From: Juri Linkov <juri@linkov.net>
To: Eli Zaretskii <eliz@gnu.org>
Cc: 33567@debbugs.gnu.org
Subject: bug#33567: Syntactic fontification of diff hunks
Date: Wed, 05 Dec 2018 01:28:45 +0200 [thread overview]
Message-ID: <87k1koygvm.fsf@mail.linkov.net> (raw)
In-Reply-To: <837egpagko.fsf@gnu.org> (Eli Zaretskii's message of "Tue, 04 Dec 2018 09:36:55 +0200")
>> For more safety, I propose to set a new buffer-local variable
>> `diff-default-directory' by such commands as diff, diff-backup,
>> dired-diff, dired-backup-diff. The existence of such variable
>> should guarantee that the referenced files really exist.
>> This variable will be like `diff-vc-backend' that says that
>> the diff-mode buffer is created by the VCS command.
>> Then anyone who want to visit a diff file in another directory,
>> could add it to the first line:
>>
>> -*- mode: diff-mode; diff-default-directory: "..." -*-
>
> I'm not sure this is a step in the right direction. What is the
> advantage of having a separate variable? How is it "safer"?
When this special variable is set by a diff command, it's safe to assume
that the files referenced from the diff buffer really exist, so it's
safe to try reading them. I don't want a patch in a mail attachment
to try reading files mentioned in the patch attachment.
>> >> > Also, if the diffs are from Git, they begin with a/, b/, etc. dummy
>> >> > directories, which usually don't exist in the file system.
>> >>
>> >> This is not a problem because diff-find-file-name used in the patch
>> >> strips such a/, b/ prefixes to get the existing file name.
>> >
>> > Not in my testing, but maybe I tried in the wrong Emacs version. Is
>> > this feature new with Emacs 27?
>>
>> For testing better try to eval e.g. `(diff-find-file-name nil t)'
>> on a hunk in a diff-mode buffer created by git.
>
> I did, but I guess this must be done inside the repository to work,
> does it? If I put the output of "git diff" on a file in some
> arbitrary directory, then visit that file and evaluate
> (diff-find-file-name nil t), I get nil.
Yes, it finds only the existing files inside the repository.
>> >> +For working revisions get highlighting according to the working
>> >> +copy of the file.
>> >
>> > I don't understand the significance of this comment. If you want to
>> > say that the produced highlighting might be wrong if the working
>> > version has changed since it was compared, then let's say that
>> > explicitly.
>>
>> This means that working revisions can't be extracted from the repository.
>> Until committed, they reside in files that are visited with find-file.
>
> We need to describe the implications of that to the users. Does the
> following text capture the issue?
>
> For diffs against the working-tree version of a file, the
> highlighting is based on the current file contents, which could be
> different from the contents when the diffs were taken. In such
> cases, the produced highlighting might be wrong.
Such problem is very rare because highlighting is added usually
immediately after creating a diff. When the file contents changes,
there is no highlighting at all - it verifies if text of the hunk
exist in the file, so highlighting never is wrong.
>> >> +If t, additionally to trying to use a version control system to get
>> >> +old revisions for fontification, also try to get fontification based
>> >> +on existing files, and on failure get fontification from hunk alone."
>> >
>> > What is the difference between using a VCS to get old revisions, and
>> > using existing files?
>>
>> This means that when a diff-mode buffer is not created by a VCS,
>> then it tries to read files with find-file.
>
> If so, I suggest the following wording:
>
> If t, try to infer fontification from the compared files, if they
> exist in the filesystem, when accessing their contents via VC
> fails.
Will add in the final patch.
>> > Also, does it mean `vc' will not fall back to `hunk-only'? Why not?
>>
>> Actually, it already falls back to `hunk-only', this is what
>> "on failure get fontification from hunk alone." tries to say.
>
> There's no such text in the description of 'vc', only in the
> description of t, which is why I asked.
Maybe then better to add text common for all cases, e.g.
"If some method fails, get fontification from hunk alone."
next prev parent reply other threads:[~2018-12-04 23:28 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-01 21:55 bug#33567: Syntactic fontification of diff hunks Juri Linkov
2018-12-02 6:56 ` Eli Zaretskii
2018-12-03 0:34 ` Juri Linkov
2018-12-03 6:49 ` Eli Zaretskii
2018-12-03 23:36 ` Juri Linkov
2018-12-04 7:01 ` Eli Zaretskii
2018-12-04 23:16 ` Juri Linkov
2018-12-05 7:19 ` Eli Zaretskii
2018-12-05 23:25 ` Juri Linkov
2018-12-06 6:53 ` Eli Zaretskii
2018-12-11 0:38 ` Juri Linkov
2018-12-11 6:23 ` Eli Zaretskii
2018-12-12 0:28 ` Juri Linkov
2018-12-12 17:11 ` Eli Zaretskii
2018-12-03 23:59 ` Juri Linkov
2018-12-04 7:36 ` Eli Zaretskii
2018-12-04 23:28 ` Juri Linkov [this message]
2018-12-05 7:25 ` Eli Zaretskii
2018-12-05 23:35 ` Juri Linkov
2018-12-12 23:17 ` Juri Linkov
2018-12-14 9:13 ` Eli Zaretskii
2018-12-16 23:27 ` Juri Linkov
2018-12-17 16:13 ` Eli Zaretskii
2018-12-17 23:11 ` Juri Linkov
2018-12-18 0:14 ` Juri Linkov
2018-12-18 15:55 ` Dmitry Gutov
2018-12-18 22:35 ` Juri Linkov
2018-12-18 23:33 ` Dmitry Gutov
2018-12-19 0:11 ` Juri Linkov
2018-12-19 0:48 ` Dmitry Gutov
2018-12-19 1:35 ` Dmitry Gutov
2018-12-19 21:49 ` Juri Linkov
2018-12-19 22:50 ` Dmitry Gutov
2018-12-20 22:00 ` Juri Linkov
2018-12-24 2:29 ` Dmitry Gutov
2018-12-25 20:35 ` Juri Linkov
2018-12-25 21:15 ` Dmitry Gutov
2018-12-26 22:49 ` Juri Linkov
2018-12-26 23:16 ` Dmitry Gutov
2018-12-27 0:18 ` Juri Linkov
2018-12-27 0:45 ` Dmitry Gutov
2018-12-27 3:34 ` Eli Zaretskii
2018-12-27 3:32 ` Eli Zaretskii
2018-12-19 21:51 ` Juri Linkov
2018-12-20 0:11 ` Dmitry Gutov
2018-12-20 21:50 ` Juri Linkov
2018-12-20 1:15 ` Dmitry Gutov
2018-12-20 22:17 ` Juri Linkov
2018-12-25 20:39 ` Juri Linkov
2018-12-26 1:40 ` Dmitry Gutov
2018-12-26 22:59 ` Juri Linkov
2018-12-26 23:56 ` Dmitry Gutov
2018-12-27 20:39 ` Juri Linkov
2018-12-29 23:07 ` Juri Linkov
2018-12-30 23:07 ` Dmitry Gutov
2018-12-26 0:43 ` Dmitry Gutov
2018-12-03 11:24 ` Dmitry Gutov
2018-12-03 23:24 ` Juri Linkov
2018-12-04 0:20 ` Dmitry Gutov
2018-12-04 6:46 ` Eli Zaretskii
2018-12-04 22:58 ` Juri Linkov
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