bug#54430: 27.1; alignment error in read-multiple-choice

bug#54430: 27.1; alignment error in read-multiple-choice

[Felician Nemeth]

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Evaluate the following expression, then ask for help with ?.

(read-multiple-choice  "Choose:"
		       '((?a "aaa")
			 (?b "bbb")
			 (?c "ccc" "a really long description of ccc")))

The description of choice "ccc" is misaligned in the help buffer:
------
Choose:

a: aaa                   b: bbb                   c: ccc
                                                  a really long
description of ccc
------

I expect the help buffer to look something like this:
------
Choose:

a: aaa                   b: bbb                   c: ccc
                                                  a really long
                                                  description of ccc
------

The patch below solves the problem, but I'm sure, it can be improved.
Additionally, I've attempted to write a test for this.

Thanks.


[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: rmc.patch --]
[-- Type: text/x-diff, Size: 2192 bytes --]

diff --git a/lisp/emacs-lisp/rmc.el b/lisp/emacs-lisp/rmc.el
index bedf598d44..63ef8929cd 100644
--- a/lisp/emacs-lisp/rmc.el
+++ b/lisp/emacs-lisp/rmc.el
@@ -188,9 +188,15 @@ read-multiple-choice
                       (goto-char start)
                       (dolist (line (split-string text "\n"))
                         (end-of-line)
-                        (if (bolp)
-                            (insert line "\n")
-                          (insert line))
+                        (if (not (bolp))
+			    (insert line)
+			  (insert (make-string
+                                   (max (- (* (mod (1- times) columns)
+                                              (+ fill-column 4))
+                                           (current-column))
+                                        0)
+				   ?\s))
+                          (insert line "\n"))
                         (forward-line 1)))))))))))
     (when (buffer-live-p buf)
       (kill-buffer buf))
diff --git a/test/lisp/emacs-lisp/rmc-tests.el b/test/lisp/emacs-lisp/rmc-tests.el
index 9d8f3d4801..ec30026199 100644
--- a/test/lisp/emacs-lisp/rmc-tests.el
+++ b/test/lisp/emacs-lisp/rmc-tests.el
@@ -38,6 +38,26 @@ test-read-multiple-choice
       (should (equal (list char str)
                      (read-multiple-choice "Do it? " '((?y "yes") (?n "no"))))))))
 
+(ert-deftest test-read-multiple-choice-help ()
+  (let ((chars '(?? ?a))
+        help)
+    (cl-letf* (((symbol-function #'read-event)
+                (lambda ()
+                  (when (= 1 (length chars))
+                    (with-current-buffer "*Multiple Choice Help*"
+                      (setq help (buffer-string))))
+                  (pop chars))))
+      (read-multiple-choice
+       "Choose:"
+       '((?a "aaa")
+	 (?b "bbb")
+	 (?c "ccc" "a really long description of ccc")))
+      (should (equal help "Choose:\n
+a: aaa                   b: bbb                   c: ccc\n\
+                                                  a really long\n\
+                                                  description of ccc\n\
+                                                  \n\
+")))))
 
 (provide 'rmc-tests)
 ;;; rmc-tests.el ends here

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Configured using:
 'configure --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --enable-libsystemd --with-pop=yes
 --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/27.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/27.1/site-lisp:/usr/share/emacs/site-lisp
 --with-sound=alsa --without-gconf --with-mailutils --build
 x86_64-linux-gnu --prefix=/usr --sharedstatedir=/var/lib
 --libexecdir=/usr/lib --localstatedir=/var/lib
 --infodir=/usr/share/info --mandir=/usr/share/man --enable-libsystemd
 --with-pop=yes
 --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/27.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/27.1/site-lisp:/usr/share/emacs/site-lisp
 --with-sound=alsa --without-gconf --with-mailutils --with-cairo
 --with-x=yes --with-x-toolkit=gtk3 --with-toolkit-scroll-bars
 'CFLAGS=-g -O2
 -ffile-prefix-map=/build/emacs-LlFm6W/emacs-27.1+1=. -fstack-protector-strong
 -Wformat -Werror=format-security -Wall' 'CPPFLAGS=-Wdate-time
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Configured features:
XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND GPM DBUS GSETTINGS GLIB NOTIFY
INOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE HARFBUZZ M17N_FLT LIBOTF
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Important settings:
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  value of $LC_TIME: hu_HU.UTF-8
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Load-path shadows:
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Memory information:
((conses 16 52259 7417)
 (symbols 48 6637 1)
 (strings 32 17703 2137)
 (string-bytes 1 565498)
 (vectors 16 10893)
 (vector-slots 8 138879 11136)
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 (intervals 56 497 4)
 (buffers 1000 14))

bug#54430: 27.1; alignment error in read-multiple-choice

[Lars Ingebrigtsen]

Felician Nemeth <felician.nemeth@gmail.com> writes:

> The patch below solves the problem, but I'm sure, it can be improved.
> Additionally, I've attempted to write a test for this.

Thanks; applied to Emacs 29 (with some changes as the formatting has
been altered).

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no