ICU-22294 UTS46 transitional=deprecated, change DEFAULT

icu4c/source/common/unicode/idna.h

@@ -70,6 +70,7 @@ class U_COMMON_API IDNA : public UObject {
      * The worker functions use transitional processing, including deviation mappings,
      * unless UIDNA_NONTRANSITIONAL_TO_ASCII or UIDNA_NONTRANSITIONAL_TO_UNICODE
      * is used in which case the deviation characters are passed through without change.
+     * <b>Unicode 15.1 UTS #46 deprecated transitional processing.</b>
      *
      * Disallowed characters are mapped to U+FFFD.
      *
@@ -82,6 +83,8 @@ class U_COMMON_API IDNA : public UObject {
      * letters, digits, hyphen (LDH) and dot/full stop are disallowed and mapped to U+FFFD.
      *
      * @param options Bit set to modify the processing and error checking.
+     *                These should include UIDNA_DEFAULT, or
+     *                UIDNA_NONTRANSITIONAL_TO_ASCII | UIDNA_NONTRANSITIONAL_TO_UNICODE.
      *                See option bit set values in uidna.h.
      * @param errorCode Standard ICU error code. Its input value must
      *                  pass the U_SUCCESS() test, or else the function returns

icu4c/source/common/unicode/uidna.h

@@ -49,11 +49,19 @@
  */
 enum {
     /**
-     * Default options value: None of the other options are set.
+     * Default options value: UTS #46 nontransitional processing.
      * For use in static worker and factory methods.
+     *
+     * Since ICU 76, this is the same as
+     * UIDNA_NONTRANSITIONAL_TO_ASCII | UIDNA_NONTRANSITIONAL_TO_UNICODE,
+     * corresponding to Unicode 15.1 UTS #46 deprecating transitional processing.
+     * (These options are ignored by the IDNA2003 implementation.)
+     *
+     * Before ICU 76, this constant did not set any of the options.
+     *
      * @stable ICU 2.6
      */
-    UIDNA_DEFAULT=0,
+    UIDNA_DEFAULT=0x30,
 #ifndef U_HIDE_DEPRECATED_API
     /**
      * Option to allow unassigned code points in domain names and labels.
@@ -91,19 +99,27 @@ enum {
     /**
      * IDNA option for nontransitional processing in ToASCII().
      * For use in static worker and factory methods.
+     *
      * <p>By default, ToASCII() uses transitional processing.
+     * Unicode 15.1 UTS #46 deprecated transitional processing.
+     *
      * <p>This option is ignored by the IDNA2003 implementation.
      * (This is only relevant for compatibility of newer IDNA implementations with IDNA2003.)
      * @stable ICU 4.6
+     * @see UIDNA_DEFAULT
      */
     UIDNA_NONTRANSITIONAL_TO_ASCII=0x10,
     /**
      * IDNA option for nontransitional processing in ToUnicode().
      * For use in static worker and factory methods.
+     *
      * <p>By default, ToUnicode() uses transitional processing.
+     * Unicode 15.1 UTS #46 deprecated transitional processing.
+     *
      * <p>This option is ignored by the IDNA2003 implementation.
      * (This is only relevant for compatibility of newer IDNA implementations with IDNA2003.)
      * @stable ICU 4.6
+     * @see UIDNA_DEFAULT
      */
     UIDNA_NONTRANSITIONAL_TO_UNICODE=0x20,
     /**
@@ -134,6 +150,8 @@ typedef struct UIDNA UIDNA;  /**< C typedef for struct UIDNA. @stable ICU 4.6 */
  * For details about the UTS #46 implementation see the IDNA C++ class in idna.h.
  *
  * @param options Bit set to modify the processing and error checking.
+ *                These should include UIDNA_DEFAULT, or
+ *                UIDNA_NONTRANSITIONAL_TO_ASCII | UIDNA_NONTRANSITIONAL_TO_UNICODE.
  *                See option bit set values in uidna.h.
  * @param pErrorCode Standard ICU error code. Its input value must
  *                  pass the U_SUCCESS() test, or else the function returns

icu4c/source/test/intltest/uts46test.cpp

@@ -42,6 +42,7 @@ class UTS46Test : public IntlTest {
     void TestNotSTD3();
     void TestInvalidPunycodeDigits();
     void TestACELabelEdgeCases();
+    void TestDefaultNontransitional();
     void TestTooLong();
     void TestSomeCases();
     void IdnaTest();
@@ -88,6 +89,7 @@ void UTS46Test::runIndexedTest(int32_t index, UBool exec, const char *&name, cha
     TESTCASE_AUTO(TestNotSTD3);
     TESTCASE_AUTO(TestInvalidPunycodeDigits);
     TESTCASE_AUTO(TestACELabelEdgeCases);
+    TESTCASE_AUTO(TestDefaultNontransitional);
     TESTCASE_AUTO(TestTooLong);
     TESTCASE_AUTO(TestSomeCases);
     TESTCASE_AUTO(IdnaTest);
@@ -354,6 +356,27 @@ void UTS46Test::TestACELabelEdgeCases() {
     }
 }
 
+void UTS46Test::TestDefaultNontransitional() {
+    IcuTestErrorCode errorCode(*this, "TestDefaultNontransitional()");
+    // Unicode 15.1 UTS #46 deprecated transitional processing.
+    // ICU 76 changed UIDNA_DEFAULT to set the nontransitional options.
+    LocalPointer<IDNA> forZero(IDNA::createUTS46Instance(0, errorCode));
+    LocalPointer<IDNA> forDefault(IDNA::createUTS46Instance(UIDNA_DEFAULT, errorCode));
+    if(errorCode.isFailure()) {
+        return;
+    }
+    UnicodeString result;
+    IDNAInfo info;
+    forZero->labelToUnicode(u"Fⓤßẞ", result, info, errorCode);
+    assertEquals("forZero.toUnicode(Fⓤßẞ)", u"fussss", result);
+    forZero->labelToASCII(u"Fⓤßẞ", result, info, errorCode);
+    assertEquals("forZero.toASCII(Fⓤßẞ)", u"fussss", result);
+    forDefault->labelToUnicode(u"Fⓤßẞ", result, info, errorCode);
+    assertEquals("forDefault.toUnicode(Fⓤßẞ)", u"fußß", result);
+    forDefault->labelToASCII(u"Fⓤßẞ", result, info, errorCode);
+    assertEquals("forDefault.toASCII(Fⓤßẞ)", u"xn--fu-hiaa", result);
+}
+
 void UTS46Test::TestTooLong() {
     // ICU-13727: Limit input length for n^2 algorithm
     // where well-formed strings are at most 59 characters long.