On Thu, Mar 19, 2026, at 10:41 AM, Akim Demaille wrote: >> Le 19 mars 2026 à 15:36, Paul Eggert <[email protected]> a écrit : >> On 2026-03-18 22:01, Nick Bowler wrote: >>> On Wed, Mar 18, 2026 at 12:57:53PM -0400, Zack Weinberg wrote: >>>> Do you happen to remember why we concatenate confdefs.h and the >>>> test program >>> A long time ago C compilations did use #include "confdefs.h" but it >>> was changed to resemble the current method in version 2.55 (2002). >>> No explicit rationale is given but it was probably done this way to >>> improve the logging around compilation failures. >> >> Thanks, then let's ask Akim. > Wow... That's not recent :) > > I believe the answer is in > https://lists.gnu.org/archive/html/autoconf-patches/2002-10/msg00072.html.
So, in short, yes, this was done so that "failed program" dumps in config.log would be more informative. I don't think it makes sense to change anything without a bunch more benchmarking, and certainly not for 2.73, but if we do conclude that going back to #include "confdefs.h" would make sense, we could retain the improved logging by dumping out _both_ confdefs.h and the test program when a compilation fails. zw
