bug#3285: 23.0.91; Messaging propertized text increases minibuffer height unnecessarily

[Brent Goodrick]

Please write in English if possible, because the Emacs maintainers
usually do not have translators to read other languages for them.

Your bug report will be posted to the emacs-pretest-bug@gnu.org mailing list.

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

This defect is reported against Emacs built from CVS top of trunk source
within the last month, but this issue may have existed before then. 

Description of the defect:

Run this command from the command-line on that version of Emacs:

emacs -q --eval="(progn (message \"%s\" (let ((doc \"(SEXP)\"))
                                                (add-text-properties 1 5 (list 
'face '((t (:inherit italic)))) doc)
                                                doc))
                        (message \"minibuffer height was %d\" (window-height 
(minibuffer-window))))"

Notice that the message shows height was 1.

Do that command again, but change it to bold:

emacs -q --eval="(progn (message \"%s\" (let ((doc \"(SEXP)\"))
                                                (add-text-properties 1 5 (list 
'face '((t (:inherit bold)))) doc)
                                                doc))
                        (message \"minibuffer height was %d\" (window-height 
(minibuffer-window))))"

Notice that the height changes to 2 lines.

The maximum height of the regular sized font versus of the bold font
can NOT be so different as to cause the minibuffer have to increase in
height from 1 line to 2 lines.

The reason this is a big deal is because of eldoc mode. Enabling it
and moving the point over the first or any subsequent argument of an
Emacs Lisp function causes eldoc mode to call `message' with
propertized text that highlights the expected argument by changing the
font of that argument to be in bold font face in the text that is
displayed. But it seems that the bold font face then causes the
minibuffer to resize vertically to 2 lines instead of only 1 line. If
you are editing code in that window that is just above the minibuffer,
then the point in that window (relative to the main window) keeps
shifting around on the screen each time the cursor moves from typing
the function name to the first argument. And it gets worse when moving
around in the buffer which is visiting Elisp code, since it is likely
that the cursor crosses over functions or arguments of those functions
thus causing the minibuffer to keep changing height.

FYI, `eldoc-highlight-function-argument' is the function in
share/emacs/23.0.91/lisp/emacs-lisp/eldoc.el.gz that propertizes the
text, but the problem, in my opinion, is not with eldoc mode, but in
how emacs decides to resize the minibuffer based upon certain faces
such as the bold face.

If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    `bt full' and `xbacktrace'.
If you would like to further debug the crash, please read the file
/home/brentg/install/Linux.i686/share/emacs/23.0.91/etc/DEBUG for instructions.


In GNU Emacs 23.0.91.1 (i686-pc-linux-gnu, GTK+ Version 2.12.11)
 of 2009-02-28 on yoga
Windowing system distributor `The X.Org Foundation', version 11.0.10402000
configured using `configure  '--with-x-toolkit' '--with-xft' 
'--prefix=/home/brentg/install/Linux.i686''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default-enable-multibyte-characters: t

Major mode: Shell

Minor modes in effect:
  desktop-save-mode: t
  erc-ring-mode: t
  erc-services-mode: t
  erc-networks-mode: t
  display-time-mode: t
  shell-dirtrack-mode: t
  iswitchb-mode: t
  delete-selection-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: 1
  transient-mark-mode: t
  abbrev-mode: t

Recent input:
C-SPC C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p 
C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p 
C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p C-r 
w i n d o w - e i <backspace> <backspace> h e i g h 
t C-l C-M-u C-f C-w C-s C-/ C-s C-w C-s M-b <help-echo> 
<help-echo> C-x o C-x o C-M-u C-M-SPC C-z C-x o C-v 
C-M-p m e s s a g e SPC M-" m i n i b u f e r <backspace> 
<backspace> f e r SPC h i e <backspace> <backspace> 
e i g h t SPC i s SPC % d C-f SPC C-e C-p C-p C-p M-b 
M-b M-b M-b M-b M-f M-f M-b C-M-u C-M-SPC C-w C-v C-a 
<tab> C-e <return> <help-echo> M-P C-l C-a C-M-SPC 
C-w C-p C-f C-M-u C-M-u C-M-n C-q C-j C-v C-n C-p C-a 
C-f C-f C-f C-f C-f C-f C-f C-f C-f \ C-f C-f C-f C-f 
C-f C-f C-f C-f C-f C-f C-f C-f C-f C-f C-f C-f C-f 
C-f C-f C-f C-f C-f C-f C-f \ > <backspace> <backspace> 
\ M-> <return> M-P M-b M-b M-b M-b M-b M-b M-f M-f 
M-f M-b C-M-SPC w a s M-> <return> M-P C-p C-p C-p 
C-e C-b C-b C-b C-b C-b C-b C-b C-b C-b C-b C-b C-b 
C-b C-M-SPC i t a l i c M-> <return> M-x e m a c <tab> 
b <tab> <backspace> <backspace> <backspace> <backspace> 
<backspace> <backspace> <backspace> <backspace> <backspace> 
<backspace> <backspace> <backspace> <backspace> <backspace> 
<backspace> <backspace> <backspace> <backspace> <backspace> 
<backspace> s c <backspace> <backspace> c s - r e <tab> 
<C-backspace> r e p o r t <tab> <tab> <tab> <tab> <tab> 
<tab> e <tab> <tab> b <tab> <return>

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