I've run into a problem with automake that I can't seem to find a clean solution for, which seem like it should be possible (even simple), but nothing simple works.
Basically the problem I have is with a source file that includes an autogenerated header file. I can add the dependencies to generate the header file just file, and once the header exists, everything works, as automake's auto dependency generation takes care of everything. The problem is the first time you run make in a clean tree, the dependency files don't exist, so automake doesn't know to generate the header file, which makes the compile of the file including the header fail without generating any dependencies. Its a chicken-and-egg problem -- you need to manually tell (auto)make to build the header file.
The obvious solution is just to add a dependency to the Makefile.am file for the header, but that doesn't work, since having a dependency for a target override automake's automatic rule generation, as the docs say:
Note that Automake does not make any distinction between rules with commands and rules that only specify dependencies. So it is not possible to append new dependencies to an automake-defined target without redefining the entire rule.
For now I've hacked around the problem by 'hiding' the dependency from automake, but this only works for GNU-make:
Makefile.am:
bin_PROGRAMS = foo
foo_SOURCES = main.c foobar.c baz.c
gen.h: system.spec
...command to regen gen.h
# foobar.c #includes gen.h, so it needs to exist prior to compiling foobar.c
$(eval foo-foobar.o: gen.h)
This does the trick, but seems ugly. Is there a better automake-safe way of doing this?
