Gnu Makefile - Handling dependencies

Question

What approach do C++ programmers on Unix platform use to create and manage Makefiles?

I was using hand made Makefiles for my projects but they don\'t handle header file

Answer 1

Instead of the sed scripts, use gcc's -MT option to modify the target of the generated dependency rules. This blog post has more info.

Answer 2

In Mozilla's build system, we use GCC's -MD switch to generate the dependency files: http://mxr.mozilla.org/mozilla-central/source/configure.in#7134 and then we use a script called mddepend.pl to check for removed header files, such that removing a header simply causes a rebuild, not an error: http://mxr.mozilla.org/mozilla-central/source/config/rules.mk#2066 http://mxr.mozilla.org/mozilla-central/source/build/unix/mddepend.pl

That script generates an .all.pp file containing all the dependencies, with extra foo.o: FORCE dependencies stuck in for missing header files. We then simply -include the .all.pp file in rules.mk right below there.

Answer 3

You can use qmake to generate Makefiles for a project even if that project is not using Qt.

Answer 4

With a more modern version of GCC, you can add the -MP flag to have GCC generate empty rules for the headers itself.

Answer 5

1. I use that approach too and can't praise it highly enough. And I write my makefiles by hand and reuse them a lot on new projects.
2. .The expression "s/ *\\$//" will work outside the context of Make. Within a makefile it doesn't work because Make tries to interpret "$/" before handing the result to the shell. So you must use "s/ *\\$$//" (note the extra $) within the makefile, but this won't work outside the context of Make (so testing it is a slight pain).

EDIT:

I've tried your makefile, and that sed statement seems to remove trailing backslashes just fine. Try something simpler, like this:

backslash:
    @echo " \\" > $@

test: backslash
    @echo without sed:
    @cat backslash
    @echo with sed:
    @sed -e 's/ *\\$$//' < backslash

EDIT: All right, now I'm hooked. Could you try these experiments and tell us the results?

Change the last character to 'z'      :  s/.$/z/
Change a trailing backslash to 'z'    :  s/\\$/z/
Change a trailing backslash to 'z'    :  sm\\$mzm
Delete a trailing backslash           :  s/\\$//
Delete spaces and a trailing backslash:  s/ *\\$//
Try all of these inside and outside of Make, with '$' and '$$'.

Answer 6

I must be missing something. Why doesn't generating dependency files work for you?