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

[Carlo Zancanaro]

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.

Carlo