bug#43126: 26.1; ansi-term not resized after X window resize

[Soumendra Ganguly]

Issue: ansi-term does not adjust the "terminal size" when the "emacs X
window"/frame is resized. Here "terminal size" refers to "struct winsize"/
"stty size"/"${COLUMNS}+${LINES}". As a result, say, output of ls(1)
becomes hard to parse visually. The bug was discovered on i3wm, which
is a tiling window manager, where X window size updates are frequent.

Reason: When the frame is resized, the window size changes, but processes
running in buffers are not notified of that change.

Fix: In lisp/window.el, add window--adjust-process-windows to
window-size-change-functions. Patch implementing proposed fix
follows.

Signed-off-by: Soumendra Ganguly <soumendr...@gmail.com>
---

--- emacs/lisp/window.el 2020-08-30 17:00:47.763965814 -0500
+++ window.el 2020-08-30 16:52:39.053035140 -0500
@@ -10166,6 +10166,11 @@
(when size
(set-process-window-size process (cdr size) (car size))))))))))

+(defun frame-resize-adjust-process-windows (frame)
+ (window--adjust-process-windows))
+
+(add-hook 'window-size-change-functions 'frame-resize-adjust-process-windows)
+
(add-hook 'window-configuration-change-hook 'window--adjust-process-windows)

;; Some of these are in tutorial--default-keys, so update that if you

---

In GNU Emacs 26.1 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.5)
of 2019-09-22, modified by Debian built on x86-grnet-01
Windowing system distributor 'The X.Org Foundation', version 11.0.12004000
System Description: Debian GNU/Linux 10 (buster)

Recent messages:
Loading /etc/emacs/site-start.d/50dictionaries-common.el (source)...
Loading debian-ispell...
Loading /var/cache/dictionaries-common/emacsen-ispell-default.el (source)...done
Loading debian-ispell...done
Loading /var/cache/dictionaries-common/emacsen-ispell-dicts.el (source)...done
Loading /etc/emacs/site-start.d/50dictionaries-common.el (source)...done
For information about GNU Emacs and the GNU system, type C-h C-a.
funcall-interactively: End of buffer [7 times]
delete-backward-char: Text is read-only
funcall-interactively: End of buffer

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/26.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/26.1/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/26.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/26.1/site-lisp:/usr/share/emacs/site-lisp
--with-sound=alsa --without-gconf --with-mailutils --with-x=yes
--with-x-toolkit=gtk3 --with-toolkit-scroll-bars 'CFLAGS=-g -O2
-fdebug-prefix-map=/build/emacs-StqULU/emacs-26.1+1=. -fstack-protector-strong
-Wformat -Werror=format-security -Wall' 'CPPFLAGS=-Wdate-time
-D_FORTIFY_SOURCE=2' LDFLAGS=-Wl,-z,relro'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY
ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 THREADS LIBSYSTEMD LCMS2

Important settings:
value of $LANG: en_US.UTF-8
locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
tooltip-mode: t
global-eldoc-mode: t
eldoc-mode: t
mouse-wheel-mode: t
file-name-shadow-mode: t
global-font-lock-mode: t
font-lock-mode: t
blink-cursor-mode: t
auto-composition-mode: t
auto-encryption-mode: t
auto-compression-mode: t
column-number-mode: t
line-number-mode: t
transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
format-spec rfc822 mml mml-sec epa derived epg gnus-util rmail
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cl-macs eieio-loaddefs password-cache url-vars seq byte-opt gv bytecomp
byte-compile cconv edmacro kmacro cl-loaddefs cl-lib wheatgrass-theme
time-date mule-util tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel term/x-win x-win term/common-win x-dnd tool-bar
dnd fontset image regexp-opt fringe tabulated-list replace newcomment
text-mode elisp-mode lisp-mode prog-mode register page menu-bar
rfn-eshadow isearch timer select scroll-bar mouse jit-lock font-lock
syntax facemenu font-core term/tty-colors frame cl-generic cham georgian
utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
japanese eucjp-ms cp51932 hebrew greek romanian slovak czech european
ethiopic indian cyrillic chinese composite charscript charprop
case-table epa-hook jka-cmpr-hook help simple abbrev obarray minibuffer
cl-preloaded nadvice loaddefs button faces cus-face macroexp files
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote dbusbind inotify lcms2
dynamic-setting system-font-setting font-render-setting move-toolbar gtk
x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 108184 12008)
(symbols 48 21948 1)
(miscs 40 45 65)
(strings 32 32721 1100)
(string-bytes 1 870341)
(vectors 16 17036)
(vector-slots 8 524671 3932)
(floats 8 50 290)
(intervals 56 266 0)
(buffers 992 11))

[Robert Pluim]

>>>>> On Sun, 30 Aug 2020 17:39:37 -0500, Soumendra Ganguly <soumendr...@gmail.com> said:

Soumendra> Issue: ansi-term does not adjust the "terminal size" when the "emacs X
Soumendra> window"/frame is resized. Here "terminal size" refers to "struct winsize"/
Soumendra> "stty size"/"${COLUMNS}+${LINES}". As a result, say, output of ls(1)
Soumendra> becomes hard to parse visually. The bug was discovered on i3wm, which
Soumendra> is a tiling window manager, where X window size updates are frequent.

Soumendra> Reason: When the frame is resized, the window size changes, but processes
Soumendra> running in buffers are not notified of that change.

Soumendra> Fix: In lisp/window.el, add window--adjust-process-windows to
Soumendra> window-size-change-functions. Patch implementing proposed fix
Soumendra> follows.

Could you check 26.3? As far as I can tell this issue was already
fixed there.

Robert