5 files changed, 60 insertions, 12 deletions
diff --git a/src/corelib/tools/qstring.cpp b/src/corelib/tools/qstring.cpp
index 08fe9b899d..b465bdc0f4 100644
--- a/src/corelib/tools/qstring.cpp
+++ b/src/corelib/tools/qstring.cpp
@@ -4896,6 +4896,50 @@ bool QString::endsWith(QChar c, Qt::CaseSensitivity cs) const
     return qt_ends_with(*this, c, cs);
 }
 
+/*!
+    Returns \c true if the string only contains uppercase letters,
+    otherwise returns \c false.
+    \since 5.12
+
+    \sa QChar::isUpper(), isLower()
+*/
+bool QString::isUpper() const
+{
+    if (isEmpty())
+        return false;
+
+    const QChar *d = data();
+
+    for (int i = 0, max = size(); i < max; ++i) {
+        if (!d[i].isUpper())
+            return false;
+    }
+
+    return true;
+}
+
+/*!
+    Returns \c true if the string only contains lowercase letters,
+    otherwise returns \c false.
+    \since 5.12
+
+    \sa QChar::isLower(), isUpper()
+ */
+bool QString::isLower() const
+{
+    if (isEmpty())
+        return false;
+
+    const QChar *d = data();
+
+    for (int i = 0, max = size(); i < max; ++i) {
+        if (!d[i].isLower())
+            return false;
+    }
+
+    return true;
+}
+
 static QByteArray qt_convert_to_latin1(QStringView string);
 
 QByteArray QString::toLatin1_helper(const QString &string)
diff --git a/src/corelib/tools/qstring.h b/src/corelib/tools/qstring.h
index 0138ae4098..d93891248f 100644
--- a/src/corelib/tools/qstring.h
+++ b/src/corelib/tools/qstring.h
@@ -409,6 +409,9 @@ public:
     bool endsWith(QLatin1String s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
     bool endsWith(QChar c, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
 
+    bool isUpper() const;
+    bool isLower() const;
+
     Q_REQUIRED_RESULT QString leftJustified(int width, QChar fill = QLatin1Char(' '), bool trunc = false) const;
     Q_REQUIRED_RESULT QString rightJustified(int width, QChar fill = QLatin1Char(' '), bool trunc = false) const;
 
diff --git a/src/corelib/tools/qtimezone.cpp b/src/corelib/tools/qtimezone.cpp
index 65c304bcf7..29299bfcd6 100644
--- a/src/corelib/tools/qtimezone.cpp
+++ b/src/corelib/tools/qtimezone.cpp
@@ -66,11 +66,10 @@ static QTimeZonePrivate *newBackendTimeZone()
     return new QAndroidTimeZonePrivate();
 #elif defined(Q_OS_UNIX) || defined(Q_OS_ANDROID_EMBEDDED)
     return new QTzTimeZonePrivate();
-    // Registry based timezone backend not available on WinRT
-#elif defined Q_OS_WIN
-    return new QWinTimeZonePrivate();
 #elif QT_CONFIG(icu)
     return new QIcuTimeZonePrivate();
+#elif defined Q_OS_WIN
+    return new QWinTimeZonePrivate();
 #else
     return new QUtcTimeZonePrivate();
 #endif // System Locales
@@ -93,11 +92,10 @@ static QTimeZonePrivate *newBackendTimeZone(const QByteArray &ianaId)
     return new QAndroidTimeZonePrivate(ianaId);
 #elif defined(Q_OS_UNIX) || defined(Q_OS_ANDROID_EMBEDDED)
     return new QTzTimeZonePrivate(ianaId);
-    // Registry based timezone backend not available on WinRT
-#elif defined Q_OS_WIN
-    return new QWinTimeZonePrivate(ianaId);
 #elif QT_CONFIG(icu)
     return new QIcuTimeZonePrivate(ianaId);
+#elif defined Q_OS_WIN
+    return new QWinTimeZonePrivate(ianaId);
 #else
     return new QUtcTimeZonePrivate(ianaId);
 #endif // System Locales
diff --git a/src/corelib/tools/qtimezoneprivate_win.cpp b/src/corelib/tools/qtimezoneprivate_win.cpp
index 8bde07c710..ec91b7e8a8 100644
--- a/src/corelib/tools/qtimezoneprivate_win.cpp
+++ b/src/corelib/tools/qtimezoneprivate_win.cpp
@@ -49,6 +49,7 @@
 QT_BEGIN_NAMESPACE
 
 #ifndef Q_OS_WINRT
+// The registry-based timezone backend is not available on WinRT, which falls back to equivalent APIs.
 #define QT_USE_REGISTRY_TIMEZONE 1
 #endif
 
diff --git a/src/corelib/tools/tools.pri b/src/corelib/tools/tools.pri
index 72224f280d..88708851d7 100644
--- a/src/corelib/tools/tools.pri
+++ b/src/corelib/tools/tools.pri
@@ -159,16 +159,18 @@ qtConfig(timezone) {
     SOURCES += \
         tools/qtimezone.cpp \
         tools/qtimezoneprivate.cpp
-    !nacl:darwin: \
+    !nacl:darwin: {
         SOURCES += tools/qtimezoneprivate_mac.mm
-    else: android:!android-embedded: \
+    } else: android:!android-embedded: {
         SOURCES += tools/qtimezoneprivate_android.cpp
-    else: unix: \
+    } else: unix: {
         SOURCES += tools/qtimezoneprivate_tz.cpp
-    else: win32: \
-        SOURCES += tools/qtimezoneprivate_win.cpp
-    qtConfig(icu): \
+        qtConfig(icu): SOURCES += tools/qtimezoneprivate_icu.cpp
+    } else: qtConfig(icu): {
         SOURCES += tools/qtimezoneprivate_icu.cpp
+    } else: win32: {
+        SOURCES += tools/qtimezoneprivate_win.cpp
+    }
 }
 
 qtConfig(datetimeparser) {