Re: [Buildroot] [PATCH 1/1] package/bird: fix build with autoconf >= 2.70

[Thomas Petazzoni <thomas.petazzoni@bootlin.com>]

Hello Fabrice,

On Fri,  5 Nov 2021 21:12:57 +0100
Fabrice Fontaine <fontaine.fabrice@gmail.com> wrote:

> +++ b/package/bird/0001-configure.ac-fix-build-with-autoconf-2.70.patch
> @@ -0,0 +1,43 @@
> +From aa5bc6d2e59c5257d777a45ee4a0e0a784c44244 Mon Sep 17 00:00:00 2001
> +From: Fabrice Fontaine <fontaine.fabrice@gmail.com>
> +Date: Fri, 5 Nov 2021 20:58:41 +0100
> +Subject: [PATCH] configure.ac: fix build with autoconf >= 2.70
> +
> +On some embedded toolchains, glob.h detection fails because -g is
> +wrongly added (even when CFLAGS is overwritten):

I fail to understand why adding -g would cause that build failure.
There is already -g0 in the command line, then -g, which enables
debugging symbols, this shouldn't cause any build failure.

Perhaps the issue is more related to the addition of -flto=4, which
enables link-time optimization?

But even then, I don't quite understand this ac_test_CFLAGS stuff. Do
you understand why their configure.ac script is doing:

# Store this value because ac_test_CFLAGS is overwritten by AC_PROG_CC
if test "$ac_test_CFLAGS" != set ; then
  bird_cflags_default=yes
fi

in the first place?

Could you help me connect the dots here ?

Thanks!

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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