Merge pull request #44507 from bruvzg/icu_update_68_2

ICU: Update to upstream release 68.2

8 files changed, 249 insertions, 41 deletions

diff --git a/thirdparty/icu4c/common/cmemory.h b/thirdparty/icu4c/common/cmemory.h
index 210bc7645e..a9d9424b4e 100644
--- a/thirdparty/icu4c/common/cmemory.h
+++ b/thirdparty/icu4c/common/cmemory.h
@@ -725,9 +725,14 @@ public:
     }
 
     MemoryPool& operator=(MemoryPool&& other) U_NOEXCEPT {
-        fCount = other.fCount;
-        fPool = std::move(other.fPool);
-        other.fCount = 0;
+        // Since `this` may contain instances that need to be deleted, we can't
+        // just throw them away and replace them with `other`. The normal way of
+        // dealing with this in C++ is to swap `this` and `other`, rather than
+        // simply overwrite: the destruction of `other` can then take care of
+        // running MemoryPool::~MemoryPool() over the still-to-be-deallocated
+        // instances.
+        std::swap(fCount, other.fCount);
+        std::swap(fPool, other.fPool);
         return *this;
     }
 
@@ -796,9 +801,6 @@ protected:
 template<typename T, int32_t stackCapacity = 8>
 class MaybeStackVector : protected MemoryPool<T, stackCapacity> {
 public:
-    using MemoryPool<T, stackCapacity>::MemoryPool;
-    using MemoryPool<T, stackCapacity>::operator=;
-
     template<typename... Args>
     T* emplaceBack(Args&&... args) {
         return this->create(args...);
diff --git a/thirdparty/icu4c/common/locid.cpp b/thirdparty/icu4c/common/locid.cpp
index 2804e36bf6..874e4a7055 100644
--- a/thirdparty/icu4c/common/locid.cpp
+++ b/thirdparty/icu4c/common/locid.cpp
@@ -35,6 +35,7 @@
 
 #include "unicode/bytestream.h"
 #include "unicode/locid.h"
+#include "unicode/localebuilder.h"
 #include "unicode/strenum.h"
 #include "unicode/stringpiece.h"
 #include "unicode/uloc.h"
@@ -1028,7 +1029,7 @@ public:
     // place the the replaced locale ID in out and return true.
     // Otherwise return false for no replacement or error.
     bool replace(
-        const Locale& locale, CharString& out, UErrorCode status);
+        const Locale& locale, CharString& out, UErrorCode& status);
 
 private:
     const char* language;
@@ -1336,10 +1337,13 @@ AliasReplacer::replaceTerritory(UVector& toBeFreed, UErrorCode& status)
         // Cannot use nullptr for language because that will construct
         // the default locale, in that case, use "und" to get the correct
         // locale.
-        Locale l(language == nullptr ? "und" : language, nullptr, script);
+        Locale l = LocaleBuilder()
+            .setLanguage(language == nullptr ? "und" : language)
+            .setScript(script)
+            .build(status);
         l.addLikelySubtags(status);
         const char* likelyRegion = l.getCountry();
-        CharString* item = nullptr;
+        LocalPointer<CharString> item;
         if (likelyRegion != nullptr && uprv_strlen(likelyRegion) > 0) {
             size_t len = uprv_strlen(likelyRegion);
             const char* foundInReplacement = uprv_strstr(replacement,
@@ -1351,20 +1355,22 @@ AliasReplacer::replaceTerritory(UVector& toBeFreed, UErrorCode& status)
                          *(foundInReplacement-1) == ' ');
                 U_ASSERT(foundInReplacement[len] == ' ' ||
                          foundInReplacement[len] == '\0');
-                item = new CharString(foundInReplacement, (int32_t)len, status);
+                item.adoptInsteadAndCheckErrorCode(
+                    new CharString(foundInReplacement, (int32_t)len, status), status);
             }
         }
-        if (item == nullptr) {
-            item = new CharString(replacement,
-                                  (int32_t)(firstSpace - replacement), status);
+        if (item.isNull() && U_SUCCESS(status)) {
+            item.adoptInsteadAndCheckErrorCode(
+                new CharString(replacement,
+                               (int32_t)(firstSpace - replacement), status), status);
         }
         if (U_FAILURE(status)) { return false; }
-        if (item == nullptr) {
+        if (item.isNull()) {
             status = U_MEMORY_ALLOCATION_ERROR;
             return false;
         }
         replacedRegion = item->data();
-        toBeFreed.addElement(item, status);
+        toBeFreed.addElement(item.orphan(), status);
     }
     U_ASSERT(!same(region, replacedRegion));
     region = replacedRegion;
@@ -1453,7 +1459,7 @@ AliasReplacer::outputToString(
         int32_t variantsStart = out.length();
         for (int32_t i = 0; i < variants.size(); i++) {
              out.append(SEP_CHAR, status)
-                 .append((const char*)((UVector*)variants.elementAt(i)),
+                 .append((const char*)(variants.elementAt(i)),
                          status);
         }
         T_CString_toUpperCase(out.data() + variantsStart);
@@ -1470,7 +1476,7 @@ AliasReplacer::outputToString(
 }
 
 bool
-AliasReplacer::replace(const Locale& locale, CharString& out, UErrorCode status)
+AliasReplacer::replace(const Locale& locale, CharString& out, UErrorCode& status)
 {
     data = AliasData::singleton(status);
     if (U_FAILURE(status)) {
@@ -2453,9 +2459,13 @@ Locale::setKeywordValue(const char* keywordName, const char* keywordValue, UErro
     if (U_FAILURE(status)) {
         return;
     }
+    if (status == U_STRING_NOT_TERMINATED_WARNING) {
+        status = U_ZERO_ERROR;
+    }
     int32_t bufferLength = uprv_max((int32_t)(uprv_strlen(fullName) + 1), ULOC_FULLNAME_CAPACITY);
     int32_t newLength = uloc_setKeywordValue(keywordName, keywordValue, fullName,
                                              bufferLength, &status) + 1;
+    U_ASSERT(status != U_STRING_NOT_TERMINATED_WARNING);
     /* Handle the case the current buffer is not enough to hold the new id */
     if (status == U_BUFFER_OVERFLOW_ERROR) {
         U_ASSERT(newLength > bufferLength);
@@ -2472,6 +2482,7 @@ Locale::setKeywordValue(const char* keywordName, const char* keywordValue, UErro
         fullName = newFullName;
         status = U_ZERO_ERROR;
         uloc_setKeywordValue(keywordName, keywordValue, fullName, newLength, &status);
+        U_ASSERT(status != U_STRING_NOT_TERMINATED_WARNING);
     } else {
         U_ASSERT(newLength <= bufferLength);
     }
diff --git a/thirdparty/icu4c/common/rbbitblb.cpp b/thirdparty/icu4c/common/rbbitblb.cpp
index bcbdab9227..70e260fc08 100644
--- a/thirdparty/icu4c/common/rbbitblb.cpp
+++ b/thirdparty/icu4c/common/rbbitblb.cpp
@@ -1402,12 +1402,13 @@ void RBBITableBuilder::exportTable(void *where) {
             U_ASSERT (sd->fAccepting <= 255);
             U_ASSERT (sd->fLookAhead <= 255);
             U_ASSERT (0 <= sd->fTagsIdx && sd->fTagsIdx <= 255);
-            row->r8.fAccepting = sd->fAccepting;
-            row->r8.fLookAhead = sd->fLookAhead;
-            row->r8.fTagsIdx   = sd->fTagsIdx;
+            RBBIStateTableRow8 *r8 = (RBBIStateTableRow8*)row;
+            r8->fAccepting = sd->fAccepting;
+            r8->fLookAhead = sd->fLookAhead;
+            r8->fTagsIdx   = sd->fTagsIdx;
             for (col=0; col<catCount; col++) {
                 U_ASSERT (sd->fDtran->elementAti(col) <= kMaxStateFor8BitsTable);
-                row->r8.fNextState[col] = sd->fDtran->elementAti(col);
+                r8->fNextState[col] = sd->fDtran->elementAti(col);
             }
         } else {
             U_ASSERT (sd->fAccepting <= 0xffff);
@@ -1603,12 +1604,13 @@ void RBBITableBuilder::exportSafeTable(void *where) {
         UnicodeString *rowString = (UnicodeString *)fSafeTable->elementAt(state);
         RBBIStateTableRow   *row = (RBBIStateTableRow *)(table->fTableData + state*table->fRowLen);
         if (use8BitsForSafeTable()) {
-            row->r8.fAccepting = 0;
-            row->r8.fLookAhead = 0;
-            row->r8.fTagsIdx    = 0;
+            RBBIStateTableRow8 *r8 = (RBBIStateTableRow8*)row;
+            r8->fAccepting = 0;
+            r8->fLookAhead = 0;
+            r8->fTagsIdx    = 0;
             for (col=0; col<catCount; col++) {
                 U_ASSERT(rowString->charAt(col) <= kMaxStateFor8BitsTable);
-                row->r8.fNextState[col] = static_cast<uint8_t>(rowString->charAt(col));
+                r8->fNextState[col] = static_cast<uint8_t>(rowString->charAt(col));
             }
         } else {
             row->r16.fAccepting = 0;
diff --git a/thirdparty/icu4c/common/uloc.cpp b/thirdparty/icu4c/common/uloc.cpp
index 522f33dbe2..ebfbb50650 100644
--- a/thirdparty/icu4c/common/uloc.cpp
+++ b/thirdparty/icu4c/common/uloc.cpp
@@ -877,6 +877,9 @@ uloc_setKeywordValue(const char* keywordName,
     if(U_FAILURE(*status)) {
         return -1;
     }
+    if (*status == U_STRING_NOT_TERMINATED_WARNING) {
+        *status = U_ZERO_ERROR;
+    }
     if (keywordName == NULL || keywordName[0] == 0 || bufferCapacity <= 1) {
         *status = U_ILLEGAL_ARGUMENT_ERROR;
         return 0;
@@ -914,6 +917,7 @@ uloc_setKeywordValue(const char* keywordName,
     startSearchHere = (char*)locale_getKeywordsStart(buffer);
     if(startSearchHere == NULL || (startSearchHere[1]==0)) {
         if(keywordValueLen == 0) { /* no keywords = nothing to remove */
+            U_ASSERT(*status != U_STRING_NOT_TERMINATED_WARNING);
             return bufLen;
         }
 
@@ -933,6 +937,7 @@ uloc_setKeywordValue(const char* keywordName,
         startSearchHere += keywordNameLen;
         *startSearchHere++ = '=';
         uprv_strcpy(startSearchHere, keywordValueBuffer);
+        U_ASSERT(*status != U_STRING_NOT_TERMINATED_WARNING);
         return needLen;
     } /* end shortcut - no @ */
 
@@ -1047,13 +1052,27 @@ uloc_setKeywordValue(const char* keywordName,
     if (!handledInputKeyAndValue || U_FAILURE(*status)) {
         /* if input key/value specified removal of a keyword not present in locale, or
          * there was an error in CharString.append, leave original locale alone. */
+        U_ASSERT(*status != U_STRING_NOT_TERMINATED_WARNING);
         return bufLen;
     }
 
     // needLen = length of the part before '@'
     needLen = (int32_t)(startSearchHere - buffer);
-    return needLen + updatedKeysAndValues.extract(
+    // Check to see can we fit the startSearchHere, if not, return
+    // U_BUFFER_OVERFLOW_ERROR without copy updatedKeysAndValues into it.
+    // We do this because this API function does not behave like most others:
+    // It promises never to set a U_STRING_NOT_TERMINATED_WARNING.
+    // When the contents fits but without the terminating NUL, in this case we need to not change
+    // the buffer contents and return with a buffer overflow error.
+    int32_t appendLength = updatedKeysAndValues.length();
+    if (appendLength >= bufferCapacity - needLen) {
+        *status = U_BUFFER_OVERFLOW_ERROR;
+        return needLen + appendLength;
+    }
+    needLen += updatedKeysAndValues.extract(
                          startSearchHere, bufferCapacity - needLen, *status);
+    U_ASSERT(*status != U_STRING_NOT_TERMINATED_WARNING);
+    return needLen;
 }
 
 /* ### ID parsing implementation **************************************************/
diff --git a/thirdparty/icu4c/common/unicode/docmain.h b/thirdparty/icu4c/common/unicode/docmain.h
index b7984ada03..edcb5d4e83 100644
--- a/thirdparty/icu4c/common/unicode/docmain.h
+++ b/thirdparty/icu4c/common/unicode/docmain.h
@@ -143,6 +143,11 @@
  *     <td>icu::MessageFormat</td>
  *   </tr>
  *   <tr>
+ *     <td>List Formatting</td>
+ *     <td>ulistformatter.h</td>
+ *     <td>icu::ListFormatter</td>
+ *   </tr>
+ *   <tr>
  *     <td>Number Formatting<br/>(includes currency and unit formatting)</td>
  *     <td>unumberformatter.h, unum.h</td>
  *     <td>icu::number::NumberFormatter (ICU 60+) or icu::NumberFormat (older versions)</td>
diff --git a/thirdparty/icu4c/common/unicode/urename.h b/thirdparty/icu4c/common/unicode/urename.h
index 20232cd209..fe59fdd893 100644
--- a/thirdparty/icu4c/common/unicode/urename.h
+++ b/thirdparty/icu4c/common/unicode/urename.h
@@ -1137,6 +1137,7 @@
 #define ulocimp_toLanguageTag U_ICU_ENTRY_POINT_RENAME(ulocimp_toLanguageTag)
 #define ulocimp_toLegacyKey U_ICU_ENTRY_POINT_RENAME(ulocimp_toLegacyKey)
 #define ulocimp_toLegacyType U_ICU_ENTRY_POINT_RENAME(ulocimp_toLegacyType)
+#define ultag_getTKeyStart U_ICU_ENTRY_POINT_RENAME(ultag_getTKeyStart)
 #define ultag_isExtensionSubtags U_ICU_ENTRY_POINT_RENAME(ultag_isExtensionSubtags)
 #define ultag_isLanguageSubtag U_ICU_ENTRY_POINT_RENAME(ultag_isLanguageSubtag)
 #define ultag_isPrivateuseValueSubtags U_ICU_ENTRY_POINT_RENAME(ultag_isPrivateuseValueSubtags)
diff --git a/thirdparty/icu4c/common/unicode/uvernum.h b/thirdparty/icu4c/common/unicode/uvernum.h
index a4cbb9e0fe..a46481a3fe 100644
--- a/thirdparty/icu4c/common/unicode/uvernum.h
+++ b/thirdparty/icu4c/common/unicode/uvernum.h
@@ -66,7 +66,7 @@
  *  This value will change in the subsequent releases of ICU
  *  @stable ICU 2.6
  */
-#define U_ICU_VERSION_MINOR_NUM 1
+#define U_ICU_VERSION_MINOR_NUM 2
 
 /** The current ICU patchlevel version as an integer.
  *  This value will change in the subsequent releases of ICU
@@ -139,7 +139,7 @@
  *  This value will change in the subsequent releases of ICU
  *  @stable ICU 2.4
  */
-#define U_ICU_VERSION "68.1"
+#define U_ICU_VERSION "68.2"
 
 /**
  * The current ICU library major version number as a string, for library name suffixes.
@@ -158,7 +158,7 @@
 /** Data version in ICU4C.
  * @internal ICU 4.4 Internal Use Only
  **/
-#define U_ICU_DATA_VERSION "68.1"
+#define U_ICU_DATA_VERSION "68.2"
 #endif  /* U_HIDE_INTERNAL_API */
 
 /*===========================================================================
diff --git a/thirdparty/icu4c/common/wintz.cpp b/thirdparty/icu4c/common/wintz.cpp
index 3730232286..580cedadb6 100644
--- a/thirdparty/icu4c/common/wintz.cpp
+++ b/thirdparty/icu4c/common/wintz.cpp
@@ -36,17 +36,58 @@
 
 U_NAMESPACE_BEGIN
 
+// Note these constants and the struct are only used when dealing with the fallback path for RDP sesssions.
+
+// This is the location of the time zones in the registry on Vista+ systems.
+// See: https://docs.microsoft.com/windows/win32/api/timezoneapi/ns-timezoneapi-dynamic_time_zone_information
+#define WINDOWS_TIMEZONES_REG_KEY_PATH L"SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones"
+
+// Max length for a registry key is 255. +1 for null.
+// See: https://docs.microsoft.com/windows/win32/sysinfo/registry-element-size-limits
+#define WINDOWS_MAX_REG_KEY_LENGTH 256
+
+#if U_PLATFORM_HAS_WINUWP_API == 0
+
+// This is the layout of the TZI binary value in the registry.
+// See: https://docs.microsoft.com/windows/win32/api/timezoneapi/ns-timezoneapi-time_zone_information
+typedef struct _REG_TZI_FORMAT {
+    LONG Bias;
+    LONG StandardBias;
+    LONG DaylightBias;
+    SYSTEMTIME StandardDate;
+    SYSTEMTIME DaylightDate;
+} REG_TZI_FORMAT;
+
+#endif // U_PLATFORM_HAS_WINUWP_API
+
 /**
-* Main Windows time zone detection function.
-* Returns the Windows time zone converted to an ICU time zone as a heap-allocated buffer, or nullptr upon failure.
+* This is main Windows time zone detection function.
+* 
+* It returns the Windows time zone converted to an ICU time zone as a heap-allocated buffer, or nullptr upon failure.
 *
-* Note: We use the Win32 API GetDynamicTimeZoneInformation (available since Vista+) to get the current time zone info.
-* This API returns a non-localized time zone name, which is mapped to an ICU time zone ID (~ Olsen ID).
+* We use the Win32 API GetDynamicTimeZoneInformation (which is available since Vista) to get the current time zone info,
+* as this API returns a non-localized time zone name which can be then mapped to an ICU time zone.
+* 
+* However, in some RDP/terminal services situations, this struct isn't always fully complete, and the TimeZoneKeyName
+* field of the struct might be NULL. This can happen with some 3rd party RDP clients, and also when using older versions
+* of the RDP protocol, which don't send the newer TimeZoneKeyNamei information and only send the StandardName and DaylightName.
+* 
+* Since these 3rd party clients and older RDP clients only send the pre-Vista time zone information to the server, this means that we 
+* need to fallback on using the pre-Vista methods to determine the time zone. This unfortunately requires examining the registry directly
+* in order to try and determine the current time zone.
+* 
+* Note that this can however still fail in some cases though if the client and server are using different languages, as the StandardName
+* that is sent by client is localized in the client's language. However, we must compare this to the names that are on the server, which
+* are localized in registry using the server's language. Despite that, this is the best we can do.
+* 
+* Note: This fallback method won't work for the UWP version though, as we can't use the registry APIs in UWP.
+* 
+* Once we have the current Windows time zone, then we can then map it to an ICU time zone ID (~ Olsen ID).
 */
 U_CAPI const char* U_EXPORT2
 uprv_detectWindowsTimeZone()
 {
-    // Obtain the DYNAMIC_TIME_ZONE_INFORMATION info to get the non-localized time zone name.
+    // We first try to obtain the time zone directly by using the TimeZoneKeyName field of the DYNAMIC_TIME_ZONE_INFORMATION struct.
     DYNAMIC_TIME_ZONE_INFORMATION dynamicTZI;
     uprv_memset(&dynamicTZI, 0, sizeof(dynamicTZI));
     SYSTEMTIME systemTimeAllZero;
@@ -86,22 +127,138 @@ uprv_detectWindowsTimeZone()
             // Note '-' before 'utcOffsetMin'. The timezone ID's sign convention
             // is that a timezone ahead of UTC is Etc/GMT-<offset> and a timezone
             // behind UTC is Etc/GMT+<offset>.
-            int ret = snprintf(gmtOffsetTz, UPRV_LENGTHOF(gmtOffsetTz), "Etc/GMT%+d", -utcOffsetMins / 60);
+            int ret = snprintf(gmtOffsetTz, UPRV_LENGTHOF(gmtOffsetTz), "Etc/GMT%+ld", -utcOffsetMins / 60);
             if (ret > 0 && ret < UPRV_LENGTHOF(gmtOffsetTz)) {
                 return uprv_strdup(gmtOffsetTz);
             }
         }
     }
 
-    // If DST is NOT disabled, but we have an empty TimeZoneKeyName, then it is unclear
-    // what we should do as this should not happen.
+    // If DST is NOT disabled, but the TimeZoneKeyName field of the struct is NULL, then we may be dealing with a
+    // RDP/terminal services session where the 'Time Zone Redirection' feature is enabled. However, either the RDP
+    // client sent the server incomplete info (some 3rd party RDP clients only send the StandardName and  DaylightName,
+    // but do not send the important TimeZoneKeyName), or if the RDP server has not appropriately populated the struct correctly.
+    //
+    // In this case we unfortunately have no choice but to fallback to using the pre-Vista method of determining the
+    // time zone, which requires examining the registry directly.
+    //
+    // Note that this can however still fail though if the client and server are using different languages, as the StandardName
+    // that is sent by client is *localized* in the client's language. However, we must compare this to the names that are
+    // on the server, which are *localized* in registry using the server's language.
+    //
+    // One other note is that this fallback method doesn't work for the UWP version, as we can't use the registry APIs.
+
+    // windowsTimeZoneName will point at timezoneSubKeyName if we had to fallback to using the registry, and we found a match.
+    WCHAR timezoneSubKeyName[WINDOWS_MAX_REG_KEY_LENGTH];
+    WCHAR *windowsTimeZoneName = dynamicTZI.TimeZoneKeyName;
+
     if (dynamicTZI.TimeZoneKeyName[0] == 0) {
+
+// We can't use the registry APIs in the UWP version.
+#if U_PLATFORM_HAS_WINUWP_API == 1
+        (void)timezoneSubKeyName; // suppress unused variable warnings.
         return nullptr;
+#else
+        // Open the path to the time zones in the Windows registry.
+        LONG ret;
+        HKEY hKeyAllTimeZones = nullptr;
+        ret = RegOpenKeyExW(HKEY_LOCAL_MACHINE, WINDOWS_TIMEZONES_REG_KEY_PATH, 0, KEY_READ,
+                            reinterpret_cast<PHKEY>(&hKeyAllTimeZones));
+        
+        if (ret != ERROR_SUCCESS) {
+            // If we can't open the key, then we can't do much, so fail.
+            return nullptr;
+        }
+
+        // Read the number of subkeys under the time zone registry path.
+        DWORD numTimeZoneSubKeys;
+        ret = RegQueryInfoKeyW(hKeyAllTimeZones, nullptr, nullptr, nullptr, &numTimeZoneSubKeys,
+                               nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr);
+        
+        if (ret != ERROR_SUCCESS) {
+            RegCloseKey(hKeyAllTimeZones);
+            return nullptr;
+        }
+
+        // Examine each of the subkeys to try and find a match for the localized standard name ("Std").
+        //
+        // Note: The name of the time zone subkey itself is not localized, but the "Std" name is localized. This means
+        // that we could fail to find a match if the RDP client and RDP server are using different languages, but unfortunately
+        // there isn't much we can do about it.
+        HKEY hKeyTimeZoneSubKey = nullptr;
+        ULONG registryValueType;
+        WCHAR registryStandardName[WINDOWS_MAX_REG_KEY_LENGTH];
+
+        for (DWORD i = 0; i < numTimeZoneSubKeys; i++) {
+            // Note: RegEnumKeyExW wants the size of the buffer in characters.
+            DWORD size = UPRV_LENGTHOF(timezoneSubKeyName);
+            ret = RegEnumKeyExW(hKeyAllTimeZones, i, timezoneSubKeyName, &size, nullptr, nullptr, nullptr, nullptr);
+
+            if (ret != ERROR_SUCCESS) {
+                RegCloseKey(hKeyAllTimeZones);
+                return nullptr;
+            }
+            
+            ret = RegOpenKeyExW(hKeyAllTimeZones, timezoneSubKeyName, 0, KEY_READ,
+                                reinterpret_cast<PHKEY>(&hKeyTimeZoneSubKey));
+            
+            if (ret != ERROR_SUCCESS) {
+                RegCloseKey(hKeyAllTimeZones);
+                return nullptr;
+            }
+
+            // Note: RegQueryValueExW wants the size of the buffer in bytes.
+            size = sizeof(registryStandardName);
+            ret = RegQueryValueExW(hKeyTimeZoneSubKey, L"Std", nullptr, &registryValueType,
+                                   reinterpret_cast<LPBYTE>(registryStandardName), &size);
+            
+            if (ret != ERROR_SUCCESS || registryValueType != REG_SZ) {
+                RegCloseKey(hKeyTimeZoneSubKey);
+                RegCloseKey(hKeyAllTimeZones);
+                return nullptr;
+            }
+
+            // Note: wcscmp does an ordinal (byte) comparison.
+            if (wcscmp(reinterpret_cast<WCHAR *>(registryStandardName), dynamicTZI.StandardName) == 0) {
+                // Since we are comparing the *localized* time zone name, it's possible that some languages might use
+                // the same string for more than one time zone. Thus we need to examine the TZI data in the registry to
+                // compare the GMT offset (the bias), and the DST transition dates, to ensure it's the same time zone
+                // as the currently reported one.
+                REG_TZI_FORMAT registryTziValue;
+                uprv_memset(&registryTziValue, 0, sizeof(registryTziValue));
+
+                // Note: RegQueryValueExW wants the size of the buffer in bytes.
+                DWORD timezoneTziValueSize = sizeof(registryTziValue);
+                ret = RegQueryValueExW(hKeyTimeZoneSubKey, L"TZI", nullptr, &registryValueType,
+                                     reinterpret_cast<LPBYTE>(&registryTziValue), &timezoneTziValueSize);
+
+                if (ret == ERROR_SUCCESS) {
+                    if ((dynamicTZI.Bias == registryTziValue.Bias) &&
+                        (memcmp((const void *)&dynamicTZI.StandardDate, (const void *)&registryTziValue.StandardDate, sizeof(SYSTEMTIME)) == 0) &&
+                        (memcmp((const void *)&dynamicTZI.DaylightDate, (const void *)&registryTziValue.DaylightDate, sizeof(SYSTEMTIME)) == 0))
+                    {
+                        // We found a matching time zone.
+                        windowsTimeZoneName = timezoneSubKeyName;
+                        break;
+                    }
+                }
+            }
+            RegCloseKey(hKeyTimeZoneSubKey);
+            hKeyTimeZoneSubKey = nullptr;
+        }
+
+        if (hKeyTimeZoneSubKey != nullptr) {
+            RegCloseKey(hKeyTimeZoneSubKey);
+        }
+        if (hKeyAllTimeZones != nullptr) {
+            RegCloseKey(hKeyAllTimeZones);
+        }
+#endif // U_PLATFORM_HAS_WINUWP_API
     }
 
     CharString winTZ;
     UErrorCode status = U_ZERO_ERROR;
-    winTZ.appendInvariantChars(UnicodeString(TRUE, dynamicTZI.TimeZoneKeyName, -1), status);
+    winTZ.appendInvariantChars(UnicodeString(TRUE, windowsTimeZoneName, -1), status);
 
     // Map Windows Timezone name (non-localized) to ICU timezone ID (~ Olson timezone id).
     StackUResourceBundle winTZBundle;
@@ -123,18 +280,29 @@ uprv_detectWindowsTimeZone()
     int regionCodeLen = GetGeoInfoW(geoId, GEO_ISO2, regionCodeW, UPRV_LENGTHOF(regionCodeW), 0);
 
     const UChar *icuTZ16 = nullptr;
-    int32_t tzLen;
+    int32_t tzListLen = 0;
 
     if (regionCodeLen != 0) {
         for (int i = 0; i < UPRV_LENGTHOF(regionCodeW); i++) {
             regionCode[i] = static_cast<char>(regionCodeW[i]);
         }
-        icuTZ16 = ures_getStringByKey(winTZBundle.getAlias(), regionCode, &tzLen, &status);
+        icuTZ16 = ures_getStringByKey(winTZBundle.getAlias(), regionCode, &tzListLen, &status);
     }
     if (regionCodeLen == 0 || U_FAILURE(status)) {
         // fallback to default "001" (world)
         status = U_ZERO_ERROR;
-        icuTZ16 = ures_getStringByKey(winTZBundle.getAlias(), "001", &tzLen, &status);
+        icuTZ16 = ures_getStringByKey(winTZBundle.getAlias(), "001", &tzListLen, &status);
+    }
+
+    // Note: We want the first entry in the string returned by ures_getStringByKey.
+    // However this string can be a space delimited list of timezones:
+    //  Ex: "America/New_York America/Detroit America/Indiana/Petersburg ..."
+    // We need to stop at the first space, so we pass tzLen (instead of tzListLen) to appendInvariantChars below.
+    int32_t tzLen = 0;
+    if (tzListLen > 0) {
+        while (!(icuTZ16[tzLen] == u'\0' || icuTZ16[tzLen] == u' ')) {
+            tzLen++;
+        }
     }
 
     // Note: cloneData returns nullptr if the status is a failure, so this