Re: configure speedup proposal: add --assume-c99 and --assume-posix2008 flags

[Paul Eggert]

Rhys Ulerich wrote:
> I only find the configure process to be frustratingly slow when run
> against compilers with license keys or with checks accessing network
> storage.

That's not my experience at all.  Take the bleeding-edge version of GNU 
grep, say, which I just now happened to be working on.  On my platform 
(RHEL 6.5 x86-64, GCC 4.9.0, dual Xeon E5620), 'configure' takes 32 
seconds real-time, whereas 'make -j8' takes 3 seconds.

No doubt there are environments where compilation is slow and 
'configure' is not the bottleneck, but these days it's veerrry common 
for 'configure' to be an unreasonably large part of the build process, 
and where parallelizing would help.