bug#50370: Fix bug in ispell-init-process error handling

[Ian W <ian@wahbe.com>]

[-- Attachment #1.1: Type: text/plain, Size: 2019 bytes --]

This fixes the error handling in ispell-init-process. I encountered this bug, and also saw it mentioned here: https://mail.gnu.org/archive/html/auctex/2021-08/msg00007.html

The previous behavior involved the ispell process terminating
prematurely (correct behavior, invalid input) and then calling
ispell-accept-output. Because ispell-process had terminated,
ispell-accept-output threw its own error, which prevented the underlying
error from being displayed.

The bug resulted in the following interaction:
ispell-word would print out:
"Starting new Ispell process aspell with default dictionary...done"
"ispell-accept-output: No Ispell process to read output from!"

The correct behavior is:
"Starting new Ispell process aspell with default dictionary...done"
"cond: Error: ~/.emacs.d/.local/etc/ispell/.pws: The language "nil" is not known. This is probably because: the file "/usr/local/Cellar/aspell/0.60.8/lib/aspell-0.60/nil.dat" can not be opened for reading.""


In GNU Emacs 28.0.50 (build 1, x86_64-apple-darwin20.5.0, NS appkit-2022.50 Version 11.4 (Build 20F71))
 of 2021-08-15 built on Ians-MacBook-Pro-2.local
Windowing system distributor 'Apple', version 10.3.2022
System Description: macOS 11.5.2

Configured using:
 'configure --disable-dependency-tracking --disable-silent-rules
 --enable-locallisppath=/usr/local/share/emacs/site-lisp
 --infodir=/usr/local/Cellar/emacs-plus@28/28.0.50/share/info/emacs
 --prefix=/usr/local/Cellar/emacs-plus@28/28.0.50 --with-xml2
 --with-gnutls --with-native-compilation --without-dbus
 --with-imagemagick --with-modules --with-rsvg --with-xwidgets --with-ns
 --disable-ns-self-contained 'CFLAGS=-I/usr/local/opt/gcc/include
 -I/usr/local/opt/libgccjit/include -I/usr/local/opt/gmp/include
 -I/usr/local/opt/jpeg/include' 'LDFLAGS=-L/usr/local/lib/gcc/11
 -I/usr/local/opt/gcc/include -I/usr/local/opt/libgccjit/include
 -I/usr/local/opt/gmp/include -I/usr/local/opt/jpeg/include''

The patch is attached.

Ian

[-- Attachment #1.2: Type: text/html, Size: 2633 bytes --]

[-- Attachment #2: patch --]
[-- Type: application/octet-stream, Size: 977 bytes --]

diff --git a/lisp/textmodes/ispell.el b/lisp/textmodes/ispell.el
index c2f6b35df8..ce0653c434 100644
--- a/lisp/textmodes/ispell.el
+++ b/lisp/textmodes/ispell.el
@@ -2923,7 +2923,13 @@ Keeps argument list for future Ispell invocations for no async support."
 	     ;; But first wait to see if some more output is going to arrive.
 	     ;; Otherwise we get cool errors like "Can't open ".
 	     (sleep-for 1)
-	     (ispell-accept-output 3)
+             ;; To avoid `ispell-accept-output' throwing it's own
+             ;; error, we check that it will receive from a valid
+             ;; process.
+	     (when (if ispell-async-processp
+                         (process-live-p ispell-process)
+                       ispell-process)
+               (ispell-accept-output 3))
 	     (error "%s" (mapconcat #'identity ispell-filter "\n"))))
       (setq ispell-filter nil)		; Discard version ID line
       (let ((extended-char-mode (ispell-get-extended-character-mode)))