Re: mktime.m4 - working mktime fails if TIME_T_IS_SIGNED us undefined.

[Paul Eggert]

On 09/22/2017 02:42 AM, Bruno Haible wrote:
> When we make changes to time_t related
> code, how to verify that it works with an unsigned time_t type?

The way I do it in tzdb 
<https://www.iana.org/time-zones/repository/tzdb-latest.tar.lz> is to 
replace the system time_t and its related low-level functions. It's a 
pain, and it does the job, and it's hard to explain. I vaguely recall 
trying simpler tricks something like what you describe, but don't 
remember why I abandoned that; perhaps I was trying for something that 
would work outside glibc.