Hi, Quoting Johannes Schauer (2016-08-22 14:58:36) > Quoting Ian Jackson (2016-08-22 12:55:48) > > But even worse is that it would no longer be possible to sensibly > > compute build orders without pre-building every package in a source > > archive, because it would not be possible to statically determine > > which binary packages are supposed to come from which sources. > > since you are talking about computing build orders and avoiding having to > pre-build every source package, I have bad news for you. It is currently > already impossible to know which source package to build to satisfy a given > dependency if that source package hasn't been built before for the > architecture > that you are building for.
since I was told that my message could easily be misunderstood, let me clarify. I did not intend to give arguments for why computing Build-Depends at build time would be a good idea. I'm much of the opposite opinion myself *especially* for the purposes of being able to auto-generate a build order in a reliable way at some point in the future. Instead, I just wanted to debunk Iain's claim that it would "no longer be possible to sensibly compute build orders without pre-building every package" as this has never been possible (without heuristics and a manually maintained set of assumptions). > This is not only because source package metadata does not tell you: [...] - > whether they will build a binary package that is Essential:yes in fact this information is already present in the Sources index if a package was rebuilt with dpkg 1.18.2 or newer. It is represented as essential=yes in the Packages-List field. Rebootstrap already makes use of this field for its purposes. (thanks guillem for correcting me!) Some good documentation of the capabilities of the Packages-List field can be found in the man page dsc(5). Thanks! cheers, josch
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