[vlc-devel] [PATCH] configure: fix compiler warning when using --enable-debug with --disable-optimizations

[Steve Lhomme]

On Mon, Feb 29, 2016 at 6:42 PM, Rémi Denis-Courmont <remi at remlab.net> wrote:
> Le 2016-02-29 12:51, Steve Lhomme a écrit :
>>
>> On Fri, Feb 26, 2016 at 7:19 PM, Rémi Denis-Courmont <remi at remlab.net>
>> wrote:
>>>
>>> Le 2016-02-26 10:29, Steve Lhomme a écrit :
>>>>
>>>>
>>>> ---
>>>>  configure.ac | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/configure.ac b/configure.ac
>>>> index cd7ccbb..0624952 100644
>>>> --- a/configure.ac
>>>> +++ b/configure.ac
>>>> @@ -1016,7 +1016,7 @@ AS_IF([test "${enable_optimizations}" != "no"], [
>>>>    ])
>>>>    AS_IF([test "${ac_cv_c_fast_math}" = "no"], [VLC_RESTORE_FLAGS])
>>>>    AH_BOTTOM([
>>>> -#ifndef __FAST_MATH__
>>>> +#if !defined(__FAST_MATH__) && defined(NDEBUG)
>>>>  # ifndef _MSC_VER
>>>>  #  pragma STDC FENV_ACCESS OFF
>>>>  #  pragma STDC FP_CONTRACT ON
>>>
>>>
>>>
>>> Why?
>>
>>
>> To avoid this kind of warning on every line (gcc 5.3.0 on mingw):
>
>
> I fail to see the link with the patch.

--disable-optimizations does not check if the compiler supports
-ffast-math and so __FAST_MATH__ is not defined

But the code in AH_BOTTOM is added to config.h (via config.h.in) no
matter what. It is processed even if you disabled optimizations. So
even if you use gcc, --fast-math is not set and we fall into this
code.
It seems gcc (4.9.3 and 5.3.0 on mingw) don't define the pragmas.

--enable-debug defines NDEBUG and would at least avoid this warning.
Otherwise we can disable these pragmas (and the MSVC ones) for GCC.

>
> --
> Rémi Denis-Courmont
> http://www.remlab.net/
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