Subject: xref next-error breaks with with-selected-window in next-error-hook
From: Jonathan Kotta <[email-masked]>
To: [email-masked]
Date: Wed, 25 Oct 2017 11:17:04 -0500
List-Id: <debbugs-submit.debbugs.gnu.org>

Evaluate:

(defun jpk/next-error-hook ()
  (let ((win (get-buffer-window next-error-last-buffer)))
    (when (window-live-p win)
      (with-selected-window win ;; breaks with xref
        (message "window: %s" win)))))
(add-hook 'next-error-hook #'jpk/next-error-hook)

Run xref-find-references on e.g. add-hook
Run next-error or previous-error at least twice.

Repeating next-error doesn't find the next match after the 2nd invocation.
Running previous-error behaves similarly.  I can use a mouse to click on an
any match, but next/previous-error will still only move between the clicked
match and the next.  I can only cycle between two matches.

For reference, this is my original hook:

(defun jpk/next-error-hook ()
  (let ((win (get-buffer-window next-error-last-buffer))
        (buf (buffer-name next-error-last-buffer))
        (recenter-redisplay nil))
    (when (window-live-p win)
      (with-selected-window win
        (recenter)))))

The question on Stack Exchange: https://emacs.stackexchange.com/q/36260/651

In GNU Emacs 25.3.1 (x86_64-pc-linux-gnu, X toolkit, Xaw scroll bars)
 of 2017-09-12 built on shannon
Windowing system distributor 'The X.Org Foundation', version 11.0.11905000
Configured using:
 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --with-x-toolkit=lucid --with-xft --without-gconf
 --without-gsettings --with-modules --with-gameuser=:games
 '--program-transform-name=s/^ctags$/ctags.emacs/' 'CFLAGS=-march=x86-64
 -mtune=generic -O2 -pipe -fstack-protector-strong -fno-plt'
 CPPFLAGS=-D_FORTIFY_SOURCE=2
 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS NOTIFY ACL GNUTLS
LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS LUCID X11
MODULES

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

Major mode: Emacs-Lisp

Minor modes in effect:
  diff-auto-refine-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-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
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Mark set
jpk/next-error-hook
(jpk/next-error-hook)
Quit [2 times]
Mark set
Note: file is write protected
window: #<window 7 on *xref*> [11 times]

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message dired format-spec rfc822 mml
mml-sec password-cache epg epg-config gnus-util mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail
rfc2047 rfc2045 ietf-drums mm-util help-fns mail-prsvr mail-utils pulse
semantic/symref/grep grep compile comint ansi-color semantic/symref
semantic/util-modes semantic/util semantic semantic/tag semantic/lex
semantic/fw mode-local find-func cedet vc-hg vc-git diff-mode easy-mmode
vc-bzr vc-src vc-sccs vc-svn vc-cvs vc-rcs vc vc-dispatcher thingatpt
xref cl-seq project ring eieio byte-opt bytecomp byte-compile cl-extra
help-mode easymenu cconv eieio-core cl-macs gv cl-loaddefs pcase cl-lib
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european ethiopic indian cyrillic chinese charscript case-table epa-hook
jka-cmpr-hook help simple abbrev minibuffer cl-preloaded nadvice
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sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote dbusbind inotify dynamic-setting
font-render-setting x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 121559 6089)
 (symbols 48 23516 0)
 (miscs 40 80 140)
 (strings 32 27164 5634)
 (string-bytes 1 818145)
 (vectors 16 17422)
 (vector-slots 8 491703 4664)
 (floats 8 264 116)
 (intervals 56 628 18)
 (buffers 976 21))

-- 
Thanks,

Jonathan Kotta

Hofstadter's Law:
    It always takes longer than you expect, even
    when you take into account Hofstadter's Law.