bug#51215: Add a navigation feature to vc and diff mode: diff-goto-line

[Uwe Brauer]

Tags: patch

<#secure method=smime mode=sign>
Hi all


Attached you find a patch, in a git compatible format, (to be installed
with git apply --patch-format=hg) provided by Davis Herring with Davis's
approval of course. Davis has already signed the FSF papers.

I would like to also discuss the whole idea connected to that patch.
Please tell me whether that is appropriate, and if it is not, we might
continue the discussion on the developer list. I will send just in case
a similar message to the developer mailing list. 

A bit of history to put that into context: 5 years ago Davis Herring
send a patch (with respect to vc.el and diff-mode.el) to the devel
list, see the link for further details.

[[https://lists.gnu.org/archive/html/emacs-devel/2016-02/msg01066.html][First 
short vc-diff patch]]

The idea of that patch can be described best by referring to is the
diff-hg package. The function `diff-hl-diff-goto-hunk' shows the
un-committed changes in a file, and allows to jump to these changes.
Strangely enough vc-diff does not provide a similar  feature. Davis' Harris
patch, however, does introduce it.

I find it especially helpful in collaboration where push and pulling
to/from a repository, using either git or mercurial. I presume most of
the users in this mailing list are acquainted with such a workflow, but
if necessary I could provide more details.

That patch was considered as interesting but certain enhancements were
required. So Davis send a much larger patch 6 month later. That patch
however was rejected as being to large. 
[[https://lists.gnu.org/archive/html/emacs-devel/2016-07/msg00727.html][Second 
longer patch, cannot be merged]]

I became very interested in that feature and was not able to install
Davis's second patch (most likely to many changes in the last 5 years)

His first patch, however, I could still apply and I tested it (using
mercurial) almost for a year and it worked flawlessly for me. 

That is why I strongly recommend to apply the patch, then 

    1. Either errors are found and these will be corrected or the patch removed
    2. Or even better the feature will enhanced

But I think to reject the patch, again, would not be a bit of a shame.

regards

Uwe Brauer 




In GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, X toolkit, cairo version 
1.14.6, Xaw3d scroll bars)
 of 2021-07-31 built on Utnapischtim
Repository revision: 83a915d3dfafd5f3d737afe1e13b75e4dd3aef96
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.11804000
System Description: Ubuntu 16.04.7 LTS

Configured using:
 'configure --prefix=/opt/emacs28 --with-x-toolkit=athena --without-pop
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diff-goto-line.patch
Description: Text Data