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Re: [RFC] Update minimum make version to 3.81

On 06/24/2016 08:46 PM, Mike Frysinger wrote:


what about using target-specific variables and relying on inheritance [1] ?
does this work ?
$(tests): CPPFLAGS += ...


It would have to be something like:

$(tests:%=$(objpfx)%.o): CPPFLAGS += -DTEST_NO_MALLOPT


did you verify that ?  target-specific variables inherit across targets.

example:
$ cat Makefile
tests = a
check: $(tests)
$(tests): CPPFLAGS += FOO
a: a.o
a.o:
	echo $(CPPFLAGS)
	false

$ make
echo FOO
FOO
...


Oh wow.  It does work (even with make 3.81).
But how is this a good idea? It means that if a target match %.o is built not via $(tests), but as a prerequisite of another target, the variable is not applied (and the target is not rebuilt for the other dependency chain, I assume).
I suppose it's unlikely that developers will try to rebuild individual .o files in subdirectories. But my, what an obscure make feature! 

Florian
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