On Thursday, February 9, 2023, Tom Tromey <t...@tromey.com> wrote: > > > It's been a long time since I worked on automake, but the dependency > tracking in automake is designed not to need to rebuild or pre-build dep > files. Doing that means invoking the compiler twice, which is slow. > Instead, automake computes dependencies as a side effect of compilation.
The hello.Po example presented above computes depfiles as a side effect of compilation. Moreover, when hello.Po is absent that makefile compiles hello.o as a side effect of hello.Po computation. In total there is only one compilation. > > What is the scenario where you both end up with an empty depfile and a > compilation that isn't out of date for some other reason? That seems > like it shouldn't be possible. > > When a depfile is missing (for any reason) the current automake makefile creates a dummy depfile. From that point on the user has to notice that make is no longer tracking dependencies and their build is incorrect. I am asking if automake can be enhanced to do something similar to hello.Po example above, in those cases when make supports that. Regards, Dmitry