This sounds a lot like boost & boist-mpi-sources which used to be two copies of boost one with main and the other with universe build dependencies, producing packages for main/universe respectively. These are now merged into a single source package and simply universe portions are compiled into separate package which is published to universe. This will be a case for many large key packages which produce optional plugins & language bindings with universe dependencies. <div class="gmail_quote">On 18 Apr 2016 7:44 p.m., "Thomas Ward" <<a href="mailto:teward@ubuntu.com">teward@ubuntu.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Steve, On 04/18/2016 02:10 PM, Steve Langasek wrote: > Hi Thomas, > > On Mon, Apr 18, 2016 at 02:00:43PM -0400, Thomas Ward wrote: >> On 04/08/2016 12:39 PM, Steve Langasek wrote: >>> Thanks to some stellar work by Dimitri Ledkov and Colin Watson, and as >>> discussed on ubuntu-devel over the past couple of months[1,2], a change has >>> been landed to Launchpad and the archive reports[3] to allow packages in >>> main to build-depend on universe (and packages in restricted to build-depend >>> on either universe or multiverse). >>> What this means for you: >>> - If you are building packages locally, you will want to update your build >>> environments for xenial and beyond to include universe in the apt >>> sources, to mirror Launchpad's behavior. >>> >>> - If you are updating a package that carries a delta to its >>> build-dependencies, you will want to check if this delta can now be >>> dropped. If readding the build-dependency results in a new runtime >>> dependency, the package will be blocked by proposed-migration in >>> -proposed until component mismatches are resolved; you will then need >>> to either re-add the delta, or follow the MIR process[4]. >>> >> I think I need some clarification on this point. The way I interpret >> this is as follows: >> >> 1. We are able to build-depend packages in Main on Universe, such that >> any Universe compile-time dependencies are no longer needed to be >> dropped for a package to be in Main. But... >> >> 2. If such build-dependencies then introduce new dependencies on the >> built binaries, the runtime-dependency packages of which are >> necessary in the built binaries must be in Main. >> >> Is this an accurate interpretation of the points made in your email, or >> am I misreading what you are stating? > You've got it exactly. > There's one follow-up here: does this apply for all binaries produced by the source package (regardless of Main/Universe), or does this apply for only produced binaries which land in Main? (Thanks to Robie for making a clarification point in private messages on IRC) There's a case where this applies - nginx - with regards to nginx-core being a binary produced in Main, but the other binaries (such as nginx-extras) being in Universe, with a Wishlist bug asking for us to drop one of the Main-inclusion deltas (which would only affect nginx-extras). Thomas -- ubuntu-devel mailing list <a href="mailto:ubuntu-devel@lists.ubuntu.com">ubuntu-devel@lists.ubuntu.com</a> Modify settings or unsubscribe at: <a href="https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel" rel="noreferrer" target="_blank">https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel</a> </blockquote></div>