Re: [PATCH 2/7] builddefs: define linux

["Darrick J. Wong" <djwong@kernel.org>]

On Thu, Feb 06, 2025 at 07:09:21PM -0600, Eric Sandeen wrote:
> On 2/6/25 4:39 PM, Darrick J. Wong wrote:
> > On Thu, Feb 06, 2025 at 03:19:57PM -0600, Eric Sandeen wrote:
> >> There are several #ifdef linux guards in the code, but nothing
> >> defined it. This caused several sparse warnings, so define it
> >> when building on linux.
> > 
> > cpp in gcc 12.2 defines this:
> > 
> > $ touch /tmp/moo.h ; cpp -dM /tmp/moo.h | grep define.linux
> > #define linux 1
> 
> Huh, on my test box too.
> And yet without this sparse coughs up lots of things for me:
> 
> tlibio.c:90:20: error: undefined identifier 'LIO_IO_TYPES'
> tlibio.c:90:33: error: undefined identifier 'LIO_WAIT_TYPES'
> tlibio.c:92:20: error: undefined identifier 'LIO_IO_TYPES'
> tlibio.c:92:33: error: undefined identifier 'LIO_WAIT_TYPES'
> tlibio.c:118:20: error: undefined identifier 'LIO_IO_TYPES'
> tlibio.c:118:33: error: undefined identifier 'LIO_WAIT_TYPES'
> 
> because i.e.:
> 
> #ifdef linux
> #define LIO_IO_TYPES            00021   /* all io types */
> #endif /* linux */
> 
> make V=1 shows:
> 
> /bin/sh ../libtool --quiet --tag=CC --mode=compile gcc -g -O2 -g -O2 -DDEBUG  -I../include -DVERSION=\"1.1.1\" -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -funsigned-char -fno-strict-aliasing -Wall   -c tlibio.c
> 
> so not sure what's going on here ?

sparse doesn't define linux by default:

$ cat > /tmp/a.c << ENDL
#ifdef linux
# warning not
#else
# warning me
#endif
ENDL
$ gcc -o /tmp/a.o /tmp/a.c
/tmp/a.c:2:3: warning: #warning not [-Wcpp]
    2 | # warning not
      |   ^~~~~~~
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/12/../../../x86_64-linux-gnu/Scrt1.o: in function `_start':
(.text+0x17): undefined reference to `main'
collect2: error: ld returned 1 exit status
$ sparse /tmp/a.c
/tmp/a.c:4:3: warning: me
$ sparse /tmp/a.c -Dlinux
/tmp/a.c:2:3: warning: not

--D

> 
> > --D
> > 
> >> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> >> ---
> >>  include/builddefs.in | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/include/builddefs.in b/include/builddefs.in
> >> index 7274cde8..00dec0ea 100644
> >> --- a/include/builddefs.in
> >> +++ b/include/builddefs.in
> >> @@ -78,7 +78,7 @@ HAVE_FICLONE = @have_ficlone@
> >>  GCCFLAGS = -funsigned-char -fno-strict-aliasing -Wall
> >>  
> >>  ifeq ($(PKG_PLATFORM),linux)
> >> -PCFLAGS = -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 $(GCCFLAGS)
> >> +PCFLAGS = -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -Dlinux $(GCCFLAGS)
> >>  endif
> >>  ifeq ($(PKG_PLATFORM),darwin)
> >>  PCFLAGS = -traditional-cpp $(GCCFLAGS)
> >> -- 
> >> 2.48.0
> >>
> >>
> > 
>