[PATCH v2] configure: Fix default -O2 being added when CFLAGS not set

[PATCH v2] configure: Fix default -O2 being added when CFLAGS not set

[Glenn Washburn]

Autoconf will set a default CFLAGS of "-g -O2" if CFLAGS is not set. CFLAGS
was defaulted to "" early in configure to prevent this. A recent commit
ad9ccf660013c208077b1e983d6c824df25ed1cf ("configure: Fix various new
autotools warnings") added AC_USE_SYSTEM_EXTENSIONS, which pulls in the
autoconf CFLAGS check, before we default CFLAGS and thus setting the
autoconf default for CFLAGS. Move the default setting of CFLAGS to before
AC_USE_SYSTEM_EXTENSIONS so that autoconf will see CFLAGS as set and not
give it a default.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Robbie Harwood <rharwood@redhat.com>
Tested-by: Paul Menzel <pmenzel@molgen.mpg.de>
---
 configure.ac | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/configure.ac b/configure.ac
index 3ffbc7c57b..c1e50c9d75 100644
--- a/configure.ac
+++ b/configure.ac
@@ -36,12 +36,12 @@ dnl description of the relationships between them.
 
 AC_INIT([GRUB],[2.11],[bug-grub@gnu.org])
 
-AC_USE_SYSTEM_EXTENSIONS
-AC_CONFIG_AUX_DIR([build-aux])
-
 # We don't want -g -O2 by default in CFLAGS
 : ${CFLAGS=""}
 
+AC_USE_SYSTEM_EXTENSIONS
+AC_CONFIG_AUX_DIR([build-aux])
+
 # Checks for build, host and target systems.
 AC_CANONICAL_BUILD
 AC_CANONICAL_HOST
-- 
2.27.0

Re: [PATCH v2] configure: Fix default -O2 being added when CFLAGS not set

[Daniel Kiper]

On Mon, Mar 28, 2022 at 12:56:22PM -0500, Glenn Washburn wrote:
> Autoconf will set a default CFLAGS of "-g -O2" if CFLAGS is not set. CFLAGS
> was defaulted to "" early in configure to prevent this. A recent commit
> ad9ccf660013c208077b1e983d6c824df25ed1cf ("configure: Fix various new
> autotools warnings") added AC_USE_SYSTEM_EXTENSIONS, which pulls in the
> autoconf CFLAGS check, before we default CFLAGS and thus setting the
> autoconf default for CFLAGS. Move the default setting of CFLAGS to before
> AC_USE_SYSTEM_EXTENSIONS so that autoconf will see CFLAGS as set and not
> give it a default.
>
> Signed-off-by: Glenn Washburn <development@efficientek.com>
> Reviewed-by: Robbie Harwood <rharwood@redhat.com>
> Tested-by: Paul Menzel <pmenzel@molgen.mpg.de>
> ---
>  configure.ac | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/configure.ac b/configure.ac
> index 3ffbc7c57b..c1e50c9d75 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -36,12 +36,12 @@ dnl description of the relationships between them.
>
>  AC_INIT([GRUB],[2.11],[bug-grub@gnu.org])
>
> -AC_USE_SYSTEM_EXTENSIONS
> -AC_CONFIG_AUX_DIR([build-aux])
> -
>  # We don't want -g -O2 by default in CFLAGS
>  : ${CFLAGS=""}
>
> +AC_USE_SYSTEM_EXTENSIONS
> +AC_CONFIG_AUX_DIR([build-aux])

I am OK with this change but I think AC_CONFIG_AUX_DIR macro move also
requires at least one sentence explanation in the commit message.

Daniel