Source: Avoid out-of-range inputs to std::isspace()

`isspace` takes `int` but documents that the value must be representable
by `unsigned char`, or be EOF.  Use a wrapper to cast to `unsigned char`
to avoid sign extension while converting to `int`.  This generalizes the
fix from commit 5e8c176e2a (cmExecuteProcessCommand: Cast c to unsigned
char before cast to int, 2024-01-05) to other `isspace` call sites.

This was detected by assertions in the MSVC standard library while
processing UTF-8 text.

Issue: #25561

1 files changed, 1 insertions, 6 deletions

diff --git a/Source/cmExecuteProcessCommand.cxx b/Source/cmExecuteProcessCommand.cxx
index 483a601..da6def9 100644
--- a/Source/cmExecuteProcessCommand.cxx
+++ b/Source/cmExecuteProcessCommand.cxx
@@ -2,7 +2,6 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmExecuteProcessCommand.h"
 
-#include <cctype> /* isspace */
 #include <cstdint>
 #include <cstdio>
 #include <iostream>
@@ -35,11 +34,7 @@
 namespace {
 bool cmExecuteProcessCommandIsWhitespace(char c)
 {
-  // isspace takes 'int' but documents that the value must be representable
-  // by 'unsigned char', or EOF.  Cast to 'unsigned char' to avoid sign
-  // extension while casting to 'int'.
-  return (isspace(static_cast<int>(static_cast<unsigned char>(c))) ||
-          c == '\n' || c == '\r');
+  return (cmIsSpace(c) || c == '\n' || c == '\r');
 }
 
 void cmExecuteProcessCommandFixText(std::vector<char>& output,