Re: xfsprogs compile warnings: _BSD_SOURCE is deprecated in glibc 2.20.

[Dave Chinner <david@fromorbit.com>]

On Tue, Apr 28, 2015 at 01:09:04PM +0200, Jan Ťulák wrote:
> In glibc 2.20, _BSD_SOURCE and _SVID_SOURCE were deprecated and should be
> replaced with _DEFAULT_SOURCE. Currently, compiling xfsprogs on a system with
> glibc in said or newer version (like current Fedora) produces tons of warnings
> like this one:
> 
> In file included from /usr/include/stdio.h:27:0,
>                   from ../include/xfs/platform_defs.h:24,
>                  from ../include/xfs/libxfs.h:25,
>                  from xfs_mkfs.c:19:
> /usr/include/features.h:148:3: warning: #warning "_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE" [-Wcpp]
>  # warning "_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE"
> 
> It can be fixed with the single line patch bellow, but I'm not sure if we can
> remove the deprecated version because of compatiblity. Glibc 2.19, which added
> _DEFAULT_SOURCE, was released in 2014, and I'm not sure how much it is
> backported and how much xfsprogs are backported too. So, do we need a better
> patch to take care of this and provide differend _SOURCE based on glibc
> version, or this patch is enough?
> 
> Source: man 7 feature_test_macros
> Here is a link in case you older version:
> http://man7.org/linux/man-pages/man7/feature_test_macros.7.html

/me smacks head against wall

Really? glibc has decided to break the build of half the world?

> Signed-off-by: Jan Ťulák <jtulak@redhat.com>
> ---
>  include/builddefs.in | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/builddefs.in b/include/builddefs.in
> index 944bcf6..6e6097a 100644
> --- a/include/builddefs.in
> +++ b/include/builddefs.in
> @@ -109,7 +109,7 @@ GCCFLAGS = -funsigned-char -fno-strict-aliasing -Wall
>  #	   -Wbitwise -Wno-transparent-union -Wno-old-initializer -Wno-decl
>  
>  ifeq ($(PKG_PLATFORM),linux)
> -PCFLAGS = -D_GNU_SOURCE -D_BSD_SOURCE -D_XOPEN_SOURCE=500 -D_FILE_OFFSET_BITS=64 $(GCCFLAGS)
> +PCFLAGS = -D_GNU_SOURCE -D_DEFAULT_SOURCE -D_XOPEN_SOURCE=500 -D_FILE_OFFSET_BITS=64 $(GCCFLAGS)

Quoting that man page:

"
_GNU_SOURCE
[...]
	Since glibc 2.19, defining _GNU_SOURCE also has the effect
	of implicitly defining _DEFAULT_SOURCE.  In glibc versions
	before 2.20, defining _GNU_SOURCE also had the effect of
	implicitly defining _BSD_SOURCE and _SVID_SOURCE.
"

IOWs, glibc is just being an obnoxious. I'd just drop the
-D_BSD_SOURCE altogether, as _GNU_SOURCE should pull in everything
we need. And looking at it further, it also defines _XOPEN_SOURCE to
>= 500, so that could probably be dropped, too.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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