On 06/16/2012 12:01 AM, Vincent Torri wrote: > > > On Fri, 15 Jun 2012, Eric Blake wrote: > >> On 06/15/2012 04:55 PM, Vincent Torri wrote: > >>> AC_DEFUN([EFL_CHECK_COMPILER_FLAG], >>> [ >>> m4_pushdef([UPEFL], m4_translit([[$1]], [-a-z], [_A-Z])) >>> m4_pushdef([UP], m4_translit([[$2]], [-a-z], [_A-Z])) >>> >>> m4_if(m4_index([$2], [-Wno-]), [0], [m4_pushdef([flagm4], >>> [m4_bpatsubst([[$2]], [no-])])], [m4_pushdef([flagm4], [$2])]) >> >> option=m4_bpatsubst([[$2]], [no-]) > > Actually, i want to store in option -Wfoo if $2 is -Wno-foo, and only > that case. It's for testing if a compiler option is available (after > discussion with gcc guys, -Wno-foo use produces a warning while -Wfoo > use produces an error). So if I pass -fno-bar, option will store -fbar, > which is not what I want. So I guess that I have to use the m4_if > construction. But you can still be shorter than using a pushdef: option=m4_bpatsubst([[$2]], [^-Wno-], [-W]) Regular expression substitutions are quite powerful. -- Eric Blake eblake@xxxxxxxxxx +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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