Add a script to check if <ctype> is included before <algorithm>

scripts/verify-ctype-algorithm-include-order.sh

@@ -0,0 +1,63 @@
+#!/bin/bash
+
+# Copyright (C) 2020  Kevin Croft <krcroft@gmail.com>
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# This script checks if <ctype> is included before <algorithm> by
+# querying records written by the dump-preprocessor-defines.sh
+# script.  It prints details and returns a non-zero exit code to
+# the shell if it detects one or more incorrect include orders.
+#
+# See the following discussions for why this script exists:
+# - https://travisdowns.github.io/blog/2019/11/19/toupper.html
+# - https://news.ycombinator.com/item?id=21579333
+#
+set -euo pipefail
+
+# Colors
+declare -gr bold="\\e[1m"
+declare -gr red="\\e[31m"
+declare -gr green="\\e[32m"
+declare -gr cyan="\\e[36m"
+declare -gr reset="\\e[0m"
+
+# Round up defines files
+# shellcheck disable=SC2207
+defines=( $(find . -name '*.defines') )
+
+# Ensure we have the expected quantity
+actual="${#defines[@]}"
+expected="$(find . -name '*.cpp' -o -name '*.c' | wc -l)"
+if (( "$actual" != "$expected" )); then
+    echo "We should have $expected .defines files but $actual were found"
+	exit 1
+fi
+
+# The header strings that we're looking for
+ctype="#define _CTYPE_H 1"
+algorithm="#define __NO_CTYPE 1"
+failures=0
+
+# Check each for the correct order
+for def in "${defines[@]}"; do
+	result="$(grep -n "${ctype}\\|${algorithm}" "$def" || true)"
+	ctype_line="$(echo "$result" | grep "$ctype"     | cut -f1 -d: || echo)"
+	algor_line="$(echo "$result" | grep "$algorithm" | cut -f1 -d: || echo)"
+	source="${def%.*}"
+	if [[ -n "$ctype_line" && -n "$algor_line" ]]; then
+		if [[ "$ctype_line" -lt "$algor_line" ]]; then
+			echo -e "${bold}${green}[PASS]${reset} $source properly includes <ctype> before <algorithm>"
+		else
+			echo -e "${bold}${red}[FAIL]${reset} $source should include <ctype> before <algorithm>"
+			(( failures++ )) || true
+		fi
+		echo "${result//^/       }"
+		echo ""
+	else
+		echo -e "${bold}${cyan}[PASS]${reset} $source only includes one or neither"
+	fi
+done
+
+if [[ "$failures" -gt "0" ]]; then
+	exit 1
+fi