GNU bug report logs - #78269
diff-outline-regexp

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Juri Linkov <juri <at> linkov.net>
To: bug-gnu-emacs <at> gnu.org
Subject: diff-outline-regexp
Date: Mon, 05 May 2025 22:10:25 +0300

I noticed that 'diff-setup-buffer-type' overrides the default value
of 'diff-outline-regexp'.  Here is the fix:

diff --git a/lisp/vc/diff-mode.el b/lisp/vc/diff-mode.el
index a5f4169a7f3..76703526b63 100644
--- a/lisp/vc/diff-mode.el
+++ b/lisp/vc/diff-mode.el
@@ -1719,7 +1719,7 @@ diff-setup-buffer-type
                       'hg
                     nil))))
   (when (eq diff-buffer-type 'git)
-    (setq diff-outline-regexp
+    (setq-local diff-outline-regexp
           (concat "\\(^diff --git.*\\|" diff-hunk-header-re "\\)")))
   (setq-local outline-level #'diff--outline-level)
   (setq-local outline-regexp diff-outline-regexp))

Probably no one noticed this problem because its current default value
is not useful to anyone:

  (defvar diff-outline-regexp
    "\\([*+][*+][*+] [^0-9]\\|@@ ...\\|\\*\\*\\* [0-9].\\|--- [0-9]..\\)")

Maybe the default should be replaced with something like

  (defvar diff-outline-regexp
    (concat "\\(^diff -.*\\|" diff-hunk-header-re "\\)"))

that is useful for file-based diff.  Or maybe the value for file-based diff
should be set in 'diff-no-select' like this?

diff --git a/lisp/vc/diff.el b/lisp/vc/diff.el
index c8a1b7c0efa..62c4ba6d302 100644
--- a/lisp/vc/diff.el
+++ b/lisp/vc/diff.el
@@ -196,6 +196,9 @@ diff-no-select
 	(erase-buffer))
       (buffer-enable-undo (current-buffer))
       (diff-mode)
+      (setq-local diff-outline-regexp
+                  (concat "\\(^" diff-command ".*\\|" diff-hunk-header-re "\\)")
+                  outline-regexp diff-outline-regexp)
       (setq-local revert-buffer-function
                   (lambda (_ignore-auto _noconfirm)
                     (diff-no-select old new switches no-async (current-buffer))))

But I might be missing more use cases.

Message #8 received at 78269 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Juri Linkov <juri <at> linkov.net>
Cc: 78269 <at> debbugs.gnu.org
Subject: Re: bug#78269: diff-outline-regexp
Date: Mon, 05 May 2025 18:42:07 -0400

> diff --git a/lisp/vc/diff-mode.el b/lisp/vc/diff-mode.el
> index a5f4169a7f3..76703526b63 100644
> --- a/lisp/vc/diff-mode.el
> +++ b/lisp/vc/diff-mode.el
> @@ -1719,7 +1719,7 @@ diff-setup-buffer-type
>                        'hg
>                      nil))))
>    (when (eq diff-buffer-type 'git)
> -    (setq diff-outline-regexp
> +    (setq-local diff-outline-regexp
>            (concat "\\(^diff --git.*\\|" diff-hunk-header-re "\\)")))
>    (setq-local outline-level #'diff--outline-level)
>    (setq-local outline-regexp diff-outline-regexp))

LGTM, thanks.

> Probably no one noticed this problem because its current default value
> is not useful to anyone:
>
>   (defvar diff-outline-regexp
>     "\\([*+][*+][*+] [^0-9]\\|@@ ...\\|\\*\\*\\* [0-9].\\|--- [0-9]..\\)")

I think the idea was to recognize file header and hunk headers, in the
case where the "diff" command itself is absent (as is the case in the
output of the (non-recursive) `diff` command).

> Maybe the default should be replaced with something like
>
>   (defvar diff-outline-regexp
>     (concat "\\(^diff -.*\\|" diff-hunk-header-re "\\)"))

LGTM (I'd even drop the `-` after `diff`).  AFAICT nowadays the "diff
..." command is absent only in cases where there's only one file in the
diff, so matching the file header is not very useful, indeed.


        Stefan

Message #11 received at 78269 <at> debbugs.gnu.org (full text, mbox):

From: Juri Linkov <juri <at> linkov.net>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: 78269 <at> debbugs.gnu.org
Subject: Re: bug#78269: diff-outline-regexp
Date: Wed, 07 May 2025 09:31:20 +0300

close 78269 31.0.50
thanks

>> -    (setq diff-outline-regexp
>> +    (setq-local diff-outline-regexp
>
> LGTM, thanks.
>
>> Probably no one noticed this problem because its current default value
>> is not useful to anyone:
>>
>>   (defvar diff-outline-regexp
>>     "\\([*+][*+][*+] [^0-9]\\|@@ ...\\|\\*\\*\\* [0-9].\\|--- [0-9]..\\)")
>
> I think the idea was to recognize file header and hunk headers, in the
> case where the "diff" command itself is absent (as is the case in the
> output of the (non-recursive) `diff` command).
>
>> Maybe the default should be replaced with something like
>>
>>   (defvar diff-outline-regexp
>>     (concat "\\(^diff -.*\\|" diff-hunk-header-re "\\)"))
>
> LGTM (I'd even drop the `-` after `diff`).  AFAICT nowadays the "diff
> ..." command is absent only in cases where there's only one file in the
> diff, so matching the file header is not very useful, indeed.

So now pushed.

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