bug#70517: 29.3; suspicious error message from compile command in Emacs 29.3

bug#70517: 29.3; suspicious error message from compile command in Emacs 29.3

[Thomas Düssel via Bug reports for GNU Emacs, the Swiss army knife of text editors]

The following error message appears in the terminal from which emacs was
started every time I use the 'compile' command:

 > emacs: writing to child signal FD: Invalid argument

The compilation itself (via make) works perfectly fine. Only this new
message is a bit annoying. And so cryptic, isn't it? It did not appear
up until the latest update.

This error message (or whatever it is) appears also, when I start emacs
from a non-X tty (Ctrl + Alt + F2) and with '-Q' option. To be precise,
it appears when I use 'M-x compile' and for longer compilation processes
it appears at the end of the compilation, not at the beginning.

Best Regards,

Tom

In GNU Emacs 29.3 (build 1, x86_64-slackware-linux-gnu, GTK+ Version
  3.24.31, cairo version 1.16.0) of 2024-03-24 built on
  z-mp.slackware.lan
Windowing system distributor 'The X.Org Foundation', version 11.0.12014000
System Description: Slackware 15.0 x86_64

Configured using:
  'configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var
  --program-prefix= --program-suffix= --mandir=/usr/man
  --infodir=/usr/info --without-gconf --without-gsettings --with-modules
  --with-x --with-x-toolkit=gtk3 --with-pdumper=no --with-dumping=unexec
  --build=x86_64-slackware-linux 'CFLAGS=-O2 -fPIC''

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM HARFBUZZ JPEG JSON LCMS2
LIBXML2 MODULES NOTIFY INOTIFY PNG RSVG SECCOMP SOUND SQLITE3 THREADS
TIFF TOOLKIT_SCROLL_BARS UNEXEC WEBP X11 XDBE XIM XINPUT2 XPM GTK3 ZLIB

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

Major mode: GNUmakefile

Minor modes in effect:
   display-line-numbers-mode: t
   windmove-mode: t
   winner-mode: t
   tooltip-mode: t
   global-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
   column-number-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:
/usr/share/emacs/29.3/lisp/textmodes/css-mode hides
~/.emacs.d/user-lisp/css-mode

Features:
(shadow sort mail-extr emacsbug message yank-media puny dired
dired-loaddefs rfc822 mml mml-sec epa derived epg rfc6068 epg-config
gnus-util text-property-search time-date mm-decode mm-bodies mm-encode
mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047
rfc2045 ietf-drums mm-util mail-prsvr mail-utils vc-git diff-mode
easy-mmode vc-dispatcher make-mode display-line-numbers buffer-move
windmove winner ring finder-inf package browse-url url url-proxy
url-privacy url-expand url-methods url-history url-cookie
generate-lisp-file url-domsuf url-util mailcap url-handlers url-parse
auth-source cl-seq eieio eieio-core cl-macs password-cache json subr-x
map byte-opt gv bytecomp byte-compile url-vars cl-loaddefs cl-lib 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 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 font-render-setting cairo
move-toolbar gtk x-toolkit xinput2 x multi-tty make-network-process
emacs)

Memory information:
((conses 16 243254 13743)
  (symbols 48 27947 2)
  (strings 32 78044 1812)
  (string-bytes 1 1836829)
  (vectors 16 26114)
  (vector-slots 8 687379 23398)
  (floats 8 62 78)
  (intervals 56 336 0)
  (buffers 976 11))

bug#70517: 29.3; suspicious error message from compile command in Emacs 29.3

[Eli Zaretskii]

> Date: Mon, 22 Apr 2024 17:55:24 +0200
> From:  Thomas Düssel via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> The following error message appears in the terminal from which emacs was
> started every time I use the 'compile' command:
> 
>  > emacs: writing to child signal FD: Invalid argument
> 
> The compilation itself (via make) works perfectly fine. Only this new
> message is a bit annoying. And so cryptic, isn't it? It did not appear
> up until the latest update.
> 
> This error message (or whatever it is) appears also, when I start emacs
> from a non-X tty (Ctrl + Alt + F2) and with '-Q' option. To be precise,
> it appears when I use 'M-x compile' and for longer compilation processes
> it appears at the end of the compilation, not at the beginning.

When a sub-process exits, Emacs writes to file descriptor which it
monitors with pselect.  This is so we don't miss SIGCHLD for some
reason.  Why in your case this write errors out with EINVAL, I don't
know.  Perhaps Paul (CC'ed) could have some ideas.

If this could happen for benign reasons, maybe we should silently
ignore these errors.

bug#70517: 29.3; suspicious error message from compile command in Emacs 29.3

[Paul Eggert]

On 2024-04-22 12:40, Eli Zaretskii wrote:
> Perhaps Paul (CC'ed) could have some ideas.

Didn't you already remove that message on the main branch in September?

https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=160b4c295d8975755d4a8cc4ba6b6b75a549ed3c

(I haven't looked into the issue.)

bug#70517: 29.3; suspicious error message from compile command in Emacs 29.3

[Eli Zaretskii]

> Date: Mon, 22 Apr 2024 12:50:20 -0700
> Cc: 70517@debbugs.gnu.org, Thomas Düssel <th.duessel@gmx.de>
> From: Paul Eggert <eggert@cs.ucla.edu>
> 
> On 2024-04-22 12:40, Eli Zaretskii wrote:
> > Perhaps Paul (CC'ed) could have some ideas.
> 
> Didn't you already remove that message on the main branch in September?
> 
> https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=160b4c295d8975755d4a8cc4ba6b6b75a549ed3c

Indeed, for completely unrelated reasons.

Thanks.

bug#70517: 29.3; suspicious error message from compile command in Emacs 29.3

[Thomas Düssel via Bug reports for GNU Emacs, the Swiss army knife of text editors]

On 4/22/24 21:40, Eli Zaretskii wrote:
>> Date: Mon, 22 Apr 2024 17:55:24 +0200
>> From:  Thomas Düssel via "Bug reports for GNU Emacs,
>>   the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
>>
>> The following error message appears in the terminal from which emacs was
>> started every time I use the 'compile' command:
>>
>>   > emacs: writing to child signal FD: Invalid argument
>>
>> The compilation itself (via make) works perfectly fine. Only this new
>> message is a bit annoying. And so cryptic, isn't it? It did not appear
>> up until the latest update.
>>
>> This error message (or whatever it is) appears also, when I start emacs
>> from a non-X tty (Ctrl + Alt + F2) and with '-Q' option. To be precise,
>> it appears when I use 'M-x compile' and for longer compilation processes
>> it appears at the end of the compilation, not at the beginning.
> When a sub-process exits, Emacs writes to file descriptor which it
> monitors with pselect.  This is so we don't miss SIGCHLD for some
> reason.  Why in your case this write errors out with EINVAL, I don't
> know.  Perhaps Paul (CC'ed) could have some ideas.
>
> If this could happen for benign reasons, maybe we should silently
> ignore these errors.

Thanks for that clarification... I received my version of 29.3 as a
regular package update
for slackware 15. My system is pimped with some 32bit libraries from
alienbob,
another distributer of slackware packages. As a user with little to no
insight in the emacs
internals I would like to know, if this error message appears on other
systems aswell and
on other slackware systems in particular. Maybe the bug-report has to go
to the slackware
package maintainer?

bug#70517: 29.3; suspicious error message from compile command in Emacs 29.3

[Eli Zaretskii]

> Date: Tue, 23 Apr 2024 00:30:41 +0200
> Cc: 70517@debbugs.gnu.org
> From: Thomas Düssel <th.duessel@gmx.de>
> 
> 
> On 4/22/24 21:40, Eli Zaretskii wrote:
> > When a sub-process exits, Emacs writes to file descriptor which it
> > monitors with pselect.  This is so we don't miss SIGCHLD for some
> > reason.  Why in your case this write errors out with EINVAL, I don't
> > know.  Perhaps Paul (CC'ed) could have some ideas.
> >
> > If this could happen for benign reasons, maybe we should silently
> > ignore these errors.
> 
> Thanks for that clarification... I received my version of 29.3 as a
> regular package update for slackware 15. My system is pimped with
> some 32bit libraries from alienbob, another distributer of slackware
> packages. As a user with little to no insight in the emacs internals
> I would like to know, if this error message appears on other systems
> aswell and on other slackware systems in particular. Maybe the
> bug-report has to go to the slackware package maintainer?

Please do report to them, it cannot possibly do any harm.  When you
do, please ask them to tell us here whether this could be caused by
some downstream change they made in Emacs, or by some of the libraries
you have installed.

Thanks.

bug#70517: 29.3; suspicious error message from compile command in Emacs 29.3

[Eli Zaretskii]

> Date: Wed, 24 Apr 2024 15:36:57 +0200
> From: Thomas Düssel <th.duessel@gmx.de>
> 
> I asked on linuxquestions.org for this. Difficulties with the emacs
> build seem to have a tradition on slackware.
> 
> Solutions are offered in customized build scripts but this is far beyond
> my scope of interest so I decided to stick with an alias dumping error
> messages to /dev/null.

OK, I'm therefore closing the bug, as in Emacs 30 this message will
not happen even if you don't redirect.