[FFmpeg-devel] [PATCHv2] configure: add -D_DEFAULT_SOURCE to silence -Wcpp

[Ganesh Ajjanagadde]

On Thu, Sep 17, 2015 at 6:45 AM, Ganesh Ajjanagadde <gajjanag at mit.edu> wrote:
> On Thu, Sep 17, 2015 at 4:54 AM, Clément Bœsch <u at pkh.me> wrote:
>> On Wed, Sep 16, 2015 at 06:55:39PM -0400, Ganesh Ajjanagadde wrote:
>>> Glibc 2.20 onwards generates a deprecation warning for usage of _BSD_SOURCE and _SVID_SOURCE.
>>> The solution from man feature_test_macros is to define both _DEFAULT_SOURCE and the old macros.
>>> This change is done in configure while testing for Glibc. Doing it in source code
>>> would require __UCLIBC__ checks, etc since uclibc also defines __GLIBC__ and __GLIBC_MINOR__,
>>> so placing it in configure avoids the repeated checks.
>>>
>>> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
>>> ---
>>>  configure                | 6 ++++++
>>>  libavformat/os_support.c | 1 -
>>>  2 files changed, 6 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/configure b/configure
>>> index cd6f629..0cd0a6c 100755
>>> --- a/configure
>>> +++ b/configure
>>> @@ -4520,6 +4520,12 @@ probe_libc(){
>>>      elif check_${pfx}cpp_condition features.h "defined __GLIBC__"; then
>>>          eval ${pfx}libc_type=glibc
>>>          add_${pfx}cppflags -D_POSIX_C_SOURCE=200112 -D_XOPEN_SOURCE=600
>>> +        # define _DEFAULT_SOURCE for glibc 2.20 onwards to silence deprecation
>>> +        # warnings for _BSD_SOURCE and _SVID_SOURCE.
>>> +        if check_${pfx}cpp_condition features.h "(__GLIBC__ == 2 && __GLIBC_MINOR__ >= 20) \
>>> +            || (__GLIBC__ > 2)"; then
>>> +            add_${pfx}cppflags -D_DEFAULT_SOURCE
>>> +        fi
>>
>> Is this adding _DEFAULT_SOURCE to every compiled file while it was scope
>> to a standalone source file before?
>
> Don't know exactly what you mean, but try e.g strings on any of these
> objects. There is no "DEFAULT_SOURCE", "BSD_SOURCE", or any such thing
> suggesting they are optimized out. Furthermore, a du on the libav*
> does not reveal any increase in size.

ping

>
>>
>>>      # MinGW headers can be installed on Cygwin, so check for newlib first.
>>>      elif check_${pfx}cpp_condition newlib.h "defined _NEWLIB_VERSION"; then
>>>          eval ${pfx}libc_type=newlib
>>> diff --git a/libavformat/os_support.c b/libavformat/os_support.c
>>> index 7950e44..3c22631 100644
>>> --- a/libavformat/os_support.c
>>> +++ b/libavformat/os_support.c
>>> @@ -21,7 +21,6 @@
>>>   */
>>>
>>>  /* needed by inet_aton() */
>>> -#define _DEFAULT_SOURCE
>>>  #define _SVID_SOURCE
>>>
>>>  #include "config.h"
>>
>> --
>> Clément B.
>>
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>>