make.m4: AM_MAKE_INCLUDE will fail if doit exists

[Philip S Tellis]

The macro AM_MAKE_INCLUDE uses doit as a make target:

doit:
        @echo done

This works as long as no file named doit exists in the current
directory.  If a file named doit exists, make will print:

make: `doit' is up to date.

(or nothing with the -s flag) and exit.

This causes the test to fail and consequently, dependency tracking gets 
turned off... leading to a whole load of misleading bug reports.

Solution:  Use the .PHONY target to tell make that doit isn't a file:

doit:
        @echo done

.PHONY: doit


Apparently this has been in since automake-1.6, and maybe 1.5 too.

Philip

Note: I am not on this list, so Cc me if you have any queries, else, 
there may not be a need to include me in further discussions.

-- 
Any program which runs right is obsolete.