Replace all ctype.h functions with locale-independent ones

src/asm/parser.y

@@ -32,7 +32,6 @@
 
 %code {
 	#include <algorithm>
-	#include <ctype.h>
 	#include <inttypes.h>
 	#include <optional>
 	#include <stdio.h>
@@ -42,6 +41,7 @@
 
 	#include "extern/utf8decoder.hpp"
 	#include "helpers.hpp"
+	#include "util.hpp" // toLower, toUpper
 
 	#include "asm/charmap.hpp"
 	#include "asm/fixpoint.hpp"
@@ -1599,11 +1599,11 @@ string_literal:
 	}
 	| OP_STRUPR LPAREN string RPAREN {
 		$$ = std::move($3);
-		std::transform(RANGE($$), $$.begin(), [](char c) { return toupper(c); });
+		std::transform(RANGE($$), $$.begin(), toUpper);
 	}
 	| OP_STRLWR LPAREN string RPAREN {
 		$$ = std::move($3);
-		std::transform(RANGE($$), $$.begin(), [](char c) { return tolower(c); });
+		std::transform(RANGE($$), $$.begin(), toLower);
 	}
 	| OP_STRRPL LPAREN string COMMA string COMMA string RPAREN {
 		$$ = act_StringReplace($3, $5, $7);

src/fix/mbc.cpp

@@ -12,7 +12,7 @@
 
 #include "helpers.hpp"  // unreachable_
 #include "platform.hpp" // strcasecmp
-#include "util.hpp"     // isBlankSpace, isLower, isDigit
+#include "util.hpp"
 
 #include "fix/warning.hpp"
 
@@ -103,12 +103,10 @@ static void skipMBCSpace(char const *&ptr) {
 }
 
 static char normalizeMBCChar(char c) {
-	if (isLower(c)) {
-		c = c - 'a' + 'A'; // Uppercase for comparison with `mbc_Name`s
-	} else if (c == '_') {
-		c = ' '; // Treat underscores as spaces
+	if (c == '_') {
+		return ' '; // Treat underscores as spaces
 	}
-	return c;
+	return toUpper(c); // Uppercase for comparison with `mbc_Name`s
 }
 
 [[noreturn]]

src/util.cpp

@@ -58,6 +58,14 @@ bool isAlphanumeric(int c) {
 	return isLetter(c) || isDigit(c);
 }
 
+char toLower(char c) {
+	return isUpper(c) ? c - 'A' + 'a' : c;
+}
+
+char toUpper(char c) {
+	return isLower(c) ? c - 'a' + 'A' : c;
+}
+
 bool startsIdentifier(int c) {
 	// This returns false for anonymous labels, which internally start with a '!',
 	// and for section fragment literal labels, which internally start with a '$'.