1 files changed, 38 insertions, 3 deletions

diff --git a/src/corelib/time/qtimezone.cpp b/src/corelib/time/qtimezone.cpp
index 558cb53a08..8ce967cf9f 100644
--- a/src/corelib/time/qtimezone.cpp
+++ b/src/corelib/time/qtimezone.cpp
@@ -455,10 +455,17 @@ QTimeZone::QTimeZone(const QByteArray &ianaId)
     d = new QUtcTimeZonePrivate(ianaId);
     // If not recognized, try creating it with the system backend.
     if (!d->isValid()) {
-        if (ianaId.isEmpty())
+        if (ianaId.isEmpty()) {
             d = newBackendTimeZone();
-        else // Constructor MUST produce invalid for unsupported ID.
+        } else { // Constructor MUST produce invalid for unsupported ID.
             d = newBackendTimeZone(ianaId);
+            if (!d->isValid()) {
+                // We may have a legacy alias for a supported IANA ID:
+                const QByteArray name = QTimeZonePrivate::aliasToIana(ianaId);
+                if (!name.isEmpty() && name != ianaId)
+                    d = newBackendTimeZone(name);
+            }
+        }
     }
     // Can also handle UTC with arbitrary (valid) offset, but only do so as
     // fall-back, since either of the above may handle it more informatively.
@@ -823,6 +830,34 @@ QByteArray QTimeZone::id() const
 }
 
 /*!
+    \since 6.8
+    Returns \c true if \a alias is an alternative name for this timezone.
+
+    The IANA (formerly Olson) database has renamed some zones during its
+    history. There are also some zones that only differed prior to 1970 but are
+    now treated as synonymous. Some backends may have data reaching to before
+    1970 and produce distinct zones in the latter case. Others may produce zones
+    indistinguishable except by id(). This method determines whether an ID
+    refers (at least since 1970) to the same zone that this timezone object
+    describes.
+
+    This method is only available when feature \c timezone is enabled.
+*/
+bool QTimeZone::aliasMatches(QByteArrayView alias) const
+{
+    if (alias == id())
+        return true;
+    QByteArray mine = QTimeZonePrivate::aliasToIana(id());
+    // Empty if id() aliases to itself, which we've already checked:
+    if (!mine.isEmpty() && alias == mine)
+        return true;
+    QByteArray its = QTimeZonePrivate::aliasToIana(alias);
+    // Empty if alias aliases to itself, which we've already compared to id()
+    // and, where relevant, mine.
+    return !its.isEmpty() && its == (mine.isEmpty() ? id() : mine);
+}
+
+/*!
     \since 6.2
 
     Returns the territory for the time zone.
@@ -908,7 +943,7 @@ QString QTimeZone::displayName(const QDateTime &atDateTime, NameType nameType,
             return systemTimeZone().displayName(atDateTime, nameType, locale);
         case Qt::UTC:
         case Qt::OffsetFromUTC:
-            return QUtcTimeZonePrivate(d.s.offset).QTimeZonePrivate::displayName(
+            return QUtcTimeZonePrivate(d.s.offset).displayName(
                 atDateTime.toMSecsSinceEpoch(), nameType, locale);
         case Qt::TimeZone:
             Q_UNREACHABLE();