bug#74604: 30.0.92; FR: M-x package-upgrade - offer an option to show a diff on upgrade

[Philip Kaludercic <philipk@posteo.net>]

Ship Mints <shipmints@gmail.com> writes:

> Isn't it the case that describe-package works only on installed packages,
> not prospectively installed packages? To help determine the value/risk of a
> package install or update, I'd think it better to show this in advance.
> Daniel's diff suggestion is similar but more technical.

describe-package (C-h p) works on all packages, but the news feature I
described wouldn't work as it uses a local file.  But that is not a
hard-constraint, we could serve news data as well.

I don't know how much sense it makes to present a diff when installing a
package.  News files are probably also not that interesting.  We could
provide a command like package-vc-checkout that just fetches the package
source and places it somewhere for the user to inspect.

> On Mon, Dec 2, 2024 at 3:59 AM Philip Kaludercic <philipk@posteo.net> wrote:
>
>> Ship Mints <shipmints@gmail.com> writes:
>>
>> > I like this idea, too. I spend a reasonable amount of time trying to
>> > understand what people have changed and if it will affect me negatively
>> > (the defensive part) or positively (for new features, user options,
>> > deprecations). Showing a source-code diff may be a bit technical for some
>> > users, though. I wonder if there could be either a link to a changelog,
>> or
>> > a way to encourage a changelog convention so one could be displayed for
>> > users prior to a decision to update a package.
>>
>> Note that packages can distribute this information.  Currently, if a
>> tarball includes a "news" file, it will be displayed by
>> `describe-package.  IIRC no package archive generates these right now.
>> But if we implement a user option like that described above (or below?),
>> then we can add that as an option as well.
>>
>> The main issue is that not all package maintainers ensure that there are
>> changelog/news sources that ELPA could use to provide this information.
>>
>> > -Stephane
>> >
>> > On Sun, Dec 1, 2024 at 5:06 PM Philip Kaludercic <philipk@posteo.net>
>> wrote:
>> >
>> >> Daniel Mendler <mail@daniel-mendler.de> writes:
>> >>
>> >> > This is a feature request for the security wishlist. When upgrading
>> >> > package it would be good to show a diff between the new and old
>> package
>> >> > files. Such an option could help performing review casually as part of
>> >> > the upgrade process and may improve the security of the package
>> >> > archives. More eyes would look at new package versions. This would
>> make
>> >> > it harder to inject malicious code either via the source repository or
>> >> > via attacks on the package archives.
>> >>
>> >> That sounds like a good option to have!  I'll look into adding something
>> >> like this via a user option that adjusts how to confirm a package
>> upgrade.
>> >>
>> >> Note that package-vc has something similar with the
>> >> `package-vc-log-incoming' command.
>> >>
>> >>
>> >>
>> >>
>>