bug#73307: Fix ctype(3) usage

[Thomas Klausner <wiz@gatalith.at>]

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Tags: patch


When compiling emacs on NetBSD-10.99.12/amd64, I get the following
warning

In file included from /usr/include/ctype.h:100,
                 from fns.c:29:
fns.c: In function 'Fyes_or_no_p':
fns.c:3582:33: warning: array subscript has type 'char' [-Wchar-subscripts]
 3582 |     if ((len > 0) && !isspace (s[len - 1]))
      |                                 ^

The NetBSD man page for ctype(3): https://man.netbsd.org/ctype.3
is quite explicit about the problems with this - ctype(3) functions only
accept -1 and "unsigned char" and you can get very weird problems if
this is disregarded.

The attached patch adds the missing cast.


In GNU Emacs 31.0.50 (build 1, x86_64--netbsd, GTK+ Version 3.24.43,
 cairo version 1.18.0) of 2024-09-16
Repository revision: f27553c30a772a0103d2e6762e4d7f588f302e4b
Repository branch: HEAD
System Description: NetBSD 10.99.12/amd64

Configured using:
 'configure --srcdir=/scratch/wip/emacs-git/work/emacs
 --localstatedir=/var --with-native-compilation --without-ns
 --without-imagemagick --without-xaw3d --with-x-toolkit=gtk3
 --prefix=/usr/pkg --build=x86_64--netbsd --host=x86_64--netbsd
 --infodir=/usr/pkg/info --mandir=/usr/pkg/man
 --enable-option-checking=yes 'CFLAGS=-O2 -g -g -fstack-clash-protection
 -I/usr/pkg/include -I/usr/include -I/usr/pkg/include/freetype2
 -I/usr/pkg/include/glib-2.0 -I/usr/pkg/include/gio-unix-2.0
 -I/usr/pkg/lib/glib-2.0/include -I/usr/pkg/include/harfbuzz
 -I/usr/pkg/include/libdrm' 'CPPFLAGS=-g -I/usr/pkg/include
 -I/usr/include -I/usr/pkg/include/freetype2 -I/usr/pkg/include/glib-2.0
 -I/usr/pkg/include/gio-unix-2.0 -I/usr/pkg/lib/glib-2.0/include
 -I/usr/pkg/include/harfbuzz -I/usr/pkg/include/libdrm'
 'LDFLAGS=-Wl,-R/usr/pkg/gcc14/lib -Wl,-zrelro -Wl,-znow -L/usr/pkg/lib
 -Wl,-R/usr/pkg/lib -L/usr/lib -Wl,-R/usr/lib''


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$NetBSD$

Fix ctype(3) usage.

--- src/fns.c.orig	2024-09-16 21:11:40.908684144 +0000
+++ src/fns.c
@@ -3579,7 +3579,7 @@ by a mouse, or by some window-system ges
   {
     char *s = SSDATA (prompt);
     ptrdiff_t len = strlen (s);
-    if ((len > 0) && !isspace (s[len - 1]))
+    if ((len > 0) && !isspace ((unsigned char)s[len - 1]))
       prompt = CALLN (Fconcat, prompt, build_string (" "));
   }
   prompt = CALLN (Fconcat, prompt, Vyes_or_no_prompt);