bug#38044: 27.0.50; There should be an easier way to look at a specific vc commit

[Eli Zaretskii]

> Cc: larsi@gnus.org, stephen.berman@gmx.net, 38044@debbugs.gnu.org,
>  juri@linkov.net
> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Tue, 19 Nov 2019 18:59:36 +0200
> 
> On 19.11.2019 18:12, Eli Zaretskii wrote:
> > If so, that's not a "log"
> > command, that's closer to a "diff" command.
> 
> It's kind of both. 'git show HEAD' is the format that I'd personally 
> expect: some meta info, including the commit message, followed by the 
> diff contents.

That's true, but I'd hesitate to introduce a new class of "show"
commands just because Git has it.  I see no problem showing the
meta-data with diffs (when Git is the back-end), perhaps with an
option to disable that.  My rationale is that other VCSes have a diff
command that shows only the diffs, and that command is used "to show"
a revision with those VCSes.

> > And don't we already have
> > a "diff" command which shows diffs for a specific revision?
> 
> It *can* do that. And we also have a command that shows the revision log 
> message and stuff: vc-annotate-show-log-revision-at-line. We could reuse 
> its logic.
> 
> And either add a diff output at the botton (making it a different 
> command an dealing with major mode having to support both the headers 
> and the diff), or rely on log-view-mode's bindings (the user can press 
> 'd' or 'D' there).

I think we should disconnect this "show" command from "log".  It is
conceptually wrong to make them related.  Of course a vc-log buffer
could have (and already has, AFAIK) a binding to a command that shows
the revision at point's line.