Re: [Xen-devel] [xen-4.0-testing test] 7147: regressions - FAIL

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Ian Campbell writes ("Re: [Xen-devel] [xen-4.0-testing test] 7147: regressions 
- FAIL"):
> It seems like gcc (at least in Debian Squeeze) does some sort of lazy
> evaluation of -W options, which seems terribly unlikely but does seem to
> be reality. Try compiling the following always with
> -Wno-unused-but-set-variable but with and without -DHACK to see what I
> mean:
> 
> $ gcc -Wno-unused-but-set-variable -DHACK ~/t.c
> /home/ianc/t.c: In function 'main':
> /home/ianc/t.c:6: warning: initialization makes pointer from integer without 
> a cast
> At top level:
> cc1: warning: unrecognized command line option "-Wno-unused-but-set-variable"
> $ gcc -Wno-unused-but-set-variable ~/t.c
> $ cat ~/t.c

This is related to my efforts to try to make new warnings easier to
cope with in future.  Note that the "unrecognised -W option" message
is itself only a warning in squeeze (which is correct), but apparently
in lenny it is an error:

mariner:~/junk> gcc -Wno-unused-but-set-variable -DHACK t.c
t.c: In function 'main':
t.c:7: warning: initialization makes pointer from integer without a cast
At top level:
cc1: error: unrecognized command line option "-Wno-unused-but-set-variable"
mariner:~/junk> gcc -Wno-unused-but-set-variable t.c
mariner:~/junk>

That makes it harder, rather than easier, to figure out what's going
on and write correct Makefiles.

Ian.

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