debhelper dh not rerunning when expected to

Question

I was converting some of my packages to use dh from the debhelper package, when I noticed that it doesn't support rerunning targets.

For example:

1. I run debian/rules build to check a build.
2. Make a small code change.
3. Run debian/rules build again, and it does nothing.

Or another common example I do:

1. I run fakeroot debian/rules binary to check if I have everything installed in the package correctly.
2. Find something missing; correct the problem.
3. Run fakeroot debian/rules binary to test out the change, and it does nothing.

This is a big change in behavior from CDBS, which I was previously using. Is there a work around for this? I don't feel like running debian/rules clean should be required in these situations.

debian/rules:

    #!/usr/bin/make -f

    export DEB_CXXFLAGS_MAINT_APPEND+=-std=gnu++0x

    %:
       dh $@

Answer 1

Yep, that's an intended and necessary behavior for dh (it has to keep track of what steps it has taken already, because it will usually be invoked several times over the course of a full package build and it can't leverage the internals of make to keep state. It's kind of a terrible hack, but it is a decent solution given the terrible problem constraints).

To be fair, it hasn't ever been well-defined what debian/rules build is supposed to do when there's already a partial build. If a build has succeeded previously and no state has been cleared, it's not unreasonable for Debhelper to treat the build as done.

It might be a solution to your problem just to use dh_clean when you want to start a build over. That won't invoke dh_auto_clean, so if your code gets built outside of the debian/ directory, it won't be touched, but the Debhelper state will be cleaned.

If instead you want to be able to "rewind" the partial debhelper build so that it thinks a build hasn't yet been done, you might try using a script that does something like

#!/bin/bash
sed -i -e '/dh_auto_build/,$ d' debian/*.debhelper.log

That will remove the "dh_auto_build" entry and everything after it from any *.debhelper.log build state, so that dh will think they haven't been done. Any steps it took up to that point will still be considered done.