On Wed, Sep 22 2021, Junio C Hamano wrote: > Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> writes: > >> I've got some WIP efforts in other areas to do that for some other >> rules. >> >> The problem is that you need to "mkdir .shrapnel" to create a >> ".shrapnel/revision.sp". So you need the ".shrapnel/revision.sp" to >> depend on the ".shrapnel". >> >> Except you'll find that the naïve implementation of that fails, since >> any file you create will bump the mtime of the containing directory, so >> you'll keep re-making ".shrapnel/revision.sp" because ".shrapnel" >> changed, because ".shrapnel/revision.sp" changed... > > We depend on GNU make anyway. Isn't its "order-only-prerequisites" > feature what you exactly want to use for the above? It looks like it, and that I should probably take more time one of these days to read the GNU make manual through. But in any case, I do think that's worthwhile in general, i.e. you can depend on %.h and not need to exclude generated %.h that we make ourselves if we put that into "gen/" or whatever, "clean" also becomes a lot easier. But I'd like to leave it for some future effort of moving *.o, *.sp etc. generated files around, rather than making *.sp an odd special-case now.
