Subject: [PATCH 0/1] Add lint checker for unused module imports.

From: Reily Siegel <[email-masked]>
Date: Sat, 4 Feb 2023 01:42:28 -0500

Julien Lepiller <[email-masked]> writes (guix-devel):

> Many modules seem to use a lot of imports that are actually useless,
> for instance (gnu packages heads) imports 20 package modules, but
> only uses 4 of them.
>
> Removing these module imports would help a lot with reducing the number
> of loops. If anyone wants to volunteer a lint checker for that,
> raise hands :D

This is a quick and dirty implementation of such a lint checker. It
compares the symbols used in a module to those provided by its
dependencies. If there is a dependency for which none of the symbols
overlap, a warning is reported. A potential downside of this approach is
that the lint checker cannot distinguish between lexically scoped
variables and variables which actually reference another module. This
has two effects:

- The implementation is slower, because lexically bound variables must
  also be checked
- The implementation may fail to report an unused import if a lexical
  binding with the same name as one of the module's exports is used

However, this does vastly simplify the implementation.

Reily Siegel (1):
  lint: Add unused-modules linter.

 guix/lint.scm | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 63 insertions(+), 1 deletion(-)