On Thu, May 16, 2019 at 7:37 AM Paul Smith <psm...@gnu.org> wrote: > > I'm publishing this back to the list as I don't like to have private > conversations on these subjects; hopefully you don't mind. > > On Wed, 2019-05-15 at 11:19 -0800, Britton Kerin wrote: > > I agree that having file behave differently would be weird, but it > > does seem like it would be nice if make functions were expanded a > > command at a time (rather than a recipe at a time). It would be too > > breaking as a general change but perhaps as a .DIRECTIVE: ? > > There's no question whatsoever that this behavior has bitten many > people, many times. It's one of the more common questions on > StackOverflow, etc. > > I'm honestly not sure why expansion is done that way (it predates my > involvement in GNU make maintenance). Offhand it seems like an > arbitrary choice: I can't think of a good reason for it. Maybe someone > else can point out a use for it. > > I wonder how much code would actually break by just changing it.
I don't know for sure, but I can testify that I've used make pretty extensively for many years, including many of the less usual features (static pattern, order-only rules etc.) and I only recently learned about this peculiarity. Not sure if that means my code is insensitive to it or unconsciously dependent in some way. > Certainly, any such code would have to be written in a weird way > although obviously "weird code" does exist. > > For example someone could write something like: > > foo: > @cat somefile > $(shell echo foo > somefile) > > which would break if we started delaying expansion until the recipe > line was being invoked. But who's going to write that? > > The only idea I have for "legitimate real-world use" is something like: > > foo: > do some things > $(DO-MORE) > > where DO-MORE is some boilerplate macro defined elsewhere, that wants > to perform some checking and invoke $(error ...) if badness is > detected. It might be relying on the entire recipe being expanded up- > front to do that error checking before any part of the recipe is > invoked. > > I just really hate lots of tweakable options: you get an exponential > increase in testing requirements etc. Sadly true. I'll test rat on my stuff if you want to try it as a flat-out change, but tbh it strikes me as a bit risky that way. Britton _______________________________________________ Bug-make mailing list Bug-make@gnu.org https://lists.gnu.org/mailman/listinfo/bug-make
