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bug#20445: excessive redisplay / echo area resizing during byte-compilat
From: |
Eli Zaretskii |
Subject: |
bug#20445: excessive redisplay / echo area resizing during byte-compilation |
Date: |
Tue, 28 Apr 2015 18:13:25 +0300 |
> From: Glenn Morris <rgm@gnu.org>
> Date: Mon, 27 Apr 2015 17:31:28 -0400
>
> Does not happen with M-x byte-recompile-file.
If you invoke byte-compile-file like this:
M-: (byte-compile-file "org.el") RET
then it flickers exactly like with the menu-bar invocation. Which is
expected, since the menu bar invokes emacs-lisp-byte-compile, which
does this:
(defun emacs-lisp-byte-compile ()
"Byte compile the file containing the current buffer."
(interactive)
(if buffer-file-name
(byte-compile-file buffer-file-name)
(error "The buffer must be saved in a file first")))
The difference between "M-x byte-compile-file" and the invocation via
M-: seems to be due to this trick in bytecomp.el:
(defun byte-compile--message (format &rest args)
"Like `message', except sometimes don't print to minibuffer.
If the variable `byte-compile--interactive' is nil, the message
is not displayed on the minibuffer."
(apply #'message format args)
(unless byte-compile--interactive
(message nil)))
And indeed, if I invoke byte-compile-file like this:
M-: (let ((byte-compile--interactive t)) (byte-compile-file "org.el")) RET
the flickering goes away.
Now to the source of the flickering: it's the resizing of the echo
area that causes that. We have this code in echo_area_display:
window_height_changed_p = display_echo_area (w);
[...]
if (window_height_changed_p <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
/* Don't do this if Emacs is shutting down. Redisplay
needs to run hooks. */
&& !NILP (Vrun_hooks))
{
/* Must update other windows. Likewise as in other
cases, don't let this update be interrupted by
pending input. */
ptrdiff_t count = SPECPDL_INDEX ();
specbind (Qredisplay_dont_pause, Qt);
windows_or_buffers_changed = 44; <<<<<<<<<<<<<<<<<<<<<<
redisplay_internal ();
And a non-zero value of windows_or_buffers_changed causes a thorough
redisplay, including, for example, the mode lines, the menu bar and
the scroll bars.
If I set resize-mini-windows to nil, the flickering disappears.
I think what causes the frequent resizes of the echo area are those
calls to (message nil) in byte-compile--message. Perhaps avoiding
that would resolve the issue.
Otherwise, I guess I'll have to say that this is the display engine
"functioning as designed".
> Does not happen with 24.5, even with the menu-bar.
The trick with byte-compile--message and byte-compile--interactive is
new on master, it didn't exist in Emacs 24.
bug#20445: excessive redisplay / echo area resizing during byte-compilation,
Eli Zaretskii <=
bug#20445: excessive redisplay / echo area resizing during byte-compilation, Artur Malabarba, 2015/04/29
bug#20445: excessive redisplay / echo area resizing during byte-compilation, Eli Zaretskii, 2015/04/29
bug#20445: excessive redisplay / echo area resizing during byte-compilation, Artur Malabarba, 2015/04/29
bug#20445: excessive redisplay / echo area resizing during byte-compilation, Artur Malabarba, 2015/04/29