[FFmpeg-devel] [PATCH] Update configure file to fix a build failure with gcc-11 on Ubuntu 21.10

[Martin Storsjö]

On Sat, 18 Sep 2021, Timo Rothenpieler wrote:

> On 18.09.2021 15:48, Gianfranco Costamagna wrote:
>> Hello Timo
>> 
>> Il giorno sab 18 set 2021 alle ore 13:15 Timo Rothenpieler <
>> timo at rothenpieler.org> ha scritto:
>> 
>>> On 18.09.2021 11:06, Gianfranco Costamagna wrote:
>>>> New gcc changed the way it exposes armhf build flags.
>>>> "the architecture now has to include the cpu features, see the man page,
>>> arM options"
>>>> 
>>>> example of build failure:
>>>> 
>>> https://launchpad.net/ubuntu/+source/ffmpeg/7:4.4-6ubuntu1/+build/22070856
>>>> 
>>>> Note: this syntax was introduced in GCC 8
>>> https://gcc.gnu.org/gcc-8/changes.html
>>>> ---
>>>>    configure | 2 +-
>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>> 
>>>> diff --git a/configure b/configure
>>>> index 7ac23123c7..571b70208c 100755
>>>> --- a/configure
>>>> +++ b/configure
>>>> @@ -5000,7 +5000,7 @@ elif enabled arm; then
>>>>            elif check_arm_arch 6ZK;      then echo armv6zk
>>>>            elif check_arm_arch 6T2;      then echo armv6t2
>>>>            elif check_arm_arch 7;        then echo armv7
>>>> -        elif check_arm_arch 7A  7_A;  then echo armv7-a
>>>> +        elif check_arm_arch 7A  7_A;  then echo armv7-a+fp
>>>>            elif check_arm_arch 7S;       then echo armv7-a
>>>>            elif check_arm_arch 7R  7_R;  then echo armv7-r
>>>>            elif check_arm_arch 7M  7_M;  then echo armv7-m
>>>> 
>>> 
>>> Does this still work with older gccs, or will those be broken after this?
>>> 
>> 
>> I checked gcc-10 and it works too.
>> The new naming has been introduced in gcc-8, so there should be no issues
>> even for backporting the package to old systems.
>> 
>> What is the oldest supported compiler for ffmpeg?
>
> At least all the way back to gcc-4, and some other exotic non-gcc compilers.
> Though I'm not sure what the minimum with armv7 support is, or when gcc 
> introduced it.
>
> If it break some older compiler that's used on some stable branch of some 
> distro, that'd be an issue.

+1, if this new syntax was introduced with GCC 8, I guess this would break 
building with GCC 7, and that's a rather new version to break IMO.

I'll try to reproduce this and look into it.

// Martin