Re: Avoid certain spurious `testsuite' rebuilds

[Noah Misch]

On Wed, Apr 05, 2006 at 04:26:22PM -0700, Paul Eggert wrote:
> Noah Misch <address@hidden> writes:
> 
> > With this patch, mktests.sh runs for each edit in lib/autoconf/*.m4
> > but only touches output files that have changed.  This eliminates
> > the spurious rebuilds.
> 
> I've written my fair share of patches that do something similar, for
> other programs, and have often lived to regret it.  I'd rather avoid
> this sort of "file X is actually a time stamp for file Y" business
> unless the efficiency issue really is a major one.

I do agree with that general sentiment.

Currently, we end up rebuilding `testsuite' whenever it it becomes out of date
with respect to any of lib/autoconf/*.m4.  Whenever one of those files changes,
we rebuild all of tests/ac*.at, and then rebuild `testsuite' itself.  Most
changes to the m4 sources change the generated test cases, so most of these
rebuilds aren't necessary.  On my middle-aged PC running GNU/Linux, rebuilding
`testsuite' takes 22 seconds.

To me, saving that 22 second delay before I can run a test case after editing
Autoconf sources is worth this amount of Makefile pain.  What do you think?