GNU bug report logs - #79648
configure.ac sets user-defined CFLAGS

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Nikolaos Chatzikonstantinou <nchatz314 <at> gmail.com>
To: bug-guile <at> gnu.org
Subject: configure.ac sets user-defined CFLAGS
Date: Sat, 18 Oct 2025 05:07:44 -0400

Hello list,

The CFLAGS variable should not be set in configure.ac. Of course, it
is fine to temporarily set it to a different value to test
compilation, but it should not set "defaults" in CFLAGS, since that
overrides whatever the user sets in the environment.

For example, I compiled with CFLAGS='-O0 g3' to debug a (different)
bug in Guile with gdb, and I did not have any access to macros. After
a lot of head scratching I resorted to asking for help and
https://sourceware.org/bugzilla/show_bug.cgi?id=32381 was pointed out
to me. In short, Guile injected -flto which enables LTO and gdb cannot
trace line numbers correctly.

Instead, configure.ac should be setting defaults in AM_CFLAGS. I will
send a patch moving -flto and -Werror=array-bounds from CFLAGS to
AM_CFLAGS.

Regards,
Nikolaos Chatzikonstantinou

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