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/* SPDX-FileCopyrightText: 2021 John Scott <jscott@posteo.net>
* SPDX-License-Identifier: GPL-3.0-or-later */
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(void) {
/* Pointers to void and pointers to char are required to have
* the same representation per the ISO C standard. Here we
* do a crude check that pointers to int probably also have the
* same representation. This in general is not a good assumption
* to make, but this is sufficient to justify our type-punning later. */
static_assert(sizeof(char*) == sizeof(void*), "this ABI does not conform to the ISO C standard");
static_assert(sizeof(char*) == sizeof(int*), "pointers to char and pointers to int do not have the same representation");
int test_int;
int *test_i = &test_int;
char *test_c = (void*)&test_int;
if(memcmp(&test_i, &test_c, sizeof(void*))) {
fputs("Pointers to char and pointers to int do not have the same representation\n", stderr);
exit(EXIT_FAILURE);
}
int integers[2];
union {
int *i;
char *c;
} pointers = { .i = integers };
pointers.c++;
/* i is now unsuitably aligned */
*pointers.i = 0;
}
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