https://github.com/libconfuse/libconfuse/commit/dc7cef956d6d7c1ec792f9561f732797b52e92d4
From: Thomas Klausner <wiz@gatalith.at>
Date: Mon, 5 May 2025 23:22:51 +0200
Subject: [PATCH] Fix isspace() arguments.

Per ANSI and POSIX, isspace() only accepts arguments that
are valid 'unsigned char' or EOF.

The code passed 'char' arguments, which on many platforms are
'signed char'. These are automatically promoted to integers, keeping
the sign, so negative values like -61 are passed to isspace(),
which is not allowed per the standards.

Casting to 'unsigned char' makes sure the isspace argument is in the
allowed range.

Fixes core dump e.g. in i3status.

Closes #180.
--- a/src/lexer.l
+++ b/src/lexer.l
@@ -397,14 +397,14 @@ static char *trim_whitespace(char *str, unsigned int len)
 	return str;

     while (len > 1) {
-	if ((str[len] == 0 || isspace(str[len])) && isspace(str[len - 1]))
+	if ((str[len] == 0 || isspace((unsigned char)str[len])) && isspace((unsigned char)str[len - 1]))
 	    len--;
 	else
 	    break;
     }
     str[len] = 0;

-    while (isspace(*str))
+    while (isspace((unsigned char)*str))
 	str++;

     return str;