Re: [PATCH 0/4] Makefile: micro-optimize light non-test builds

[Junio C Hamano <gitster@pobox.com>]

Jeff King <peff@peff.net> writes:

> On Tue, Jan 26, 2021 at 05:38:08PM -0800, Junio C Hamano wrote:
>
>> The steps 2/4 and 3/4 did look like a useful feature, but I wonder
>> why we even need to introduce NO_TEST_TOOLS in the first place.
>> Wouldn't it be more natural to arrange them to be built by making
>> "test::" target depend on them?  IOW, why do we need to have "all::"
>> (our default) target depend on them?
>
> Hmm. That is definitely more logical, and giving "make" more information
> to make a good decision about what is needed. I do wonder if it would be
> annoying in two cases, though:
>
>   - people trigger the tests in other ways besides "make test". For
>     instance, "make && cd t && make" works, as does just
>     "make && cd t && ./t1234". With a more clever Makefile, those would
>     fail (or worse, run out-of-date versions of the helpers, producing
>     confusing results).
>
>   - during refactoring, I often compile-test as I go (i.e., run "make"
>     to see which callers still need changed, then fix them, repeat).
>     If that didn't catch test helpers, then I'd think I was done and get
>     bit later by "make test" trying to build more code. Not the end of
>     the world, but a minor annoyance.
>
> So I think even though I'd argue that giving "make" that extra
> dependency information is "more correct", we are fighting uphill against
> existing behavior, as well as things that make doesn't know (like that I
> expect to be ready to run tests as long as "make all" has finished).

Hmph, true, but as "make test" at the top-level merely redirects to
"make -C t", I imagined that the default target in the t/Makefile
would depend on doing "make -C .. test-programs" before running
tests.

The recursive dependencies end somewhere, though ;-)