[RFC] Update minimum make version to 3.81

[Florian Weimer]

On 06/24/2016 07:49 PM, Mike Frysinger wrote:
> On 24 Jun 2016 18:31, Florian Weimer wrote:
>> On 06/24/2016 06:10 PM, Mike Frysinger wrote:
>>> On 24 Jun 2016 13:24, Florian Weimer wrote:
>>>> On 06/11/2016 12:27 AM, Roland McGrath wrote:
>>>>> eval is a pretty horrible feature and I'd probably object to introducing
>>>>> any uses of it into libc's makefiles.  We already have lots of things that
>>>>> might have been done that way, but are instead done with generated makefiles.
>>>>
>>>> I would like to put this into malloc/Makefile:
>>>>
>>>> $(foreach t,$(tests),$(eval CFLAGS-$t.c += -DTEST_NO_MALLOPT))
>>>>
>>>> What's the alternative for adding a -D flag to every test compilation in
>>>> a subdirectory?
>>>
>>> maybe something like (untested):
>>> CPPFLAGS += $(if $(filter $(@F),$(tests)),-DTEST_NO_MALLOPT)
>>
>> Hmm, right.  It's relying on the delayed expansion.  Not sure how this
>> is less evil, though.  It also has at least quadratic run-time behavior.
>
> 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

I like your first suggestion better because it doesn't construct the 
full target name, so you only need to know about $(*F).

Florian