Re: [PATCH] build: speed up configure for releases

[Jim Meyering]

Eric Blake wrote:
> At this point, we're pretty good about picking up gnulib dependencies
> without having to be warned about them.  The time spent in configure
> to check for declarations is pretty expensive, and really only needs
> to be done by a maintainer every once in a while, rather than by
> every downstream client on every configure run.
>
> * configure.ac (gl_ASSERT_NO_GNULIB_POSIXCHECK): Comment out,
> with a note why.
> ---
>
> I've been camping on this one for a long time; I guess it would be
> even more impressive if I compared benchmark numbers of the timing
> difference between using this patch and omitting it.

I too have considered that.
I could go either way, but would need the nudge of actual numbers.

Since I rarely configure without using a cache, I suspect
that the speed difference will be negligible for me.

On the other hand, for most people, even a speed-up of just
a few seconds would probably be welcome.

How about a compromise: leave the code there, but guard it with
some new envvar setting that is normally off.
Then add something to my-distcheck so that for at least one
./configure run it is enabled.  That will preserve the safety net
*and* save most people the cost of those added tests.