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CHECK_GNU_MAKE()
1.2 (2003/02/02) 0.5.57 : Installed_Packages
John Darrington <j.darrington@elvis.murdoch.edu.au>
This macro searches for a GNU version of make. If a match is found, the makefile variable `ifGNUmake' is set to the empty string, otherwise it is set to "#". This is useful for including a special features in a Makefile, which cannot be handled by other versions of make. The variable _cv_gnu_make_command is set to the command to invoke GNU make if it exists, the empty string otherwise.
Here is an example of its use:
Makefile.in might contain:
# A failsafe way of putting a dependency rule into a makefile
$(DEPEND):
$(CC) -MM $(srcdir)/*.c > $(DEPEND)
@ifGNUmake@ ifeq ($(DEPEND),$(wildcard $(DEPEND)))
@ifGNUmake@ include $(DEPEND)
@ifGNUmake@ endif
Then configure.in would normally contain:
CHECK_GNU_MAKE()
AC_OUTPUT(Makefile)
Then perhaps to cause gnu make to override any other make, we could do something like this (note that GNU make always looks for GNUmakefile first):
if ! test x$_cv_gnu_make_command = x ; then
mv Makefile GNUmakefile
echo .DEFAULT: > Makefile ;
echo \ $_cv_gnu_make_command \$@ >> Makefile;
fi
Then, if any (well almost any) other make is called, and GNU make also exists, then the other make wraps the GNU make.
AC_DEFUN(
[CHECK_GNU_MAKE], [ AC_CACHE_CHECK( for GNU make,_cv_gnu_make_command,
_cv_gnu_make_command='' ;
dnl Search all the common names for GNU make
for a in "$MAKE" make gmake gnumake ; do
if test -z "$a" ; then continue ; fi ;
if ( sh -c "$a --version" 2> /dev/null | grep GNU 2>&1 > /dev/null ) ; then
_cv_gnu_make_command=$a ;
break;
fi
done ;
) ;
dnl If there was a GNU version, then set @ifGNUmake@ to the empty string, '#' otherwise
if test "x$_cv_gnu_make_command" != "x" ; then
ifGNUmake='' ;
else
ifGNUmake='#' ;
AC_MSG_RESULT("Not found");
fi
AC_SUBST(ifGNUmake)
] )