Russell,
Thanks for your suggestion. The problem is, as I mentioned in the initial post, on amd64 sizeof(time_t) is always 8 bytes, as well as long and long long, so sizeof(time_t) == sizeof(long int) == sizeof(long long int).
I've actually tried the following directly in configure.ac (for this test it's not needed to run a custom code):
#if (SIZEOF_TIME_T == SIZEOF_LONG_LONG_INT)
#define TIME_T_FMT "%lld"
#elif (SIZEOF_TIME_T == SIZEOF_LONG)
#define TIME_T_FMT "%ld"
#else
#error dont know what to use for TIME_T_FMT
#endif
But both checks are true so it makes no sense.
I need something that would not depend on the size of the type. Not sure it's even possible.
Thanks anyway.
Regards,
Anatoli
On 22/10/20 22:09, Russell Shaw wrote:
>
> On 23/10/20 9:23 am, Anatoli wrote:
>> Hi All,
>>
>> Is there a way to determine with autoconf what's the base type of a typedef?
>>
>> I'm trying to accomplish the following:
>>
>> There are standard types time_t, off_t, size_t and similar that are defined
>> differently on different platforms/OS.
>>
>> For example, time_t is defined as "long int" on Linux amd64, but as "long
>> long int" on OpenBSD amd64. So when printing a time_t var with printf & co,
>> on Linux it's OK to use "%ld" format specifier, but on OpenBSD it should be
>> "%lld".
> You could use an AC_COMPILE thing to run a small bit of C that does something like:
>
> int
> test(int argc, char **argv)
> {
> time_t t = -1;
>
> if(t < 0) {
> if(sizeof(time_t) == sizeof(int)) {
> printf("d");
> }
> else if(sizeof(time_t) == sizeof(long int)) {
> printf("ld");
> }
> else if(sizeof(time_t) == sizeof(long long int)) {
> printf("lld");
> }
> else {
> printf("error");
> }
> }
> else {
> if(sizeof(time_t) == sizeof(int)) {
> printf("u");
> }
> else if(sizeof(time_t) == sizeof(long int)) {
> printf("lu");
> }
> else if(sizeof(time_t) == sizeof(long long int)) {
> printf("llu");
> }
> else {
> printf("error");
> }
> }
>
> return 0;
> }
>
