On Thu, Mar 18, 2010 at 07:42:37PM +0100, Stefano Zacchiroli wrote: > I believe this might have caused false negative in the past > (i.e. packages whose build-deps cannot be satisfied, but for which > edos-builddebcheck was not reporting it, simply because they were not > part of the "fake" Packages file generated). Ralf, do you confirm that > possibility?
That's of course a possibility. Though the cases that I have been told about always had a different explanation, if memory serves me right. > > There is a serious problem with addsources.py: it "simplifies" an > > altenative build-dependency into a single package. On Kurt's example, > > it changes > > > > Build-Depends: libc6-dev (>> 2.3.5) | libc6.1-dev (>> 2.3.5) > > > > into > > > > Depends: libc6.1-dev (>> 2.3.5) > > > > which is hardly acceptable :-) > > This, in turn, is by design :-) I don't remember if I or someone else > added the support for it, but we currently have a list of > build-essential packages, which currently reads as follow: > > buildessentials = ['apt', 'binutils', 'cpio', 'cpp', 'dpkg-dev', > 'g++', 'gcc', 'libc6-dev', 'make', 'patch', > 'perl', 'perl-modules'] > > the function dep_for_me() in the Python code checks, for each build-dep, > if it is part of that list. If a build-dep is, it gets "simplified > away". In your example it is trivially the case for 'libc6-dev', which > gets removed. > > Now, as I understand it, the code which currently throws away essential > build-deps is too simple: it currently does not care about versions at > all, while it probably should. Is this the root of the problem? If it > is, there are various thoughts before fixing this naively: > > - how can add-sources.py know the version of the build-essential > packages which will be installed while actually building? > > - should it know that in the first place? > > I don't currently remember the rationale of ignoring build-essential > (were there cases where they are not installable, according to their > deps?), so I'm a bit at loss here ... I am really disappointed that I can no longer blame python for this bug (but don't worry, I'll find something else to blame python for :-) Dropping a build-dependency on a build-essential package is of course only correct when - it is an unversionend build-dependency - and if it occurs as element of a conjunction, not as element of a disjunction: true and x is equivalent to x, but true or x is not equivalent to x. A correct simlification would be to simplify (..|x|..) to True, that is remove it simply from the conjunct, in case x is build-essential and has no version constraint. I don't remember either the reason why we put this stuff in the first place. I guess it was due to some mis-guided ideas about optimization. I suggest we just scrap it. -Ralf. PS: Premature optimization is the root of all evil -- Donald Knuth (http://c2.com/cgi/wiki?PrematureOptimization) -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]
