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 makefile variable `ifnGNUmake' is set to #, otherwise it is set to the empty string. This is useful for including a special features in a Makefile, which can be handled by other versions of make or to specify else like clause. * The variable `_cv_gnu_make_command` is set to the command to invoke GNU make if it exists, the empty string otherwise. * The variable `ax_cv_gnu_make_command` is set to the command to invoke GNU make by copying `_cv_gnu_make_command`, otherwise it is unset. * If GNU Make is found, its version is extracted from the output of `make --version` as the last field of a record of space-separated columns and saved into the variable `ax_check_gnu_make_version`. * Additionally if GNU Make is found, run shell code run-if-true else run shell code run-if-false.
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 $(DEPEND) @ifGNUmake@ else fallback code @ifGNUmake@ endif
Then configure.in would normally contain:
Then perhaps to cause gnu make to override any other make, we could do something like this (note that GNU make always looks for GNUmakefile first):
if ! test x$_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.
Download the latest version of ax_check_gnu_make.m4 or browse the macro’s revision history.
Copyright © 2008 John Darrington firstname.lastname@example.org
Copyright © 2015 Enrico M. Crisostomo email@example.com
Copying and distribution of this file, with or without modification, are permitted in any medium without royalty provided the copyright notice and this notice are preserved. This file is offered as-is, without any warranty.