bug#68547: [PATCH] ; Fix 'mode-line-format-right-align' with ElDoc

[Eshel Yaron via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

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João Távora <joaotavora@gmail.com> writes:

> On Sat, Jan 20, 2024 at 9:57 AM Eli Zaretskii <eliz@gnu.org> wrote:
>>
>> > Date: Wed, 17 Jan 2024 20:44:04 +0100
>> > From:  Eshel Yaron via "Bug reports for GNU Emacs,
>> >  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
>> >
>> > Tags: patch
>> >
>> > The new mode line right alignment requires setting `mode-line-format` to
>> > a list that contains (as in `memq`) the symbol
>> > `mode-line-format-right-align`.  This is a bit brittle, and currently
>> > `eldoc-minibuffer-message` modifies `mode-line-format` in a way that
>> > happens to break `mode-line-format-right-align`.  To see that, set
>> > `mode-line-format` to '("" mode-line-format-right-align "foo bar") and
>> > then type `M-: (list`.  Now ElDoc info appears on the mode line, but
>> > "bar" is no longer visible.
>> >
>> > This patch makes ElDoc modify `mode-line-format` in an equivalent way
>> > that avoids messing with `mode-line-format-right-align`.
>>
>> Thanks.
>>
>> João, any objections or comments?
>
> I think it looks good.  I just think the patch is a little
> too newline friendly, i.e. the if can probably fit in a single
> line without reaching 80 columns and it'll make it easier to
> read.

Yes, it fits nicely.  See updated patch below.


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From 9c69e20ed172a2bfa56056a62077ae1c68b9b979 Mon Sep 17 00:00:00 2001
From: Eshel Yaron <me@eshelyaron.com>
Date: Mon, 1 Jan 2024 22:14:59 +0100
Subject: [PATCH v2] ; Fix 'mode-line-format-right-align' with ElDoc
 (Bug#68547)

* lisp/emacs-lisp/eldoc.el (eldoc-minibuffer-message): Avoid nesting
'mode-line-format', since that breaks 'mode-line-format-right-align'.
---
 lisp/emacs-lisp/eldoc.el | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/lisp/emacs-lisp/eldoc.el b/lisp/emacs-lisp/eldoc.el
index 06970d40e8a..912a7357ca7 100644
--- a/lisp/emacs-lisp/eldoc.el
+++ b/lisp/emacs-lisp/eldoc.el
@@ -312,9 +312,11 @@ eldoc-minibuffer-message
                      (not (and (listp mode-line-format)
                                (assq 'eldoc-mode-line-string mode-line-format))))
 	    (setq mode-line-format
-		  (list "" '(eldoc-mode-line-string
-			     (" " eldoc-mode-line-string " "))
-			mode-line-format)))
+                  (funcall
+                   (if (listp mode-line-format) #'append #'list)
+                   (list "" '(eldoc-mode-line-string
+			      (" " eldoc-mode-line-string " ")))
+                   mode-line-format)))
           (setq eldoc-mode-line-string
                 (when (stringp format-string)
                   (apply #'format-message format-string args)))
-- 
2.42.0