024, alignment);
  free(mem);
}

int main(void) { ptrtointtoptr(); }

shell

misterspoon@pc ~/d/t/tryc> clang -std=c89 -Weverything ptrtoint_inttoptr.c && ./a.out
0x623AA76542A0, 0x623AA76542A0