On 09/18/2014 07:10 PM, Reimar Döffinger wrote:
On 18.09.2014, at 17:26, Michael Niedermayer <michae...@gmx.at> wrote:
On Thu, Sep 18, 2014 at 04:22:27PM +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 <jkra...@posteo.de>
---
Changes v1 -> v2:
- do not set _XOPEN_SOURCE twice for glibc and uclibc
why do you not add the musl check at the end of the if/elif chain as
suggested ?
does that have some issue or problem ?
now your patch removes POSIX_C_SOURCE=200112 for glibc & uclibc
maybe thats ok, maybe its not but it certainly doesnt belong in a
patch that adds musl support
If you think this change is desireable, please submit a seperate
patch
May I suggest to change configure to always add these (POSIX_C_SOURCE and
_XOPEN_SOURCE) and we just remove them specifically for cases that cause issues?
And this time _document_ why we even have these hacks.
Because as it it's impossible to know if all those special case are there for a
reason or if they only exist because it's fun and nicely obfuscates configure.
I would suggest two possibilities:
a) Define POSIX_C_SOURCE and _XOPEN_SOURCE at the beginning of
probe_libc as default setting for all the libs:
probe_libc(){
[..]
add_${pfx}cppflags -D_POSIX_C_SOURCE=200112L -D_XOPEN_SOURCE=600
if uclibc ...
elif glibc ...
b) Define it at the end after all the specific lib handlers:
elif solaris
else
add_${pfx}cppflags -D_POSIX_C_SOURCE=200112L -D_XOPEN_SOURCE=600
fi
What's your opinion?
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