Re: [PATCH, libgo]: Fix build warning

[Uros Bizjak <ubizjak at gmail dot com>]

On Wed, Dec 17, 2014 at 10:54 AM, Uros Bizjak <ubizjak@gmail.com> wrote:
> On Tue, Dec 16, 2014 at 8:58 PM, Uros Bizjak <ubizjak@gmail.com> wrote:
>
>>>> When building libgo on CentOS 5.11, following warnings appear:
>>>>
>>>> In file included from /usr/include/fcntl.h:38:0,
>>>>                  from sysinfo.c:6:
>>>> /home/uros/gcc-build/gcc/include-fixed/sys/stat.h:317:16: warning:
>>>> inline function âlstat64â declared but never defined
>>>>  __inline__ int lstat64 (__const char *__restrict __file,
>>>>                 ^
>>>> /home/uros/gcc-build/gcc/include-fixed/sys/stat.h:286:16: warning:
>>>> inline function âfstatat64â declared but never defined
>>>>  __inline__ int fstatat64 (int __fd, __const char *__restrict __file,
>>>>                 ^
>>>> /home/uros/gcc-build/gcc/include-fixed/sys/stat.h:255:16: warning:
>>>> inline function âfstat64â declared but never defined
>>>>  __inline__ int fstat64 (int __fd, struct stat64 *__buf) __THROW
>>>> __nonnull ((2));
>>>>                 ^
>>>> /home/uros/gcc-build/gcc/include-fixed/sys/stat.h:250:16: warning:
>>>> inline function âstat64â declared but never defined
>>>>  __inline__ int stat64 (__const char *__restrict __file,
>>>>                 ^
>>>> These are emitted from:
>>>>
>>>> CC="/home/uros/gcc-build/./gcc/xgcc -B/home/uros/gcc-build/./gcc/
>>>> -B/usr/local/x86_64-unknown-linux-gnu/bin/
>>>> -B/usr/local/x86_64-unknown-linux-gnu/lib/ -isystem /usr/
>>>> local/x86_64-unknown-linux-gnu/include -isystem
>>>> /usr/local/x86_64-unknown-linux-gnu/sys-include    -DHAVE_CONFIG_H -I.
>>>> -I../../../gcc-svn/trunk/libgo  -I ../../../gcc-svn/trunk/libgo/run
>>>> time -I../../../gcc-svn/trunk/libgo/../libffi/include
>>>> -I../libffi/include -pthread  -D_GNU_SOURCE -D_LARGEFILE_SOURCE
>>>> -D_FILE_OFFSET_BITS=64" /bin/sh ../../../gcc-svn/trunk/libgo/mksysin
>>>> fo.sh
>>>>
>>>> due to the sys/stat.h, which protects above functions with:
>>>>
>>>> # if defined __USE_LARGEFILE64 \
>>>>   && (! defined __USE_FILE_OFFSET64 \
>>>>       || (defined __REDIRECT_NTH && defined __OPTIMIZE__))
>>>>
>>>> Adding -O to OSCFLAGS fixes this issue, as __OPTIMIZE__ is defined with -O.
>>>>
>>>> Patch was bootstrapped and regression tested on x86_64-linux-gnu
>>>> (CentOS 5.11), where it removes the above warnings.
>>>>
>>>> OK for mainline?
>>>
>>>
>>> This seems a bit dubious, as it seems that the same problem would
>>> occur for any C program that #include's <sys/stat.h> and is compiled
>>> without optimization.
>>
>> Please note that the above command also defines __USE_FILE_OFFSET64,
>> but indeed, I don't see these warnings on Fedora 20.
>>
>>> I don't mind passing -O when running mksysinfo.sh, but your patch will
>>> pass -O to all the C file compilations.  That doesn't seem like a good
>>> idea--some people might want to debug that code.  Can you try either
>>> only addding -O for CentOS, or addding it only to mksysinfo.sh?
>>
>> You are right, the proposed change was too broad. I am testing following patch:
>
> The (now attached, to avoid mailer mangling) patch also fixes
> mentioned build warnings.
>
> Bootstrapped and regression tested on CentOS 5.11.

As an alternative, we can change mksysinfo.sh directly:

--cut here--
Index: mksysinfo.sh
===================================================================
--- mksysinfo.sh        (revision 218813)
+++ mksysinfo.sh        (working copy)
@@ -204,7 +204,7 @@
 };
 EOF

-${CC} -fdump-go-spec=gen-sysinfo.go -std=gnu99 -S -o sysinfo.s sysinfo.c
+${CC} -O -fdump-go-spec=gen-sysinfo.go -std=gnu99 -S -o sysinfo.s sysinfo.c

 echo 'package syscall' > ${OUT}
 echo 'import "unsafe"' >> ${OUT}
--cut here--

Also bootstrapped and regression tested on x86_64-linux-gnu, CentOS 5.11.

Uros.