On 12/14/2012 08:08 AM, Viktor Mihajlovski wrote: > Some older versions of GCC report a false positive on code like > char * haystack, needle; > strchr(haystack, needle); > > Added an extra check in configure.ac which will > #define BROKEN_GCC_WLOGICALOP 1 > in this case, allowing to special handle "offending" code. > > Signed-off-by: Viktor Mihajlovski <mihaj...@linux.vnet.ibm.com> > --- > configure.ac | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+)
I know this is already pushed, but I think it would fit better under m4/virt-compile-warnings.m4 rather than at the top-level configure.ac. > + > +if test "x$gcc_false_strchr_warning" = xyes; then > + AC_DEFINE_UNQUOTED([BROKEN_GCC_WLOGICALOP], 1, > + [GCC -Wlogical-op is reporting false positive on strchr]) > +fi Potential ouch. This sets BROKEN_GCC_WLOGICALOP to 1 on all non-gcc compilers. Then in patch 2/3, you blindly use this condition to request a pragma: +/* + we need to ignore warnings about strchr caused by -Wlogical-op + for some GCC versions. + Doing it via a local pragma keeps the damage smaller than + disabling it on the package level. + Unfortunately, the affected GCCs don't allow diagnostic push/pop + which would have further reduced the impact. + */ +# if BROKEN_GCC_WLOGICALOP +# pragma GCC diagnostic ignored "-Wlogical-op" +# endif We are not guaranteed that other compilers behave nicely when presented with unknown #pragma GCC. So far, our use of such pragmas has been guarded by knowing that we are using gcc; so I'd feel better if the configure-time check for setting this flag were limited to just gcc in the first place (which it would be easier to do by moving this test to m4/virt-compile-warnings.m4). -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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