Note: I wrote most of this before Neil Williams' recent comments on the 3.0 family of formats, so despite the timing this isn't really a reaction to that although I do have a couple of responses. On the whole I think I agree that the Lintian message is a bit heavy-handed and I'm not sure I'm thrilled about the idea of the default source format being changed (though I can see why the dpkg maintainers are interested in that). That said, as far as I personally am concerned, there is a vast cognitive benefit to me in having as much as possible be common to all my packages. Once I have more than a couple of packages that require patching and benefit from the 3.0 (quilt) format as a result, I find it in my interest to use it for all my non-native packages even if they're patchless right now, so that for instance if they need patches in the future I can handle them the same way. It's not unheard of for me to apply temporary patches even to packages I actively maintain upstream, so I don't discount those either. I haven't decided what to do with my native packages yet; unless they're big enough for bzip2 compression to be worthwhile, there doesn't seem to be much immediate advantage to 3.0 (native).
Anyway, on to the main body of this post:
+ +I've been one of the holdouts resisting use of patch systems for a long time, on the basis that I felt strongly that dpkg-source -x ought to give you the source that's actually built, rather than having to mess around with debian/rules targets in order to see it. Now that the 3.0 (quilt) format is available to fix this bug, I felt that I ought to revisit my resistance and start trying to use it. Migrating to it from monolithic diffs is of course a bit more work than migrating to it from other patch systems, so it's taken me a little while to get round to it. I'd been thinking about holding off until there was better integration with revision control (e.g. bzr looms), as I feel that patch files really ought to be an export format, but I eventually decided that I shouldn't let the perfect be the enemy of the good. I have enough experience with co-maintaining packages that use build-time patch systems to be able to compare my reactions.
After experimenting with a couple of small packages, I moved over to the deep end and converted openssh a few weekends ago, since quite a few people have requested over the years that the Debian changes to openssh be easier to audit. This was a substantial job - over 6000 lines of upstream patches - but not actually as much work as I expected. I took a fairly simplistic approach: first, I unapplied all the upstream patches from my tree; then I ran bzr di | interdiff -q /dev/stdin /dev/null >x, reduced it to a single logically-discrete patch, applied it to a new quilt patch using quilt fold, and repeated until x was empty. This was maybe an hour or two of work, and then I went through and tagged all the patches according to DEP-3, which took another few hours. After the first pass, I ended up with 38 patches and a much clearer idea of what has been forwarded upstream and what hasn't; I currently have 5 patches to forward or eliminate, down from 18.
Good things:
+ +dpkg-source -x gives you, so it's the natural representation in revision control too), bzr blame works just as you'd expect and displays both upstream and Debian changes at once. I rely on tools like blame a lot, and I really hate the way build-time patch systems make it hard to use revision control when the tree is in a built state, so this was a hard requirement for me.Bad things:
+ +.pc directory, and the tree checks out in the patched state (as it should), so I needed some way for developers to get quilt working easily after a checkout. This is sort of the reverse of the previous problem, where users had to do something special after dpkg-source -x, and I consider it less serious so I'm willing to put up with it. I ended up a rune in debian/rules that ought to live somewhere more common.quilt pop -a, force a merge despite the modified working tree, and then quilt push && quilt refresh -pab until I get back to the top of the stack, modulo slight fiddliness when a patch disappears entirely; thus effectively using quilt's conflict resolution rather than bzr's. I suppose this will serve as additional incentive to reduce my patch count. I know that people have been working on making this work nicely with topgit, although I'm certainly not going to put up with the rest of git due to that; I'm happy to wait for looms to become usable and integrated. :-)On the whole I'm satisfied with this, and the benefits definitely outweigh the costs. Thanks to the dpkg team for all their work on this!