Re: Why does %build-inputs contain the transitive closure of inputs?!

[Jakub Kądziołka]

On Sat, Aug 08, 2020 at 10:26:08AM +1000, Carlo Zancanaro wrote:
> Hi Jakub,
> 
> On Sat, Aug 08 2020, Jakub Kądziołka wrote:
> > Why? I would expect only libgit2 to be present, and not all of its
> > dependencies. ...
> 
> If you take a look at the definition for libgit2 in
> gnu/packages/version-control.scm you'll see that this isn't all the
> dependencies for libgit2, it's only the propagated-inputs. For instance,
> libssh2 and http-parser are both inputs for libgit2, but they don't appear
> in your list because they're not propagated.
> 
> > ... It seems to me that this has only downsides - the entire transitive
> > closure needs to be present during build, even when the actually used
> > dependencies don't reference it, and the names of inputs used by
> > packages are now public API, and changing them can break the build of
> > any transitively dependent package.
> 
> The way propagated inputs work is that they're installed alongside the
> package, so in some sense they are part of the public API of the package.
> They should be used with care, but as far as I can tell everything is
> working properly here.

You're absolutely right. This even explains the original weirdness I
saw. Serves me right for hacking at 1 AM...

Sorry for the noise :/

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