Re: determine base type of a typedef

[Russell Shaw]

On 23/10/20 6:06 pm, Russell Shaw wrote:
> On 23/10/20 5:54 pm, Anatoli wrote:
> > 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.
> I might be missing something simple because i got up too early.
>
> If a platform has time_t the same size as a long and long long, does it matter 
> whether the printf uses "%ld" or "%lld" ?

[For GNU C this is "the same" as both are of 8 bytes, but clang generates a 
warning like: "warning: format specifies type 'long' but the argument has type 
'time_t' (aka 'long long')".]

I see that is the actual problem.