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#77755
31.0.50; Synchronous man does not handle error cases properly
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This is about some deficiencies with the user option
`Man-prefer-synchronous-call', which got added in Emacs 30. So it is in
fact also a bug in Emacs 30. (Thanks to Sebastian for adding that new
option, prior to Emacs 30 I have been using my private hacks to get
synchronous man page invocations.)
Anyway, when using a non-nil value for that option, some edge/error
cases behave awkwardly:
1. ./src/emacs -Q --eval '(setq Man-prefer-synchronous-call t)'
M-x man RET foobarbaz RET
Results in the error "Can't find the foobarbaz manpage" (OK) with the
minibuffer window being selected (not OK).
The minibuffer being selected is IMO a result of the following form
from function `Man-bgproc-sentinel':
(let ((old-window (old-selected-window)))
(when (window-live-p old-window)
(select-window old-window)))
IIUC, that form (or its predecessor) got added by Juri in bug#38164,
commit 611b85b6 to keep the minibuffer selected when an async `man'
fails at the time when the user is operating in the minibuffer.
Unfortunately, that hack ensures that the minibuffer is *always*
selected if a synchronous `man' fails.
2. ./src/emacs -Q --eval '(setq Man-prefer-synchronous-call t)'
M-x man RET -k foobarbaz RET
Results in the error "Can't find the k foobarbaz manpage" (not OK),
again with the minibuffer window being selected (not OK).
With async `man' this results in the error message "-k foobarbaz: no
matches", which I consider OK.
Here the problem is IMO that the following branch to detect failing
"man -k" calls in function `Man-bgproc-sentinel':
((and (string-match "\\(\\`\\|\\s-\\)-k\\s-" Man-arguments)
(eq (process-status process) 'exit)
(= (process-exit-status process) 0)
(= (point-min) (point-max)))
(setq message (format "%s: no matches" Man-arguments)
delete-buff t))
never gets selected in the synchronous case since the `(eq
(process-status process) 'exit)' form always evaluates to nil for
that case.
The attached tentative patch would fix both issues.
What do you think?
In GNU Emacs 31.0.50 (build 25, x86_64-pc-linux-gnu, GTK+ Version
3.24.38, cairo version 1.16.0) of 2025-04-11 built on sappc2
Repository revision: 695edc5b55bec645fe2df8924513826b202022b6
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12201009
System Description: Debian GNU/Linux 12 (bookworm)
Configured using:
'configure --with-native-compilation --with-mailutils'
Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES NATIVE_COMP
NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND THREADS TIFF
TOOLKIT_SCROLL_BARS WEBP X11 XDBE XIM XINERAMA XINPUT2 XPM XRANDR GTK3
ZLIB
Important settings:
value of $LC_COLLATE: POSIX
value of $LC_TIME: POSIX
value of $LANG: en_US.UTF-8
value of $XMODIFIERS: @im=ibus
locale-coding-system: utf-8-unix
Major mode: Lisp Interaction
Minor modes in effect:
tooltip-mode: t
global-eldoc-mode: t
eldoc-mode: t
show-paren-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
minibuffer-regexp-mode: t
line-number-mode: t
indent-tabs-mode: t
transient-mark-mode: t
auto-composition-mode: t
auto-encryption-mode: t
auto-compression-mode: t
Load-path shadows:
None found.
Features:
(shadow sort mail-extr comp-run bytecomp byte-compile comp-common rx
emacsbug lisp-mnt message mailcap yank-media puny dired dired-loaddefs
rfc822 mml mml-sec password-cache epa derived epg rfc6068 epg-config
gnus-util text-property-search time-date subr-x mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader cl-loaddefs
cl-lib sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils
rmc iso-transl tooltip cconv eldoc paren electric uniquify ediff-hook
vc-hooks lisp-float-type elisp-mode mwheel term/x-win x-win
term/common-win x-dnd touch-screen tool-bar dnd fontset image regexp-opt
fringe tabulated-list replace newcomment text-mode lisp-mode prog-mode
register page tab-bar menu-bar rfn-eshadow isearch easymenu timer select
scroll-bar mouse jit-lock font-lock syntax font-core term/tty-colors
frame minibuffer nadvice seq simple cl-generic indonesian philippine
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 emoji-zwj charscript
charprop case-table epa-hook jka-cmpr-hook help abbrev obarray oclosure
cl-preloaded button loaddefs theme-loaddefs faces cus-face macroexp
files window text-properties overlay sha1 md5 base64 format env
code-pages mule custom widget keymap hashtable-print-readable backquote
threads dbusbind inotify lcms2 dynamic-setting system-font-setting
font-render-setting cairo gtk x-toolkit xinput2 x multi-tty move-toolbar
make-network-process tty-child-frames native-compile emacs)
Memory information:
((conses 16 58466 9024) (symbols 48 6197 0) (strings 32 15326 1600)
(string-bytes 1 470967) (vectors 16 9931)
(vector-slots 8 139569 9476) (floats 8 22 13) (intervals 56 242 0)
(buffers 984 10))
[0001-Better-handle-errors-after-sync-man-invocations.patch (text/x-patch, attachment)]
This bug report was last modified 32 days ago.
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Copyright (C) 1999 Darren O. Benham,
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1994-97 Ian Jackson.