Thank you Paul, that helped me, and at first glance see no disruption to my past applications (which, FWIW, largely consists of the ill-advised but still useful pattern of auto-creating directories to hold targets).
~ malcolm_c...@stowers.org From: Paul Smith <psm...@gnu.org> Sent: Monday, March 17, 2025 9:23 AM To: Cook, Malcolm <m...@stowers.org>; bug-make@gnu.org Subject: Re: order-only prerequisites themselves get rebuilt when not needed The patch attached to the savannah issue Dmitry provided below does include a doc change. I haven't reviewed it yet. Basically the current behavior is: To build target A: - First try to build all prerequisites - Compare the modification time of all NON-ORDER-ONLY prerequisites - If any NON-ORDER-ONLY prerequisite is newer than A: - Run the recipe to build A The proposed behavior is (as I understand it): To build target A: - First try to build all NON-ORDER-ONLY prerequisites - Compare the modification time of all NON-ORDER-ONLY prerequisites - If any NON-ORDER-ONLY prerequisite is newer than A: - Try to build all ORDER-ONLY prerequisites - Run the recipe to build A The big difference is that if A doesn't need to be rebuilt, then order- only prerequisites are not even considered. On Mon, 2025-03-17 at 14:02 +0000, Cook, Malcolm wrote: > Hi, as someone who uses order only prerequisites frequently, I would > appreciate at restatement of what the proposed change to behavior is > so I can advise whether I expect my use cases to be affected. > > Perhaps in addition to a code patch a proposed documentation patch > could help other lurkers get up to speed with the proposal....??? > > > > From: > bug-make-bounces+mec=stowers....@gnu.org<mailto:bug-make-bounces+mec=stowers....@gnu.org> > Sent: Monday, March 17, 2025 7:10:06 AM > To: bug-make@gnu.org<mailto:bug-make@gnu.org> > <bug-make@gnu.org<mailto:bug-make@gnu.org>> > Subject: Re: order-only prerequisites themselves get rebuilt when not > needed > > On Sat, 2025-03-15 at 08:28 -0400, Dmitry Goncharov wrote: > > On Mon, Mar 10, 2025 at 8:12 AM Paul Smith > > <psm...@gnu.org<mailto:psm...@gnu.org>> wrote: > > > > > > On Sat, 2025-03-08 at 11:34 -0900, Britton Kerin wrote: > > > > What confuses me is that since the explicitly requested foo > > > > exists and isn't out of date with respect to any non-order-only > > > > prereqs (in the example it doesn't have any) and therefore > > > > isn't > > > > getting rebuilt, I wouldn't expect there to be any need to > > > > rebuild it's order-only prereqs either. > > > > > > That's certainly a reasonable way for it to work, but that's not > > > how it works. > > > > Can we change how it works? > > i attached a patch here > > https://savannah.gnu.org/bugs/index.php?66915<https://savannah.gnu.org/bugs/index.php?66915>. > > The question we have think carefully about is what sort of backward- > compatibility issues, if any, we could introduce. Are there > situations where people are relying on the current behavior? > > Secondly, we should consider which behavior is easier to work around. > If there is a reasonable workaround to one choice but not a good way > to obtain the other behavior, we should choose the harder to obtain > behavior. > > I'm not really convinced that this need rises to the level of "keep > both behaviors with some new syntax or option to choose between them" > so I would prefer not to go that way unless it's proven necessary.
