For a long time, using $(srcdir) in targets and prerequisites in Makefiles have seemed a little magic to me. It breaks too often, usually in ways like automatic dependency generation not working.
So I've tried to create a small toy project, and a testscript that builds the projects in various ways, checking that it behaves as it should. I've gotten the generated files to work properly, but I'm not sure I'm doing it in the right way. The project can be found at http://www.lysator.liu.se/~nisse/misc/make-example-0.0.tar.gz. The README file is as follows: This is a dummy project written to illustrate how to write make rules for automatically generated files. For now, it uses only system-independent automatically generated files. The rules are: * sh-gen.h and c-gen.h are generated by the shell-script sh-gen and C progran c-gen.c, respectively. * These files are generated by the maintainer, in the source directory. * They should be included when the program is distributed. * The program foo depends on the generated files. If the sh-gen or c-gen.c are modified, foo. and foo must be rebuilt. * Everything should work both for builds in the source directory, and for builds that use a separate build directory. And in the separate build directory case, it should work with both a relative and an absolute filename for srcdir. * When building a from a distribution, the c-gen binary will not be built. The script ./check-example tries to check that the build process works as intended. The basic problem with using a target like sh-gen.h rather than $(srcdir)/sh-gen.h is that dependencies don't work properly when building in a separate directory. We get the dependencies: foo.o: ../sh-gen.h sh-gen.h: ../sh-gen and it doesn't follow that f..o depends on sh-gen. A workaround is to add the rules .PHONY: $(srcdir)/sh-gen.h $(srcdir)/sh-gen.h: sh-gen.h That generates a some warnings make: Circular ../sh-gen.h <- ../sh-gen.h dependency dropped. but it actually seems to work. Another problem is the c-gen binary. On one system where I tried this, make distcheck tried to rebuild c-gen.h, which failed because the source dir is readonly. This was with make 3.79.1, automake 1.6.1. I have no idea why that happened, the targets built by make should depend only on c-gen.h, which in turn depends on c-gen.c, not on the binary. _______________________________________________ Bug-make mailing list [EMAIL PROTECTED] http://mail.gnu.org/mailman/listinfo/bug-make
