Question

I have a makefile that gives a non-obvious failure when an older version of gmake is used. I’d like to have a rule that checks the version is at least version 3.82 or later. I’ve gotten as far as the following rule, but the comparison is brittle, I really want a comparison allowing for later versions too:

GMAKE_VERSION :=  $(shell gmake --version | head -n 1 | sed 's/GNU Make //')

.PHONY: testMake
testMake:
    @if [ "$(GMAKE_VERSION)" != "3.82" ];               \
    then                                \
        echo >&2 "Unexpected gmakefile version "        \
            "$(GMAKE_VERSION), expecting 3.82 or later.";   \
        false;                          \
    fi

What GNU makefile rule can ensure the version of make is at least v3.82?

Answer 1

Here is how I would implement it:

# Check Make version (we need at least GNU Make 3.82). Fortunately,
# 'undefine' directive has been introduced exactly in GNU Make 3.82.
ifeq ($(filter undefine,$(value .FEATURES)),)
$(error Unsupported Make version. \
    The build system does not work properly with GNU Make $(MAKE_VERSION), \
    please use GNU Make 3.82 or above.)
endif

The check is based on testing .FEATURES built-in variable. From GNU Make 3.82 NEWS file:

New make directive: undefine allows you to undefine a variable so that
it appears as if it was never set. Both $(flavor) and $(origin) functions
will return ‘undefined’ for such a variable. To detect this feature search
for undefine in the .FEATURES special variable.