Re: [PATCH v2] Makefile: make the "sparse" target non-.PHONY

On Thu, Sep 23 2021, Jeff King wrote:

On Thu, Sep 23, 2021 at 02:07:16AM +0200, Ævar Arnfjörð Bjarmason wrote:

quoted

We ensure that the recursive dependencies are correct by depending on
the *.o file, which in turn will have correct dependencies by either
depending on all header files, or under
"COMPUTE_HEADER_DEPENDENCIES=yes" the headers it needs.

This means that a plain "make sparse" is much slower, as we'll now
need to make the *.o files just to create the *.sp files, but
incrementally creating the *.sp files is *much* faster and less
verbose, it thus becomes viable to run "sparse" along with "all" as
e.g. "git rebase --exec 'make all sparse'".

OK. I think this solves the dependency issues sufficiently. It is a
tradeoff that you must do the normal build in order to do the sparse
check now. That is certainly fine for my workflow (I am building Git all
the time, and only occasionally run "make sparse"). I don't know if
others would like it less (e.g., if Ramsay is frequently running sparse
checks without having just built).

(I'd say "I do not care that much either way", but then I do not care
all that much either way about incremental sparse checks either, so I'm
not sure my opinion really matters).

Aside: As I recall you make a lot of use of ccache (as I do), so is the
"meh" on incremental builds synonymous with it not being piped through
$(CC) in this case?