Re: Make 3.79.1 on OpenVMS

[Henning Makholm]

Scripsit "Paul D. Smith" <address@hidden>
> %% address@hidden (Paul Jarc) writes:
>   pj> "Paul D. Smith" <address@hidden> wrote:

>   >> Hm.  However, I can't think of any way to write a configure test on
>   >> whether or not time_t is signed or unsigned.

>   pj> if ((time_t)-1<(time_t)0) signed(); else unsigned();

> Not bad but this requires being able to run a program.  This is a no-no
> if you want your app to be cross-compilable.

How about trying to just compile this source file:

  #include <time.h>
  #define IS_SIGNED ((time_t)-1 < (time_t)0)
  int foo [ 1 - 2*IS_SIGNED ] = { 42 };

If time_t is signed, the C compiler ought to refuse to compile it
because the array bound will be negative.

Of course it won't help in environments where the compiler returns no
useful success/failure state to the configure scripts. But in such
an environment even the vanilla autoconf tests will have trouble.

-- 
Henning Makholm                           "First chapter, the plot advances,
                                 second chapter, Ayla makes a discovery that
                       significantly enhances Palaeolithic technology, third
               chapter, Ayla has sex with someone, and repeat ad infinitum."