ICU-22434 Not calling setFirstDayOfWeek(MONDAY) if the locale has fw

The Calendar constructor already take care of the fw override.
We should not set the first day of week for iso8601 to Monday if
we have a fw keyword/type in the locale.

ICU-22434 Fix incorrect calendar keyword extraction

icu4c/source/i18n/calendar.cpp

@@ -247,20 +247,6 @@ static UBool isStandardSupportedKeyword(const char *keyword, UErrorCode& status)
     return (calType != CALTYPE_UNKNOWN);
 }
 
-// only used with service registration.
-static void getCalendarKeyword(const UnicodeString &id, char *targetBuffer, int32_t targetBufferSize) {
-    UnicodeString calendarKeyword = UNICODE_STRING_SIMPLE("calendar=");
-    int32_t calKeyLen = calendarKeyword.length();
-    int32_t keyLen = 0;
-
-    int32_t keywordIdx = id.indexOf((char16_t)0x003D); /* '=' */
-    if (id[0] == 0x40/*'@'*/
-        && id.compareBetween(1, keywordIdx+1, calendarKeyword, 0, calKeyLen) == 0)
-    {
-        keyLen = id.extract(keywordIdx+1, id.length(), targetBuffer, targetBufferSize, US_INV);
-    }
-    targetBuffer[keyLen] = 0;
-}
 #endif
 
 static ECalType getCalendarTypeForLocale(const char *locid) {
@@ -458,10 +444,7 @@ class BasicCalendarFactory : public LocaleKeyFactory {
         lkey->canonicalLocale(canLoc);
 
         char keyword[ULOC_FULLNAME_CAPACITY];
-        UnicodeString str;
-
-        key.currentID(str);
-        getCalendarKeyword(str, keyword, (int32_t) sizeof(keyword));
+        curLoc.getKeywordValue("calendar", keyword, (int32_t) sizeof(keyword), status);
 
 #ifdef U_DEBUG_CALSVC
         fprintf(stderr, "BasicCalendarFactory::create() - cur %s, can %s\n", (const char*)curLoc.getName(), (const char*)canLoc.getName());

icu4c/source/i18n/iso8601cal.cpp

@@ -14,7 +14,13 @@ UOBJECT_DEFINE_RTTI_IMPLEMENTATION(ISO8601Calendar)
 ISO8601Calendar::ISO8601Calendar(const Locale& aLocale, UErrorCode& success)
 :   GregorianCalendar(aLocale, success)
 {
-    setFirstDayOfWeek(UCAL_MONDAY);
+    UErrorCode fwStatus = U_ZERO_ERROR;
+    int32_t fwLength = aLocale.getKeywordValue("fw", nullptr, 0, fwStatus);
+    // Do not set first day of week for iso8601 to Monday if we have fw keyword
+    // and let the value set by the Calendar constructor to take care of it.
+    if (U_SUCCESS(fwStatus) && fwLength == 0) {
+        setFirstDayOfWeek(UCAL_MONDAY);
+    }
     setMinimalDaysInFirstWeek(4);
 }
 

icu4c/source/test/cintltst/ccaltst.c

@@ -44,6 +44,8 @@ void TestJpnCalAddSetNextEra(void);
 void TestUcalOpenBufferRead(void);
 void TestGetTimeZoneOffsetFromLocal(void);
 
+void TestFWWithISO8601(void);
+
 void addCalTest(TestNode** root);
 
 void addCalTest(TestNode** root)
@@ -68,6 +70,7 @@ void addCalTest(TestNode** root)
     addTest(root, &TestJpnCalAddSetNextEra, "tsformat/ccaltst/TestJpnCalAddSetNextEra");
     addTest(root, &TestUcalOpenBufferRead, "tsformat/ccaltst/TestUcalOpenBufferRead");
     addTest(root, &TestGetTimeZoneOffsetFromLocal, "tsformat/ccaltst/TestGetTimeZoneOffsetFromLocal");
+    addTest(root, &TestFWWithISO8601, "tsformat/ccaltst/TestFWWithISO8601");
 }
 
 /* "GMT" */
@@ -2794,4 +2797,33 @@ TestGetTimeZoneOffsetFromLocal() {
     ucal_close(cal);
 }
 
+void
+TestFWWithISO8601() {
+    /* UCAL_SUNDAY is 1, UCAL_MONDAY is 2, ..., UCAL_SATURDAY is 7 */
+    const char* LOCALES[] = {
+        "",
+        "en-u-ca-iso8601-fw-sun",
+        "en-u-ca-iso8601-fw-mon",
+        "en-u-ca-iso8601-fw-tue",
+        "en-u-ca-iso8601-fw-wed",
+        "en-u-ca-iso8601-fw-thu",
+        "en-u-ca-iso8601-fw-fri",
+        "en-u-ca-iso8601-fw-sat",
+    };
+    for (int32_t i = UCAL_SUNDAY; i <= UCAL_SATURDAY; i++) {
+        const char* locale = LOCALES[i];
+        UErrorCode status = U_ZERO_ERROR;
+        UCalendar* cal = ucal_open(0, 0, locale, UCAL_TRADITIONAL, &status);
+        if(U_FAILURE(status)){
+            log_data_err("FAIL: error in ucal_open caldef : %s\n - (Are you missing data?)", u_errorName(status));
+        }
+        int32_t actual = ucal_getAttribute(cal, UCAL_FIRST_DAY_OF_WEEK);
+        if (i != actual) {
+            log_err("ERROR: ucal_getAttribute(\"%s\", UCAL_FIRST_DAY_OF_WEEK) should be %d but get %d\n",
+                    locale, i, actual);
+        }
+        ucal_close(cal);
+    }
+}
+
 #endif /* #if !UCONFIG_NO_FORMATTING */

icu4c/source/test/intltest/caltest.cpp

@@ -185,7 +185,9 @@ void CalendarTest::runIndexedTest( int32_t index, UBool exec, const char* &name,
     TESTCASE_AUTO(TestActualLimitsOrdinalMonth);
     TESTCASE_AUTO(TestChineseCalendarMonthInSpecialYear);
     TESTCASE_AUTO(TestClearMonth);
-
+
+    TESTCASE_AUTO(TestFWWithISO8601);
+
     TESTCASE_AUTO_END;
 }
 
@@ -5494,6 +5496,31 @@ void CalendarTest::TestChineseCalendarMonthInSpecialYear() {
         }
     }
 }
+
+void CalendarTest::TestFWWithISO8601() {
+    // ICU UCAL_SUNDAY is 1, UCAL_MONDAY is 2, ... UCAL_SATURDAY is 7.
+    const char *locales[]  = {
+      "",
+      "en-u-ca-iso8601-fw-sun",
+      "en-u-ca-iso8601-fw-mon",
+      "en-u-ca-iso8601-fw-tue",
+      "en-u-ca-iso8601-fw-wed",
+      "en-u-ca-iso8601-fw-thu",
+      "en-u-ca-iso8601-fw-fri",
+      "en-u-ca-iso8601-fw-sat"
+    };
+    for (int i = UCAL_SUNDAY; i <= UCAL_SATURDAY; i++) {
+        UErrorCode status = U_ZERO_ERROR;
+        const char* locale = locales[i];
+        LocalPointer<Calendar> cal(
+            Calendar::createInstance(
+                Locale(locale), status), status);
+        if (failure(status, "Constructor failed")) continue;
+        std::string msg("Calendar::createInstance(\"");
+        msg = msg + locale + "\")->getFirstDayOfWeek()";
+        assertEquals(msg.c_str(), i, cal->getFirstDayOfWeek());
+    }
+}
 #endif /* #if !UCONFIG_NO_FORMATTING */
 
 //eof

icu4c/source/test/intltest/caltest.h

@@ -330,6 +330,8 @@ class CalendarTest: public CalendarTimeZoneTest {
     void TestLimitsOrdinalMonth();
     void TestActualLimitsOrdinalMonth();
 
+    void TestFWWithISO8601();
+
     void RunChineseCalendarInTemporalLeapYearTest(Calendar* cal);
     void RunIslamicCalendarInTemporalLeapYearTest(Calendar* cal);
     void Run366DaysIsLeapYearCalendarInTemporalLeapYearTest(Calendar* cal);

icu4j/main/classes/core/src/com/ibm/icu/util/Calendar.java

@@ -12,9 +12,11 @@
 import java.io.ObjectOutputStream;
 import java.io.Serializable;
 import java.text.StringCharacterIterator;
+import java.util.Arrays;
 import java.util.ArrayList;
 import java.util.Date;
 import java.util.Locale;
+import java.util.List;
 import java.util.MissingResourceException;
 
 import com.ibm.icu.impl.CalType;
@@ -1831,7 +1833,12 @@ private static Calendar createInstance(ULocale locale) {
         case ISO8601:
             // Only differs week numbering rule from Gregorian
             cal = new GregorianCalendar(zone, locale);
-            cal.setFirstDayOfWeek(MONDAY);
+            String type = locale.getUnicodeLocaleType("fw");
+            // Only set fw to Monday for ISO8601 if there aer no fw keyword.
+            // If there is a fw keyword, the Calendar constructor already set it to the fw value.
+            if (locale.getKeywordValue("fw") == null) {
+                cal.setFirstDayOfWeek(MONDAY);
+            }
             cal.setMinimalDaysInFirstWeek(4);
             break;
 

icu4j/main/tests/core/src/com/ibm/icu/dev/test/calendar/CalendarRegressionTest.java

@@ -2654,15 +2654,31 @@ public void TestRespectUExtensionFw() { // ICU-22226
                 "en-US-u-fw-sun",
                 "en-US-u-fw-mon",
                 "en-US-u-fw-thu",
-                "en-US-u-fw-sat"
+                "en-US-u-fw-sat",
+                // ICU-22434
+                "en-US-u-ca-iso8601-fw-sun",
+                "en-US-u-ca-iso8601-fw-mon",
+                "en-US-u-ca-iso8601-fw-tue",
+                "en-US-u-ca-iso8601-fw-wed",
+                "en-US-u-ca-iso8601-fw-thu",
+                "en-US-u-ca-iso8601-fw-fri",
+                "en-US-u-ca-iso8601-fw-sat",
         };
         int[] expectedValues = {
                 Calendar.SUNDAY,
                 Calendar.SUNDAY,
                 Calendar.SUNDAY,
                 Calendar.MONDAY,
                 Calendar.THURSDAY,
-                Calendar.SATURDAY
+                Calendar.SATURDAY,
+                // ICU-22434
+                Calendar.SUNDAY,
+                Calendar.MONDAY,
+                Calendar.TUESDAY,
+                Calendar.WEDNESDAY,
+                Calendar.THURSDAY,
+                Calendar.FRIDAY,
+                Calendar.SATURDAY,
         };
 
         assertEquals(
@@ -2672,7 +2688,8 @@ public void TestRespectUExtensionFw() { // ICU-22226
 
         for (int i = 0; i < localeIds.length; i++) {
             assertEquals(
-                    "Calendar.getFirstDayOfWeek() does not seem to respect fw extension u in locale id",
+                    "Calendar.getFirstDayOfWeek() does not seem to respect fw extension u in locale id " +
+                    localeIds[i],
                     expectedValues[i],
                     Calendar.getInstance(Locale.forLanguageTag(localeIds[i])).getFirstDayOfWeek());
         }