Hi there, On Wed, 09 Dec 2015, 10:54:15 +0100, Willy TARREAU wrote: > On Wed, Dec 09, 2015 at 09:52:22AM +0000, David CARLIER wrote: > > Hi Willy, > > > > Not in my knowledge, I have not tested in any old OS version though > > just current Debian Stable and Alpine Linux (which uses musl's libc). > > That should be alright to backport it to 1.5 but not vital as such. > > OK then I'll keep it only in 1.7 for now (principle of least surprize) > and will backport it if people encounter issues on older versions and > ask for it.
FWIW, David's patch is completely right. __USE_* features shouldn't be defined manually, but should be inherited from their proper definition by #include'ing <features.h>, with glibc at least. It has always been my understanding, that _GNU_SOURCE_ should be defined to be able to use a variety of extensions including ISO Standard C, Extensions to ISO C89 from ISO C99, Extensions to ISO C99 from ISO C11, ... /usr/include/features.h says the following: /* These are defined by the user (or the compiler) to specify the desired environment: ... _GNU_SOURCE All of the above, plus GNU extensions. Further down it is described that there are lots of __USE_* defines, including __USE_GNU, which are all #undef'ined at the beginning of that file and then get defined based on the user-controllable defines like _GNU_SOURCE_ or _POSIX_SOURCE_. This means defining __USE_GNU on the command line may stop to work in a source file which somehow #include's features.h, because it decides to #undef __USE_GNU and later on not define it. Similar feature dependencies and rules also exist (at least existed for a long period) in AIX, HP-UX, and Solaris - don't remember if that file is still also called <features.h>, though. To cut a long story short, the __USE_* defines should not be used directly, but rather _GNU_SOURCE_ etc. instead. Detailed documentation can be found in the glibc info file in section "1.3.4 Feature Test Macros". > Thanks! > Willy HTH, cheers. l8er manfred
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