ICU-22940 MF2 ICU4C: Update for bidi support

Per unicode-org/message-format-wg#884

Author: catamorphism

icu4c/source/i18n/messageformat2.cpp

@@ -469,8 +469,8 @@ void MessageFormatter::resolvePreferences(MessageContext& context, UVector& res,
             if (!key.isWildcard()) {
                 // 2ii(b)(a) Assert that key is a literal.
                 // (Not needed)
-                // 2ii(b)(b) Let `ks` be the resolved value of `key`.
-                ks = key.asLiteral().unquoted();
+                // 2ii(b)(b) Let `ks` be the resolved value of `key` in Unicode Normalization Form C.
+                ks = normalizeNFC(key.asLiteral().unquoted());
                 // 2ii(b)(c) Append `ks` as the last element of the list `keys`.
                 ksP.adoptInstead(create<UnicodeString>(std::move(ks), status));
                 CHECK_ERROR(status);
@@ -531,7 +531,7 @@ void MessageFormatter::filterVariants(const UVector& pref, UVector& vars, UError
             // 2i(c). Assert that `key` is a literal.
             // (Not needed)
             // 2i(d). Let `ks` be the resolved value of `key`.
-            UnicodeString ks = key.asLiteral().unquoted();
+            UnicodeString ks = normalizeNFC(key.asLiteral().unquoted());
             // 2i(e). Let `matches` be the list of strings at index `i` of `pref`.
             const UVector& matches = *(static_cast<UVector*>(pref[i])); // `matches` is a vector of strings
             // 2i(f). If `matches` includes `ks`
@@ -593,7 +593,7 @@ void MessageFormatter::sortVariants(const UVector& pref, UVector& vars, UErrorCo
                 // 5iii(c)(a). Assert that `key` is a literal.
                 // (Not needed)
                 // 5iii(c)(b). Let `ks` be the resolved value of `key`.
-                UnicodeString ks = key.asLiteral().unquoted();
+                UnicodeString ks = normalizeNFC(key.asLiteral().unquoted());
                 // 5iii(c)(c) Let matchpref be the integer position of ks in `matches`.
                 matchpref = vectorFind(matches, ks);
                 U_ASSERT(matchpref >= 0);

icu4c/source/i18n/messageformat2_formatter.cpp

@@ -45,7 +45,8 @@ namespace message2 {
 
         // Parse the pattern
         MFDataModel::Builder tree(errorCode);
-        Parser(pat, tree, *errors, normalizedInput).parse(parseError, errorCode);
+        Parser(pat, tree, *errors, normalizedInput, errorCode)
+            .parse(parseError, errorCode);
 
         // Fail on syntax errors
         if (errors->hasSyntaxError()) {