bug#26170: Bug #26170 Hunting: doc: Explanation of propagated-inputs unclear

[pelzflorian (Florian Pelz)]

Thank you for bringing up this bug again with detailed
cross-referencing.  Sorry for not sending a patch earlier.

I do not think it makes sense to close yet.  I attach a proposed patch
now (its text is not properly wrapped yet).  It may contain
misunderstandings about propagated inputs as I have not packaged much.

On Wed, Sep 09, 2020 at 03:25:31PM +0200, zimoun wrote:
> Currently, the term “propagated inputs” in the index [2] goes to the
> section “Invoking guix package” [3] and explaining:
> 
>         Sometimes packages have propagated inputs: these are
>         dependencies that automatically get installed along with the
>         required package (see propagated-inputs in package objects, for
>         information about propagated inputs in package definitions).
> 
>         An example is the GNU MPC library: its C header files refer to
>         those of the GNU MPFR library, which in turn refer to those of
>         the GMP library. Thus, when installing MPC, the MPFR and GMP
>         libraries also get installed in the profile; removing MPC also
>         removes MPFR and GMP—unless they had also been explicitly
>         installed by the user.
> 
> with the hyperlink [4] mentioning:

Note the text currently in the manual is the same as back then when I
filed the bug.

When starting to read about propagated inputs in the documentation of
`guix package --install`, I agree, it is clear enough, the reader will
understand that propagated inputs get treated like with `guix package
--install` and the reader need not think about profiles and the store.

However, back then I may have gotten confused because I started off
reading the Defining Packages section without the context of `guix
package --install`.  In this context, I may have been thinking of
installation to a directory rather than a user running `guix install`.


> 3) more examples like the above example for GNOME Evolution (which
> however I have yet to finish packaging and submit as a patch; maybe
> dconf is a better example – I presume it is also needed at run time and
> not just).

I was mistaken about 3).  I am glad Ricardo Wurmus packaged Evolution.
Apparently I was wrong and evolution does not need
evolution-data-server as a propagated-input.

Regards,
Florian

0001-doc-Clarify-what-propagated-inputs-are.patch
Description: Text document