[FFmpeg-devel] [PATCH 1/1] configure: Refactor setting of feature test macro _XOPEN_SOURCE

[Michael Niedermayer]

On Thu, Sep 18, 2014 at 09:51:19AM +0200, Jörg Krause wrote:
> glibc, uclibc, and musl uses feature test macros to expose definitions 
> conforming to the standards ISO C, POSIX and extensions. According to
> which feature test macros are defined by the user or the compiler, 
> the header file <features.h> used by these libraries internally defines
> various other macros.
> 
> glibc and uclibc also defines release test macros, eg __GLIBC__ and
> __UCLIBC__ in <features.h>. musl does not have (and do not want) such 
> a macro like __MUSL__. 
> 
> Building ffmpeg with the musl toolchain needs the feature test macro
> _XOPEN_SOURCE=600 to be defined. As it is not possible to detect musl  
> check for the <features.h> header file, which is assumed to be specific 
> to glibc, uclibc, and musl.  
> 
> Signed-off-by: Jörg Krause <jkrause at posteo.de>
> ---
>  configure | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/configure b/configure
> index 110a3fd..528e4fc 100755
> --- a/configure
> +++ b/configure
> @@ -4182,6 +4182,11 @@ esac
>  probe_libc(){
>      pfx=$1
>      pfx_no_=${pfx%_}
> +    # feature test macros are understood by glibc, uclibc, and musl
> +    if check_header features.h; then
> +        # _XOPEN_SOURCE=600 implicitly defines _POSIX_C_SOURCE=200112L
> +        add_${pfx}cppflags -D_XOPEN_SOURCE=600
> +    fi

this adds "-D_XOPEN_SOURCE=600" twice to the flags for glibc

adding this as an elif entry at the end should avoid that

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In a rich man's house there is no place to spit but his face.
-- Diogenes of Sinope
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