Merge "Merge remote-tracking branch 'origin/5.7' into dev" into refs/staging/dev

118 files changed, 951 insertions, 638 deletions

diff --git a/src/angle/README.qt b/src/angle/README.qt
index ce5b6332bc..2d484a0280 100644
--- a/src/angle/README.qt
+++ b/src/angle/README.qt
@@ -1,6 +1,6 @@
 This is the ANGLE project from:
 
-http://code.google.com/p/angleproject/
+https://chromium.googlesource.com/angle/angle/+/master/README.md
 
 The upstream version used here can be found in:
 
diff --git a/src/angle/src/common/common.pri b/src/angle/src/common/common.pri
index 83cd1e8687..9eae06d410 100644
--- a/src/angle/src/common/common.pri
+++ b/src/angle/src/common/common.pri
@@ -21,7 +21,7 @@ lib_replace.CONFIG = path
 QMAKE_PRL_INSTALL_REPLACE += lib_replace
 
 # DirectX is included in the Windows 8 Kit, but everything else requires the DX SDK.
-winrt|if(msvc:!win32-msvc2005:!win32-msvc2008:!win32-msvc2010) {
+winrt|msvc {
     FXC = fxc.exe
 } else {
     DX_DIR = $$(DXSDK_DIR)
diff --git a/src/corelib/Qt5CoreConfigExtras.cmake.in b/src/corelib/Qt5CoreConfigExtras.cmake.in
index f492148a50..a5ed8b2ea3 100644
--- a/src/corelib/Qt5CoreConfigExtras.cmake.in
+++ b/src/corelib/Qt5CoreConfigExtras.cmake.in
@@ -46,21 +46,6 @@ if (NOT TARGET Qt5::rcc)
     )
 endif()
 
-if (NOT TARGET Qt5::qdoc)
-    add_executable(Qt5::qdoc IMPORTED)
-
-!!IF isEmpty(CMAKE_BIN_DIR_IS_ABSOLUTE)
-    set(imported_location \"${_qt5Core_install_prefix}/$${CMAKE_BIN_DIR}qdoc$$CMAKE_BIN_SUFFIX\")
-!!ELSE
-    set(imported_location \"$${CMAKE_BIN_DIR}qdoc$$CMAKE_BIN_SUFFIX\")
-!!ENDIF
-    _qt5_Core_check_file_exists(${imported_location})
-
-    set_target_properties(Qt5::qdoc PROPERTIES
-        IMPORTED_LOCATION ${imported_location}
-    )
-endif()
-
 set(Qt5Core_QMAKE_EXECUTABLE Qt5::qmake)
 set(Qt5Core_MOC_EXECUTABLE Qt5::moc)
 set(Qt5Core_RCC_EXECUTABLE Qt5::rcc)
diff --git a/src/corelib/arch/qatomic_cxx11.h b/src/corelib/arch/qatomic_cxx11.h
index bb49aae4fb..9658aca37c 100644
--- a/src/corelib/arch/qatomic_cxx11.h
+++ b/src/corelib/arch/qatomic_cxx11.h
@@ -53,44 +53,168 @@ QT_END_NAMESPACE
 #pragma qt_sync_stop_processing
 #endif
 
-#define Q_ATOMIC_INT_REFERENCE_COUNTING_IS_SOMETIMES_NATIVE
-#define Q_ATOMIC_INT_TEST_AND_SET_IS_SOMETIMES_NATIVE
-#define Q_ATOMIC_INT_FETCH_AND_STORE_IS_SOMETIMES_NATIVE
-#define Q_ATOMIC_INT_FETCH_AND_ADD_IS_SOMETIMES_NATIVE
+/* Attempt to detect whether the atomic operations exist in hardware
+ * or whether they are emulated by way of a lock.
+ *
+ * C++11 29.4 [atomics.lockfree] p1 says
+ *
+ *  The ATOMIC_..._LOCK_FREE macros indicate the lock-free property of the
+ *  corresponding atomic types, with the signed and unsigned variants grouped
+ *  together. The properties also apply to the corresponding (partial)
+ *  specializations of the atomic template. A value of 0 indicates that the
+ *  types are never lock-free. A value of 1 indicates that the types are
+ *  sometimes lock-free. A value of 2 indicates that the types are always
+ *  lock-free.
+ *
+ * We have a problem when the value is 1: we'd need to check at runtime, but
+ * QAtomicInteger requires a constexpr answer (defect introduced in Qt 5.0). So
+ * we'll err in the side of caution and say it isn't.
+ */
+
+// ### Qt 6: make non-constexpr (see above)
+template <int N> struct QAtomicTraits
+{ static Q_DECL_CONSTEXPR inline bool isLockFree() Q_DECL_NOTHROW; };
 
 #define Q_ATOMIC_INT32_IS_SUPPORTED
-#define Q_ATOMIC_INT32_REFERENCE_COUNTING_IS_SOMETIMES_NATIVE
-#define Q_ATOMIC_INT32_TEST_AND_SET_IS_SOMETIMES_NATIVE
-#define Q_ATOMIC_INT32_FETCH_AND_STORE_IS_SOMETIMES_NATIVE
-#define Q_ATOMIC_INT32_FETCH_AND_ADD_IS_SOMETIMES_NATIVE
+#if ATOMIC_INT_LOCK_FREE == 2
+#  define Q_ATOMIC_INT_REFERENCE_COUNTING_IS_ALWAYS_NATIVE
+#  define Q_ATOMIC_INT_TEST_AND_SET_IS_ALWAYS_NATIVE
+#  define Q_ATOMIC_INT_FETCH_AND_STORE_IS_ALWAYS_NATIVE
+#  define Q_ATOMIC_INT_FETCH_AND_ADD_IS_ALWAYS_NATIVE
+#  define Q_ATOMIC_INT32_REFERENCE_COUNTING_IS_ALWAYS_NATIVE
+#  define Q_ATOMIC_INT32_TEST_AND_SET_IS_ALWAYS_NATIVE
+#  define Q_ATOMIC_INT32_FETCH_AND_STORE_IS_ALWAYS_NATIVE
+#  define Q_ATOMIC_INT32_FETCH_AND_ADD_IS_ALWAYS_NATIVE
+
+template <> Q_DECL_CONSTEXPR inline bool QAtomicTraits<4>::isLockFree() Q_DECL_NOTHROW
+{ return true; }
+#elif ATOMIC_INT_LOCK_FREE == 1
+#  define Q_ATOMIC_INT_REFERENCE_COUNTING_IS_SOMETIMES_NATIVE
+#  define Q_ATOMIC_INT_TEST_AND_SET_IS_SOMETIMES_NATIVE
+#  define Q_ATOMIC_INT_FETCH_AND_STORE_IS_SOMETIMES_NATIVE
+#  define Q_ATOMIC_INT_FETCH_AND_ADD_IS_SOMETIMES_NATIVE
+#  define Q_ATOMIC_INT32_REFERENCE_COUNTING_IS_SOMETIMES_NATIVE
+#  define Q_ATOMIC_INT32_TEST_AND_SET_IS_SOMETIMES_NATIVE
+#  define Q_ATOMIC_INT32_FETCH_AND_STORE_IS_SOMETIMES_NATIVE
+#  define Q_ATOMIC_INT32_FETCH_AND_ADD_IS_SOMETIMES_NATIVE
+
+template <> Q_DECL_CONSTEXPR inline bool QAtomicTraits<4>::isLockFree() Q_DECL_NOTHROW
+{ return false; }
+#else
+#  define Q_ATOMIC_INT_REFERENCE_COUNTING_IS_NEVER_NATIVE
+#  define Q_ATOMIC_INT_TEST_AND_SET_IS_NEVER_NATIVE
+#  define Q_ATOMIC_INT_FETCH_AND_STORE_IS_NEVER_NATIVE
+#  define Q_ATOMIC_INT_FETCH_AND_ADD_IS_NEVER_NATIVE
+#  define Q_ATOMIC_INT32_REFERENCE_COUNTING_IS_NEVER_NATIVE
+#  define Q_ATOMIC_INT32_TEST_AND_SET_IS_NEVER_NATIVE
+#  define Q_ATOMIC_INT32_FETCH_AND_STORE_IS_NEVER_NATIVE
+#  define Q_ATOMIC_INT32_FETCH_AND_ADD_IS_NEVER_NATIVE
+
+template <> Q_DECL_CONSTEXPR inline bool QAtomicTraits<4>::isLockFree() Q_DECL_NOTHROW
+{ return false; }
+#endif
 
-#define Q_ATOMIC_POINTER_REFERENCE_COUNTING_IS_SOMETIMES_NATIVE
-#define Q_ATOMIC_POINTER_TEST_AND_SET_IS_SOMETIMES_NATIVE
-#define Q_ATOMIC_POINTER_FETCH_AND_STORE_IS_SOMETIMES_NATIVE
-#define Q_ATOMIC_POINTER_FETCH_AND_ADD_IS_SOMETIMES_NATIVE
+#if ATOMIC_POINTER_LOCK_FREE == 2
+#  define Q_ATOMIC_POINTER_REFERENCE_COUNTING_IS_ALWAYS_NATIVE
+#  define Q_ATOMIC_POINTER_TEST_AND_SET_IS_ALWAYS_NATIVE
+#  define Q_ATOMIC_POINTER_FETCH_AND_STORE_IS_ALWAYS_NATIVE
+#  define Q_ATOMIC_POINTER_FETCH_AND_ADD_IS_ALWAYS_NATIVE
+#elif ATOMIC_POINTER_LOCK_FREE == 1
+#  define Q_ATOMIC_POINTER_REFERENCE_COUNTING_IS_SOMETIMES_NATIVE
+#  define Q_ATOMIC_POINTER_TEST_AND_SET_IS_SOMETIMES_NATIVE
+#  define Q_ATOMIC_POINTER_FETCH_AND_STORE_IS_SOMETIMES_NATIVE
+#  define Q_ATOMIC_POINTER_FETCH_AND_ADD_IS_SOMETIMES_NATIVE
+#else
+#  define Q_ATOMIC_POINTER_REFERENCE_COUNTING_IS_NEVER_NATIVE
+#  define Q_ATOMIC_POINTER_TEST_AND_SET_IS_NEVER_NATIVE
+#  define Q_ATOMIC_POINTER_FETCH_AND_STORE_IS_NEVER_NATIVE
+#  define Q_ATOMIC_POINTER_FETCH_AND_ADD_IS_NEVER_NATIVE
+#endif
 
 template<> struct QAtomicOpsSupport<1> { enum { IsSupported = 1 }; };
-template<> struct QAtomicOpsSupport<2> { enum { IsSupported = 1 }; };
-template<> struct QAtomicOpsSupport<8> { enum { IsSupported = 1 }; };
-
 #define Q_ATOMIC_INT8_IS_SUPPORTED
-#define Q_ATOMIC_INT8_REFERENCE_COUNTING_IS_ALWAYS_NATIVE
-#define Q_ATOMIC_INT8_TEST_AND_SET_IS_ALWAYS_NATIVE
-#define Q_ATOMIC_INT8_FETCH_AND_STORE_IS_ALWAYS_NATIVE
-#define Q_ATOMIC_INT8_FETCH_AND_ADD_IS_ALWAYS_NATIVE
+#if ATOMIC_CHAR_LOCK_FREE == 2
+#  define Q_ATOMIC_INT8_REFERENCE_COUNTING_IS_ALWAYS_NATIVE
+#  define Q_ATOMIC_INT8_TEST_AND_SET_IS_ALWAYS_NATIVE
+#  define Q_ATOMIC_INT8_FETCH_AND_STORE_IS_ALWAYS_NATIVE
+#  define Q_ATOMIC_INT8_FETCH_AND_ADD_IS_ALWAYS_NATIVE
+
+template <> Q_DECL_CONSTEXPR inline bool QAtomicTraits<1>::isLockFree() Q_DECL_NOTHROW
+{ return true; }
+#elif ATOMIC_CHAR_LOCK_FREE == 1
+#  define Q_ATOMIC_INT8_REFERENCE_COUNTING_IS_SOMETIMES_NATIVE
+#  define Q_ATOMIC_INT8_TEST_AND_SET_IS_SOMETIMES_NATIVE
+#  define Q_ATOMIC_INT8_FETCH_AND_STORE_IS_SOMETIMES_NATIVE
+#  define Q_ATOMIC_INT8_FETCH_AND_ADD_IS_SOMETIMES_NATIVE
+
+template <> Q_DECL_CONSTEXPR inline bool QAtomicTraits<1>::isLockFree() Q_DECL_NOTHROW
+{ return false; }
+#else
+#  define Q_ATOMIC_INT8_REFERENCE_COUNTING_IS_NEVER_NATIVE
+#  define Q_ATOMIC_INT8_TEST_AND_SET_IS_NEVER_NATIVE
+#  define Q_ATOMIC_INT8_FETCH_AND_STORE_IS_NEVER_NATIVE
+#  define Q_ATOMIC_INT8_FETCH_AND_ADD_IS_NEVER_NATIVE
 
+template <> Q_DECL_CONSTEXPR bool QAtomicTraits<1>::isLockFree() Q_DECL_NOTHROW
+{ return false; }
+#endif
+
+template<> struct QAtomicOpsSupport<2> { enum { IsSupported = 1 }; };
 #define Q_ATOMIC_INT16_IS_SUPPORTED
-#define Q_ATOMIC_INT16_REFERENCE_COUNTING_IS_ALWAYS_NATIVE
-#define Q_ATOMIC_INT16_TEST_AND_SET_IS_ALWAYS_NATIVE
-#define Q_ATOMIC_INT16_FETCH_AND_STORE_IS_ALWAYS_NATIVE
-#define Q_ATOMIC_INT16_FETCH_AND_ADD_IS_ALWAYS_NATIVE
+#if ATOMIC_SHORT_LOCK_FREE == 2
+#  define Q_ATOMIC_INT16_REFERENCE_COUNTING_IS_ALWAYS_NATIVE
+#  define Q_ATOMIC_INT16_TEST_AND_SET_IS_ALWAYS_NATIVE
+#  define Q_ATOMIC_INT16_FETCH_AND_STORE_IS_ALWAYS_NATIVE
+#  define Q_ATOMIC_INT16_FETCH_AND_ADD_IS_ALWAYS_NATIVE
+
+template <> Q_DECL_CONSTEXPR inline bool QAtomicTraits<2>::isLockFree() Q_DECL_NOTHROW
+{ return false; }
+#elif ATOMIC_SHORT_LOCK_FREE == 1
+#  define Q_ATOMIC_INT16_REFERENCE_COUNTING_IS_SOMETIMES_NATIVE
+#  define Q_ATOMIC_INT16_TEST_AND_SET_IS_SOMETIMES_NATIVE
+#  define Q_ATOMIC_INT16_FETCH_AND_STORE_IS_SOMETIMES_NATIVE
+#  define Q_ATOMIC_INT16_FETCH_AND_ADD_IS_SOMETIMES_NATIVE
+
+template <> Q_DECL_CONSTEXPR inline bool QAtomicTraits<2>::isLockFree() Q_DECL_NOTHROW
+{ return false; }
+#else
+#  define Q_ATOMIC_INT16_REFERENCE_COUNTING_IS_NEVER_NATIVE
+#  define Q_ATOMIC_INT16_TEST_AND_SET_IS_NEVER_NATIVE
+#  define Q_ATOMIC_INT16_FETCH_AND_STORE_IS_NEVER_NATIVE
+#  define Q_ATOMIC_INT16_FETCH_AND_ADD_IS_NEVER_NATIVE
+
+template <> Q_DECL_CONSTEXPR inline bool QAtomicTraits<2>::isLockFree() Q_DECL_NOTHROW
+{ return false; }
+#endif
 
 #ifndef QT_NO_STD_ATOMIC64
+template<> struct QAtomicOpsSupport<8> { enum { IsSupported = 1 }; };
 #  define Q_ATOMIC_INT64_IS_SUPPORTED
-#  define Q_ATOMIC_INT64_REFERENCE_COUNTING_IS_ALWAYS_NATIVE
-#  define Q_ATOMIC_INT64_TEST_AND_SET_IS_ALWAYS_NATIVE
-#  define Q_ATOMIC_INT64_FETCH_AND_STORE_IS_ALWAYS_NATIVE
-#  define Q_ATOMIC_INT64_FETCH_AND_ADD_IS_ALWAYS_NATIVE
+#  if ATOMIC_LLONG_LOCK_FREE == 2
+#    define Q_ATOMIC_INT16_REFERENCE_COUNTING_IS_ALWAYS_NATIVE
+#    define Q_ATOMIC_INT16_TEST_AND_SET_IS_ALWAYS_NATIVE
+#    define Q_ATOMIC_INT16_FETCH_AND_STORE_IS_ALWAYS_NATIVE
+#    define Q_ATOMIC_INT16_FETCH_AND_ADD_IS_ALWAYS_NATIVE
+
+template <> Q_DECL_CONSTEXPR inline bool QAtomicTraits<8>::isLockFree() Q_DECL_NOTHROW
+{ return true; }
+#  elif ATOMIC_LLONG_LOCK_FREE == 1
+#    define Q_ATOMIC_INT16_REFERENCE_COUNTING_IS_SOMETIMES_NATIVE
+#    define Q_ATOMIC_INT16_TEST_AND_SET_IS_SOMETIMES_NATIVE
+#    define Q_ATOMIC_INT16_FETCH_AND_STORE_IS_SOMETIMES_NATIVE
+#    define Q_ATOMIC_INT16_FETCH_AND_ADD_IS_SOMETIMES_NATIVE
+
+template <> Q_DECL_CONSTEXPR inline bool QAtomicTraits<8>::isLockFree() Q_DECL_NOTHROW
+{ return false; }
+#  else
+#    define Q_ATOMIC_INT16_REFERENCE_COUNTING_IS_NEVER_NATIVE
+#    define Q_ATOMIC_INT16_TEST_AND_SET_IS_NEVER_NATIVE
+#    define Q_ATOMIC_INT16_FETCH_AND_STORE_IS_NEVER_NATIVE
+#    define Q_ATOMIC_INT16_FETCH_AND_ADD_IS_NEVER_NATIVE
+
+template <> Q_DECL_CONSTEXPR inline bool QAtomicTraits<8>::isLockFree() Q_DECL_NOTHROW
+{ return false; }
+#  endif
 #endif
 
 template <typename X> struct QAtomicOps
@@ -133,7 +257,7 @@ template <typename X> struct QAtomicOps
         _q_value.store(newValue, std::memory_order_release);
     }
 
-    static inline Q_DECL_CONSTEXPR bool isReferenceCountingNative() Q_DECL_NOTHROW { return true; }
+    static inline Q_DECL_CONSTEXPR bool isReferenceCountingNative() Q_DECL_NOTHROW { return isTestAndSetNative(); }
     static inline Q_DECL_CONSTEXPR bool isReferenceCountingWaitFree() Q_DECL_NOTHROW { return false; }
     template <typename T>
     static inline bool ref(std::atomic<T> &_q_value)
@@ -147,7 +271,8 @@ template <typename X> struct QAtomicOps
         return --_q_value != 0;
     }
 
-    static inline Q_DECL_CONSTEXPR bool isTestAndSetNative() Q_DECL_NOTHROW { return false; }
+    static inline Q_DECL_CONSTEXPR bool isTestAndSetNative() Q_DECL_NOTHROW
+    { return QAtomicTraits<sizeof(X)>::isLockFree(); }
     static inline Q_DECL_CONSTEXPR bool isTestAndSetWaitFree() Q_DECL_NOTHROW { return false; }
 
     template <typename T>
@@ -186,7 +311,7 @@ template <typename X> struct QAtomicOps
         return tmp;
     }
 
-    static inline Q_DECL_CONSTEXPR bool isFetchAndStoreNative() Q_DECL_NOTHROW { return false; }
+    static inline Q_DECL_CONSTEXPR bool isFetchAndStoreNative() Q_DECL_NOTHROW { return isTestAndSetNative(); }
     static inline Q_DECL_CONSTEXPR bool isFetchAndStoreWaitFree() Q_DECL_NOTHROW { return false; }
 
     template <typename T>
@@ -213,7 +338,7 @@ template <typename X> struct QAtomicOps
         return _q_value.exchange(newValue, std::memory_order_acq_rel);
     }
 
-    static inline Q_DECL_CONSTEXPR bool isFetchAndAddNative() Q_DECL_NOTHROW { return false; }
+    static inline Q_DECL_CONSTEXPR bool isFetchAndAddNative() Q_DECL_NOTHROW { return isTestAndSetNative(); }
     static inline Q_DECL_CONSTEXPR bool isFetchAndAddWaitFree() Q_DECL_NOTHROW { return false; }
 
     template <typename T> static inline
diff --git a/src/corelib/doc/snippets/code/src_corelib_global_qglobal.cpp b/src/corelib/doc/snippets/code/src_corelib_global_qglobal.cpp
index ae969ca269..1169ad5536 100644
--- a/src/corelib/doc/snippets/code/src_corelib_global_qglobal.cpp
+++ b/src/corelib/doc/snippets/code/src_corelib_global_qglobal.cpp
@@ -603,13 +603,13 @@ template<> class QTypeInfo<A> : public QTypeInfoMerger<A, B, C, D> {};
         void overloadedFunction();
         void overloadedFunction(int, QString);
     };
-    ... qOverload<>(&Foo:overloadedFunction)
-    ... qOverload<int, QString>(&Foo:overloadedFunction)
+    ... qOverload<>(&Foo::overloadedFunction)
+    ... qOverload<int, QString>(&Foo::overloadedFunction)
 //! [52]
 
 //! [53]
-    ... QOverload<>::of(&Foo:overloadedFunction)
-    ... QOverload<int, QString>::of(&Foo:overloadedFunction)
+    ... QOverload<>::of(&Foo::overloadedFunction)
+    ... QOverload<int, QString>::of(&Foo::overloadedFunction)
 //! [53]
 
 //! [54]
@@ -617,8 +617,8 @@ template<> class QTypeInfo<A> : public QTypeInfoMerger<A, B, C, D> {};
         void overloadedFunction(int, QString);
         void overloadedFunction(int, QString) const;
     };
-    ... qConstOverload<>(&Foo:overloadedFunction)
-    ... qNonConstOverload<int, QString>(&Foo:overloadedFunction)
+    ... qConstOverload<>(&Foo::overloadedFunction)
+    ... qNonConstOverload<int, QString>(&Foo::overloadedFunction)
 //! [54]
 
 //! [qlikely]
diff --git a/src/corelib/doc/snippets/code/src_corelib_kernel_qvariant.cpp b/src/corelib/doc/snippets/code/src_corelib_kernel_qvariant.cpp
index 576aea1cf5..ca1ea21b02 100644
--- a/src/corelib/doc/snippets/code/src_corelib_kernel_qvariant.cpp
+++ b/src/corelib/doc/snippets/code/src_corelib_kernel_qvariant.cpp
@@ -147,10 +147,7 @@ QVariant data = QVariant::fromValue(object);
 
 //! [9]
 
-QList<int> intList;
-intList.push_back(7);
-intList.push_back(11);
-intList.push_back(42);
+QList<int> intList = {7, 11, 42};
 
 QVariant variant = QVariant::fromValue(intList);
 if (variant.canConvert<QVariantList>()) {
diff --git a/src/corelib/global/qlogging.cpp b/src/corelib/global/qlogging.cpp
index 0fe095b8d3..3aee15051f 100644
--- a/src/corelib/global/qlogging.cpp
+++ b/src/corelib/global/qlogging.cpp
@@ -1123,7 +1123,7 @@ void QMessagePattern::setPattern(const QString &pattern)
                 if (m.hasMatch()) {
                     int depth = m.capturedRef(1).toInt();
                     if (depth <= 0)
-                        error += QStringLiteral("QT_MESSAGE_PATTERN: %{backtrace} depth must be a number greater than 0\n");
+                        error += QLatin1String("QT_MESSAGE_PATTERN: %{backtrace} depth must be a number greater than 0\n");
                     else
                         backtraceDepth = depth;
                 }
@@ -1135,7 +1135,7 @@ void QMessagePattern::setPattern(const QString &pattern)
                 backtraceParams.backtraceSeparator = backtraceSeparator;
                 backtraceArgs.append(backtraceParams);
 #else
-                error += QStringLiteral("QT_MESSAGE_PATTERN: %{backtrace} is not supported by this Qt build\n");
+                error += QLatin1String("QT_MESSAGE_PATTERN: %{backtrace} is not supported by this Qt build\n");
 #endif
             }
 
@@ -1156,7 +1156,7 @@ void QMessagePattern::setPattern(const QString &pattern)
             else if (lexeme == QLatin1String(endifTokenC)) {
                 tokens[i] = endifTokenC;
                 if (!inIf && !nestedIfError)
-                    error += QStringLiteral("QT_MESSAGE_PATTERN: %{endif} without an %{if-*}\n");
+                    error += QLatin1String("QT_MESSAGE_PATTERN: %{endif} without an %{if-*}\n");
                 inIf = false;
             } else {
                 tokens[i] = emptyTokenC;
@@ -1172,9 +1172,9 @@ void QMessagePattern::setPattern(const QString &pattern)
         }
     }
     if (nestedIfError)
-        error += QStringLiteral("QT_MESSAGE_PATTERN: %{if-*} cannot be nested\n");
+        error += QLatin1String("QT_MESSAGE_PATTERN: %{if-*} cannot be nested\n");
     else if (inIf)
-        error += QStringLiteral("QT_MESSAGE_PATTERN: missing %{endif}\n");
+        error += QLatin1String("QT_MESSAGE_PATTERN: missing %{endif}\n");
     if (!error.isEmpty()) {
 #if defined(Q_OS_WINRT)
         OutputDebugString(reinterpret_cast<const wchar_t*>(error.utf16()));
diff --git a/src/corelib/io/qdatastream.h b/src/corelib/io/qdatastream.h
index c7f8840a82..5956f9ac40 100644
--- a/src/corelib/io/qdatastream.h
+++ b/src/corelib/io/qdatastream.h
@@ -195,6 +195,29 @@ private:
     int readBlock(char *data, int len);
 };
 
+namespace QtPrivate {
+
+class StreamStateSaver
+{
+public:
+    inline StreamStateSaver(QDataStream *s) : stream(s), oldStatus(s->status())
+    {
+        stream->resetStatus();
+    }
+    inline ~StreamStateSaver()
+    {
+        if (oldStatus != QDataStream::Ok) {
+            stream->resetStatus();
+            stream->setStatus(oldStatus);
+        }
+    }
+
+private:
+    QDataStream *stream;
+    QDataStream::Status oldStatus;
+};
+
+} // QtPrivate namespace
 
 /*****************************************************************************
   QDataStream inline functions
@@ -239,6 +262,8 @@ inline QDataStream &QDataStream::operator<<(quint64 i)
 template <typename T>
 QDataStream& operator>>(QDataStream& s, QList<T>& l)
 {
+    QtPrivate::StreamStateSaver stateSaver(&s);
+
     l.clear();
     quint32 c;
     s >> c;
@@ -247,10 +272,13 @@ QDataStream& operator>>(QDataStream& s, QList<T>& l)
     {
         T t;
         s >> t;
-        l.append(t);
-        if (s.atEnd())
+        if (s.status() != QDataStream::Ok) {
+            l.clear();
             break;
+        }
+        l.append(t);
     }
+
     return s;
 }
 
@@ -266,6 +294,8 @@ QDataStream& operator<<(QDataStream& s, const QList<T>& l)
 template <typename T>
 QDataStream& operator>>(QDataStream& s, QLinkedList<T>& l)
 {
+    QtPrivate::StreamStateSaver stateSaver(&s);
+
     l.clear();
     quint32 c;
     s >> c;
@@ -273,10 +303,13 @@ QDataStream& operator>>(QDataStream& s, QLinkedList<T>& l)
     {
         T t;
         s >> t;
-        l.append(t);
-        if (s.atEnd())
+        if (s.status() != QDataStream::Ok) {
+            l.clear();
             break;
+        }
+        l.append(t);
     }
+
     return s;
 }
 
@@ -293,6 +326,8 @@ QDataStream& operator<<(QDataStream& s, const QLinkedList<T>& l)
 template<typename T>
 QDataStream& operator>>(QDataStream& s, QVector<T>& v)
 {
+    QtPrivate::StreamStateSaver stateSaver(&s);
+
     v.clear();
     quint32 c;
     s >> c;
@@ -300,8 +335,13 @@ QDataStream& operator>>(QDataStream& s, QVector<T>& v)
     for(quint32 i = 0; i < c; ++i) {
         T t;
         s >> t;
+        if (s.status() != QDataStream::Ok) {
+            v.clear();
+            break;
+        }
         v[i] = t;
     }
+
     return s;
 }
 
@@ -317,16 +357,21 @@ QDataStream& operator<<(QDataStream& s, const QVector<T>& v)
 template <typename T>
 QDataStream &operator>>(QDataStream &in, QSet<T> &set)
 {
+    QtPrivate::StreamStateSaver stateSaver(&in);
+
     set.clear();
     quint32 c;
     in >> c;
     for (quint32 i = 0; i < c; ++i) {
         T t;
         in >> t;
-        set << t;
-        if (in.atEnd())
+        if (in.status() != QDataStream::Ok) {
+            set.clear();
             break;
+        }
+        set << t;
     }
+
     return in;
 }
 
@@ -345,10 +390,9 @@ QDataStream& operator<<(QDataStream &out, const QSet<T> &set)
 template <class Key, class T>
 Q_OUTOFLINE_TEMPLATE QDataStream &operator>>(QDataStream &in, QHash<Key, T> &hash)
 {
-    QDataStream::Status oldStatus = in.status();
-    in.resetStatus();
-    hash.clear();
+    QtPrivate::StreamStateSaver stateSaver(&in);
 
+    hash.clear();
     quint32 n;
     in >> n;
 
@@ -364,10 +408,6 @@ Q_OUTOFLINE_TEMPLATE QDataStream &operator>>(QDataStream &in, QHash<Key, T> &has
 
     if (in.status() != QDataStream::Ok)
         hash.clear();
-    if (oldStatus != QDataStream::Ok) {
-        in.resetStatus();
-        in.setStatus(oldStatus);
-    }
     return in;
 }
 
@@ -391,10 +431,9 @@ template <class aKey, class aT>
 Q_OUTOFLINE_TEMPLATE QDataStream &operator>>(QDataStream &in, QMap<aKey, aT> &map)
 #endif
 {
-    QDataStream::Status oldStatus = in.status();
-    in.resetStatus();
-    map.clear();
+    QtPrivate::StreamStateSaver stateSaver(&in);
 
+    map.clear();
     quint32 n;
     in >> n;
 
@@ -410,10 +449,6 @@ Q_OUTOFLINE_TEMPLATE QDataStream &operator>>(QDataStream &in, QMap<aKey, aT> &ma
     }
     if (in.status() != QDataStream::Ok)
         map.clear();
-    if (oldStatus != QDataStream::Ok) {
-        in.resetStatus();
-        in.setStatus(oldStatus);
-    }
     return in;
 }
 
diff --git a/src/corelib/io/qdir.cpp b/src/corelib/io/qdir.cpp
index 8197ea63e7..91953ebf26 100644
--- a/src/corelib/io/qdir.cpp
+++ b/src/corelib/io/qdir.cpp
@@ -694,7 +694,7 @@ QString QDir::filePath(const QString &fileName) const
 {
     const QDirPrivate* d = d_ptr.constData();
     if (isAbsolutePath(fileName))
-        return QString(fileName);
+        return fileName;
 
     QString ret = d->dirEntry.filePath();
     if (!fileName.isEmpty()) {
diff --git a/src/corelib/io/qfileselector.cpp b/src/corelib/io/qfileselector.cpp
index 63a15c9fac..920281cef7 100644
--- a/src/corelib/io/qfileselector.cpp
+++ b/src/corelib/io/qfileselector.cpp
@@ -388,7 +388,7 @@ QStringList QFileSelectorPrivate::platformSelectors()
 #  endif
     QString productName = QSysInfo::productType();
 #     ifdef Q_OS_MACOS
-    if (productName != QStringLiteral("osx"))
+    if (productName != QLatin1String("osx"))
         ret << QStringLiteral("osx"); // compatibility
 #     endif
     if (productName != QLatin1String("unknown"))
diff --git a/src/corelib/io/qlockfile_unix.cpp b/src/corelib/io/qlockfile_unix.cpp
index 79141d1e8f..924d2e7214 100644
--- a/src/corelib/io/qlockfile_unix.cpp
+++ b/src/corelib/io/qlockfile_unix.cpp
@@ -71,12 +71,12 @@
 #elif defined(Q_OS_HAIKU)
 #   include <kernel/OS.h>
 #elif defined(Q_OS_BSD4) && !defined(QT_PLATFORM_UIKIT)
-# if !defined(Q_OS_NETBSD)
-#   include <sys/user.h>
-# endif
 #   include <sys/cdefs.h>
 #   include <sys/param.h>
 #   include <sys/sysctl.h>
+# if !defined(Q_OS_NETBSD)
+#   include <sys/user.h>
+# endif
 #endif
 
 QT_BEGIN_NAMESPACE
diff --git a/src/corelib/io/qsettings.cpp b/src/corelib/io/qsettings.cpp
index ed3273eb2e..856108e417 100644
--- a/src/corelib/io/qsettings.cpp
+++ b/src/corelib/io/qsettings.cpp
@@ -248,8 +248,7 @@ QString QSettingsPrivate::actualKey(const QString &key) const
 {
     QString n = normalizedKey(key);
     Q_ASSERT_X(!n.isEmpty(), "QSettings", "empty key");
-    n.prepend(groupPrefix);
-    return n;
+    return groupPrefix + n;
 }
 
 /*
@@ -324,10 +323,9 @@ void QSettingsPrivate::processChild(QStringRef key, ChildSpec spec, QStringList
 void QSettingsPrivate::beginGroupOrArray(const QSettingsGroup &group)
 {
     groupStack.push(group);
-    if (!group.name().isEmpty()) {
-        groupPrefix += group.name();
-        groupPrefix += QLatin1Char('/');
-    }
+    const QString name = group.name();
+    if (!name.isEmpty())
+        groupPrefix += name + QLatin1Char('/');
 }
 
 /*
@@ -403,9 +401,9 @@ QString QSettingsPrivate::variantToString(const QVariant &v)
 
         case QVariant::ByteArray: {
             QByteArray a = v.toByteArray();
-            result = QLatin1String("@ByteArray(");
-            result += QString::fromLatin1(a.constData(), a.size());
-            result += QLatin1Char(')');
+            result = QLatin1String("@ByteArray(")
+                     + QLatin1String(a.constData(), a.size())
+                     + QLatin1Char(')');
             break;
         }
 
@@ -425,33 +423,17 @@ QString QSettingsPrivate::variantToString(const QVariant &v)
 #ifndef QT_NO_GEOM_VARIANT
         case QVariant::Rect: {
             QRect r = qvariant_cast<QRect>(v);
-            result += QLatin1String("@Rect(");
-            result += QString::number(r.x());
-            result += QLatin1Char(' ');
-            result += QString::number(r.y());
-            result += QLatin1Char(' ');
-            result += QString::number(r.width());
-            result += QLatin1Char(' ');
-            result += QString::number(r.height());
-            result += QLatin1Char(')');
+            result = QString::asprintf("@Rect(%d %d %d %d)", r.x(), r.y(), r.width(), r.height());
             break;
         }
         case QVariant::Size: {
             QSize s = qvariant_cast<QSize>(v);
-            result += QLatin1String("@Size(");
-            result += QString::number(s.width());
-            result += QLatin1Char(' ');
-            result += QString::number(s.height());
-            result += QLatin1Char(')');
+            result = QString::asprintf("@Size(%d %d)", s.width(), s.height());
             break;
         }
         case QVariant::Point: {
             QPoint p = qvariant_cast<QPoint>(v);
-            result += QLatin1String("@Point(");
-            result += QString::number(p.x());
-            result += QLatin1Char(' ');
-            result += QString::number(p.y());
-            result += QLatin1Char(')');
+            result = QString::asprintf("@Point(%d %d)", p.x(), p.y());
             break;
         }
 #endif // !QT_NO_GEOM_VARIANT
@@ -474,9 +456,9 @@ QString QSettingsPrivate::variantToString(const QVariant &v)
                 s << v;
             }
 
-            result = QLatin1String(typeSpec);
-            result += QString::fromLatin1(a.constData(), a.size());
-            result += QLatin1Char(')');
+            result = QLatin1String(typeSpec)
+                     + QLatin1String(a.constData(), a.size())
+                     + QLatin1Char(')');
 #else
             Q_ASSERT(!"QSettings: Cannot save custom types without QDataStream support");
 #endif
@@ -647,8 +629,7 @@ void QSettingsPrivate::iniEscapedString(const QString &str, QByteArray &result,
                 && ((ch >= '0' && ch <= '9')
                     || (ch >= 'a' && ch <= 'f')
                     || (ch >= 'A' && ch <= 'F'))) {
-            result += "\\x";
-            result += QByteArray::number(ch, 16);
+            result += "\\x" + QByteArray::number(ch, 16);
             continue;
         }
 
@@ -687,8 +668,7 @@ void QSettingsPrivate::iniEscapedString(const QString &str, QByteArray &result,
             break;
         default:
             if (ch <= 0x1F || (ch >= 0x7F && !useCodec)) {
-                result += "\\x";
-                result += QByteArray::number(ch, 16);
+                result += "\\x" + QByteArray::number(ch, 16);
                 escapeNextIfDigit = true;
 #ifndef QT_NO_TEXTCODEC
             } else if (useCodec) {
@@ -1038,10 +1018,33 @@ static inline int pathHashKey(QSettings::Format format, QSettings::Scope scope)
     return int((uint(format) << 1) | uint(scope == QSettings::SystemScope));
 }
 
+#ifndef Q_OS_WIN
+static QString make_user_path()
+{
+    static Q_CONSTEXPR QChar sep = QLatin1Char('/');
+#ifndef QSETTINGS_USE_QSTANDARDPATHS
+    // Non XDG platforms (OS X, iOS, Android...) have used this code path erroneously
+    // for some time now. Moving away from that would require migrating existing settings.
+    QByteArray env = qgetenv("XDG_CONFIG_HOME");
+    if (env.isEmpty()) {
+        return QDir::homePath() + QLatin1String("/.config/");
+    } else if (env.startsWith('/')) {
+        return QFile::decodeName(env) + sep;
+    } else {
+        return QDir::homePath() + sep + QFile::decodeName(env) + sep;
+    }
+#else
+    // When using a proper XDG platform, use QStandardPaths rather than the above hand-written code;
+    // it makes the use of test mode from unit tests possible.
+    // Ideally all platforms should use this, but see above for the migration issue.
+    return QStandardPaths::writableLocation(QStandardPaths::GenericConfigLocation) + sep;
+#endif
+}
+#endif // !Q_OS_WIN
+
 static void initDefaultPaths(QMutexLocker *locker)
 {
     PathHash *pathHash = pathHashFunc();
-    QString systemPath;
 
     locker->unlock();
 
@@ -1050,8 +1053,7 @@ static void initDefaultPaths(QMutexLocker *locker)
        avoid a dead-lock, we can't hold the global mutex while
        calling it.
     */
-    systemPath = QLibraryInfo::location(QLibraryInfo::SettingsPath);
-    systemPath += QLatin1Char('/');
+    QString systemPath = QLibraryInfo::location(QLibraryInfo::SettingsPath) + QLatin1Char('/');
 
     locker->relock();
     if (pathHash->isEmpty()) {
@@ -1067,38 +1069,14 @@ static void initDefaultPaths(QMutexLocker *locker)
         pathHash->insert(pathHashKey(QSettings::IniFormat, QSettings::SystemScope),
                          windowsConfigPath(CSIDL_COMMON_APPDATA) + QDir::separator());
 #else
-
-#ifndef QSETTINGS_USE_QSTANDARDPATHS
-        // Non XDG platforms (OS X, iOS, Android...) have used this code path erroneously
-        // for some time now. Moving away from that would require migrating existing settings.
-        QString userPath;
-        QByteArray env = qgetenv("XDG_CONFIG_HOME");
-        if (env.isEmpty()) {
-            userPath = QDir::homePath();
-            userPath += QLatin1Char('/');
-            userPath += QLatin1String(".config");
-        } else if (env.startsWith('/')) {
-            userPath = QFile::decodeName(env);
-        } else {
-            userPath = QDir::homePath();
-            userPath += QLatin1Char('/');
-            userPath += QFile::decodeName(env);
-        }
-#else
-        // When using a proper XDG platform, use QStandardPaths rather than the above hand-written code;
-        // it makes the use of test mode from unit tests possible.
-        // Ideally all platforms should use this, but see above for the migration issue.
-        QString userPath = QStandardPaths::writableLocation(QStandardPaths::GenericConfigLocation);
-#endif
-        userPath += QLatin1Char('/');
-
+        const QString userPath = make_user_path();
         pathHash->insert(pathHashKey(QSettings::IniFormat, QSettings::UserScope), userPath);
         pathHash->insert(pathHashKey(QSettings::IniFormat, QSettings::SystemScope), systemPath);
 #ifndef Q_OS_MAC
         pathHash->insert(pathHashKey(QSettings::NativeFormat, QSettings::UserScope), userPath);
         pathHash->insert(pathHashKey(QSettings::NativeFormat, QSettings::SystemScope), systemPath);
 #endif
-#endif
+#endif // Q_OS_WIN
     }
 }
 
@@ -3486,8 +3464,7 @@ QSettings::Format QSettings::registerFormat(const QString &extension, ReadFunc r
         return QSettings::InvalidFormat;
 
     QConfFileCustomFormat info;
-    info.extension = QLatin1Char('.');
-    info.extension += extension;
+    info.extension = QLatin1Char('.') + extension;
     info.readFunc = readFunc;
     info.writeFunc = writeFunc;
     info.caseSensitivity = caseSensitivity;
diff --git a/src/corelib/io/qsettings_winrt.cpp b/src/corelib/io/qsettings_winrt.cpp
index 0a87e7ce66..708287ce5e 100644
--- a/src/corelib/io/qsettings_winrt.cpp
+++ b/src/corelib/io/qsettings_winrt.cpp
@@ -92,7 +92,7 @@ static IApplicationDataContainer *subContainer(IApplicationDataContainer *parent
     if (FAILED(hr))
         return 0;
 
-    while (SUCCEEDED(S_OK) && current) {
+    while (SUCCEEDED(hr) && current) {
         ComPtr<ContainerItem> item;
         hr = iterator->get_Current(&item);
         if (FAILED(hr))
diff --git a/src/corelib/io/qstorageinfo_unix.cpp b/src/corelib/io/qstorageinfo_unix.cpp
index 0daf041954..ae5c42ffd1 100644
--- a/src/corelib/io/qstorageinfo_unix.cpp
+++ b/src/corelib/io/qstorageinfo_unix.cpp
@@ -1,6 +1,7 @@
 /****************************************************************************
 **
 ** Copyright (C) 2014 Ivan Komissarov <ABBAPOH@gmail.com>
+** Copyright (C) 2016 Intel Corporation.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
@@ -153,29 +154,41 @@ static bool isParentOf(const String &parent, const QString &dirName)
              parent.size() == 1);
 }
 
-static bool isPseudoFs(const QStorageIterator &it)
-{
+static bool shouldIncludeFs(const QStorageIterator &it)
+{
+    /*
+     * This function implements a heuristic algorithm to determine whether a
+     * given mount should be reported to the user. Our objective is to list
+     * only entries that the end-user would find useful.
+     *
+     * We therefore ignore:
+     *  - mounted in /dev, /proc, /sys: special mounts
+     *    (this will catch /sys/fs/cgroup, /proc/sys/fs/binfmt_misc, /dev/pts,
+     *    some of which are tmpfs on Linux)
+     *  - mounted in /var/run or /var/lock: most likely pseudofs
+     *    (on earlier systemd versions, /var/run was a bind-mount of /run, so
+     *    everything would be unnecessarily duplicated)
+     *  - filesystem type is "rootfs": artifact of the root-pivot on some Linux
+     *    initrd
+     *  - if the filesystem total size is zero, it's a pseudo-fs (not checked here).
+     */
+
     QString mountDir = it.rootPath();
     if (isParentOf(QLatin1String("/dev"), mountDir)
         || isParentOf(QLatin1String("/proc"), mountDir)
         || isParentOf(QLatin1String("/sys"), mountDir)
         || isParentOf(QLatin1String("/var/run"), mountDir)
         || isParentOf(QLatin1String("/var/lock"), mountDir)) {
-        return true;
+        return false;
     }
 
-    QByteArray type = it.fileSystemType();
-    if (type == "tmpfs")
+#ifdef Q_OS_LINUX
+    if (it.fileSystemType() == "rootfs")
         return false;
-#if defined(Q_OS_LINUX)
-    if (type == "rootfs" || type == "rpc_pipefs")
-        return true;
 #endif
 
-    if (!it.device().startsWith('/'))
-        return true;
-
-    return false;
+    // size checking in mountedVolumes()
+    return true;
 }
 
 #if defined(Q_OS_BSD4)
@@ -557,11 +570,14 @@ QList<QStorageInfo> QStorageInfoPrivate::mountedVolumes()
     QList<QStorageInfo> volumes;
 
     while (it.next()) {
-        if (isPseudoFs(it))
+        if (!shouldIncludeFs(it))
             continue;
 
         const QString mountDir = it.rootPath();
-        volumes.append(QStorageInfo(mountDir));
+        QStorageInfo info(mountDir);
+        if (info.bytesTotal() == 0)
+            continue;
+        volumes.append(info);
     }
 
     return volumes;
diff --git a/src/corelib/io/qurl.cpp b/src/corelib/io/qurl.cpp
index e20a98fbf1..71a0228eeb 100644
--- a/src/corelib/io/qurl.cpp
+++ b/src/corelib/io/qurl.cpp
@@ -816,7 +816,7 @@ static const ushort * const fragmentInUrl = userNameInUrl + 6;
 
 static inline void parseDecodedComponent(QString &data)
 {
-    data.replace(QLatin1Char('%'), QStringLiteral("%25"));
+    data.replace(QLatin1Char('%'), QLatin1String("%25"));
 }
 
 static inline QString
@@ -981,10 +981,12 @@ inline bool QUrlPrivate::setScheme(const QString &value, int len, bool doSetErro
             needsLowercasing = i;
             continue;
         }
-        if (p[i] >= '0' && p[i] <= '9' && i > 0)
-            continue;
-        if (p[i] == '+' || p[i] == '-' || p[i] == '.')
-            continue;
+        if (i) {
+            if (p[i] >= '0' && p[i] <= '9')
+                continue;
+            if (p[i] == '+' || p[i] == '-' || p[i] == '.')
+                continue;
+        }
 
         // found something else
         // don't call setError needlessly:
@@ -1472,7 +1474,7 @@ QString QUrlPrivate::toLocalFile(QUrl::FormattingOptions options) const
 
     // magic for shared drive on windows
     if (!host.isEmpty()) {
-        tmp = QStringLiteral("//") + host;
+        tmp = QLatin1String("//") + host;
 #ifdef Q_OS_WIN // QTBUG-42346, WebDAV is visible as local file on Windows only.
         if (scheme == webDavScheme())
             tmp += webDavSslTag();
diff --git a/src/corelib/io/qurlidna.cpp b/src/corelib/io/qurlidna.cpp
index 11b2280cd1..16bb924b17 100644
--- a/src/corelib/io/qurlidna.cpp
+++ b/src/corelib/io/qurlidna.cpp
@@ -2269,7 +2269,7 @@ Q_AUTOTEST_EXPORT void qt_punycodeEncoder(const QChar *s, int ucLength, QString
     }
 
     // prepend ACE prefix
-    output->insert(outLen, QStringLiteral("xn--"));
+    output->insert(outLen, QLatin1String("xn--"));
     return;
 }
 
diff --git a/src/corelib/json/qjsondocument.cpp b/src/corelib/json/qjsondocument.cpp
index ee9aa49016..86fd63ead4 100644
--- a/src/corelib/json/qjsondocument.cpp
+++ b/src/corelib/json/qjsondocument.cpp
@@ -359,16 +359,14 @@ QByteArray QJsonDocument::toJson(JsonFormat format) const
 #endif
 
 /*!
- Parses a UTF-8 encoded JSON document and creates a QJsonDocument
+ Parses \a json as a UTF-8 encoded JSON document, and creates a QJsonDocument
  from it.
 
- \a json contains the json document to be parsed.
+ Returns a valid (non-null) QJsonDocument if the parsing succeeds. If it fails,
+ the returned document will be null, and the optional \a error variable will contain
+ further details about the error.
 
- The optional \a error variable can be used to pass in a QJsonParseError data
- structure that will contain information about possible errors encountered during
- parsing.
-
- \sa toJson(), QJsonParseError
+ \sa toJson(), QJsonParseError, isNull()
  */
 QJsonDocument QJsonDocument::fromJson(const QByteArray &json, QJsonParseError *error)
 {
diff --git a/src/corelib/kernel/qcore_unix_p.h b/src/corelib/kernel/qcore_unix_p.h
index 7ea7e90d94..c393609188 100644
--- a/src/corelib/kernel/qcore_unix_p.h
+++ b/src/corelib/kernel/qcore_unix_p.h
@@ -80,6 +80,10 @@
 #include <errno.h>
 #include <fcntl.h>
 
+#if !defined(QT_POSIX_IPC) && !defined(QT_NO_SHAREDMEMORY) && !defined(Q_OS_ANDROID)
+#  include <sys/ipc.h>
+#endif
+
 #if defined(Q_OS_VXWORKS)
 #  include <ioLib.h>
 #endif
diff --git a/src/corelib/kernel/qeventloop.cpp b/src/corelib/kernel/qeventloop.cpp
index e960d355e1..e4b819d9d2 100644
--- a/src/corelib/kernel/qeventloop.cpp
+++ b/src/corelib/kernel/qeventloop.cpp
@@ -188,8 +188,10 @@ int QEventLoop::exec(ProcessEventsFlags flags)
         {
             if (exceptionCaught) {
                 qWarning("Qt has caught an exception thrown from an event handler. Throwing\n"
-                         "exceptions from an event handler is not supported in Qt. You must\n"
-                         "reimplement QApplication::notify() and catch all exceptions there.\n");
+                         "exceptions from an event handler is not supported in Qt.\n"
+                         "You must not let any exception whatsoever propagate through Qt code.\n"
+                         "If that is not possible, in Qt 5 you must at least reimplement\n"
+                         "QCoreApplication::notify() and catch all exceptions there.\n");
             }
             locker.relock();
             QEventLoop *eventLoop = d->threadData->eventLoops.pop();
diff --git a/src/corelib/kernel/qmetaobject.cpp b/src/corelib/kernel/qmetaobject.cpp
index f5b879aea8..633fcfda91 100644
--- a/src/corelib/kernel/qmetaobject.cpp
+++ b/src/corelib/kernel/qmetaobject.cpp
@@ -1353,7 +1353,7 @@ static inline QByteArray findMethodCandidates(const QMetaObject *metaObject, con
     for (int i = 0; i < metaObject->methodCount(); ++i) {
         const QMetaMethod method = metaObject->method(i);
         if (method.name() == memberByteArray)
-            candidateMessage.append("    " + method.methodSignature() + '\n');
+            candidateMessage += "    " + method.methodSignature() + '\n';
     }
     if (!candidateMessage.isEmpty()) {
         candidateMessage.prepend("\nCandidates are:\n");
diff --git a/src/corelib/thread/qreadwritelock.cpp b/src/corelib/thread/qreadwritelock.cpp
index 5665bf74f6..6302a3a515 100644
--- a/src/corelib/thread/qreadwritelock.cpp
+++ b/src/corelib/thread/qreadwritelock.cpp
@@ -244,6 +244,9 @@ bool QReadWriteLock::tryLockForRead(int timeout)
         }
 
         if (d == dummyLockedForWrite) {
+            if (!timeout)
+                return false;
+
             // locked for write, assign a d_ptr and wait.
             auto val = QReadWriteLockPrivate::allocate();
             val->writerCount = 1;
@@ -345,6 +348,9 @@ bool QReadWriteLock::tryLockForWrite(int timeout)
         }
 
         if (isUncontendedLocked(d)) {
+            if (!timeout)
+                return false;
+
             // locked for either read or write, assign a d_ptr and wait.
             auto val = QReadWriteLockPrivate::allocate();
             if (d == dummyLockedForWrite)
diff --git a/src/corelib/tools/qdatetime.cpp b/src/corelib/tools/qdatetime.cpp
index d6b90efb33..ee5ee5c362 100644
--- a/src/corelib/tools/qdatetime.cpp
+++ b/src/corelib/tools/qdatetime.cpp
@@ -3513,7 +3513,7 @@ qint64 QDateTime::toMSecsSinceEpoch() const
 
     case Qt::TimeZone:
 #ifdef QT_BOOTSTRAPPED
-        break;
+        return 0;
 #else
         return QDateTimePrivate::zoneMSecsToEpochMSecs(d->m_msecs, d->m_timeZone);
 #endif
@@ -3771,7 +3771,7 @@ QString QDateTime::toString(Qt::DateFormat format) const
                                                    .arg(tm.toString(Qt::TextDate))
                                                    .arg(dt.year());
         if (timeSpec() != Qt::LocalTime) {
-            buf += QStringLiteral(" GMT");
+            buf += QLatin1String(" GMT");
             if (getSpec(d) == Qt::OffsetFromUTC)
                 buf += toOffsetString(Qt::TextDate, offsetFromUtc());
         }
@@ -5019,7 +5019,12 @@ QDataStream &operator>>(QDataStream &in, QDate &date)
 
 QDataStream &operator<<(QDataStream &out, const QTime &time)
 {
-    return out << quint32(time.mds);
+    if (out.version() >= QDataStream::Qt_4_0) {
+        return out << quint32(time.mds);
+    } else {
+        // Qt3 had no support for reading -1, QTime() was valid and serialized as 0
+        return out << quint32(time.isNull() ? 0 : time.mds);
+    }
 }
 
 /*!
@@ -5034,7 +5039,12 @@ QDataStream &operator>>(QDataStream &in, QTime &time)
 {
     quint32 ds;
     in >> ds;
-    time.mds = int(ds);
+    if (in.version() >= QDataStream::Qt_4_0) {
+        time.mds = int(ds);
+    } else {
+        // Qt3 would write 0 for a null time
+        time.mds = (ds == 0) ? QTime::NullTime : int(ds);
+    }
     return in;
 }
 
diff --git a/src/corelib/tools/qstring.cpp b/src/corelib/tools/qstring.cpp
index 32f12bd092..a8e924b62d 100644
--- a/src/corelib/tools/qstring.cpp
+++ b/src/corelib/tools/qstring.cpp
@@ -1786,17 +1786,12 @@ void QString::reallocData(uint alloc, bool grow)
     }
 }
 
+#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
 void QString::expand(int i)
 {
-    int sz = d->size;
-    resize(qMax(i + 1, sz));
-    if (d->size - 1 > sz) {
-        ushort *n = d->data() + d->size - 1;
-        ushort *e = d->data() + sz;
-        while (n != e)
-           * --n = ' ';
-    }
+    resize(qMax(i + 1, d->size), QLatin1Char(' '));
 }
+#endif
 
 /*! \fn void QString::clear()
 
@@ -1982,7 +1977,10 @@ QString &QString::insert(int i, QLatin1String str)
         return *this;
 
     int len = str.size();
-    expand(qMax(d->size, i) + len - 1);
+    if (Q_UNLIKELY(i > d->size))
+        resize(i + len, QLatin1Char(' '));
+    else
+        resize(d->size + len);
 
     ::memmove(d->data() + i + len, d->data() + i, (d->size - i - len) * sizeof(QChar));
     qt_from_latin1(d->data() + i, s, uint(len));
@@ -2012,7 +2010,10 @@ QString& QString::insert(int i, const QChar *unicode, int size)
         return *this;
     }
 
-    expand(qMax(d->size, i) + size - 1);
+    if (Q_UNLIKELY(i > d->size))
+        resize(i + size, QLatin1Char(' '));
+    else
+        resize(d->size + size);
 
     ::memmove(d->data() + i + size, d->data() + i, (d->size - i - size) * sizeof(QChar));
     memcpy(d->data() + i, s, size * sizeof(QChar));
@@ -2032,7 +2033,10 @@ QString& QString::insert(int i, QChar ch)
         i += d->size;
     if (i < 0)
         return *this;
-    expand(qMax(i, d->size));
+    if (Q_UNLIKELY(i > d->size))
+        resize(i + 1, QLatin1Char(' '));
+    else
+        resize(d->size + 1);
     ::memmove(d->data() + i + 1, d->data() + i, (d->size - i - 1) * sizeof(QChar));
     d->data()[i] = ch.unicode();
     return *this;
@@ -2404,26 +2408,40 @@ QString &QString::replace(const QString &before, const QString &after, Qt::CaseS
     return replace(before.constData(), before.size(), after.constData(), after.size(), cs);
 }
 
+namespace { // helpers for replace and its helper:
+QChar *textCopy(const QChar *start, int len)
+{
+    const size_t size = len * sizeof(QChar);
+    QChar *const copy = static_cast<QChar *>(::malloc(size));
+    Q_CHECK_PTR(copy);
+    ::memcpy(copy, start, size);
+    return copy;
+}
+
+bool pointsIntoRange(const QChar *ptr, const ushort *base, int len)
+{
+    const QChar *const start = reinterpret_cast<const QChar *>(base);
+    return start <= ptr && ptr < start + len;
+}
+} // end namespace
+
 /*!
   \internal
  */
 void QString::replace_helper(uint *indices, int nIndices, int blen, const QChar *after, int alen)
 {
-    // copy *after in case it lies inside our own d->data() area
-    // (which we could possibly invalidate via a realloc or corrupt via memcpy operations.)
-    QChar *afterBuffer = const_cast<QChar *>(after);
-    if (after >= reinterpret_cast<QChar *>(d->data()) && after < reinterpret_cast<QChar *>(d->data()) + d->size) {
-        afterBuffer = static_cast<QChar *>(::malloc(alen*sizeof(QChar)));
-        Q_CHECK_PTR(afterBuffer);
-        ::memcpy(afterBuffer, after, alen*sizeof(QChar));
-    }
+    // Copy after if it lies inside our own d->data() area (which we could
+    // possibly invalidate via a realloc or modify by replacement).
+    QChar *afterBuffer = 0;
+    if (pointsIntoRange(after, d->data(), d->size)) // Use copy in place of vulnerable original:
+        after = afterBuffer = textCopy(after, alen);
 
     QT_TRY {
         if (blen == alen) {
             // replace in place
             detach();
             for (int i = 0; i < nIndices; ++i)
-                memcpy(d->data() + indices[i], afterBuffer, alen * sizeof(QChar));
+                memcpy(d->data() + indices[i], after, alen * sizeof(QChar));
         } else if (alen < blen) {
             // replace from front
             detach();
@@ -2439,7 +2457,7 @@ void QString::replace_helper(uint *indices, int nIndices, int blen, const QChar
                     to += msize;
                 }
                 if (alen) {
-                    memcpy(d->data() + to, afterBuffer, alen*sizeof(QChar));
+                    memcpy(d->data() + to, after, alen * sizeof(QChar));
                     to += alen;
                 }
                 movestart = indices[i] + blen;
@@ -2462,17 +2480,15 @@ void QString::replace_helper(uint *indices, int nIndices, int blen, const QChar
                 int moveto = insertstart + alen;
                 memmove(d->data() + moveto, d->data() + movestart,
                         (moveend - movestart)*sizeof(QChar));
-                memcpy(d->data() + insertstart, afterBuffer, alen*sizeof(QChar));
+                memcpy(d->data() + insertstart, after, alen * sizeof(QChar));
                 moveend = movestart-blen;
             }
         }
     } QT_CATCH(const std::bad_alloc &) {
-        if (afterBuffer != after)
-            ::free(afterBuffer);
+        ::free(afterBuffer);
         QT_RETHROW;
     }
-    if (afterBuffer != after)
-        ::free(afterBuffer);
+    ::free(afterBuffer);
 }
 
 /*!
@@ -2501,31 +2517,48 @@ QString &QString::replace(const QChar *before, int blen,
         return *this;
 
     QStringMatcher matcher(before, blen, cs);
+    QChar *beforeBuffer = 0, *afterBuffer = 0;
 
     int index = 0;
     while (1) {
         uint indices[1024];
         uint pos = 0;
-        while (pos < 1023) {
+        while (pos < 1024) {
             index = matcher.indexIn(*this, index);
             if (index == -1)
                 break;
             indices[pos++] = index;
-            index += blen;
-            // avoid infinite loop
-            if (!blen)
+            if (blen) // Step over before:
+                index += blen;
+            else // Only count one instance of empty between any two characters:
                 index++;
         }
-        if (!pos)
+        if (!pos) // Nothing to replace
             break;
 
+        if (Q_UNLIKELY(index != -1)) {
+            /*
+              We're about to change data, that before and after might point
+              into, and we'll need that data for our next batch of indices.
+            */
+            if (!afterBuffer && pointsIntoRange(after, d->data(), d->size))
+                after = afterBuffer = textCopy(after, alen);
+
+            if (!beforeBuffer && pointsIntoRange(before, d->data(), d->size)) {
+                beforeBuffer = textCopy(before, blen);
+                matcher = QStringMatcher(beforeBuffer, blen, cs);
+            }
+        }
+
         replace_helper(indices, pos, blen, after, alen);
 
-        if (index == -1)
+        if (Q_LIKELY(index == -1)) // Nothing left to replace
             break;
-        // index has to be adjusted in case we get back into the loop above.
+        // The call to replace_helper just moved what index points at:
         index += pos*(alen-blen);
     }
+    ::free(afterBuffer);
+    ::free(beforeBuffer);
 
     return *this;
 }
@@ -2556,26 +2589,26 @@ QString& QString::replace(QChar ch, const QString &after, Qt::CaseSensitivity cs
         uint indices[1024];
         uint pos = 0;
         if (cs == Qt::CaseSensitive) {
-            while (pos < 1023 && index < d->size) {
+            while (pos < 1024 && index < d->size) {
                 if (d->data()[index] == cc)
                     indices[pos++] = index;
                 index++;
             }
         } else {
-            while (pos < 1023 && index < d->size) {
+            while (pos < 1024 && index < d->size) {
                 if (QChar::toCaseFolded(d->data()[index]) == cc)
                     indices[pos++] = index;
                 index++;
             }
         }
-        if (!pos)
+        if (!pos) // Nothing to replace
             break;
 
         replace_helper(indices, pos, 1, after.constData(), after.d->size);
 
-        if (index == -1)
+        if (Q_LIKELY(index == -1)) // Nothing left to replace
             break;
-        // index has to be adjusted in case we get back into the loop above.
+        // The call to replace_helper just moved what index points at:
         index += pos*(after.d->size - 1);
     }
     return *this;
@@ -5001,7 +5034,7 @@ void QString::truncate(int pos)
     Removes \a n characters from the end of the string.
 
     If \a n is greater than or equal to size(), the result is an
-    empty string.
+    empty string; if \a n is negative, it is equivalent to passing zero.
 
     Example:
     \snippet qstring/main.cpp 15
diff --git a/src/corelib/tools/qstring.h b/src/corelib/tools/qstring.h
index ec959b50a0..a110c129de 100644
--- a/src/corelib/tools/qstring.h
+++ b/src/corelib/tools/qstring.h
@@ -821,7 +821,9 @@ private:
     friend inline bool operator> (QChar, QLatin1String) Q_DECL_NOTHROW;
 
     void reallocData(uint alloc, bool grow = false);
+#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
     void expand(int i);
+#endif
     QString multiArg(int numArgs, const QString **args) const;
     static int compare_helper(const QChar *data1, int length1,
                               const QChar *data2, int length2,
@@ -1008,7 +1010,7 @@ public:
     inline operator QChar() const
     { return i < s.d->size ? s.d->data()[i] : 0; }
     inline QCharRef &operator=(QChar c)
-    { if (i >= s.d->size) s.expand(i); else s.detach();
+    { if (i >= s.d->size) s.resize(i + 1, QLatin1Char(' ')); else s.detach();
       s.d->data()[i] = c.unicode(); return *this; }
 
     // An operator= for each QChar cast constructors
diff --git a/src/corelib/tools/qstringbuilder.h b/src/corelib/tools/qstringbuilder.h
index 8ce98cbd71..b2832b5fbe 100644
--- a/src/corelib/tools/qstringbuilder.h
+++ b/src/corelib/tools/qstringbuilder.h
@@ -82,7 +82,7 @@ struct QStringBuilderCommon
     T toLower() const { return resolved().toLower(); }
 
 protected:
-    const T resolved() const { return *static_cast<const Builder*>(this); }
+    T resolved() const { return *static_cast<const Builder*>(this); }
 };
 
 template<typename Builder, typename T>
diff --git a/src/corelib/tools/qtimezoneprivate_icu.cpp b/src/corelib/tools/qtimezoneprivate_icu.cpp
index a7036808db..c088fe7694 100644
--- a/src/corelib/tools/qtimezoneprivate_icu.cpp
+++ b/src/corelib/tools/qtimezoneprivate_icu.cpp
@@ -332,7 +332,7 @@ QString QIcuTimeZonePrivate::displayName(QTimeZone::TimeType timeType,
 {
     // Return standard offset format name as ICU C api doesn't support it yet
     if (nameType == QTimeZone::OffsetName) {
-        const Data nowData = data(QDateTime::currentDateTimeUtc().toMSecsSinceEpoch());
+        const Data nowData = data(QDateTime::currentMSecsSinceEpoch());
         // We can't use transitions reliably to find out right dst offset
         // Instead use dst offset api to try get it if needed
         if (timeType == QTimeZone::DaylightTime)
diff --git a/src/corelib/tools/qtimezoneprivate_mac.mm b/src/corelib/tools/qtimezoneprivate_mac.mm
index 3a665c2b00..77c04ac20c 100644
--- a/src/corelib/tools/qtimezoneprivate_mac.mm
+++ b/src/corelib/tools/qtimezoneprivate_mac.mm
@@ -59,6 +59,7 @@ QT_BEGIN_NAMESPACE
 
 // Create the system default time zone
 QMacTimeZonePrivate::QMacTimeZonePrivate()
+    : m_nstz(0)
 {
     init(systemTimeZoneId());
 }
@@ -106,7 +107,7 @@ QString QMacTimeZonePrivate::displayName(QTimeZone::TimeType timeType,
 {
     // TODO Mac doesn't support OffsetName yet so use standard offset name
     if (nameType == QTimeZone::OffsetName) {
-        const Data nowData = data(QDateTime::currentDateTimeUtc().toMSecsSinceEpoch());
+        const Data nowData = data(QDateTime::currentMSecsSinceEpoch());
         // TODO Cheat for now, assume if has dst the offset if 1 hour
         if (timeType == QTimeZone::DaylightTime && hasDaylightTime())
             return isoOffsetFormat(nowData.standardTimeOffset + 3600);
diff --git a/src/gui/accessible/qaccessible.cpp b/src/gui/accessible/qaccessible.cpp
index 757543281c..e95315aea8 100644
--- a/src/gui/accessible/qaccessible.cpp
+++ b/src/gui/accessible/qaccessible.cpp
@@ -758,7 +758,7 @@ void QAccessible::deleteAccessibleInterface(Id id)
 */
 QAccessible::Id QAccessible::uniqueId(QAccessibleInterface *iface)
 {
-    Id id = QAccessibleCache::instance()->idToInterface.key(iface);
+    Id id = QAccessibleCache::instance()->idForInterface(iface);
     if (!id)
         id = registerAccessibleInterface(iface);
     return id;
@@ -771,7 +771,7 @@ QAccessible::Id QAccessible::uniqueId(QAccessibleInterface *iface)
 */
 QAccessibleInterface *QAccessible::accessibleInterface(Id id)
 {
-    return QAccessibleCache::instance()->idToInterface.value(id);
+    return QAccessibleCache::instance()->interfaceForId(id);
 }
 
 
diff --git a/src/gui/accessible/qaccessiblecache.cpp b/src/gui/accessible/qaccessiblecache.cpp
index 6fbe9b5582..43c4b15cb0 100644
--- a/src/gui/accessible/qaccessiblecache.cpp
+++ b/src/gui/accessible/qaccessiblecache.cpp
@@ -83,6 +83,11 @@ QAccessibleInterface *QAccessibleCache::interfaceForId(QAccessible::Id id) const
     return idToInterface.value(id);
 }
 
+QAccessible::Id QAccessibleCache::idForInterface(QAccessibleInterface *iface) const
+{
+    return interfaceToId.value(iface);
+}
+
 QAccessible::Id QAccessibleCache::insert(QObject *object, QAccessibleInterface *iface) const
 {
     Q_ASSERT(iface);
@@ -90,7 +95,7 @@ QAccessible::Id QAccessibleCache::insert(QObject *object, QAccessibleInterface *
 
     // object might be 0
     Q_ASSERT(!objectToId.contains(object));
-    Q_ASSERT_X(!idToInterface.values().contains(iface), "", "Accessible interface inserted into cache twice!");
+    Q_ASSERT_X(!interfaceToId.contains(iface), "", "Accessible interface inserted into cache twice!");
 
     QAccessible::Id id = acquireId();
     QObject *obj = iface->object();
@@ -100,6 +105,7 @@ QAccessible::Id QAccessibleCache::insert(QObject *object, QAccessibleInterface *
         connect(obj, &QObject::destroyed, this, &QAccessibleCache::objectDestroyed);
     }
     idToInterface.insert(id, iface);
+    interfaceToId.insert(iface, id);
     return id;
 }
 
@@ -115,6 +121,7 @@ void QAccessibleCache::objectDestroyed(QObject* obj)
 void QAccessibleCache::deleteInterface(QAccessible::Id id, QObject *obj)
 {
     QAccessibleInterface *iface = idToInterface.take(id);
+    interfaceToId.take(iface);
     if (!obj)
         obj = iface->object();
     if (obj)
diff --git a/src/gui/accessible/qaccessiblecache_p.h b/src/gui/accessible/qaccessiblecache_p.h
index 5f62f43b6a..f054ee9678 100644
--- a/src/gui/accessible/qaccessiblecache_p.h
+++ b/src/gui/accessible/qaccessiblecache_p.h
@@ -70,6 +70,7 @@ class Q_GUI_EXPORT QAccessibleCache  :public QObject
 public:
     static QAccessibleCache *instance();
     QAccessibleInterface *interfaceForId(QAccessible::Id id) const;
+    QAccessible::Id idForInterface(QAccessibleInterface *iface) const;
     QAccessible::Id insert(QObject *object, QAccessibleInterface *iface) const;
     void deleteInterface(QAccessible::Id id, QObject *obj = 0);
 
@@ -85,6 +86,7 @@ private:
     QAccessible::Id acquireId() const;
 
     mutable QHash<QAccessible::Id, QAccessibleInterface *> idToInterface;
+    mutable QHash<QAccessibleInterface *, QAccessible::Id> interfaceToId;
     mutable QHash<QObject *, QAccessible::Id> objectToId;
 
 #ifdef Q_OS_MAC
diff --git a/src/gui/image/qicon.cpp b/src/gui/image/qicon.cpp
index 0dec4b512d..c65ac7f92d 100644
--- a/src/gui/image/qicon.cpp
+++ b/src/gui/image/qicon.cpp
@@ -1227,8 +1227,8 @@ bool QIcon::hasThemeIcon(const QString &name)
 /*!
     \since 5.6
 
-    Indicate that this icon is a mask image, and hence can potentially
-    be modified based on where it's displayed.
+    Indicate that this icon is a mask image(boolean \a isMask), and hence can
+    potentially be modified based on where it's displayed.
     \sa isMask()
 */
 void QIcon::setIsMask(bool isMask)
diff --git a/src/gui/itemmodels/qstandarditemmodel.cpp b/src/gui/itemmodels/qstandarditemmodel.cpp
index 3279880601..e965045524 100644
--- a/src/gui/itemmodels/qstandarditemmodel.cpp
+++ b/src/gui/itemmodels/qstandarditemmodel.cpp
@@ -1796,11 +1796,12 @@ QStandardItem *QStandardItem::takeChild(int row, int column)
 QList<QStandardItem*> QStandardItem::takeRow(int row)
 {
     Q_D(QStandardItem);
+    QList<QStandardItem*> items;
     if ((row < 0) || (row >= rowCount()))
-        return QList<QStandardItem*>();
+        return items;
     if (d->model)
         d->model->d_func()->rowsAboutToBeRemoved(this, row, row);
-    QList<QStandardItem*> items;
+
     int index = d->childIndex(row, 0);  // Will return -1 if there are no columns
     if (index != -1) {
         int col_count = d->columnCount();
@@ -1829,13 +1830,15 @@ QList<QStandardItem*> QStandardItem::takeRow(int row)
 QList<QStandardItem*> QStandardItem::takeColumn(int column)
 {
     Q_D(QStandardItem);
+    QList<QStandardItem*> items;
     if ((column < 0) || (column >= columnCount()))
-        return QList<QStandardItem*>();
+        return items;
     if (d->model)
         d->model->d_func()->columnsAboutToBeRemoved(this, column, column);
-    QList<QStandardItem*> items;
 
-    for (int row = d->rowCount() - 1; row >= 0; --row) {
+    const int rowCount = d->rowCount();
+    items.reserve(rowCount);
+    for (int row = rowCount - 1; row >= 0; --row) {
         int index = d->childIndex(row, column);
         QStandardItem *ch = d->children.at(index);
         if (ch)
diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index 7afeadcced..416c899270 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -3355,28 +3355,6 @@ bool QGuiApplication::isSavingSession() const
     return d->is_saving_session;
 }
 
-/*!
-    \since 5.2
-
-    Function that can be used to sync Qt state with the Window Systems state.
-
-    This function will first empty Qts events by calling QCoreApplication::processEvents(),
-    then the platform plugin will sync up with the windowsystem, and finally Qts events
-    will be delived by another call to QCoreApplication::processEvents();
-
-    This function is timeconsuming and its use is discouraged.
-*/
-void QGuiApplication::sync()
-{
-    QCoreApplication::processEvents();
-    if (QGuiApplicationPrivate::platform_integration
-            && QGuiApplicationPrivate::platform_integration->hasCapability(QPlatformIntegration::SyncState)) {
-        QGuiApplicationPrivate::platform_integration->sync();
-        QCoreApplication::processEvents();
-        QWindowSystemInterface::flushWindowSystemEvents();
-    }
-}
-
 void QGuiApplicationPrivate::commitData()
 {
     Q_Q(QGuiApplication);
@@ -3402,6 +3380,28 @@ void QGuiApplicationPrivate::saveState()
 #endif //QT_NO_SESSIONMANAGER
 
 /*!
+    \since 5.2
+
+    Function that can be used to sync Qt state with the Window Systems state.
+
+    This function will first empty Qts events by calling QCoreApplication::processEvents(),
+    then the platform plugin will sync up with the windowsystem, and finally Qts events
+    will be delived by another call to QCoreApplication::processEvents();
+
+    This function is timeconsuming and its use is discouraged.
+*/
+void QGuiApplication::sync()
+{
+    QCoreApplication::processEvents();
+    if (QGuiApplicationPrivate::platform_integration
+            && QGuiApplicationPrivate::platform_integration->hasCapability(QPlatformIntegration::SyncState)) {
+        QGuiApplicationPrivate::platform_integration->sync();
+        QCoreApplication::processEvents();
+        QWindowSystemInterface::flushWindowSystemEvents();
+    }
+}
+
+/*!
     \property QGuiApplication::layoutDirection
     \brief the default layout direction for this application
 
@@ -3647,7 +3647,8 @@ QPixmap QGuiApplicationPrivate::getPixmapCursor(Qt::CursorShape cshape)
 
 void QGuiApplicationPrivate::notifyThemeChanged()
 {
-    if (!(applicationResourceFlags & ApplicationPaletteExplicitlySet)) {
+    if (!(applicationResourceFlags & ApplicationPaletteExplicitlySet) &&
+        !QCoreApplication::testAttribute(Qt::AA_SetPalette)) {
         clearPalette();
         initPalette();
     }
diff --git a/src/gui/kernel/qplatformintegrationfactory.cpp b/src/gui/kernel/qplatformintegrationfactory.cpp
index 566d025b28..1e04a673eb 100644
--- a/src/gui/kernel/qplatformintegrationfactory.cpp
+++ b/src/gui/kernel/qplatformintegrationfactory.cpp
@@ -86,7 +86,7 @@ QStringList QPlatformIntegrationFactory::keys(const QString &platformPluginPath)
         QCoreApplication::addLibraryPath(platformPluginPath);
         list = directLoader()->keyMap().values();
         if (!list.isEmpty()) {
-            const QString postFix = QStringLiteral(" (from ")
+            const QString postFix = QLatin1String(" (from ")
                                     + QDir::toNativeSeparators(platformPluginPath)
                                     + QLatin1Char(')');
             const QStringList::iterator end = list.end();
diff --git a/src/gui/kernel/qplatformthemefactory.cpp b/src/gui/kernel/qplatformthemefactory.cpp
index 40ba844e57..223d7344e3 100644
--- a/src/gui/kernel/qplatformthemefactory.cpp
+++ b/src/gui/kernel/qplatformthemefactory.cpp
@@ -88,7 +88,7 @@ QStringList QPlatformThemeFactory::keys(const QString &platformPluginPath)
         QCoreApplication::addLibraryPath(platformPluginPath);
         list += directLoader()->keyMap().values();
         if (!list.isEmpty()) {
-            const QString postFix = QStringLiteral(" (from ")
+            const QString postFix = QLatin1String(" (from ")
                     + QDir::toNativeSeparators(platformPluginPath)
                     + QLatin1Char(')');
             const QStringList::iterator end = list.end();
diff --git a/src/gui/opengl/qopenglframebufferobject.cpp b/src/gui/opengl/qopenglframebufferobject.cpp
index bcc17457d3..3e82d5a649 100644
--- a/src/gui/opengl/qopenglframebufferobject.cpp
+++ b/src/gui/opengl/qopenglframebufferobject.cpp
@@ -1284,6 +1284,7 @@ static inline QImage qt_gl_read_framebuffer_rgba8(const QSize &size, bool includ
     const char *ver = reinterpret_cast<const char *>(funcs->glGetString(GL_VERSION));
 
     // Blacklist GPU chipsets that have problems with their BGRA support.
+#ifndef Q_OS_IOS
     const bool blackListed = (qstrcmp(renderer, "PowerVR Rogue G6200") == 0
                              && ::strstr(ver, "1.3") != 0) ||
                              (qstrcmp(renderer, "Mali-T760") == 0
@@ -1291,7 +1292,9 @@ static inline QImage qt_gl_read_framebuffer_rgba8(const QSize &size, bool includ
                              (qstrcmp(renderer, "Mali-T720") == 0
                              && ::strstr(ver, "3.1") != 0) ||
                              qstrcmp(renderer, "PowerVR SGX 554") == 0;
-
+#else
+    const bool blackListed = true;
+#endif
     const bool supports_bgra = has_bgra_ext && !blackListed;
 
     if (supports_bgra) {
diff --git a/src/gui/text/qfontengine_ft.cpp b/src/gui/text/qfontengine_ft.cpp
index e89522f5af..26ed81a091 100644
--- a/src/gui/text/qfontengine_ft.cpp
+++ b/src/gui/text/qfontengine_ft.cpp
@@ -259,7 +259,6 @@ QFreetypeFace *QFreetypeFace::getFace(const QFontEngine::FaceId &face_id,
         newFreetype->ref.store(1);
         newFreetype->xsize = 0;
         newFreetype->ysize = 0;
-        newFreetype->scalableBitmapScaleFactor = 1;
         newFreetype->matrix.xx = 0x10000;
         newFreetype->matrix.yy = 0x10000;
         newFreetype->matrix.xy = 0;
@@ -335,10 +334,11 @@ void QFreetypeFace::release(const QFontEngine::FaceId &face_id)
 }
 
 
-void QFreetypeFace::computeSize(const QFontDef &fontDef, int *xsize, int *ysize, bool *outline_drawing)
+void QFreetypeFace::computeSize(const QFontDef &fontDef, int *xsize, int *ysize, bool *outline_drawing, QFixed *scalableBitmapScaleFactor)
 {
     *ysize = qRound(fontDef.pixelSize * 64);
     *xsize = *ysize * fontDef.stretch / 100;
+    *scalableBitmapScaleFactor = 1;
     *outline_drawing = false;
 
     if (!(face->face_flags & FT_FACE_FLAG_SCALABLE)) {
@@ -376,7 +376,7 @@ void QFreetypeFace::computeSize(const QFontDef &fontDef, int *xsize, int *ysize,
         // to make sure we can select the desired bitmap strike index
         if (FT_Select_Size(face, best) == 0) {
             if (isScalableBitmap())
-                scalableBitmapScaleFactor = QFixed::fromReal((qreal)fontDef.pixelSize / face->available_sizes[best].height);
+                *scalableBitmapScaleFactor = QFixed::fromReal((qreal)fontDef.pixelSize / face->available_sizes[best].height);
             *xsize = face->available_sizes[best].x_ppem;
             *ysize = face->available_sizes[best].y_ppem;
         } else {
@@ -729,7 +729,7 @@ bool QFontEngineFT::init(FaceId faceId, bool antialias, GlyphFormat format,
         symbol = bool(fontDef.family.contains(QLatin1String("symbol"), Qt::CaseInsensitive));
     }
 
-    freetype->computeSize(fontDef, &xsize, &ysize, &defaultGlyphSet.outline_drawing);
+    freetype->computeSize(fontDef, &xsize, &ysize, &defaultGlyphSet.outline_drawing, &scalableBitmapScaleFactor);
 
     FT_Face face = lockFace();
 
@@ -1294,24 +1294,24 @@ int QFontEngineFT::synthesized() const
 QFixed QFontEngineFT::ascent() const
 {
     QFixed v = QFixed::fromFixed(metrics.ascender);
-    if (freetype->scalableBitmapScaleFactor != 1)
-        v *= freetype->scalableBitmapScaleFactor;
+    if (scalableBitmapScaleFactor != 1)
+        v *= scalableBitmapScaleFactor;
     return v;
 }
 
 QFixed QFontEngineFT::descent() const
 {
     QFixed v = QFixed::fromFixed(-metrics.descender);
-    if (freetype->scalableBitmapScaleFactor != 1)
-        v *= freetype->scalableBitmapScaleFactor;
+    if (scalableBitmapScaleFactor != 1)
+        v *= scalableBitmapScaleFactor;
     return v;
 }
 
 QFixed QFontEngineFT::leading() const
 {
     QFixed v = QFixed::fromFixed(metrics.height - metrics.ascender + metrics.descender);
-    if (freetype->scalableBitmapScaleFactor != 1)
-        v *= freetype->scalableBitmapScaleFactor;
+    if (scalableBitmapScaleFactor != 1)
+        v *= scalableBitmapScaleFactor;
     return v;
 }
 
@@ -1326,7 +1326,7 @@ QFixed QFontEngineFT::xHeight() const
             return answer;
         }
     } else {
-        return QFixed(freetype->face->size->metrics.y_ppem) * freetype->scalableBitmapScaleFactor;
+        return QFixed(freetype->face->size->metrics.y_ppem) * scalableBitmapScaleFactor;
     }
     return QFontEngine::xHeight();
 }
@@ -1352,8 +1352,8 @@ QFixed QFontEngineFT::averageCharWidth() const
 qreal QFontEngineFT::maxCharWidth() const
 {
     QFixed max_advance = QFixed::fromFixed(metrics.max_advance);
-    if (freetype->scalableBitmapScaleFactor != 1)
-        max_advance *= freetype->scalableBitmapScaleFactor;
+    if (scalableBitmapScaleFactor != 1)
+        max_advance *= scalableBitmapScaleFactor;
     return max_advance.toReal();
 }
 
@@ -1639,7 +1639,7 @@ bool QFontEngineFT::shouldUseDesignMetrics(QFontEngine::ShaperFlags flags) const
 
 QFixed QFontEngineFT::scaledBitmapMetrics(QFixed m) const
 {
-    return m * freetype->scalableBitmapScaleFactor;
+    return m * scalableBitmapScaleFactor;
 }
 
 glyph_metrics_t QFontEngineFT::scaledBitmapMetrics(const glyph_metrics_t &m) const
@@ -1677,8 +1677,8 @@ void QFontEngineFT::recalcAdvances(QGlyphLayout *glyphs, QFontEngine::ShaperFlag
                 delete g;
         }
 
-        if (freetype->scalableBitmapScaleFactor != 1)
-            glyphs->advances[i] *= freetype->scalableBitmapScaleFactor;
+        if (scalableBitmapScaleFactor != 1)
+            glyphs->advances[i] *= scalableBitmapScaleFactor;
     }
     if (face)
         unlockFace();
@@ -1981,9 +1981,9 @@ QImage QFontEngineFT::bitmapForGlyph(glyph_t g, QFixed subPixelPosition, const Q
     else if (defaultFormat == GlyphFormat::Format_Mono)
         img = QImage(glyph->data, glyph->width, glyph->height, QImage::Format_Mono).copy();
 
-    if (!img.isNull() && (!t.isIdentity() || freetype->scalableBitmapScaleFactor != 1)) {
+    if (!img.isNull() && (!t.isIdentity() || scalableBitmapScaleFactor != 1)) {
         QTransform trans(t);
-        const qreal scaleFactor = freetype->scalableBitmapScaleFactor.toReal();
+        const qreal scaleFactor = scalableBitmapScaleFactor.toReal();
         trans.scale(scaleFactor, scaleFactor);
         img = img.transformed(trans, Qt::SmoothTransformation);
     }
diff --git a/src/gui/text/qfontengine_ft_p.h b/src/gui/text/qfontengine_ft_p.h
index 3f4bf84753..3cdf0cda47 100644
--- a/src/gui/text/qfontengine_ft_p.h
+++ b/src/gui/text/qfontengine_ft_p.h
@@ -75,7 +75,7 @@ class QFontconfigDatabase;
 class QFreetypeFace
 {
 public:
-    void computeSize(const QFontDef &fontDef, int *xsize, int *ysize, bool *outline_drawing);
+    void computeSize(const QFontDef &fontDef, int *xsize, int *ysize, bool *outline_drawing, QFixed *scalableBitmapScaleFactor);
     QFontEngine::Properties properties() const;
     bool getSfntTable(uint tag, uchar *buffer, uint *length) const;
 
@@ -96,7 +96,6 @@ public:
     FT_Face face;
     int xsize; // 26.6
     int ysize; // 26.6
-    QFixed scalableBitmapScaleFactor;
     FT_Matrix matrix;
     FT_CharMap unicode_map;
     FT_CharMap symbol_map;
@@ -340,6 +339,7 @@ private:
 
     FT_Size_Metrics metrics;
     mutable bool kerning_pairs_loaded;
+    QFixed scalableBitmapScaleFactor;
 };
 
 inline uint qHash(const QFontEngineFT::GlyphAndSubPixelPosition &g)
diff --git a/src/gui/text/qtextdocumentfragment.cpp b/src/gui/text/qtextdocumentfragment.cpp
index a1a562c839..5727b34e86 100644
--- a/src/gui/text/qtextdocumentfragment.cpp
+++ b/src/gui/text/qtextdocumentfragment.cpp
@@ -428,7 +428,7 @@ QTextHtmlImporter::QTextHtmlImporter(QTextDocument *_doc, const QString &_html,
     QString html = _html;
     const int startFragmentPos = html.indexOf(QLatin1String("<!--StartFragment-->"));
     if (startFragmentPos != -1) {
-        QString qt3RichTextHeader(QLatin1String("<meta name=\"qrichtext\" content=\"1\" />"));
+        const QLatin1String qt3RichTextHeader("<meta name=\"qrichtext\" content=\"1\" />");
 
         // Hack for Qt3
         const bool hasQtRichtextMetaTag = html.contains(qt3RichTextHeader);
diff --git a/src/gui/text/qtexthtmlparser.cpp b/src/gui/text/qtexthtmlparser.cpp
index 103a208c26..7bca50325c 100644
--- a/src/gui/text/qtexthtmlparser.cpp
+++ b/src/gui/text/qtexthtmlparser.cpp
@@ -1418,16 +1418,16 @@ static bool setFloatAttribute(qreal *destination, const QString &value)
     return ok;
 }
 
-static void setWidthAttribute(QTextLength *width, QString value)
+static void setWidthAttribute(QTextLength *width, const QString &valueStr)
 {
     bool ok = false;
-    qreal realVal = value.toDouble(&ok);
+    qreal realVal = valueStr.toDouble(&ok);
     if (ok) {
         *width = QTextLength(QTextLength::FixedLength, realVal);
     } else {
-        value = value.trimmed();
+        QStringRef value = QStringRef(&valueStr).trimmed();
         if (!value.isEmpty() && value.endsWith(QLatin1Char('%'))) {
-            value.chop(1);
+            value.truncate(value.size() - 1);
             realVal = value.toDouble(&ok);
             if (ok)
                 *width = QTextLength(QTextLength::PercentageLength, realVal);
@@ -1438,9 +1438,7 @@ static void setWidthAttribute(QTextLength *width, QString value)
 #ifndef QT_NO_CSSPARSER
 void QTextHtmlParserNode::parseStyleAttribute(const QString &value, const QTextDocument *resourceProvider)
 {
-    QString css = value;
-    css.prepend(QLatin1String("* {"));
-    css.append(QLatin1Char('}'));
+    const QString css = QLatin1String("* {") + value + QLatin1Char('}');
     QCss::Parser parser(css);
     QCss::StyleSheet sheet;
     parser.parse(&sheet, Qt::CaseInsensitive);
diff --git a/src/gui/text/qtextimagehandler.cpp b/src/gui/text/qtextimagehandler.cpp
index acd18994ad..18311ed161 100644
--- a/src/gui/text/qtextimagehandler.cpp
+++ b/src/gui/text/qtextimagehandler.cpp
@@ -111,7 +111,7 @@ static QPixmap getPixmap(QTextDocument *doc, const QTextImageFormat &format, con
         doc->addResource(QTextDocument::ImageResource, url, pm);
     }
 
-    if (name.contains(QStringLiteral("@2x")))
+    if (name.contains(QLatin1String("@2x")))
         pm.setDevicePixelRatio(sourcePixelRatio);
 
     return pm;
diff --git a/src/network/access/qftp.cpp b/src/network/access/qftp.cpp
index 19b519243c..7b6f830333 100644
--- a/src/network/access/qftp.cpp
+++ b/src/network/access/qftp.cpp
@@ -2034,7 +2034,7 @@ int QFtp::rename(const QString &oldname, const QString &newname)
 */
 int QFtp::rawCommand(const QString &command)
 {
-    QString cmd = command.trimmed() + QLatin1String("\r\n");
+    const QString cmd = QStringRef(&command).trimmed() + QLatin1String("\r\n");
     return d_func()->addCommand(new QFtpCommand(RawCommand, QStringList(cmd)));
 }
 
@@ -2253,8 +2253,8 @@ void QFtpPrivate::_q_startNextCommand()
     // Proxy support, replace the Login argument in place, then fall
     // through.
     if (c->command == QFtp::Login && !proxyHost.isEmpty()) {
-        QString loginString = c->rawCmds.constFirst().trimmed();
-        loginString += QLatin1Char('@') + host;
+        QString loginString;
+        loginString += QStringRef(&c->rawCmds.constFirst()).trimmed() + QLatin1Char('@') + host;
         if (port && port != 21)
             loginString += QLatin1Char(':') + QString::number(port);
         loginString += QLatin1String("\r\n");
diff --git a/src/network/access/qnetworkaccessftpbackend.cpp b/src/network/access/qnetworkaccessftpbackend.cpp
index 153a33f782..d242bdba82 100644
--- a/src/network/access/qnetworkaccessftpbackend.cpp
+++ b/src/network/access/qnetworkaccessftpbackend.cpp
@@ -306,8 +306,6 @@ void QNetworkAccessFtpBackend::ftpDone()
         state = CheckingFeatures;
         if (operation() == QNetworkAccessManager::GetOperation) {
             // send help command to find out if server supports "SIZE" and "MDTM"
-            QString command = url().path();
-            command.prepend(QLatin1String("%1 "));
             helpId = ftp->rawCommand(QLatin1String("HELP")); // get supported commands
         } else {
             ftpDone();
@@ -316,14 +314,13 @@ void QNetworkAccessFtpBackend::ftpDone()
         state = Statting;
         if (operation() == QNetworkAccessManager::GetOperation) {
             // logged in successfully, send the stat requests (if supported)
-            QString command = url().path();
-            command.prepend(QLatin1String("%1 "));
+            const QString path = url().path();
             if (supportsSize) {
                 ftp->rawCommand(QLatin1String("TYPE I"));
-                sizeId = ftp->rawCommand(command.arg(QLatin1String("SIZE"))); // get size
+                sizeId = ftp->rawCommand(QLatin1String("SIZE ") + path); // get size
             }
             if (supportsMdtm)
-                mdtmId = ftp->rawCommand(command.arg(QLatin1String("MDTM"))); // get modified time
+                mdtmId = ftp->rawCommand(QLatin1String("MDTM ") + path); // get modified time
             if (!supportsSize && !supportsMdtm)
                 ftpDone();      // no commands sent, move to the next state
         } else {
diff --git a/src/network/kernel/qauthenticator.cpp b/src/network/kernel/qauthenticator.cpp
index 469879c78b..107addae58 100644
--- a/src/network/kernel/qauthenticator.cpp
+++ b/src/network/kernel/qauthenticator.cpp
@@ -1277,7 +1277,7 @@ static QByteArray qEncodeNtlmv2Response(const QAuthenticatorPrivate *ctx,
         time = QDateTime::currentSecsSinceEpoch() + 11644473600;
 
         // represented as 100 nano seconds
-        time = Q_UINT64_C(time * 10000000);
+        time = time * Q_UINT64_C(10000000);
         ds << time;
     }
 
diff --git a/src/network/socket/qnativesocketengine_unix.cpp b/src/network/socket/qnativesocketengine_unix.cpp
index 7ef9d7f26b..fcb8a60c8f 100644
--- a/src/network/socket/qnativesocketengine_unix.cpp
+++ b/src/network/socket/qnativesocketengine_unix.cpp
@@ -902,10 +902,7 @@ qint64 QNativeSocketEnginePrivate::nativeReceiveDatagram(char *data, qint64 maxS
             if (cmsgptr->cmsg_level == IPPROTO_IP && cmsgptr->cmsg_type == IP_RECVIF
                     && cmsgptr->cmsg_len >= CMSG_LEN(sizeof(sockaddr_dl))) {
                 sockaddr_dl *sdl = reinterpret_cast<sockaddr_dl *>(CMSG_DATA(cmsgptr));
-#    if defined(Q_OS_OPENBSD)
-#      define LLINDEX(s) ((s)->sdl_index)
-#    endif
-                header->ifindex = LLINDEX(sdl);
+                header->ifindex = sdl->sdl_index;
             }
 #  endif
 #endif
diff --git a/src/network/ssl/qsslsocket.cpp b/src/network/ssl/qsslsocket.cpp
index 580b0fbdde..2371dd7212 100644
--- a/src/network/ssl/qsslsocket.cpp
+++ b/src/network/ssl/qsslsocket.cpp
@@ -55,7 +55,8 @@
     QSslSocket establishes a secure, encrypted TCP connection you can
     use for transmitting encrypted data. It can operate in both client
     and server mode, and it supports modern SSL protocols, including
-    SSLv3 and TLSv1_0. By default, QSslSocket uses TLSv1_0, but you can
+    SSL 3 and TLS 1.2. By default, QSslSocket uses only SSL protocols
+    which are considered to be secure (QSsl::SecureProtocols), but you can
     change the SSL protocol by calling setProtocol() as long as you do
     it before the handshake has started.
 
@@ -2394,6 +2395,13 @@ void QSslSocketPrivate::_q_disconnectedSlot()
 #endif
     disconnected();
     emit q->disconnected();
+
+    q->setLocalPort(0);
+    q->setLocalAddress(QHostAddress());
+    q->setPeerPort(0);
+    q->setPeerAddress(QHostAddress());
+    q->setPeerName(QString());
+    cachedSocketDescriptor = -1;
 }
 
 /*!
diff --git a/src/network/ssl/qsslsocket_mac.cpp b/src/network/ssl/qsslsocket_mac.cpp
index 194acbeacc..438ea9a38e 100644
--- a/src/network/ssl/qsslsocket_mac.cpp
+++ b/src/network/ssl/qsslsocket_mac.cpp
@@ -321,7 +321,7 @@ long QSslSocketPrivate::sslLibraryVersionNumber()
 
 QString QSslSocketPrivate::sslLibraryVersionString()
 {
-    return QStringLiteral("Secure Transport, ") + QSysInfo::prettyProductName();
+    return QLatin1String("Secure Transport, ") + QSysInfo::prettyProductName();
 }
 
 long QSslSocketPrivate::sslLibraryBuildVersionNumber()
@@ -436,7 +436,7 @@ void QSslSocketBackendPrivate::startClientEncryption()
         // Error description/code were set, 'error' emitted
         // by initSslContext, but OpenSSL socket also sets error
         // emits a signal twice, so ...
-        setErrorAndEmit(QAbstractSocket::SslInternalError, "Unable to init SSL Context");
+        setErrorAndEmit(QAbstractSocket::SslInternalError, QStringLiteral("Unable to init SSL Context"));
         return;
     }
 
@@ -449,7 +449,7 @@ void QSslSocketBackendPrivate::startServerEncryption()
         // Error description/code were set, 'error' emitted
         // by initSslContext, but OpenSSL socket also sets error
         // emits a signal twice, so ...
-        setErrorAndEmit(QAbstractSocket::SslInternalError, "Unable to init SSL Context");
+        setErrorAndEmit(QAbstractSocket::SslInternalError, QStringLiteral("Unable to init SSL Context"));
         return;
     }
 
@@ -470,7 +470,7 @@ void QSslSocketBackendPrivate::transmit()
 
     if (connectionEncrypted && !writeBuffer.isEmpty()) {
         qint64 totalBytesWritten = 0;
-        while (writeBuffer.nextDataBlockSize() > 0) {
+        while (writeBuffer.nextDataBlockSize() > 0 && context) {
             const size_t nextDataBlockSize = writeBuffer.nextDataBlockSize();
             size_t writtenBytes = 0;
             const OSStatus err = SSLWrite(context, writeBuffer.readPointer(), nextDataBlockSize, &writtenBytes);
@@ -505,7 +505,7 @@ void QSslSocketBackendPrivate::transmit()
 
     if (connectionEncrypted) {
         QVarLengthArray<char, 4096> data;
-        while (true) {
+        while (context) {
             size_t readBytes = 0;
             data.resize(4096);
             const OSStatus err = SSLRead(context, data.data(), data.size(), &readBytes);
@@ -780,7 +780,7 @@ bool QSslSocketBackendPrivate::initSslContext()
 
     context.reset(qt_createSecureTransportContext(mode));
     if (!context) {
-        setErrorAndEmit(QAbstractSocket::SslInternalError, "SSLCreateContext failed");
+        setErrorAndEmit(QAbstractSocket::SslInternalError, QStringLiteral("SSLCreateContext failed"));
         return false;
     }
 
@@ -808,7 +808,7 @@ bool QSslSocketBackendPrivate::initSslContext()
 
     if (!setSessionProtocol()) {
         destroySslContext();
-        setErrorAndEmit(QAbstractSocket::SslInternalError, "Failed to set protocol version");
+        setErrorAndEmit(QAbstractSocket::SslInternalError, QStringLiteral("Failed to set protocol version"));
         return false;
     }
 
@@ -1121,7 +1121,10 @@ bool QSslSocketBackendPrivate::verifyPeerTrust()
     // report errors
     if (!errors.isEmpty() && !canIgnoreVerify) {
         sslErrors = errors;
-        if (!checkSslErrors())
+        // checkSslErrors unconditionally emits sslErrors:
+        // a user's slot can abort/close/disconnect on this
+        // signal, so we also test the socket's state:
+        if (!checkSslErrors() || q->state() != QAbstractSocket::ConnectedState)
             return false;
     } else {
         sslErrors.clear();
@@ -1219,8 +1222,7 @@ bool QSslSocketBackendPrivate::startHandshake()
     // check protocol version ourselves, as Secure Transport does not enforce
     // the requested min / max versions.
     if (!verifySessionProtocol()) {
-        setErrorAndEmit(QAbstractSocket::SslHandshakeFailedError,
-                 "Protocol version mismatch");
+        setErrorAndEmit(QAbstractSocket::SslHandshakeFailedError, QStringLiteral("Protocol version mismatch"));
         plainSocket->disconnectFromHost();
         return false;
     }
diff --git a/src/platformsupport/clipboard/qmacmime.mm b/src/platformsupport/clipboard/qmacmime.mm
index 02d1295b0f..d48da8da15 100644
--- a/src/platformsupport/clipboard/qmacmime.mm
+++ b/src/platformsupport/clipboard/qmacmime.mm
@@ -412,9 +412,7 @@ QVariant QMacPasteboardMimeUnicodeText::convertToMime(const QString &mimetype, Q
     // I can only handle two types (system and unicode) so deal with them that way
     QVariant ret;
     if (flavor == QLatin1String("public.utf8-plain-text")) {
-        ret = QString(QCFString(CFStringCreateWithBytes(kCFAllocatorDefault,
-                                             reinterpret_cast<const UInt8 *>(firstData.constData()),
-                                             firstData.size(), CFStringGetSystemEncoding(), false)));
+        ret = QString::fromUtf8(firstData);
     } else if (flavor == QLatin1String("public.utf16-plain-text")) {
         ret = QString(reinterpret_cast<const QChar *>(firstData.constData()),
                       firstData.size() / sizeof(QChar));
diff --git a/src/platformsupport/dbustray/qdbustrayicon.cpp b/src/platformsupport/dbustray/qdbustrayicon.cpp
index 724992f348..da368bf9b7 100644
--- a/src/platformsupport/dbustray/qdbustrayicon.cpp
+++ b/src/platformsupport/dbustray/qdbustrayicon.cpp
@@ -66,7 +66,7 @@ Q_LOGGING_CATEGORY(qLcTray, "qt.qpa.tray")
 
 static const QString KDEItemFormat = QStringLiteral("org.kde.StatusNotifierItem-%1-%2");
 static const QString KDEWatcherService = QStringLiteral("org.kde.StatusNotifierWatcher");
-static const QString TempFileTemplate =  QDir::tempPath() + QStringLiteral("/qt-trayicon-XXXXXX.png");
+static const QString TempFileTemplate =  QDir::tempPath() + QLatin1String("/qt-trayicon-XXXXXX.png");
 static const QString XdgNotificationService = QStringLiteral("org.freedesktop.Notifications");
 static const QString XdgNotificationPath = QStringLiteral("/org/freedesktop/Notifications");
 static const QString DefaultAction = QStringLiteral("default");
@@ -156,7 +156,7 @@ QTemporaryFile *QDBusTrayIcon::tempIcon(const QIcon &icon)
         QDBusConnection session = QDBusConnection::sessionBus();
         uint pid = session.interface()->servicePid(KDEWatcherService).value();
         QString processName = QLockFilePrivate::processNameByPid(pid);
-        necessary = processName.endsWith(QStringLiteral("indicator-application-service"));
+        necessary = processName.endsWith(QLatin1String("indicator-application-service"));
         necessity_checked = true;
     }
     if (!necessary)
diff --git a/src/platformsupport/fontdatabases/mac/qcoretextfontdatabase.mm b/src/platformsupport/fontdatabases/mac/qcoretextfontdatabase.mm
index 1a17f75488..5fec53d1ed 100644
--- a/src/platformsupport/fontdatabases/mac/qcoretextfontdatabase.mm
+++ b/src/platformsupport/fontdatabases/mac/qcoretextfontdatabase.mm
@@ -585,8 +585,7 @@ QStringList QCoreTextFontDatabase::fallbacksForFamily(const QString &family, QFo
                     fallbackList.append(familyNameFromPostScriptName(item));
             }
 
-            if (QCoreTextFontEngine::supportsColorGlyphs())
-                fallbackList.append(QLatin1String("Apple Color Emoji"));
+            fallbackList.append(QLatin1String("Apple Color Emoji"));
 
             // Since we are only returning a list of default fonts for the current language, we do not
             // cover all unicode completely. This was especially an issue for some of the common script
diff --git a/src/platformsupport/fontdatabases/mac/qfontengine_coretext.mm b/src/platformsupport/fontdatabases/mac/qfontengine_coretext.mm
index 251ba2b9ac..a0047c0b7d 100644
--- a/src/platformsupport/fontdatabases/mac/qfontengine_coretext.mm
+++ b/src/platformsupport/fontdatabases/mac/qfontengine_coretext.mm
@@ -224,11 +224,9 @@ void QCoreTextFontEngine::init()
     synthesisFlags = 0;
     CTFontSymbolicTraits traits = CTFontGetSymbolicTraits(ctfont);
 
-#if defined(QT_PLATFORM_UIKIT) || MAC_OS_X_VERSION_MAX_ALLOWED >= 1070
-    if (supportsColorGlyphs() && (traits & kCTFontColorGlyphsTrait))
+    if (traits & kCTFontColorGlyphsTrait)
         glyphFormat = QFontEngine::Format_ARGB;
     else
-#endif
         glyphFormat = defaultGlyphFormat;
 
     if (traits & kCTFontItalicTrait)
@@ -659,9 +657,7 @@ QImage QCoreTextFontEngine::imageForGlyph(glyph_t glyph, QFixed subPixelPosition
             CGContextSetTextPosition(ctx, pos_x + 0.5 * lineThickness().toReal(), pos_y);
             CGContextShowGlyphsWithAdvances(ctx, &cgGlyph, &CGSizeZero, 1);
         }
-    }
-#if defined(QT_PLATFORM_UIKIT) || MAC_OS_X_VERSION_MAX_ALLOWED >= 1070
-    else if (supportsColorGlyphs()) {
+    } else {
         // CGContextSetTextMatrix does not work with color glyphs, so we use
         // the CTM instead. This means we must translate the CTM as well, to
         // set the glyph position, instead of using CGContextSetTextPosition.
@@ -672,7 +668,6 @@ QImage QCoreTextFontEngine::imageForGlyph(glyph_t glyph, QFixed subPixelPosition
         // glyphs in the Apple Color Emoji font, so we use CTFontDrawGlyphs instead.
         CTFontDrawGlyphs(ctfont, &cgGlyph, &CGPointZero, 1, ctx);
     }
-#endif
 
     CGContextRelease(ctx);
     CGColorSpaceRelease(colorspace);
diff --git a/src/platformsupport/fontdatabases/mac/qfontengine_coretext_p.h b/src/platformsupport/fontdatabases/mac/qfontengine_coretext_p.h
index 27289239c6..b7c9edc528 100644
--- a/src/platformsupport/fontdatabases/mac/qfontengine_coretext_p.h
+++ b/src/platformsupport/fontdatabases/mac/qfontengine_coretext_p.h
@@ -116,21 +116,6 @@ public:
 
     QFontEngine::Properties properties() const Q_DECL_OVERRIDE;
 
-    static bool supportsColorGlyphs()
-    {
-#if defined(QT_PLATFORM_UIKIT)
-        return true;
-#elif MAC_OS_X_VERSION_MAX_ALLOWED >= 1070
-  #if MAC_OS_X_VERSION_MIN_REQUIRED < 1070
-        return &CTFontDrawGlyphs;
-  #else
-        return true;
-  #endif
-#else
-        return false;
-#endif
-    }
-
     static bool ct_getSfntTable(void *user_data, uint tag, uchar *buffer, uint *length);
     static QFont::Weight qtWeightFromCFWeight(float value);
 
diff --git a/src/platformsupport/input/tslib/qtslib.cpp b/src/platformsupport/input/tslib/qtslib.cpp
index ed21cc1cef..75ac3c50e0 100644
--- a/src/platformsupport/input/tslib/qtslib.cpp
+++ b/src/platformsupport/input/tslib/qtslib.cpp
@@ -64,7 +64,7 @@ QTsLibMouseHandler::QTsLibMouseHandler(const QString &key,
 
     QByteArray device = qgetenv("TSLIB_TSDEVICE");
 
-    if (specification.startsWith(QStringLiteral("/dev/")))
+    if (specification.startsWith(QLatin1String("/dev/")))
         device = specification.toLocal8Bit();
 
     if (device.isEmpty())
diff --git a/src/platformsupport/services/genericunix/qgenericunixservices.cpp b/src/platformsupport/services/genericunix/qgenericunixservices.cpp
index 727da3132a..5242f00193 100644
--- a/src/platformsupport/services/genericunix/qgenericunixservices.cpp
+++ b/src/platformsupport/services/genericunix/qgenericunixservices.cpp
@@ -101,7 +101,7 @@ static inline bool detectWebBrowser(const QByteArray &desktop,
     if (desktop == QByteArray("KDE")) {
         // Konqueror launcher
         if (checkExecutable(QStringLiteral("kfmclient"), browser)) {
-            browser->append(QStringLiteral(" exec"));
+            browser->append(QLatin1String(" exec"));
             return true;
         }
     } else if (desktop == QByteArray("GNOME")) {
@@ -121,7 +121,7 @@ static inline bool launch(const QString &launcher, const QUrl &url)
     if (debug)
         qDebug("Launching %s", qPrintable(command));
 #if defined(QT_NO_PROCESS)
-    const bool ok = ::system(qPrintable(command + QStringLiteral(" &")));
+    const bool ok = ::system(qPrintable(command + QLatin1String(" &")));
 #else
     const bool ok = QProcess::startDetached(command);
 #endif
diff --git a/src/platformsupport/themes/genericunix/qgenericunixthemes.cpp b/src/platformsupport/themes/genericunix/qgenericunixthemes.cpp
index 32ca381b93..118b4988a5 100644
--- a/src/platformsupport/themes/genericunix/qgenericunixthemes.cpp
+++ b/src/platformsupport/themes/genericunix/qgenericunixthemes.cpp
@@ -170,7 +170,7 @@ QStringList QGenericUnixTheme::xdgIconThemePaths()
 {
     QStringList paths;
     // Add home directory first in search path
-    const QFileInfo homeIconDir(QDir::homePath() + QStringLiteral("/.icons"));
+    const QFileInfo homeIconDir(QDir::homePath() + QLatin1String("/.icons"));
     if (homeIconDir.isDir())
         paths.prepend(homeIconDir.absoluteFilePath());
 
@@ -247,8 +247,8 @@ public:
     static QString kdeGlobals(const QString &kdeDir, int kdeVersion)
     {
         if (kdeVersion > 4)
-            return kdeDir + QStringLiteral("/kdeglobals");
-        return kdeDir + QStringLiteral("/share/config/kdeglobals");
+            return kdeDir + QLatin1String("/kdeglobals");
+        return kdeDir + QLatin1String("/share/config/kdeglobals");
     }
 
     void refresh();
@@ -559,22 +559,22 @@ QPlatformTheme *QKdeTheme::createKdeTheme()
     if (!kdeDirsVar.isEmpty())
         kdeDirs += kdeDirsVar.split(QLatin1Char(':'), QString::SkipEmptyParts);
 
-    const QString kdeVersionHomePath = QDir::homePath() + QStringLiteral("/.kde") + QLatin1String(kdeVersionBA);
+    const QString kdeVersionHomePath = QDir::homePath() + QLatin1String("/.kde") + QLatin1String(kdeVersionBA);
     if (QFileInfo(kdeVersionHomePath).isDir())
         kdeDirs += kdeVersionHomePath;
 
-    const QString kdeHomePath = QDir::homePath() + QStringLiteral("/.kde");
+    const QString kdeHomePath = QDir::homePath() + QLatin1String("/.kde");
     if (QFileInfo(kdeHomePath).isDir())
         kdeDirs += kdeHomePath;
 
-    const QString kdeRcPath = QStringLiteral("/etc/kde") + QLatin1String(kdeVersionBA) + QStringLiteral("rc");
+    const QString kdeRcPath = QLatin1String("/etc/kde") + QLatin1String(kdeVersionBA) + QLatin1String("rc");
     if (QFileInfo(kdeRcPath).isReadable()) {
         QSettings kdeSettings(kdeRcPath, QSettings::IniFormat);
         kdeSettings.beginGroup(QStringLiteral("Directories-default"));
         kdeDirs += kdeSettings.value(QStringLiteral("prefixes")).toStringList();
     }
 
-    const QString kdeVersionPrefix = QStringLiteral("/etc/kde") + QLatin1String(kdeVersionBA);
+    const QString kdeVersionPrefix = QLatin1String("/etc/kde") + QLatin1String(kdeVersionBA);
     if (QFileInfo(kdeVersionPrefix).isDir())
         kdeDirs += kdeVersionPrefix;
 
diff --git a/src/plugins/bearer/connman/qconnmanservice_linux_p.h b/src/plugins/bearer/connman/qconnmanservice_linux_p.h
index e773db9b20..0e774d50c3 100644
--- a/src/plugins/bearer/connman/qconnmanservice_linux_p.h
+++ b/src/plugins/bearer/connman/qconnmanservice_linux_p.h
@@ -218,6 +218,7 @@ protected:
 private:
     QVariantMap properties();
     QVariantMap propertiesMap;
+private Q_SLOTS:
     void scanReply(QDBusPendingCallWatcher *call);
 
 };
diff --git a/src/plugins/platforminputcontexts/compose/generator/qtablegenerator.cpp b/src/plugins/platforminputcontexts/compose/generator/qtablegenerator.cpp
index 52d14e5324..d507751d5e 100644
--- a/src/plugins/platforminputcontexts/compose/generator/qtablegenerator.cpp
+++ b/src/plugins/platforminputcontexts/compose/generator/qtablegenerator.cpp
@@ -278,7 +278,7 @@ QString TableGenerator::findComposeFile()
 
     // check if user’s home directory has a file named .XCompose
     if (cleanState()) {
-        QString path = qgetenv("HOME") + QStringLiteral("/.XCompose");
+        QString path = qgetenv("HOME") + QLatin1String("/.XCompose");
         if (QFile::exists(path))
             return path;
     }
diff --git a/src/plugins/platforms/cocoa/qcocoaintegration.mm b/src/plugins/platforms/cocoa/qcocoaintegration.mm
index b0b91c6633..21a2ba3611 100644
--- a/src/plugins/platforms/cocoa/qcocoaintegration.mm
+++ b/src/plugins/platforms/cocoa/qcocoaintegration.mm
@@ -456,6 +456,10 @@ QCocoaScreen *QCocoaIntegration::screenAtIndex(int index)
     if (index >= mScreens.count())
         updateScreens();
 
+    // It is possible that the screen got removed while updateScreens was called
+    // so we do a sanity check to be certain
+    if (index >= mScreens.count())
+        return 0;
     return mScreens.at(index);
 }
 
diff --git a/src/plugins/platforms/cocoa/qcocoamenu.h b/src/plugins/platforms/cocoa/qcocoamenu.h
index 7951a2ff70..6b80162e4d 100644
--- a/src/plugins/platforms/cocoa/qcocoamenu.h
+++ b/src/plugins/platforms/cocoa/qcocoamenu.h
@@ -93,6 +93,9 @@ public:
     void setAttachedItem(NSMenuItem *item);
     NSMenuItem *attachedItem() const;
 
+    bool isOpen() const;
+    void setIsOpen(bool isOpen);
+
 private:
     QCocoaMenuItem *itemOrNull(int index) const;
     void insertNative(QCocoaMenuItem *item, QCocoaMenuItem *beforeItem);
@@ -100,9 +103,10 @@ private:
     QList<QCocoaMenuItem *> m_menuItems;
     NSMenu *m_nativeMenu;
     NSMenuItem *m_attachedItem;
+    quintptr m_tag;
     bool m_enabled;
     bool m_visible;
-    quintptr m_tag;
+    bool m_isOpen;
 };
 
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/cocoa/qcocoamenu.mm b/src/plugins/platforms/cocoa/qcocoamenu.mm
index a388155c03..06ec2aa479 100644
--- a/src/plugins/platforms/cocoa/qcocoamenu.mm
+++ b/src/plugins/platforms/cocoa/qcocoamenu.mm
@@ -137,12 +137,14 @@ QT_NAMESPACE_ALIAS_OBJC_CLASS(QCocoaMenuDelegate);
 - (void) menuWillOpen:(NSMenu*)m
 {
     Q_UNUSED(m);
+    m_menu->setIsOpen(true);
     emit m_menu->aboutToShow();
 }
 
 - (void) menuDidClose:(NSMenu*)m
 {
     Q_UNUSED(m);
+    m_menu->setIsOpen(false);
     // wrong, but it's the best we can do
     emit m_menu->aboutToHide();
 }
@@ -257,9 +259,10 @@ QT_BEGIN_NAMESPACE
 
 QCocoaMenu::QCocoaMenu() :
     m_attachedItem(0),
+    m_tag(0),
     m_enabled(true),
     m_visible(true),
-    m_tag(0)
+    m_isOpen(false)
 {
     QMacAutoReleasePool pool;
 
@@ -330,6 +333,8 @@ void QCocoaMenu::insertNative(QCocoaMenuItem *item, QCocoaMenuItem *beforeItem)
     item->nsItem().target = m_nativeMenu.delegate;
     if (!item->menu())
         [item->nsItem() setAction:@selector(itemFired:)];
+    else if (isOpen() && item->nsItem()) // Someone's adding new items after aboutToShow() was emitted
+        item->menu()->setAttachedItem(item->nsItem());
 
     if (item->isMerged())
         return;
@@ -353,6 +358,16 @@ void QCocoaMenu::insertNative(QCocoaMenuItem *item, QCocoaMenuItem *beforeItem)
     item->setMenuParent(this);
 }
 
+bool QCocoaMenu::isOpen() const
+{
+    return m_isOpen;
+}
+
+void QCocoaMenu::setIsOpen(bool isOpen)
+{
+    m_isOpen = isOpen;
+}
+
 void QCocoaMenu::removeMenuItem(QPlatformMenuItem *menuItem)
 {
     QMacAutoReleasePool pool;
diff --git a/src/plugins/platforms/cocoa/qcocoamenubar.mm b/src/plugins/platforms/cocoa/qcocoamenubar.mm
index 86f6dda2e9..96b40259b4 100644
--- a/src/plugins/platforms/cocoa/qcocoamenubar.mm
+++ b/src/plugins/platforms/cocoa/qcocoamenubar.mm
@@ -179,9 +179,11 @@ void QCocoaMenuBar::syncMenu(QPlatformMenu *menu)
             }
     }
 
-    NSMenuItem *nativeMenuItem = nativeItemForMenu(cocoaMenu);
-    nativeMenuItem.title = cocoaMenu->nsMenu().title;
-    nativeMenuItem.hidden = shouldHide;
+    if (NSMenuItem *attachedItem = cocoaMenu->attachedItem()) {
+        // Non-nil attached item means the item's submenu is set
+        attachedItem.title = cocoaMenu->nsMenu().title;
+        attachedItem.hidden = shouldHide;
+    }
 }
 
 NSMenuItem *QCocoaMenuBar::nativeItemForMenu(QCocoaMenu *menu) const
diff --git a/src/plugins/platforms/cocoa/qcocoatheme.mm b/src/plugins/platforms/cocoa/qcocoatheme.mm
index aa9eb38384..01b654af68 100644
--- a/src/plugins/platforms/cocoa/qcocoatheme.mm
+++ b/src/plugins/platforms/cocoa/qcocoatheme.mm
@@ -260,34 +260,14 @@ QPixmap QCocoaTheme::standardPixmap(StandardPixmap sp, const QSizeF &size) const
     }
     if (iconType != 0) {
         QPixmap pixmap;
-        IconRef icon;
-        IconRef overlayIcon = 0;
-        if (iconType != kGenericApplicationIcon) {
-            GetIconRef(kOnSystemDisk, kSystemIconsCreator, iconType, &icon);
-        } else {
-            FSRef fsRef;
-            ProcessSerialNumber psn = { 0, kCurrentProcess };
-            GetProcessBundleLocation(&psn, &fsRef);
-            GetIconRefFromFileInfo(&fsRef, 0, 0, 0, 0, kIconServicesNormalUsageFlag, &icon, 0);
-            if (sp == MessageBoxCritical) {
-                overlayIcon = icon;
-                GetIconRef(kOnSystemDisk, kSystemIconsCreator, kAlertCautionIcon, &icon);
-            }
-        }
+        IconRef icon = Q_NULLPTR;
+        GetIconRef(kOnSystemDisk, kSystemIconsCreator, iconType, &icon);
 
         if (icon) {
             pixmap = qt_mac_convert_iconref(icon, size.width(), size.height());
             ReleaseIconRef(icon);
         }
 
-        if (overlayIcon) {
-            QSizeF littleSize = size / 2;
-            QPixmap overlayPix = qt_mac_convert_iconref(overlayIcon, littleSize.width(), littleSize.height());
-            QPainter painter(&pixmap);
-            painter.drawPixmap(littleSize.width(), littleSize.height(), overlayPix);
-            ReleaseIconRef(overlayIcon);
-        }
-
         return pixmap;
     }
 
diff --git a/src/plugins/platforms/cocoa/qnsview.mm b/src/plugins/platforms/cocoa/qnsview.mm
index 7834c2991d..a72cbd010a 100644
--- a/src/plugins/platforms/cocoa/qnsview.mm
+++ b/src/plugins/platforms/cocoa/qnsview.mm
@@ -443,7 +443,8 @@ static bool _q_dontOverrideCtrlLMB = false;
             NSUInteger screenIndex = [[NSScreen screens] indexOfObject:self.window.screen];
             if (screenIndex != NSNotFound) {
                 QCocoaScreen *cocoaScreen = QCocoaIntegration::instance()->screenAtIndex(screenIndex);
-                QWindowSystemInterface::handleWindowScreenChanged(m_window, cocoaScreen->screen());
+                if (cocoaScreen)
+                    QWindowSystemInterface::handleWindowScreenChanged(m_window, cocoaScreen->screen());
                 m_platformWindow->updateExposedGeometry();
             }
         }
diff --git a/src/plugins/platforms/eglfs/api/qeglfsdeviceintegration.cpp b/src/plugins/platforms/eglfs/api/qeglfsdeviceintegration.cpp
index c6aab9d86c..3848e99221 100644
--- a/src/plugins/platforms/eglfs/api/qeglfsdeviceintegration.cpp
+++ b/src/plugins/platforms/eglfs/api/qeglfsdeviceintegration.cpp
@@ -82,7 +82,7 @@ QStringList QEglFSDeviceIntegrationFactory::keys(const QString &pluginPath)
         QCoreApplication::addLibraryPath(pluginPath);
         list = directLoader()->keyMap().values();
         if (!list.isEmpty()) {
-            const QString postFix = QStringLiteral(" (from ")
+            const QString postFix = QLatin1String(" (from ")
                     + QDir::toNativeSeparators(pluginPath)
                     + QLatin1Char(')');
             const QStringList::iterator end = list.end();
diff --git a/src/plugins/platforms/minimal/minimal.pro b/src/plugins/platforms/minimal/minimal.pro
index bd6f2d8e6f..3aca27b555 100644
--- a/src/plugins/platforms/minimal/minimal.pro
+++ b/src/plugins/platforms/minimal/minimal.pro
@@ -11,7 +11,7 @@ HEADERS =   qminimalintegration.h \
 OTHER_FILES += minimal.json
 
 CONFIG += qpa/genericunixfontdatabase
-darwin: DEFINES += QT_NO_FONTCONFIG
+win32|darwin: DEFINES += QT_NO_FONTCONFIG
 
 PLUGIN_TYPE = platforms
 PLUGIN_CLASS_NAME = QMinimalIntegrationPlugin
diff --git a/src/plugins/platforms/qnx/qqnxrasterwindow.cpp b/src/plugins/platforms/qnx/qqnxrasterwindow.cpp
index b075690e3d..7f11de228e 100644
--- a/src/plugins/platforms/qnx/qqnxrasterwindow.cpp
+++ b/src/plugins/platforms/qnx/qqnxrasterwindow.cpp
@@ -178,7 +178,7 @@ void QQnxRasterWindow::adjustBufferSize()
 {
     // When having a raster window we don't need any buffers, since
     // Qt will draw to the parent TLW backing store.
-    const QSize windowSize = window()->parent() ? QSize(1,1) : window()->size();
+    const QSize windowSize = window()->parent() ? QSize(0,0) : window()->size();
     if (windowSize != bufferSize())
         setBufferSize(windowSize);
 }
@@ -194,6 +194,13 @@ void QQnxRasterWindow::resetBuffers()
     m_currentBufferIndex = -1;
     m_previousDirty = QRegion();
     m_scrolled = QRegion();
+    if (window()->parent() && bufferSize() == QSize(1,1)) {
+        // If we have a parent then we're not really rendering.  But if we don't render we'll
+        // be invisible and any children won't show up.  This should be harmless since we're
+        // rendering into a 1x1 window that has transparency set to discard.
+        renderBuffer();
+        post(QRegion(0,0,1,1));
+    }
 }
 
 void QQnxRasterWindow::blitPreviousToCurrent(const QRegion &region, int dx, int dy, bool flush)
diff --git a/src/plugins/platforms/qnx/qqnxwindow.cpp b/src/plugins/platforms/qnx/qqnxwindow.cpp
index e04f16db92..f4e6ca9804 100644
--- a/src/plugins/platforms/qnx/qqnxwindow.cpp
+++ b/src/plugins/platforms/qnx/qqnxwindow.cpp
@@ -386,7 +386,12 @@ void QQnxWindow::setBufferSize(const QSize &size)
     // Set the transparency. According to QNX technical support, setting the window
     // transparency property should always be done *after* creating the window
     // buffers in order to guarantee the property is paid attention to.
-    if (window()->requestedFormat().alphaBufferSize() == 0) {
+    if (size.isEmpty()) {
+        // We can't create 0x0 buffers and instead make them 1x1.  But to allow these windows to
+        // still be 'visible' (thus allowing their children to be visible), we need to allow
+        // them to be posted but still not show up.
+        val[0] = SCREEN_TRANSPARENCY_DISCARD;
+    } else if (window()->requestedFormat().alphaBufferSize() == 0) {
         // To avoid overhead in the composition manager, disable blending
         // when the underlying window buffer doesn't have an alpha channel.
         val[0] = SCREEN_TRANSPARENCY_NONE;
diff --git a/src/plugins/platforms/windows/qwindowscontext.cpp b/src/plugins/platforms/windows/qwindowscontext.cpp
index ef0962c2ff..3a683bd7a0 100644
--- a/src/plugins/platforms/windows/qwindowscontext.cpp
+++ b/src/plugins/platforms/windows/qwindowscontext.cpp
@@ -47,6 +47,7 @@
 #include "qwindowsmime.h"
 #include "qwindowsinputcontext.h"
 #include "qwindowstabletsupport.h"
+#include "qwindowstheme.h"
 #include <private/qguiapplication_p.h>
 #ifndef QT_NO_ACCESSIBILITY
 # include "accessible/qwindowsaccessibility.h"
@@ -339,7 +340,9 @@ void QWindowsContext::setProcessDpiAwareness(QtWindows::ProcessDpiAwareness dpiA
     qCDebug(lcQpaWindows) << __FUNCTION__ << dpiAwareness;
     if (QWindowsContext::shcoredll.isValid()) {
         const HRESULT hr = QWindowsContext::shcoredll.setProcessDpiAwareness(dpiAwareness);
-        if (FAILED(hr)) {
+        // E_ACCESSDENIED means set externally (MSVC manifest or external app loading Qt plugin).
+        // Silence warning in that case unless debug is enabled.
+        if (FAILED(hr) && (hr != E_ACCESSDENIED || lcQpaWindows().isDebugEnabled())) {
             qWarning().noquote().nospace() << "SetProcessDpiAwareness("
                 << dpiAwareness << ") failed: " << QWindowsContext::comErrorString(hr)
                 << ", using " << QWindowsContext::processDpiAwareness();
@@ -428,28 +431,29 @@ QString QWindowsContext::registerWindowClass(const QWindow *w)
         break;
     }
     // Create a unique name for the flag combination
-    QString cname = QStringLiteral("Qt5QWindow");
+    QString cname;
+    cname += QLatin1String("Qt5QWindow");
     switch (type) {
     case Qt::Tool:
-        cname += QStringLiteral("Tool");
+        cname += QLatin1String("Tool");
         break;
     case Qt::ToolTip:
-        cname += QStringLiteral("ToolTip");
+        cname += QLatin1String("ToolTip");
         break;
     case Qt::Popup:
-        cname += QStringLiteral("Popup");
+        cname += QLatin1String("Popup");
         break;
     default:
         break;
     }
     if (style & CS_DROPSHADOW)
-        cname += QStringLiteral("DropShadow");
+        cname += QLatin1String("DropShadow");
     if (style & CS_SAVEBITS)
-        cname += QStringLiteral("SaveBits");
+        cname += QLatin1String("SaveBits");
     if (style & CS_OWNDC)
-        cname += QStringLiteral("OwnDC");
+        cname += QLatin1String("OwnDC");
     if (icon)
-        cname += QStringLiteral("Icon");
+        cname += QLatin1String("Icon");
 
     return registerWindowClass(cname, qWindowsWndProc, style, GetSysColorBrush(COLOR_WINDOW), icon);
 }
@@ -714,8 +718,8 @@ static inline QString errorMessageFromComError(const _com_error &comError)
          return result;
      }
      if (const WORD wCode = comError.WCode())
-         return QStringLiteral("IDispatch error #") + QString::number(wCode);
-     return QStringLiteral("Unknown error 0x0") + QString::number(comError.Error(), 16);
+         return QString::asprintf("IDispatch error #%u", uint(wCode));
+     return QString::asprintf("Unknown error 0x0%x", uint(comError.Error()));
 }
 
 /*!
@@ -736,6 +740,9 @@ QByteArray QWindowsContext::comErrorString(HRESULT hr)
     case E_UNEXPECTED:
         result += QByteArrayLiteral("E_UNEXPECTED");
         break;
+    case E_ACCESSDENIED:
+        result += QByteArrayLiteral("E_ACCESSDENIED");
+        break;
     case CO_E_ALREADYINITIALIZED:
         result += QByteArrayLiteral("CO_E_ALREADYINITIALIZED");
         break;
@@ -891,6 +898,8 @@ bool QWindowsContext::windowsProc(HWND hwnd, UINT message,
 #endif
     case QtWindows::DisplayChangedEvent:
         return d->m_screenManager.handleDisplayChange(wParam, lParam);
+        if (QWindowsTheme *t = QWindowsTheme::instance())
+            t->displayChanged();
     case QtWindows::SettingChangedEvent:
         return d->m_screenManager.handleScreenChanges();
     default:
diff --git a/src/plugins/platforms/windows/qwindowseglcontext.cpp b/src/plugins/platforms/windows/qwindowseglcontext.cpp
index 6124b004b6..a4738dc100 100644
--- a/src/plugins/platforms/windows/qwindowseglcontext.cpp
+++ b/src/plugins/platforms/windows/qwindowseglcontext.cpp
@@ -367,7 +367,7 @@ QSurfaceFormat QWindowsEGLStaticContext::formatFromConfig(EGLDisplay display, EG
     \list
     \o Install the Direct X SDK
     \o Checkout and build ANGLE (SVN repository) as explained here:
-       \l{http://code.google.com/p/angleproject/wiki/DevSetup}{ANGLE-Project}.
+       \l{https://chromium.googlesource.com/angle/angle/+/master/README.md}
        When building for 64bit, de-activate the "WarnAsError" option
        in every project file (as otherwise integer conversion
        warnings will break the build).
diff --git a/src/plugins/platforms/windows/qwindowsmime.cpp b/src/plugins/platforms/windows/qwindowsmime.cpp
index d6375693d8..30d438a127 100644
--- a/src/plugins/platforms/windows/qwindowsmime.cpp
+++ b/src/plugins/platforms/windows/qwindowsmime.cpp
@@ -696,7 +696,7 @@ QVariant QWindowsMimeText::convertToMime(const QString &mime, LPDATAOBJECT pData
         QByteArray data = getData(CF_UNICODETEXT, pDataObj);
         if (!data.isEmpty()) {
             str = QString::fromWCharArray(reinterpret_cast<const wchar_t *>(data.constData()));
-            str.replace(QStringLiteral("\r\n"), QStringLiteral("\n"));
+            str.replace(QLatin1String("\r\n"), QLatin1String("\n"));
         } else {
             data = getData(CF_TEXT, pDataObj);
             if (!data.isEmpty()) {
diff --git a/src/plugins/platforms/windows/qwindowsmousehandler.cpp b/src/plugins/platforms/windows/qwindowsmousehandler.cpp
index 45fbb4fdd3..3f6230172e 100644
--- a/src/plugins/platforms/windows/qwindowsmousehandler.cpp
+++ b/src/plugins/platforms/windows/qwindowsmousehandler.cpp
@@ -420,6 +420,8 @@ static bool isValidWheelReceiver(QWindow *candidate)
 {
     if (candidate) {
         const QWindow *toplevel = QWindowsWindow::topLevelOf(candidate);
+        if (toplevel->type() == Qt::ForeignWindow)
+            return true;
         if (const QWindowsWindow *ww = QWindowsWindow::windowsWindowOf(toplevel))
             return !ww->testFlag(QWindowsWindow::BlockedByModal);
     }
diff --git a/src/plugins/platforms/windows/qwindowsopengltester.cpp b/src/plugins/platforms/windows/qwindowsopengltester.cpp
index d5d50a69cd..5283d6b260 100644
--- a/src/plugins/platforms/windows/qwindowsopengltester.cpp
+++ b/src/plugins/platforms/windows/qwindowsopengltester.cpp
@@ -226,15 +226,16 @@ QWindowsOpenGLTester::Renderers QWindowsOpenGLTester::detectSupportedRenderers(c
     if (!glesOnly && testDesktopGL())
         result |= QWindowsOpenGLTester::DesktopGl;
 
-    QSet<QString> features;
     const char bugListFileVar[] = "QT_OPENGL_BUGLIST";
+    QString buglistFileName = QStringLiteral(":/qt-project.org/windows/openglblacklists/default.json");
+
     if (qEnvironmentVariableIsSet(bugListFileVar)) {
         const QString fileName = resolveBugListFile(QFile::decodeName(qgetenv(bugListFileVar)));
         if (!fileName.isEmpty())
-            features = QOpenGLConfig::gpuFeatures(qgpu, fileName);
-    } else {
-        features = QOpenGLConfig::gpuFeatures(qgpu, QStringLiteral(":/qt-project.org/windows/openglblacklists/default.json"));
+            buglistFileName = fileName;
     }
+
+    QSet<QString> features = QOpenGLConfig::gpuFeatures(qgpu, buglistFileName);
     qCDebug(lcQpaGl) << "GPU features:" << features;
 
     if (features.contains(QStringLiteral("disable_desktopgl"))) { // Qt-specific
diff --git a/src/plugins/platforms/windows/qwindowsservices.cpp b/src/plugins/platforms/windows/qwindowsservices.cpp
index d559273950..6cc56372ec 100644
--- a/src/plugins/platforms/windows/qwindowsservices.cpp
+++ b/src/plugins/platforms/windows/qwindowsservices.cpp
@@ -87,9 +87,8 @@ static inline QString mailCommand()
             keyName = QString::fromWCharArray(command);
         RegCloseKey(handle);
     }
-    if (keyName.isEmpty())
-        keyName = QStringLiteral("mailto");
-    keyName += QStringLiteral("\\Shell\\Open\\Command");
+    const QLatin1String mailto = keyName.isEmpty() ? QLatin1String("mailto") : QLatin1String();
+    keyName += mailto + QLatin1String("\\Shell\\Open\\Command");
     if (debug)
         qDebug() << __FUNCTION__ << "keyName=" << keyName;
     command[0] = 0;
@@ -123,7 +122,7 @@ static inline bool launchMail(const QUrl &url)
     }
     // Pass the url as the parameter. Should use QProcess::startDetached(),
     // but that cannot handle a Windows command line [yet].
-    command.replace(QStringLiteral("%1"), url.toString(QUrl::FullyEncoded));
+    command.replace(QLatin1String("%1"), url.toString(QUrl::FullyEncoded));
     if (debug)
         qDebug() << __FUNCTION__ << "Launching" << command;
     //start the process
diff --git a/src/plugins/platforms/windows/qwindowstabletsupport.cpp b/src/plugins/platforms/windows/qwindowstabletsupport.cpp
index 3689978b41..46306d438f 100644
--- a/src/plugins/platforms/windows/qwindowstabletsupport.cpp
+++ b/src/plugins/platforms/windows/qwindowstabletsupport.cpp
@@ -53,7 +53,7 @@
 #include <QtGui/QGuiApplication>
 #include <QtGui/QWindow>
 #include <QtCore/QDebug>
-#include <QtCore/QScopedArrayPointer>
+#include <QtCore/QVarLengthArray>
 #include <QtCore/QtMath>
 
 #include <private/qguiapplication_p.h>
@@ -233,7 +233,7 @@ QString QWindowsTabletSupport::description() const
     const unsigned size = m_winTab32DLL.wTInfo(WTI_INTERFACE, IFC_WINTABID, 0);
     if (!size)
         return QString();
-    QScopedPointer<TCHAR> winTabId(new TCHAR[size + 1]);
+    QVarLengthArray<TCHAR> winTabId(size + 1);
     m_winTab32DLL.wTInfo(WTI_INTERFACE, IFC_WINTABID, winTabId.data());
     WORD implementationVersion = 0;
     m_winTab32DLL.wTInfo(WTI_INTERFACE, IFC_IMPLVERSION, &implementationVersion);
@@ -246,11 +246,11 @@ QString QWindowsTabletSupport::description() const
         .arg(implementationVersion >> 8).arg(implementationVersion & 0xFF)
         .arg(opts, 0, 16);
     if (opts & CXO_MESSAGES)
-        result += QStringLiteral(" CXO_MESSAGES");
+        result += QLatin1String(" CXO_MESSAGES");
     if (opts & CXO_CSRMESSAGES)
-        result += QStringLiteral(" CXO_CSRMESSAGES");
+        result += QLatin1String(" CXO_CSRMESSAGES");
     if (m_tiltSupport)
-        result += QStringLiteral(" tilt");
+        result += QLatin1String(" tilt");
     return result;
 }
 
diff --git a/src/plugins/platforms/windows/qwindowstheme.cpp b/src/plugins/platforms/windows/qwindowstheme.cpp
index 397da61604..e84033f5e4 100644
--- a/src/plugins/platforms/windows/qwindowstheme.cpp
+++ b/src/plugins/platforms/windows/qwindowstheme.cpp
@@ -319,6 +319,7 @@ QWindowsTheme::QWindowsTheme()
     std::fill(m_fonts, m_fonts + NFonts, static_cast<QFont *>(0));
     std::fill(m_palettes, m_palettes + NPalettes, static_cast<QPalette *>(0));
     refresh();
+    refreshIconPixmapSizes();
 }
 
 QWindowsTheme::~QWindowsTheme()
@@ -330,7 +331,7 @@ QWindowsTheme::~QWindowsTheme()
 
 static inline QStringList iconThemeSearchPaths()
 {
-    const QFileInfo appDir(QCoreApplication::applicationDirPath() + QStringLiteral("/icons"));
+    const QFileInfo appDir(QCoreApplication::applicationDirPath() + QLatin1String("/icons"));
     return appDir.isDir() ? QStringList(appDir.absoluteFilePath()) : QStringList();
 }
 
@@ -382,16 +383,8 @@ QVariant QWindowsTheme::themeHint(ThemeHint hint) const
         return QVariant(int(WindowsKeyboardScheme));
     case UiEffects:
         return QVariant(uiEffects());
-    case IconPixmapSizes: {
-        QList<int> sizes;
-        sizes << 16 << 32;
-#ifdef USE_IIMAGELIST
-        sizes << 48; // sHIL_EXTRALARGE
-        if (QSysInfo::WindowsVersion >= QSysInfo::WV_VISTA)
-            sizes << 256; // SHIL_JUMBO
-#endif // USE_IIMAGELIST
-        return QVariant::fromValue(sizes);
-    }
+    case IconPixmapSizes:
+        return m_fileIconSizes;
     case DialogSnapToDefaultButton:
         return QVariant(booleanSystemParametersInfo(SPI_GETSNAPTODEFBUTTON, false));
     case ContextMenuOnMouseRelease:
@@ -459,6 +452,15 @@ void QWindowsTheme::refreshFonts()
     m_fonts[FixedFont] = new QFont(fixedFont);
 }
 
+enum FileIconSize {
+    // Standard icons obtainable via shGetFileInfo(), SHGFI_SMALLICON, SHGFI_LARGEICON
+    SmallFileIcon, LargeFileIcon,
+    // Larger icons obtainable via SHGetImageList()
+    ExtraLargeFileIcon,
+    JumboFileIcon, // Vista onwards
+    FileIconSizeCount
+};
+
 bool QWindowsTheme::usePlatformNativeDialog(DialogType type) const
 {
     return QWindowsDialogs::useHelper(type);
@@ -475,6 +477,27 @@ void QWindowsTheme::windowsThemeChanged(QWindow * window)
     QWindowSystemInterface::handleThemeChange(window);
 }
 
+static int fileIconSizes[FileIconSizeCount];
+
+void QWindowsTheme::refreshIconPixmapSizes()
+{
+    // Standard sizes: 16, 32, 48, 256
+    fileIconSizes[SmallFileIcon] = GetSystemMetrics(SM_CXSMICON); // corresponds to SHGFI_SMALLICON);
+    fileIconSizes[LargeFileIcon] = GetSystemMetrics(SM_CXICON); // corresponds to SHGFI_LARGEICON
+    fileIconSizes[ExtraLargeFileIcon] =
+        fileIconSizes[LargeFileIcon] + fileIconSizes[LargeFileIcon] / 2;
+    fileIconSizes[JumboFileIcon] = 8 * fileIconSizes[LargeFileIcon]; // empirical, has not been observed to work
+    QList<int> sizes;
+    sizes << fileIconSizes[SmallFileIcon] << fileIconSizes[LargeFileIcon];
+#ifdef USE_IIMAGELIST
+    sizes << fileIconSizes[ExtraLargeFileIcon]; // sHIL_EXTRALARGE
+    if (QSysInfo::WindowsVersion >= QSysInfo::WV_VISTA)
+        sizes << fileIconSizes[JumboFileIcon]; // SHIL_JUMBO
+#endif // USE_IIMAGELIST
+    qCDebug(lcQpaWindows) << __FUNCTION__ << sizes;
+    m_fileIconSizes = QVariant::fromValue(sizes);
+}
+
 // Defined in qpixmap_win.cpp
 Q_GUI_EXPORT QPixmap qt_pixmapFromWinHICON(HICON icon);
 
@@ -702,10 +725,12 @@ QPixmap QWindowsTheme::fileIconPixmap(const QFileInfo &fileInfo, const QSizeF &s
     QPixmap pixmap;
     const QString filePath = QDir::toNativeSeparators(fileInfo.filePath());
     const int width = int(size.width());
-    const int iconSize = width > 16 ? SHGFI_LARGEICON : SHGFI_SMALLICON;
+    const int iconSize = width > fileIconSizes[SmallFileIcon] ? SHGFI_LARGEICON : SHGFI_SMALLICON;
     const int requestedImageListSize =
 #ifdef USE_IIMAGELIST
-        width > 48 ? sHIL_JUMBO : (width > 32 ? sHIL_EXTRALARGE : 0);
+        width > fileIconSizes[ExtraLargeFileIcon]
+            ? sHIL_JUMBO
+            : (width > fileIconSizes[LargeFileIcon] ? sHIL_EXTRALARGE : 0);
 #else
         0;
 #endif // !USE_IIMAGELIST
diff --git a/src/plugins/platforms/windows/qwindowstheme.h b/src/plugins/platforms/windows/qwindowstheme.h
index acf89306c2..fa1fb4d998 100644
--- a/src/plugins/platforms/windows/qwindowstheme.h
+++ b/src/plugins/platforms/windows/qwindowstheme.h
@@ -43,6 +43,8 @@
 #include "qwindowsthreadpoolrunner.h"
 #include <qpa/qplatformtheme.h>
 
+#include <QtCore/QVariant>
+
 QT_BEGIN_NAMESPACE
 
 class QWindow;
@@ -68,6 +70,7 @@ public:
                            QPlatformTheme::IconOptions iconOptions = 0) const Q_DECL_OVERRIDE;
 
     void windowsThemeChanged(QWindow *window);
+    void displayChanged() { refreshIconPixmapSizes(); }
 
     static const char *name;
 
@@ -77,11 +80,13 @@ private:
     void refreshPalettes();
     void clearFonts();
     void refreshFonts();
+    void refreshIconPixmapSizes();
 
     static QWindowsTheme *m_instance;
     QPalette *m_palettes[NPalettes];
     QFont *m_fonts[NFonts];
     mutable QWindowsThreadPoolRunner m_threadPoolRunner;
+    QVariant m_fileIconSizes;
 };
 
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/windows/qwindowswindow.cpp b/src/plugins/platforms/windows/qwindowswindow.cpp
index e58058010d..29f0af4621 100644
--- a/src/plugins/platforms/windows/qwindowswindow.cpp
+++ b/src/plugins/platforms/windows/qwindowswindow.cpp
@@ -2395,9 +2395,10 @@ void QWindowsWindow::aboutToMakeCurrent()
 
 void QWindowsWindow::setHasBorderInFullScreenStatic(QWindow *window, bool border)
 {
-    if (!window->handle())
-        return;
-    static_cast<QWindowsWindow *>(window->handle())->setHasBorderInFullScreen(border);
+    if (QPlatformWindow *handle = window->handle())
+        static_cast<QWindowsWindow *>(handle)->setHasBorderInFullScreen(border);
+    else
+        qWarning("%s invoked without window handle; call has no effect.", Q_FUNC_INFO);
 }
 
 void QWindowsWindow::setHasBorderInFullScreen(bool border)
diff --git a/src/plugins/platforms/winrt/qwinrtclipboard.cpp b/src/plugins/platforms/winrt/qwinrtclipboard.cpp
index aee9fc617d..2811f1f018 100644
--- a/src/plugins/platforms/winrt/qwinrtclipboard.cpp
+++ b/src/plugins/platforms/winrt/qwinrtclipboard.cpp
@@ -102,7 +102,7 @@ QMimeData *QWinRTClipboard::mimeData(QClipboard::Mode mode)
     quint32 size;
     const wchar_t *textStr = result.GetRawBuffer(&size);
     QString text = QString::fromWCharArray(textStr, size);
-    text.replace(QStringLiteral("\r\n"), QStringLiteral("\n"));
+    text.replace(QLatin1String("\r\n"), QLatin1String("\n"));
     m_mimeData.setText(text);
 
     return &m_mimeData;
diff --git a/src/plugins/platforms/winrt/qwinrtdrag.cpp b/src/plugins/platforms/winrt/qwinrtdrag.cpp
index 2ef50aa4e2..055aacbf56 100644
--- a/src/plugins/platforms/winrt/qwinrtdrag.cpp
+++ b/src/plugins/platforms/winrt/qwinrtdrag.cpp
@@ -504,8 +504,8 @@ static HRESULT qt_drop(IInspectable *sender, ABI::Windows::UI::Xaml::IDragEventA
 class QtDragEventHandler##name : public IDragEventHandler \
 { \
 public: \
-    virtual HRESULT STDMETHODCALLTYPE Invoke(IInspectable *sender, \
-                            ABI::Windows::UI::Xaml::IDragEventArgs *e) \
+    STDMETHODIMP Invoke(IInspectable *sender, \
+                        ABI::Windows::UI::Xaml::IDragEventArgs *e) \
     { \
         return qt_##func(sender, e);\
     } \
diff --git a/src/plugins/platforms/xcb/qxcbconnection.cpp b/src/plugins/platforms/xcb/qxcbconnection.cpp
index 5d46c53b30..7065bb0ffb 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection.cpp
@@ -265,8 +265,8 @@ void QXcbConnection::updateScreens(const xcb_randr_notify_event_t *event)
                 } else {
                     screen = createScreen(virtualDesktop, output, outputInfo.data());
                     qCDebug(lcQpaScreen) << "output" << screen->name() << "is connected and enabled";
-                    QHighDpiScaling::updateHighDpiScaling();
                 }
+                QHighDpiScaling::updateHighDpiScaling();
             }
         } else if (screen) {
             if (output.crtc == XCB_NONE && output.mode == XCB_NONE) {
diff --git a/src/plugins/platforms/xcb/qxcbkeyboard.cpp b/src/plugins/platforms/xcb/qxcbkeyboard.cpp
index 7168e6e3bd..811ef4251a 100644
--- a/src/plugins/platforms/xcb/qxcbkeyboard.cpp
+++ b/src/plugins/platforms/xcb/qxcbkeyboard.cpp
@@ -979,10 +979,21 @@ QList<int> QXcbKeyboard::possibleKeys(const QKeyEvent *event) const
     xkb_layout_index_t lockedLayout = xkb_state_serialize_layout(xkb_state, XKB_STATE_LAYOUT_LOCKED);
     xkb_mod_mask_t latchedMods = xkb_state_serialize_mods(xkb_state, XKB_STATE_MODS_LATCHED);
     xkb_mod_mask_t lockedMods = xkb_state_serialize_mods(xkb_state, XKB_STATE_MODS_LOCKED);
+    xkb_mod_mask_t depressedMods = xkb_state_serialize_mods(xkb_state, XKB_STATE_MODS_DEPRESSED);
 
-    xkb_state_update_mask(kb_state, 0, latchedMods, lockedMods, 0, 0, lockedLayout);
-
+    xkb_state_update_mask(kb_state, depressedMods, latchedMods, lockedMods, 0, 0, lockedLayout);
     quint32 keycode = event->nativeScanCode();
+    // handle shortcuts for level three and above
+    xkb_layout_index_t layoutIndex = xkb_state_key_get_layout(kb_state, keycode);
+    xkb_level_index_t levelIndex = 0;
+    if (layoutIndex != XKB_LAYOUT_INVALID) {
+        levelIndex = xkb_state_key_get_level(kb_state, keycode, layoutIndex);
+        if (levelIndex == XKB_LEVEL_INVALID)
+            levelIndex = 0;
+    }
+    if (levelIndex <= 1)
+        xkb_state_update_mask(kb_state, 0, latchedMods, lockedMods, 0, 0, lockedLayout);
+
     xkb_keysym_t sym = xkb_state_key_get_one_sym(kb_state, keycode);
     if (sym == XKB_KEY_NoSymbol) {
         xkb_state_unref(kb_state);
diff --git a/src/plugins/platforms/xcb/qxcbmime.cpp b/src/plugins/platforms/xcb/qxcbmime.cpp
index 825a8acd1f..f7244739a5 100644
--- a/src/plugins/platforms/xcb/qxcbmime.cpp
+++ b/src/plugins/platforms/xcb/qxcbmime.cpp
@@ -131,6 +131,11 @@ bool QXcbMime::mimeDataForAtom(QXcbConnection *connection, xcb_atom_t a, QMimeDa
         ret = true;
     } else if ((a == XCB_ATOM_PIXMAP || a == XCB_ATOM_BITMAP) && mimeData->hasImage()) {
         ret = true;
+    } else if (atomName == QLatin1String("text/plain")
+               && mimeData->hasFormat(QLatin1String("text/uri-list"))) {
+        // Return URLs also as plain text.
+        *data = QInternalMimeData::renderDataHelper(atomName, mimeData);
+        ret = true;
     }
     return ret;
 }
@@ -149,8 +154,10 @@ QVector<xcb_atom_t> QXcbMime::mimeAtomsForFormat(QXcbConnection *connection, con
     }
 
     // special cases for uris
-    if (format == QLatin1String("text/uri-list"))
+    if (format == QLatin1String("text/uri-list")) {
         atoms.append(connection->internAtom("text/x-moz-url"));
+        atoms.append(connection->internAtom("text/plain"));
+    }
 
     //special cases for images
     if (format == QLatin1String("image/ppm"))
diff --git a/src/printsupport/kernel/qprintengine_win.cpp b/src/printsupport/kernel/qprintengine_win.cpp
index a57b72b13e..b3dc33895b 100644
--- a/src/printsupport/kernel/qprintengine_win.cpp
+++ b/src/printsupport/kernel/qprintengine_win.cpp
@@ -394,6 +394,9 @@ int QWin32PrintEngine::metric(QPaintDevice::PaintDeviceMetric m) const
     case QPaintDevice::PdmDevicePixelRatio:
         val = 1;
         break;
+    case QPaintDevice::PdmDevicePixelRatioScaled:
+        val = 1 * QPaintDevice::devicePixelRatioFScale();
+        break;
     default:
         qWarning("QPrinter::metric: Invalid metric command");
         return 0;
diff --git a/src/testlib/qtest.h b/src/testlib/qtest.h
index 49a0c2104b..63e79c777f 100644
--- a/src/testlib/qtest.h
+++ b/src/testlib/qtest.h
@@ -108,43 +108,63 @@ template<> inline char *toString(const QDateTime &dateTime)
 
 template<> inline char *toString(const QChar &c)
 {
+    const ushort uc = c.unicode();
+    if (uc < 128) {
+        char msg[32] = {'\0'};
+        qsnprintf(msg, sizeof(msg), "QChar: '%c' (0x%x)", char(uc), unsigned(uc));
+        return qstrdup(msg);
+    }
     return qstrdup(qPrintable(QString::fromLatin1("QChar: '%1' (0x%2)").arg(c).arg(QString::number(static_cast<int>(c.unicode()), 16))));
 }
 
 template<> inline char *toString(const QPoint &p)
 {
-    return qstrdup(QString::fromLatin1("QPoint(%1,%2)").arg(p.x()).arg(p.y()).toLatin1().constData());
+    char msg[128] = {'\0'};
+    qsnprintf(msg, sizeof(msg), "QPoint(%d,%d)", p.x(), p.y());
+    return qstrdup(msg);
 }
 
 template<> inline char *toString(const QSize &s)
 {
-    return qstrdup(QString::fromLatin1("QSize(%1x%2)").arg(s.width()).arg(s.height()).toLatin1().constData());
+    char msg[128] = {'\0'};
+    qsnprintf(msg, sizeof(msg), "QSize(%dx%d)", s.width(), s.height());
+    return qstrdup(msg);
 }
 
 template<> inline char *toString(const QRect &s)
 {
-    return qstrdup(QString::fromLatin1("QRect(%1,%2 %5x%6) (bottomright %3,%4)").arg(s.left()).arg(s.top()).arg(s.right()).arg(s.bottom()).arg(s.width()).arg(s.height()).toLatin1().constData());
+    char msg[256] = {'\0'};
+    qsnprintf(msg, sizeof(msg), "QRect(%d,%d %dx%d) (bottomright %d,%d)",
+              s.left(), s.top(), s.width(), s.height(), s.right(), s.bottom());
+    return qstrdup(msg);
 }
 
 template<> inline char *toString(const QPointF &p)
 {
-    return qstrdup(QString::fromLatin1("QPointF(%1,%2)").arg(p.x()).arg(p.y()).toLatin1().constData());
+    char msg[64] = {'\0'};
+    qsnprintf(msg, sizeof(msg), "QPointF(%g,%g)", p.x(), p.y());
+    return qstrdup(msg);
 }
 
 template<> inline char *toString(const QSizeF &s)
 {
-    return qstrdup(QString::fromLatin1("QSizeF(%1x%2)").arg(s.width()).arg(s.height()).toLatin1().constData());
+    char msg[64] = {'\0'};
+    qsnprintf(msg, sizeof(msg), "QSizeF(%gx%g)", s.width(), s.height());
+    return qstrdup(msg);
 }
 
 template<> inline char *toString(const QRectF &s)
 {
-    return qstrdup(QString::fromLatin1("QRectF(%1,%2 %5x%6) (bottomright %3,%4)").arg(s.left()).arg(s.top()).arg(s.right()).arg(s.bottom()).arg(s.width()).arg(s.height()).toLatin1().constData());
+    char msg[256] = {'\0'};
+    qsnprintf(msg, sizeof(msg), "QRectF(%g,%g %gx%g) (bottomright %g,%g)",
+              s.left(), s.top(), s.width(), s.height(), s.right(), s.bottom());
+    return qstrdup(msg);
 }
 
 template<> inline char *toString(const QUrl &uri)
 {
     if (!uri.isValid())
-        return qstrdup(qPrintable(QStringLiteral("Invalid URL: ") + uri.errorString()));
+        return qstrdup(qPrintable(QLatin1String("Invalid URL: ") + uri.errorString()));
     return qstrdup(uri.toEncoded().constData());
 }
 
diff --git a/src/testlib/qtest_gui.h b/src/testlib/qtest_gui.h
index 5027aea732..d0d56e7bd0 100644
--- a/src/testlib/qtest_gui.h
+++ b/src/testlib/qtest_gui.h
@@ -58,6 +58,7 @@
 #include <QtGui/qcolor.h>
 #include <QtGui/qpixmap.h>
 #include <QtGui/qimage.h>
+#include <QtGui/qregion.h>
 
 #ifdef QT_WIDGETS_LIB
 #include <QtGui/qicon.h>
@@ -82,6 +83,39 @@ template<> inline char *toString(const QColor &color)
     return qstrdup(color.name().toLocal8Bit().constData());
 }
 
+template<> inline char *toString(const QRegion &region)
+{
+    QByteArray result = "QRegion(";
+    if (region.isNull()) {
+        result += "null";
+    } else if (region.isEmpty()) {
+        result += "empty";
+    } else {
+        const QVector<QRect> &rects = region.rects();
+        const int rectCount = rects.size();
+        if (rectCount > 1) {
+            result += QByteArray::number(rectCount);
+            result += " rectangles, ";
+        }
+        for (int i = 0; i < rectCount; ++i) {
+            if (i)
+                result += ", ";
+            const QRect &r = rects.at(i);
+            result += QByteArray::number(r.width());
+            result += 'x';
+            result += QByteArray::number(r.height());
+            if (r.x() >= 0)
+                result += '+';
+            result += QByteArray::number(r.x());
+            if (r.y() >= 0)
+                result += '+';
+            result += QByteArray::number(r.y());
+        }
+    }
+    result += ')';
+    return qstrdup(result.constData());
+}
+
 inline bool qCompare(QIcon const &t1, QIcon const &t2, const char *actual, const char *expected,
                     const char *file, int line)
 {
diff --git a/src/testlib/qtestcase.cpp b/src/testlib/qtestcase.cpp
index b6c70fdd86..cfa7d1b8ca 100644
--- a/src/testlib/qtestcase.cpp
+++ b/src/testlib/qtestcase.cpp
@@ -958,7 +958,7 @@ bool TestMethods::invokeTest(int index, const char *data, WatchDog *watchDog) co
     QBenchmarkTestMethodData::current = &benchmarkData;
 
     const QByteArray &name = m_methods[index].name();
-    QBenchmarkGlobalData::current->context.slotName = QLatin1String(name) + QStringLiteral("()");
+    QBenchmarkGlobalData::current->context.slotName = QLatin1String(name) + QLatin1String("()");
 
     char member[512];
     QTestTable table;
diff --git a/src/tools/moc/preprocessor.cpp b/src/tools/moc/preprocessor.cpp
index b9359ff3f4..415003e6b1 100644
--- a/src/tools/moc/preprocessor.cpp
+++ b/src/tools/moc/preprocessor.cpp
@@ -188,7 +188,8 @@ Symbols Preprocessor::tokenize(const QByteArray& input, int lineNum, Preprocesso
                 token = keywords[state].ident;
 
             if (token == NOTOKEN) {
-                ++data;
+                if (*data)
+                    ++data;
                 // an error really, but let's ignore this input
                 // to not confuse moc later. However in pre-processor
                 // only mode let's continue.
@@ -362,7 +363,6 @@ Symbols Preprocessor::tokenize(const QByteArray& input, int lineNum, Preprocesso
                     ++data;
                     continue;
                 }
-
                 int nextindex = pp_keywords[state].next;
                 int next = 0;
                 if (*data == pp_keywords[state].defchar)
@@ -381,7 +381,8 @@ Symbols Preprocessor::tokenize(const QByteArray& input, int lineNum, Preprocesso
 
             switch (token) {
             case NOTOKEN:
-                ++data;
+                if (*data)
+                    ++data;
                 break;
             case PP_DEFINE:
                 mode = PrepareDefine;
@@ -1260,7 +1261,6 @@ void Preprocessor::parseDefineArguments(Macro *m)
                     error("missing ')' in macro argument list");
                 break;
             } else if (!is_identifier(l.constData(), l.length())) {
-                qDebug() << l;
                 error("Unexpected character in macro argument list.");
             }
         }
diff --git a/src/tools/uic/cpp/cppwriteincludes.cpp b/src/tools/uic/cpp/cppwriteincludes.cpp
index e93e6bb26c..a99d6adf07 100644
--- a/src/tools/uic/cpp/cppwriteincludes.cpp
+++ b/src/tools/uic/cpp/cppwriteincludes.cpp
@@ -291,9 +291,8 @@ void WriteIncludes::writeHeaders(const OrderedSet &headers, bool global)
         const StringMap::const_iterator hit = m_oldHeaderToNewHeader.constFind(sit.key());
         const bool mapped =  hit != m_oldHeaderToNewHeader.constEnd();
         const  QString header =  mapped ? hit.value() : sit.key();
-        if (!header.trimmed().isEmpty()) {
+        if (!QStringRef(&header).trimmed().isEmpty())
             m_output << "#include " << openingQuote << header << closingQuote << QLatin1Char('\n');
-        }
     }
 }
 
diff --git a/src/tools/uic/cpp/cppwriteinitialization.cpp b/src/tools/uic/cpp/cppwriteinitialization.cpp
index 8c8141f9e5..ade3c5db35 100644
--- a/src/tools/uic/cpp/cppwriteinitialization.cpp
+++ b/src/tools/uic/cpp/cppwriteinitialization.cpp
@@ -1255,14 +1255,14 @@ void WriteInitialization::writeProperties(const QString &varName,
         QString setFunction;
 
         if (stdset) {
-            setFunction = QLatin1String("->set");
-            setFunction += propertyName.left(1).toUpper();
-            setFunction += propertyName.mid(1);
-            setFunction += QLatin1Char('(');
+            setFunction = QLatin1String("->set")
+                        + propertyName.left(1).toUpper()
+                        + propertyName.midRef(1)
+                        + QLatin1Char('(');
         } else {
-            setFunction = QLatin1String("->setProperty(\"");
-            setFunction += propertyName;
-            setFunction += QLatin1String("\", QVariant");
+            setFunction += QLatin1String("->setProperty(\"")
+                         + propertyName
+                         + QLatin1String("\", QVariant");
             if (p->kind() == DomProperty::Enum)
                 setFunction += QLatin1String("::fromValue");
             setFunction += QLatin1Char('(');
@@ -1286,9 +1286,9 @@ void WriteInitialization::writeProperties(const QString &varName,
                 if (stdset)
                     propertyValue = fixString(p->elementCstring(), m_dindent);
                 else {
-                    propertyValue = QLatin1String("QByteArray(");
-                    propertyValue += fixString(p->elementCstring(), m_dindent);
-                    propertyValue += QLatin1Char(')');
+                    propertyValue = QLatin1String("QByteArray(")
+                                  + fixString(p->elementCstring(), m_dindent)
+                                  + QLatin1Char(')');
                 }
             }
             break;
@@ -1304,11 +1304,8 @@ void WriteInitialization::writeProperties(const QString &varName,
             break;
         case DomProperty::Enum:
             propertyValue = p->elementEnum();
-            if (!propertyValue.contains(QLatin1String("::"))) {
-                QString scope  = className;
-                scope += QLatin1String("::");
-                propertyValue.prepend(scope);
-            }
+            if (!propertyValue.contains(QLatin1String("::")))
+                propertyValue = className + QLatin1String("::") + propertyValue;
             break;
         case DomProperty::Set:
             propertyValue = p->elementSet();
@@ -1898,31 +1895,29 @@ QString WriteInitialization::pixCall(const QString &t, const QString &text) cons
         if (m_option.extractImages) {
             const QString format = image->elementData()->attributeFormat();
             const QString extension = format.left(format.indexOf(QLatin1Char('.'))).toLower();
-            QString rc = QLatin1String("QPixmap(QString::fromUtf8(\":/");
-            rc += m_generatedClass;
-            rc += QLatin1String("/images/");
-            rc += text;
-            rc += QLatin1Char('.');
-            rc += extension;
-            rc += QLatin1String("\"))");
-            return rc;
-        }
-        QString rc = WriteIconInitialization::iconFromDataFunction();
-        rc += QLatin1Char('(');
-        rc += text;
-        rc += QLatin1String("_ID)");
-        return rc;
+            return QLatin1String("QPixmap(QString::fromUtf8(\":/")
+                 + m_generatedClass
+                 + QLatin1String("/images/")
+                 + text
+                 + QLatin1Char('.')
+                 + extension
+                 + QLatin1String("\"))");
+        }
+        return WriteIconInitialization::iconFromDataFunction()
+             + QLatin1Char('(')
+             + text
+             + QLatin1String("_ID)");
     }
 
     QString pixFunc = m_uic->pixmapFunction();
     if (pixFunc.isEmpty())
         pixFunc = QLatin1String("QString::fromUtf8");
 
-    type += QLatin1Char('(');
-    type += pixFunc;
-    type += QLatin1Char('(');
-    type += fixString(text, m_dindent);
-    type += QLatin1String("))");
+    type += QLatin1Char('(')
+          + pixFunc
+          + QLatin1Char('(')
+          + fixString(text, m_dindent)
+          + QLatin1String("))");
     return type;
 }
 
@@ -2316,23 +2311,20 @@ QString WriteInitialization::trCall(const QString &str, const QString &commentHi
 
     if (m_option.translateFunction.isEmpty()) {
         if (m_option.idBased) {
-            result = QLatin1String("qtTrId(");
+            result += QLatin1String("qtTrId(");
         } else {
-            result = QLatin1String("QApplication::translate(\"");
-            result += m_generatedClass;
-            result += QLatin1Char('"');
-            result += QLatin1String(", ");
+            result += QLatin1String("QApplication::translate(\"")
+                    + m_generatedClass
+                    + QLatin1String("\", ");
         }
     } else {
-        result = m_option.translateFunction;
-        result += QLatin1Char('(');
+        result += m_option.translateFunction + QLatin1Char('(');
     }
 
     result += fixString(str, m_dindent);
 
     if (!m_option.idBased) {
-        result += QLatin1String(", ");
-        result += comment;
+        result += QLatin1String(", ") + comment;
     }
 
     result += QLatin1Char(')');
@@ -2473,10 +2465,8 @@ void WriteInitialization::acceptWidgetScripts(const DomScripts &widgetScripts, D
     QString script;
     for (const DomScript *domScript : qAsConst(scripts)) {
         const QString snippet = domScript->text();
-        if (!snippet.isEmpty()) {
-            script += snippet.trimmed();
-            script += QLatin1Char('\n');
-        }
+        if (!snippet.isEmpty())
+            script += QStringRef(&snippet).trimmed() + QLatin1Char('\n');
     }
     if (script.isEmpty())
         return;
diff --git a/src/widgets/accessible/qaccessiblewidgets.cpp b/src/widgets/accessible/qaccessiblewidgets.cpp
index 2f57fa08ee..95888924fb 100644
--- a/src/widgets/accessible/qaccessiblewidgets.cpp
+++ b/src/widgets/accessible/qaccessiblewidgets.cpp
@@ -824,12 +824,12 @@ QString QAccessibleTextWidget::attributes(int offset, int *startOffset, int *end
     AttributeFormatter attrs;
     QString family = charFormatFont.family();
     if (!family.isEmpty()) {
-        family = family.replace('\\',QStringLiteral("\\\\"));
-        family = family.replace(':',QStringLiteral("\\:"));
-        family = family.replace(',',QStringLiteral("\\,"));
-        family = family.replace('=',QStringLiteral("\\="));
-        family = family.replace(';',QStringLiteral("\\;"));
-        family = family.replace('\"',QStringLiteral("\\\""));
+        family = family.replace('\\', QLatin1String("\\\\"));
+        family = family.replace(':', QLatin1String("\\:"));
+        family = family.replace(',', QLatin1String("\\,"));
+        family = family.replace('=', QLatin1String("\\="));
+        family = family.replace(';', QLatin1String("\\;"));
+        family = family.replace('\"', QLatin1String("\\\""));
         attrs["font-family"] = QString::fromLatin1("\"%1\"").arg(family);
     }
 
diff --git a/src/widgets/dialogs/qfilesystemmodel.cpp b/src/widgets/dialogs/qfilesystemmodel.cpp
index 5424a4126a..11b3659990 100644
--- a/src/widgets/dialogs/qfilesystemmodel.cpp
+++ b/src/widgets/dialogs/qfilesystemmodel.cpp
@@ -87,7 +87,7 @@ QT_BEGIN_NAMESPACE
     about the underlying files and directories related to items in the model.
     Directories can be created and removed using mkdir(), rmdir().
 
-    \note QFileSystemModel requires an instance of a GUI application.
+    \note QFileSystemModel requires an instance of \l QApplication.
 
     \section1 Example Usage
 
diff --git a/src/widgets/graphicsview/qgraphicsanchorlayout_p.cpp b/src/widgets/graphicsview/qgraphicsanchorlayout_p.cpp
index 53db11d2d7..4c01219d87 100644
--- a/src/widgets/graphicsview/qgraphicsanchorlayout_p.cpp
+++ b/src/widgets/graphicsview/qgraphicsanchorlayout_p.cpp
@@ -1082,7 +1082,7 @@ bool QGraphicsAnchorLayoutPrivate::simplifyGraphIteration(QGraphicsAnchorLayoutP
             if (candidates.isEmpty())
                 after = (beforeSequence == adjacents.last() ? adjacents.first() : adjacents.last());
             else
-                after = (candidates.last() == adjacents.last() ? adjacents.first() : adjacents.last());
+                after = (candidates.constLast() == adjacents.last() ? adjacents.first() : adjacents.last());
 
             // ### At this point we assumed that candidates will not contain 'after', this may not hold
             // when simplifying FLOATing anchors.
@@ -1134,9 +1134,9 @@ bool QGraphicsAnchorLayoutPrivate::simplifyGraphIteration(QGraphicsAnchorLayoutP
 
         // One restriction we have is to not simplify half of an anchor and let the other half
         // unsimplified. So we remove center edges before and after the sequence.
-        const AnchorData *firstAnchor = g.edgeData(beforeSequence, candidates.first());
+        const AnchorData *firstAnchor = g.edgeData(beforeSequence, candidates.constFirst());
         if (firstAnchor->isCenterAnchor) {
-            beforeSequence = candidates.first();
+            beforeSequence = candidates.constFirst();
             candidates.remove(0);
 
             // If there's not candidates to be simplified, leave.
@@ -1144,9 +1144,9 @@ bool QGraphicsAnchorLayoutPrivate::simplifyGraphIteration(QGraphicsAnchorLayoutP
                 continue;
         }
 
-        const AnchorData *lastAnchor = g.edgeData(candidates.last(), afterSequence);
+        const AnchorData *lastAnchor = g.edgeData(candidates.constLast(), afterSequence);
         if (lastAnchor->isCenterAnchor) {
-            afterSequence = candidates.last();
+            afterSequence = candidates.constLast();
             candidates.remove(candidates.count() - 1);
 
             if (candidates.isEmpty())
diff --git a/src/widgets/graphicsview/qgraphicsitem.cpp b/src/widgets/graphicsview/qgraphicsitem.cpp
index b00a950823..4b5e380f4b 100644
--- a/src/widgets/graphicsview/qgraphicsitem.cpp
+++ b/src/widgets/graphicsview/qgraphicsitem.cpp
@@ -2151,7 +2151,7 @@ bool QGraphicsItem::isBlockedByModalPanel(QGraphicsItem **blockingPanel) const
     if (!blockingPanel)
         blockingPanel = &dummy;
 
-    QGraphicsScenePrivate *scene_d = d_ptr->scene->d_func();
+    const QGraphicsScenePrivate *scene_d = d_ptr->scene->d_func();
     if (scene_d->modalPanels.isEmpty())
         return false;
 
diff --git a/src/widgets/graphicsview/qgraphicsscene.cpp b/src/widgets/graphicsview/qgraphicsscene.cpp
index da5c2849ae..aa781e8f8b 100644
--- a/src/widgets/graphicsview/qgraphicsscene.cpp
+++ b/src/widgets/graphicsview/qgraphicsscene.cpp
@@ -940,7 +940,7 @@ void QGraphicsScenePrivate::grabMouse(QGraphicsItem *item, bool implicit)
 {
     // Append to list of mouse grabber items, and send a mouse grab event.
     if (mouseGrabberItems.contains(item)) {
-        if (mouseGrabberItems.last() == item) {
+        if (mouseGrabberItems.constLast() == item) {
             Q_ASSERT(!implicit);
             if (!lastMouseGrabberItemHasImplicitMouseGrab) {
                 qWarning("QGraphicsItem::grabMouse: already a mouse grabber");
@@ -950,14 +950,14 @@ void QGraphicsScenePrivate::grabMouse(QGraphicsItem *item, bool implicit)
             }
         } else {
             qWarning("QGraphicsItem::grabMouse: already blocked by mouse grabber: %p",
-                     mouseGrabberItems.last());
+                     mouseGrabberItems.constLast());
         }
         return;
     }
 
     // Send ungrab event to the last grabber.
     if (!mouseGrabberItems.isEmpty()) {
-        QGraphicsItem *last = mouseGrabberItems.last();
+        QGraphicsItem *last = mouseGrabberItems.constLast();
         if (lastMouseGrabberItemHasImplicitMouseGrab) {
             // Implicit mouse grab is immediately lost.
             last->ungrabMouse();
@@ -987,12 +987,12 @@ void QGraphicsScenePrivate::ungrabMouse(QGraphicsItem *item, bool itemIsDying)
         return;
     }
 
-    if (item != mouseGrabberItems.last()) {
+    if (item != mouseGrabberItems.constLast()) {
         // Recursively ungrab the next mouse grabber until we reach this item
         // to ensure state consistency.
         ungrabMouse(mouseGrabberItems.at(index + 1), itemIsDying);
     }
-    if (!popupWidgets.isEmpty() && item == popupWidgets.last()) {
+    if (!popupWidgets.isEmpty() && item == popupWidgets.constLast()) {
         // If the item is a popup, go via removePopup to ensure state
         // consistency and that it gets hidden correctly - beware that
         // removePopup() reenters this function to continue removing the grab.
@@ -1017,7 +1017,7 @@ void QGraphicsScenePrivate::ungrabMouse(QGraphicsItem *item, bool itemIsDying)
     // items get a GrabMouse event, but this is a rare case with a simple
     // implementation and it does ensure a consistent state.
     if (!itemIsDying && !mouseGrabberItems.isEmpty()) {
-        QGraphicsItem *last = mouseGrabberItems.last();
+        QGraphicsItem *last = mouseGrabberItems.constLast();
         QEvent event(QEvent::GrabMouse);
         sendEvent(last, &event);
     }
@@ -1039,11 +1039,11 @@ void QGraphicsScenePrivate::clearMouseGrabber()
 void QGraphicsScenePrivate::grabKeyboard(QGraphicsItem *item)
 {
     if (keyboardGrabberItems.contains(item)) {
-        if (keyboardGrabberItems.last() == item)
+        if (keyboardGrabberItems.constLast() == item)
             qWarning("QGraphicsItem::grabKeyboard: already a keyboard grabber");
         else
             qWarning("QGraphicsItem::grabKeyboard: already blocked by keyboard grabber: %p",
-                     keyboardGrabberItems.last());
+                     keyboardGrabberItems.constLast());
         return;
     }
 
@@ -1051,7 +1051,7 @@ void QGraphicsScenePrivate::grabKeyboard(QGraphicsItem *item)
     if (!keyboardGrabberItems.isEmpty()) {
         // Just send ungrab event to current grabber.
         QEvent ungrabEvent(QEvent::UngrabKeyboard);
-        sendEvent(keyboardGrabberItems.last(), &ungrabEvent);
+        sendEvent(keyboardGrabberItems.constLast(), &ungrabEvent);
     }
 
     keyboardGrabberItems << item;
@@ -1071,7 +1071,7 @@ void QGraphicsScenePrivate::ungrabKeyboard(QGraphicsItem *item, bool itemIsDying
         qWarning("QGraphicsItem::ungrabKeyboard: not a keyboard grabber");
         return;
     }
-    if (item != keyboardGrabberItems.last()) {
+    if (item != keyboardGrabberItems.constLast()) {
         // Recursively ungrab the topmost keyboard grabber until we reach this
         // item to ensure state consistency.
         ungrabKeyboard(keyboardGrabberItems.at(index + 1), itemIsDying);
@@ -1088,7 +1088,7 @@ void QGraphicsScenePrivate::ungrabKeyboard(QGraphicsItem *item, bool itemIsDying
 
     // Send notification about mouse regrab.
     if (!itemIsDying && !keyboardGrabberItems.isEmpty()) {
-        QGraphicsItem *last = keyboardGrabberItems.last();
+        QGraphicsItem *last = keyboardGrabberItems.constLast();
         QEvent event(QEvent::GrabKeyboard);
         sendEvent(last, &event);
     }
@@ -1100,7 +1100,7 @@ void QGraphicsScenePrivate::ungrabKeyboard(QGraphicsItem *item, bool itemIsDying
 void QGraphicsScenePrivate::clearKeyboardGrabber()
 {
     if (!keyboardGrabberItems.isEmpty())
-        ungrabKeyboard(keyboardGrabberItems.first());
+        ungrabKeyboard(keyboardGrabberItems.constFirst());
 }
 
 void QGraphicsScenePrivate::enableMouseTrackingOnViews()
@@ -1142,8 +1142,8 @@ void QGraphicsScenePrivate::storeMouseButtonsForMouseGrabber(QGraphicsSceneMouse
     for (int i = 0x1; i <= 0x10; i <<= 1) {
         if (event->buttons() & i) {
             mouseGrabberButtonDownPos.insert(Qt::MouseButton(i),
-                                             mouseGrabberItems.last()->d_ptr->genericMapFromScene(event->scenePos(),
-                                                                                                  event->widget()));
+                                             mouseGrabberItems.constLast()->d_ptr->genericMapFromScene(event->scenePos(),
+                                                                                                       event->widget()));
             mouseGrabberButtonDownScenePos.insert(Qt::MouseButton(i), event->scenePos());
             mouseGrabberButtonDownScreenPos.insert(Qt::MouseButton(i), event->screenPos());
         }
@@ -1308,7 +1308,7 @@ void QGraphicsScenePrivate::sendMouseEvent(QGraphicsSceneMouseEvent *mouseEvent)
         return;
     }
 
-    QGraphicsItem *item = mouseGrabberItems.last();
+    QGraphicsItem *item = mouseGrabberItems.constLast();
     if (item->isBlockedByModalPanel())
         return;
 
@@ -1335,7 +1335,7 @@ void QGraphicsScenePrivate::mousePressEventHandler(QGraphicsSceneMouseEvent *mou
 
     // Deliver to any existing mouse grabber.
     if (!mouseGrabberItems.isEmpty()) {
-        if (mouseGrabberItems.last()->isBlockedByModalPanel())
+        if (mouseGrabberItems.constLast()->isBlockedByModalPanel())
             return;
         // The event is ignored by default, but we disregard the event's
         // accepted state after delivery; the mouse is grabbed, after all.
@@ -1401,7 +1401,7 @@ void QGraphicsScenePrivate::mousePressEventHandler(QGraphicsSceneMouseEvent *mou
 
     // Any item will do.
     if (sceneModality && cachedItemsUnderMouse.isEmpty())
-        cachedItemsUnderMouse << modalPanels.first();
+        cachedItemsUnderMouse << modalPanels.constFirst();
 
     // Find a mouse grabber by sending mouse press events to all mouse grabber
     // candidates one at a time, until the event is accepted. It's accepted by
@@ -1450,7 +1450,7 @@ void QGraphicsScenePrivate::mousePressEventHandler(QGraphicsSceneMouseEvent *mou
             sendMouseEvent(mouseEvent);
         }
 
-        bool dontSendUngrabEvents = mouseGrabberItems.isEmpty() || mouseGrabberItems.last() != item;
+        bool dontSendUngrabEvents = mouseGrabberItems.isEmpty() || mouseGrabberItems.constLast() != item;
         if (disabled) {
             ungrabMouse(item, /* itemIsDying = */ dontSendUngrabEvents);
             break;
@@ -2167,8 +2167,8 @@ QList<QGraphicsItem *> QGraphicsScene::collidingItems(const QGraphicsItem *item,
 */
 QGraphicsItem *QGraphicsScene::itemAt(const QPointF &position, const QTransform &deviceTransform) const
 {
-    QList<QGraphicsItem *> itemsAtPoint = items(position, Qt::IntersectsItemShape,
-                                                Qt::DescendingOrder, deviceTransform);
+    const QList<QGraphicsItem *> itemsAtPoint = items(position, Qt::IntersectsItemShape,
+                                                      Qt::DescendingOrder, deviceTransform);
     return itemsAtPoint.isEmpty() ? 0 : itemsAtPoint.first();
 }
 
@@ -3771,7 +3771,7 @@ void QGraphicsScene::focusOutEvent(QFocusEvent *focusEvent)
 
     // Remove all popups when the scene loses focus.
     if (!d->popupWidgets.isEmpty())
-        d->removePopup(d->popupWidgets.first());
+        d->removePopup(d->popupWidgets.constFirst());
 }
 
 /*!
@@ -3868,7 +3868,7 @@ bool QGraphicsScenePrivate::dispatchHoverEvent(QGraphicsSceneHoverEvent *hoverEv
 
     // Find the common ancestor item for the new topmost hoverItem and the
     // last item in the hoverItem list.
-    QGraphicsItem *commonAncestorItem = (item && !hoverItems.isEmpty()) ? item->commonAncestorItem(hoverItems.last()) : 0;
+    QGraphicsItem *commonAncestorItem = (item && !hoverItems.isEmpty()) ? item->commonAncestorItem(hoverItems.constLast()) : 0;
     while (commonAncestorItem && !itemAcceptsHoverEvents_helper(commonAncestorItem))
         commonAncestorItem = commonAncestorItem->parentItem();
     if (commonAncestorItem && commonAncestorItem->panel() != item->panel()) {
@@ -3909,7 +3909,7 @@ bool QGraphicsScenePrivate::dispatchHoverEvent(QGraphicsSceneHoverEvent *hoverEv
     // Generate a move event for the item itself
     if (item
         && !hoverItems.isEmpty()
-        && item == hoverItems.last()) {
+        && item == hoverItems.constLast()) {
         sendHoverEvent(QEvent::GraphicsSceneHoverMove, item, hoverEvent);
         return true;
     }
@@ -3959,7 +3959,7 @@ void QGraphicsScene::keyPressEvent(QKeyEvent *keyEvent)
     // ### Merge this function with keyReleaseEvent; they are identical
     // ### (except this comment).
     Q_D(QGraphicsScene);
-    QGraphicsItem *item = !d->keyboardGrabberItems.isEmpty() ? d->keyboardGrabberItems.last() : 0;
+    QGraphicsItem *item = !d->keyboardGrabberItems.isEmpty() ? d->keyboardGrabberItems.constLast() : 0;
     if (!item)
         item = focusItem();
     if (item) {
@@ -3991,7 +3991,7 @@ void QGraphicsScene::keyReleaseEvent(QKeyEvent *keyEvent)
     // ### Merge this function with keyPressEvent; they are identical (except
     // ### this comment).
     Q_D(QGraphicsScene);
-    QGraphicsItem *item = !d->keyboardGrabberItems.isEmpty() ? d->keyboardGrabberItems.last() : 0;
+    QGraphicsItem *item = !d->keyboardGrabberItems.isEmpty() ? d->keyboardGrabberItems.constLast() : 0;
     if (!item)
         item = focusItem();
     if (item) {
@@ -4100,9 +4100,9 @@ void QGraphicsScene::mouseReleaseEvent(QGraphicsSceneMouseEvent *mouseEvent)
     // Reset the mouse grabber when the last mouse button has been released.
     if (!mouseEvent->buttons()) {
         if (!d->mouseGrabberItems.isEmpty()) {
-            d->lastMouseGrabberItem = d->mouseGrabberItems.last();
+            d->lastMouseGrabberItem = d->mouseGrabberItems.constLast();
             if (d->lastMouseGrabberItemHasImplicitMouseGrab)
-                d->mouseGrabberItems.last()->ungrabMouse();
+                d->mouseGrabberItems.constLast()->ungrabMouse();
         } else {
             d->lastMouseGrabberItem = 0;
         }
@@ -5902,7 +5902,7 @@ void QGraphicsScenePrivate::touchEventHandler(QTouchEvent *sceneTouchEvent)
                 cachedItemsUnderMouse = itemsAtPosition(touchPoint.screenPos().toPoint(),
                                                         touchPoint.scenePos(),
                                                         static_cast<QWidget *>(sceneTouchEvent->target()));
-                item = cachedItemsUnderMouse.isEmpty() ? 0 : cachedItemsUnderMouse.first();
+                item = cachedItemsUnderMouse.isEmpty() ? 0 : cachedItemsUnderMouse.constFirst();
             }
 
             if (sceneTouchEvent->device()->type() == QTouchDevice::TouchScreen) {
@@ -6013,7 +6013,7 @@ bool QGraphicsScenePrivate::sendTouchBeginEvent(QGraphicsItem *origin, QTouchEve
 {
     Q_Q(QGraphicsScene);
 
-    if (cachedItemsUnderMouse.isEmpty() || cachedItemsUnderMouse.first() != origin) {
+    if (cachedItemsUnderMouse.isEmpty() || cachedItemsUnderMouse.constFirst() != origin) {
         const QTouchEvent::TouchPoint &firstTouchPoint = touchEvent->touchPoints().first();
         cachedItemsUnderMouse = itemsAtPosition(firstTouchPoint.screenPos().toPoint(),
                                                 firstTouchPoint.scenePos(),
@@ -6129,7 +6129,7 @@ void QGraphicsScenePrivate::enterModal(QGraphicsItem *panel, QGraphicsItem::Pane
     }
 
     if (!mouseGrabberItems.isEmpty() && lastMouseGrabberItemHasImplicitMouseGrab) {
-        QGraphicsItem *item = mouseGrabberItems.last();
+        QGraphicsItem *item = mouseGrabberItems.constLast();
         if (item->isBlockedByModalPanel())
             ungrabMouse(item, /*itemIsDying =*/ false);
     }
diff --git a/src/widgets/graphicsview/qgraphicsview.cpp b/src/widgets/graphicsview/qgraphicsview.cpp
index 44e80ebeb9..3f7d2d1cd1 100644
--- a/src/widgets/graphicsview/qgraphicsview.cpp
+++ b/src/widgets/graphicsview/qgraphicsview.cpp
@@ -2375,7 +2375,7 @@ QGraphicsItem *QGraphicsView::itemAt(const QPoint &pos) const
     Q_D(const QGraphicsView);
     if (!d->scene)
         return 0;
-    QList<QGraphicsItem *> itemsAtPos = items(pos);
+    const QList<QGraphicsItem *> itemsAtPos = items(pos);
     return itemsAtPos.isEmpty() ? 0 : itemsAtPos.first();
 }
 
@@ -2860,7 +2860,7 @@ bool QGraphicsView::viewportEvent(QEvent *event)
         // the mouse grab.
         // Remove all popups when the scene loses focus.
         if (!d->scene->d_func()->popupWidgets.isEmpty())
-            d->scene->d_func()->removePopup(d->scene->d_func()->popupWidgets.first());
+            d->scene->d_func()->removePopup(d->scene->d_func()->popupWidgets.constFirst());
         QApplication::sendEvent(d->scene, event);
         break;
     case QEvent::Show:
@@ -2884,7 +2884,7 @@ bool QGraphicsView::viewportEvent(QEvent *event)
             || (QApplication::activeModalWidget() && QApplication::activeModalWidget() != window())
             || (QApplication::activeWindow() != window())) {
             if (!d->scene->d_func()->popupWidgets.isEmpty())
-                d->scene->d_func()->removePopup(d->scene->d_func()->popupWidgets.first());
+                d->scene->d_func()->removePopup(d->scene->d_func()->popupWidgets.constFirst());
         }
         d->useLastMouseEvent = false;
         // a hack to pass a viewport pointer to the scene inside the leave event
diff --git a/src/widgets/itemviews/qcolumnview.cpp b/src/widgets/itemviews/qcolumnview.cpp
index 26173b5e92..6c7c914bc0 100644
--- a/src/widgets/itemviews/qcolumnview.cpp
+++ b/src/widgets/itemviews/qcolumnview.cpp
@@ -412,9 +412,9 @@ void QColumnViewPrivate::updateScrollbars()
     // find the total horizontal length of the laid out columns
     int horizontalLength = 0;
     if (!columns.isEmpty()) {
-        horizontalLength = (columns.last()->x() + columns.last()->width()) - columns.first()->x();
+        horizontalLength = (columns.constLast()->x() + columns.constLast()->width()) - columns.constFirst()->x();
         if (horizontalLength <= 0) // reverse mode
-            horizontalLength = (columns.first()->x() + columns.first()->width()) - columns.last()->x();
+            horizontalLength = (columns.constFirst()->x() + columns.constFirst()->width()) - columns.constLast()->x();
     }
 
     QSize viewportSize = viewport->size();
@@ -629,7 +629,7 @@ void QColumnViewPrivate::closeColumns(const QModelIndex &parent, bool build)
     while (!dirsToAppend.isEmpty()) {
         QAbstractItemView *newView = createColumn(dirsToAppend.takeLast(), true);
         if (!dirsToAppend.isEmpty())
-            newView->setCurrentIndex(dirsToAppend.last());
+            newView->setCurrentIndex(dirsToAppend.constLast());
     }
 
     if (build && !alreadyExists)
@@ -713,8 +713,8 @@ QAbstractItemView *QColumnViewPrivate::createColumn(const QModelIndex &index, bo
         columnSizes.resize(qMax(columnSizes.count(), columns.count() + 1));
         columnSizes[columns.count()] = initialWidth;
     }
-    if (!columns.isEmpty() && columns.last()->isHidden())
-        columns.last()->setVisible(true);
+    if (!columns.isEmpty() && columns.constLast()->isHidden())
+        columns.constLast()->setVisible(true);
 
     columns.append(view);
     doLayout();
@@ -835,7 +835,7 @@ void QColumnViewPrivate::setPreviewWidget(QWidget *widget)
 {
     Q_Q(QColumnView);
     if (previewColumn) {
-        if (!columns.isEmpty() && columns.last() == previewColumn)
+        if (!columns.isEmpty() && columns.constLast() == previewColumn)
             columns.removeLast();
         previewColumn->deleteLater();
     }
@@ -1003,11 +1003,11 @@ void QColumnViewPrivate::_q_changeCurrentColumn()
             parentColumn->setCurrentIndex(current.parent());
     }
 
-    if (columns.last()->isHidden()) {
-        columns.last()->setVisible(true);
+    if (columns.constLast()->isHidden()) {
+        columns.constLast()->setVisible(true);
     }
-    if (columns.last()->selectionModel())
-        columns.last()->selectionModel()->clear();
+    if (columns.constLast()->selectionModel())
+        columns.constLast()->selectionModel()->clear();
     updateScrollbars();
 }
 
diff --git a/src/widgets/itemviews/qdirmodel.cpp b/src/widgets/itemviews/qdirmodel.cpp
index 315d2503a4..95e6a1840d 100644
--- a/src/widgets/itemviews/qdirmodel.cpp
+++ b/src/widgets/itemviews/qdirmodel.cpp
@@ -212,7 +212,7 @@ void QDirModelPrivate::invalidate()
     Directories can be created and removed using mkdir(), rmdir(), and the
     model will be automatically updated to take the changes into account.
 
-    \note QDirModel requires an instance of a GUI application.
+    \note QDirModel requires an instance of \l QApplication.
 
     \sa nameFilters(), setFilter(), filter(), QListView, QTreeView, QFileSystemModel,
     {Dir View Example}, {Model Classes}
@@ -885,7 +885,7 @@ QModelIndex QDirModel::index(const QString &path, int column) const
 
 #if defined(Q_OS_WIN)
     if (absolutePath.startsWith(QLatin1String("//"))) { // UNC path
-        QString host = pathElements.first();
+        QString host = pathElements.constFirst();
         int r = 0;
         for (; r < d->root.children.count(); ++r)
             if (d->root.children.at(r).info.fileName() == host)
diff --git a/src/widgets/itemviews/qlistview.cpp b/src/widgets/itemviews/qlistview.cpp
index 3303aac6ed..0788e0287a 100644
--- a/src/widgets/itemviews/qlistview.cpp
+++ b/src/widgets/itemviews/qlistview.cpp
@@ -2396,9 +2396,9 @@ QPoint QListModeViewBase::initStaticLayout(const QListViewLayoutInfo &info)
     } else if (info.wrap) {
         if (info.flow == QListView::LeftToRight) {
             x = batchSavedPosition;
-            y = segmentPositions.last();
+            y = segmentPositions.constLast();
         } else { // flow == QListView::TopToBottom
-            x = segmentPositions.last();
+            x = segmentPositions.constLast();
             y = batchSavedPosition;
         }
     } else { // not first and not wrap
@@ -2613,7 +2613,7 @@ int QListModeViewBase::perItemScrollingPageSteps(int length, int bounds, bool wr
     int steps = positions.count() - 1;
     int max = qMax(length, bounds);
     int min = qMin(length, bounds);
-    int pos = min - (max - positions.last());
+    int pos = min - (max - positions.constLast());
 
     while (pos >= 0 && steps > 0) {
         pos -= (positions.at(steps) - positions.at(steps - 1));
diff --git a/src/widgets/itemviews/qtreeview.cpp b/src/widgets/itemviews/qtreeview.cpp
index ca1e8f13ee..cfe68d6b6a 100644
--- a/src/widgets/itemviews/qtreeview.cpp
+++ b/src/widgets/itemviews/qtreeview.cpp
@@ -2356,10 +2356,10 @@ void QTreeView::setSelection(const QRect &rect, QItemSelectionModel::SelectionFl
         return;
     }
     if (!topLeft.isValid() && !d->viewItems.isEmpty())
-        topLeft = d->viewItems.first().index;
+        topLeft = d->viewItems.constFirst().index;
     if (!bottomRight.isValid() && !d->viewItems.isEmpty()) {
         const int column = d->header->logicalIndex(d->header->count() - 1);
-        const QModelIndex index = d->viewItems.last().index;
+        const QModelIndex index = d->viewItems.constLast().index;
         bottomRight = index.sibling(index.row(), column);
     }
 
@@ -2667,9 +2667,9 @@ void QTreeView::selectAll()
     SelectionMode mode = d->selectionMode;
     d->executePostedLayout(); //make sure we lay out the items
     if (mode != SingleSelection && mode != NoSelection && !d->viewItems.isEmpty()) {
-        const QModelIndex &idx = d->viewItems.last().index;
+        const QModelIndex &idx = d->viewItems.constLast().index;
         QModelIndex lastItemIndex = idx.sibling(idx.row(), d->model->columnCount(idx.parent()) - 1);
-        d->select(d->viewItems.first().index, lastItemIndex,
+        d->select(d->viewItems.constFirst().index, lastItemIndex,
                   QItemSelectionModel::ClearAndSelect
                   |QItemSelectionModel::Rows);
     }
diff --git a/src/widgets/kernel/qformlayout.cpp b/src/widgets/kernel/qformlayout.cpp
index ce5e58642c..0bc1c029fe 100644
--- a/src/widgets/kernel/qformlayout.cpp
+++ b/src/widgets/kernel/qformlayout.cpp
@@ -65,13 +65,9 @@ public:
     T &operator()(int r, int c) { return m_storage[r * NumColumns + c]; }
 
     int rowCount() const { return m_storage.size() / NumColumns; }
-    void addRow(const T &value);
     void insertRow(int r, const T &value);
     void removeRow(int r);
 
-    bool find(const T &value, int *rowPtr, int *colPtr) const ;
-    int count(const T &value) const { return m_storage.count(value);  }
-
     // Hmmpf.. Some things are faster that way.
     const Storage &storage() const { return m_storage; }
 
@@ -82,13 +78,6 @@ private:
 };
 
 template <class T, int NumColumns>
-void FixedColumnMatrix<T, NumColumns>::addRow(const T &value)
-{
-    for (int i = 0; i < NumColumns; ++i)
-        m_storage.append(value);
-}
-
-template <class T, int NumColumns>
 void FixedColumnMatrix<T, NumColumns>::insertRow(int r, const T &value)
 {
     typename Storage::iterator it = m_storage.begin();
@@ -103,16 +92,6 @@ void FixedColumnMatrix<T, NumColumns>::removeRow(int r)
 }
 
 template <class T, int NumColumns>
-bool FixedColumnMatrix<T, NumColumns>::find(const T &value, int *rowPtr, int *colPtr) const
-{
-    const int idx = m_storage.indexOf(value);
-    if (idx == -1)
-        return false;
-    storageIndexToPosition(idx, rowPtr, colPtr);
-    return true;
-}
-
-template <class T, int NumColumns>
 void FixedColumnMatrix<T, NumColumns>::storageIndexToPosition(int idx, int *rowPtr, int *colPtr)
 {
     *rowPtr = idx / NumColumns;
diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index a71089793c..25874e9bcc 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -565,7 +565,7 @@ void QWidget::setAutoFillBackground(bool enabled)
 
     Composite widgets can also be created by subclassing a standard widget,
     such as QWidget or QFrame, and adding the necessary layout and child
-    widgets in the constructor of the subclass. Many of the \l{Qt Examples}
+    widgets in the constructor of the subclass. Many of the \l{Qt Widgets Examples}
     {examples provided with Qt} use this approach, and it is also covered in
     the Qt \l{Tutorials}.
 
diff --git a/src/widgets/kernel/qwidgetbackingstore.cpp b/src/widgets/kernel/qwidgetbackingstore.cpp
index 242e62572b..81fbe49a43 100644
--- a/src/widgets/kernel/qwidgetbackingstore.cpp
+++ b/src/widgets/kernel/qwidgetbackingstore.cpp
@@ -1012,9 +1012,11 @@ static QPlatformTextureList *widgetTexturesFor(QWidget *tlw, QWidget *widget)
 // The Windows compositor handles fullscreen OpenGL window specially. Besides
 // having trouble with popups, it also has issues with flip-flopping between
 // OpenGL-based and normal flushing. Therefore, stick with GL for fullscreen
-// windows. (QTBUG-53515)
+// windows (QTBUG-53515). Similary, translucent windows should not switch to
+// layered native windows (QTBUG-54734).
 #if defined(Q_OS_WIN) && !defined(Q_OS_WINRT) && !defined(Q_OS_WINCE)
                 || tlw->windowState().testFlag(Qt::WindowFullScreen)
+                || tlw->testAttribute(Qt::WA_TranslucentBackground)
 #endif
                 )
         {
diff --git a/src/widgets/styles/qcommonstyle.cpp b/src/widgets/styles/qcommonstyle.cpp
index 6b9e5577a4..36975c5877 100644
--- a/src/widgets/styles/qcommonstyle.cpp
+++ b/src/widgets/styles/qcommonstyle.cpp
@@ -5248,6 +5248,13 @@ static QPixmap cachedPixmapFromXPM(const char * const *xpm)
     return result;
 }
 
+#ifndef QT_NO_IMAGEFORMAT_PNG
+static inline QString clearText16IconPath()
+{
+    return QStringLiteral(":/qt-project.org/styles/commonstyle/images/cleartext-16.png");
+}
+#endif // !QT_NO_IMAGEFORMAT_PNG
+
 static QIcon clearTextIcon(bool rtl)
 {
     const QString directionalThemeName = rtl
@@ -5260,7 +5267,7 @@ static QIcon clearTextIcon(bool rtl)
 
     QIcon icon;
 #ifndef QT_NO_IMAGEFORMAT_PNG
-    QPixmap clearText16(QStringLiteral(":/qt-project.org/styles/commonstyle/images/cleartext-16.png"));
+    QPixmap clearText16(clearText16IconPath());
     Q_ASSERT(!clearText16.size().isEmpty());
     icon.addPixmap(clearText16);
     QPixmap clearText32(QStringLiteral(":/qt-project.org/styles/commonstyle/images/cleartext-32.png"));
@@ -5575,6 +5582,8 @@ QPixmap QCommonStyle::standardPixmap(StandardPixmap sp, const QStyleOption *opti
         return QPixmap(QLatin1String(":/qt-project.org/styles/commonstyle/images/media-volume-16.png"));
     case SP_MediaVolumeMuted:
         return QPixmap(QLatin1String(":/qt-project.org/styles/commonstyle/images/media-volume-muted-16.png"));
+    case SP_LineEditClearButton:
+        return QPixmap(clearText16IconPath());
 #endif // QT_NO_IMAGEFORMAT_PNG
     default:
         break;
diff --git a/src/widgets/styles/qmacstyle_mac.mm b/src/widgets/styles/qmacstyle_mac.mm
index 56531b10de..d28bd644c6 100644
--- a/src/widgets/styles/qmacstyle_mac.mm
+++ b/src/widgets/styles/qmacstyle_mac.mm
@@ -2933,7 +2933,7 @@ int QMacStyle::styleHint(StyleHint sh, const QStyleOption *opt, const QWidget *w
             QImage img;
 
             QSize pixmapSize = opt->rect.size();
-            if (pixmapSize.isValid()) {
+            if (!pixmapSize.isEmpty()) {
                 QPixmap pix(pixmapSize);
                 pix.fill(QColor(fillR, fillG, fillB));
                 QPainter pix_paint(&pix);
diff --git a/src/widgets/styles/qstyle.cpp b/src/widgets/styles/qstyle.cpp
index d72a898ee9..93bc00f662 100644
--- a/src/widgets/styles/qstyle.cpp
+++ b/src/widgets/styles/qstyle.cpp
@@ -733,7 +733,7 @@ void QStyle::drawItemPixmap(QPainter *painter, const QRect &rect, int alignment,
 
     \value State_None Indicates that the widget does not have a state.
     \value State_Active Indicates that the widget is active.
-    \value State_AutoRaise Used to indicate if auto-raise appearance should be usd on a tool button.
+    \value State_AutoRaise Used to indicate if auto-raise appearance should be used on a tool button.
     \value State_Children Used to indicate if an item view branch has children.
     \value State_DownArrow Used to indicate if a down arrow should be visible on the widget.
     \value State_Editing Used to indicate if an editor is opened on the widget.
diff --git a/src/widgets/util/qcompleter.cpp b/src/widgets/util/qcompleter.cpp
index 5425644b41..3006f0c9ce 100644
--- a/src/widgets/util/qcompleter.cpp
+++ b/src/widgets/util/qcompleter.cpp
@@ -1044,6 +1044,10 @@ void QCompleter::setModel(QAbstractItemModel *model)
 {
     Q_D(QCompleter);
     QAbstractItemModel *oldModel = d->proxy->sourceModel();
+#ifndef QT_NO_FILESYSTEMMODEL
+    if (qobject_cast<const QFileSystemModel *>(oldModel))
+        setCompletionRole(Qt::EditRole); // QTBUG-54642, clear FileNameRole set by QFileSystemModel
+#endif
     d->proxy->setSourceModel(model);
     if (d->popup)
         setPopup(d->popup); // set the model and make new connections
diff --git a/src/widgets/widgets/qabstractspinbox.cpp b/src/widgets/widgets/qabstractspinbox.cpp
index 774f5a708d..5778d16456 100644
--- a/src/widgets/widgets/qabstractspinbox.cpp
+++ b/src/widgets/widgets/qabstractspinbox.cpp
@@ -757,8 +757,7 @@ bool QAbstractSpinBox::event(QEvent *event)
     case QEvent::HoverEnter:
     case QEvent::HoverLeave:
     case QEvent::HoverMove:
-        if (const QHoverEvent *he = static_cast<const QHoverEvent *>(event))
-            d->updateHoverControl(he->pos());
+        d->updateHoverControl(static_cast<const QHoverEvent *>(event)->pos());
         break;
     case QEvent::ShortcutOverride:
         if (d->edit->event(event))
diff --git a/src/widgets/widgets/qcombobox.cpp b/src/widgets/widgets/qcombobox.cpp
index 51e23ca7f9..af178ce8f5 100644
--- a/src/widgets/widgets/qcombobox.cpp
+++ b/src/widgets/widgets/qcombobox.cpp
@@ -2108,9 +2108,9 @@ void QComboBoxPrivate::setCurrentIndex(const QModelIndex &mi)
     if (lineEdit) {
         const QString newText = itemText(normalized);
         if (lineEdit->text() != newText) {
-            lineEdit->setText(newText);
+            lineEdit->setText(newText); // may cause lineEdit -> nullptr (QTBUG-54191)
 #ifndef QT_NO_COMPLETER
-            if (lineEdit->completer())
+            if (lineEdit && lineEdit->completer())
                 lineEdit->completer()->setCompletionPrefix(newText);
 #endif
         }
diff --git a/src/widgets/widgets/qdatetimeedit.cpp b/src/widgets/widgets/qdatetimeedit.cpp
index cfba2cc87f..b168c98410 100644
--- a/src/widgets/widgets/qdatetimeedit.cpp
+++ b/src/widgets/widgets/qdatetimeedit.cpp
@@ -52,6 +52,8 @@
 #include <qset.h>
 #include <qstyle.h>
 
+#include <algorithm>
+
 #ifndef QT_NO_DATETIMEEDIT
 
 //#define QDATETIMEEDIT_QDTEDEBUG
@@ -246,9 +248,10 @@ void QDateTimeEdit::setDateTime(const QDateTime &datetime)
     Q_D(QDateTimeEdit);
     if (datetime.isValid()) {
         d->clearCache();
+        const QDate date = datetime.date();
         if (!(d->sections & DateSections_Mask))
-            setDateRange(datetime.date(), datetime.date());
-        d->setValue(QDateTime(datetime.date(), datetime.time(), d->spec), EmitIfChanged);
+            setDateRange(date, date);
+        d->setValue(QDateTime(date, datetime.time(), d->spec), EmitIfChanged);
     }
 }
 
@@ -861,14 +864,6 @@ QString QDateTimeEdit::displayFormat() const
     return isRightToLeft() ? d->unreversedFormat : d->displayFormat;
 }
 
-template<typename C> static inline C reverse(const C &l)
-{
-    C ret;
-    for (int i=l.size() - 1; i>=0; --i)
-        ret.append(l.at(i));
-    return ret;
-}
-
 void QDateTimeEdit::setDisplayFormat(const QString &format)
 {
     Q_D(QDateTimeEdit);
@@ -882,8 +877,8 @@ void QDateTimeEdit::setDisplayFormat(const QString &format)
                 d->displayFormat += d->sectionNode(i).format();
             }
             d->displayFormat += d->separators.at(0);
-            d->separators = reverse(d->separators);
-            d->sectionNodes = reverse(d->sectionNodes);
+            std::reverse(d->separators.begin(), d->separators.end());
+            std::reverse(d->sectionNodes.begin(), d->sectionNodes.end());
         }
 
         d->formatExplicitlySet = true;
@@ -1776,15 +1771,18 @@ void QDateTimeEditPrivate::setSelected(int sectionIndex, bool forward)
 
 int QDateTimeEditPrivate::sectionAt(int pos) const
 {
-    if (pos < separators.first().size()) {
+    if (pos < separators.first().size())
         return (pos == 0 ? FirstSectionIndex : NoSectionIndex);
-    } else if (displayText().size() - pos < separators.last().size() + 1) {
+
+    const QString text = displayText();
+    const int textSize = text.size();
+    if (textSize - pos < separators.last().size() + 1) {
         if (separators.last().size() == 0) {
             return sectionNodes.count() - 1;
         }
-        return (pos == displayText().size() ? LastSectionIndex : NoSectionIndex);
+        return (pos == textSize ? LastSectionIndex : NoSectionIndex);
     }
-    updateCache(value, displayText());
+    updateCache(value, text);
 
     for (int i=0; i<sectionNodes.size(); ++i) {
         const int tmp = sectionPos(i);
@@ -1805,12 +1803,14 @@ int QDateTimeEditPrivate::sectionAt(int pos) const
 int QDateTimeEditPrivate::closestSection(int pos, bool forward) const
 {
     Q_ASSERT(pos >= 0);
-    if (pos < separators.first().size()) {
+    if (pos < separators.first().size())
         return forward ? 0 : FirstSectionIndex;
-    } else if (displayText().size() - pos < separators.last().size() + 1) {
+
+    const QString text = displayText();
+    if (text.size() - pos < separators.last().size() + 1)
         return forward ? LastSectionIndex : sectionNodes.size() - 1;
-    }
-    updateCache(value, displayText());
+
+    updateCache(value, text);
     for (int i=0; i<sectionNodes.size(); ++i) {
         const int tmp = sectionPos(sectionNodes.at(i));
         if (pos < tmp + sectionSize(i)) {
diff --git a/src/widgets/widgets/qdockarealayout.cpp b/src/widgets/widgets/qdockarealayout.cpp
index 55e774024a..b347e93807 100644
--- a/src/widgets/widgets/qdockarealayout.cpp
+++ b/src/widgets/widgets/qdockarealayout.cpp
@@ -3170,7 +3170,7 @@ void QDockAreaLayout::splitDockWidget(QDockWidget *after,
                                                QDockWidget *dockWidget,
                                                Qt::Orientation orientation)
 {
-    QList<int> path = indexOf(after);
+    const QList<int> path = indexOf(after);
     if (path.isEmpty())
         return;
 
diff --git a/src/widgets/widgets/qdockwidget.cpp b/src/widgets/widgets/qdockwidget.cpp
index d2fa9a7c06..9e95d086bd 100644
--- a/src/widgets/widgets/qdockwidget.cpp
+++ b/src/widgets/widgets/qdockwidget.cpp
@@ -811,7 +811,8 @@ void QDockWidgetPrivate::endDrag(bool abort)
                 } else {
                     setResizerActive(false);
                 }
-                undockedGeometry = q->geometry();
+                if (q->isFloating()) // Might not be floating when dragging a QDockWidgetGroupWindow
+                    undockedGeometry = q->geometry();
                 q->activateWindow();
             } else {
                 // The tab was not plugged back in the QMainWindow but the QDockWidget cannot
diff --git a/src/widgets/widgets/qfontcombobox.cpp b/src/widgets/widgets/qfontcombobox.cpp
index 1d736c8e96..9bd33409ae 100644
--- a/src/widgets/widgets/qfontcombobox.cpp
+++ b/src/widgets/widgets/qfontcombobox.cpp
@@ -162,7 +162,7 @@ static QFontDatabase::WritingSystem writingSystemForFont(const QFont &font, bool
         return QFontDatabase::TraditionalChinese;
     }
 
-    system = writingSystems.last();
+    system = writingSystems.constLast();
 
     if (!*hasLatin) {
         // we need to show something
diff --git a/src/widgets/widgets/qmainwindow.cpp b/src/widgets/widgets/qmainwindow.cpp
index 5dfa439b2e..c31e9750bf 100644
--- a/src/widgets/widgets/qmainwindow.cpp
+++ b/src/widgets/widgets/qmainwindow.cpp
@@ -1729,10 +1729,20 @@ QMenu *QMainWindow::createPopupMenu()
         menu = new QMenu(this);
         for (int i = 0; i < dockwidgets.size(); ++i) {
             QDockWidget *dockWidget = dockwidgets.at(i);
-            if (dockWidget->parentWidget() == this
-                && !d->layout->layoutState.dockAreaLayout.indexOf(dockWidget).isEmpty()) {
-                menu->addAction(dockwidgets.at(i)->toggleViewAction());
+            // filter to find out if we own this QDockWidget
+            if (dockWidget->parentWidget() == this) {
+                if (d->layout->layoutState.dockAreaLayout.indexOf(dockWidget).isEmpty())
+                    continue;
+            } else if (QDockWidgetGroupWindow *dwgw =
+                           qobject_cast<QDockWidgetGroupWindow *>(dockWidget->parentWidget())) {
+                if (dwgw->parentWidget() != this)
+                    continue;
+                if (dwgw->layoutInfo()->indexOf(dockWidget).isEmpty())
+                    continue;
+            } else {
+                continue;
             }
+            menu->addAction(dockwidgets.at(i)->toggleViewAction());
         }
         menu->addSeparator();
     }
diff --git a/src/widgets/widgets/qmainwindowlayout.cpp b/src/widgets/widgets/qmainwindowlayout.cpp
index ee6da73302..c5b08387a3 100644
--- a/src/widgets/widgets/qmainwindowlayout.cpp
+++ b/src/widgets/widgets/qmainwindowlayout.cpp
@@ -2384,13 +2384,10 @@ void QMainWindowLayout::hover(QLayoutItem *widgetItem, const QPoint &mousePos)
             QWidget *w = qobject_cast<QWidget*>(c);
             if (!w)
                 continue;
-            if (w == widget)
-                continue;
-            if (!w->isTopLevel() || !w->isVisible() || w->isMinimized())
-                continue;
             if (!qobject_cast<QDockWidget*>(w) && !qobject_cast<QDockWidgetGroupWindow *>(w))
                 continue;
-            candidates << w;
+            if (w != widget && w->isTopLevel() && w->isVisible() && !w->isMinimized())
+                candidates << w;
             if (QDockWidgetGroupWindow *group = qobject_cast<QDockWidgetGroupWindow *>(w)) {
                 // Sometimes, there are floating QDockWidget that have a QDockWidgetGroupWindow as a parent.
                 foreach (QObject *c, group->children()) {
diff --git a/src/widgets/widgets/qspinbox.cpp b/src/widgets/widgets/qspinbox.cpp
index a5c096c3a8..0daa624ae8 100644
--- a/src/widgets/widgets/qspinbox.cpp
+++ b/src/widgets/widgets/qspinbox.cpp
@@ -479,9 +479,8 @@ QString QSpinBox::textFromValue(int value) const
     QString str;
 
     if (d->displayIntegerBase != 10) {
-        str = QString::number(qAbs(value), d->displayIntegerBase);
-        if (value < 0)
-            str.prepend('-');
+        const QLatin1String prefix = value < 0 ? QLatin1String("-") : QLatin1String();
+        str = prefix + QString::number(qAbs(value), d->displayIntegerBase);
     } else {
         str = locale().toString(value);
         if (!d->showGroupSeparator && (qAbs(value) >= 1000 || value == INT_MIN)) {
diff --git a/src/widgets/widgets/qwidgettextcontrol.cpp b/src/widgets/widgets/qwidgettextcontrol.cpp
index 77b5a4830b..d5ecb150a8 100644
--- a/src/widgets/widgets/qwidgettextcontrol.cpp
+++ b/src/widgets/widgets/qwidgettextcontrol.cpp
@@ -2641,8 +2641,8 @@ void QWidgetTextControl::insertFromMimeData(const QMimeData *source)
 #ifndef QT_NO_TEXTHTMLPARSER
     if (source->hasFormat(QLatin1String("application/x-qrichtext")) && d->acceptRichText) {
         // x-qrichtext is always UTF-8 (taken from Qt3 since we don't use it anymore).
-        QString richtext = QString::fromUtf8(source->data(QLatin1String("application/x-qrichtext")));
-        richtext.prepend(QLatin1String("<meta name=\"qrichtext\" content=\"1\" />"));
+        const QString richtext = QLatin1String("<meta name=\"qrichtext\" content=\"1\" />")
+                + QString::fromUtf8(source->data(QLatin1String("application/x-qrichtext")));
         fragment = QTextDocumentFragment::fromHtml(richtext, d->doc);
         hasData = true;
     } else if (source->hasHtml() && d->acceptRichText) {
diff --git a/src/winmain/qtmain_winrt.cpp b/src/winmain/qtmain_winrt.cpp
index 1ac0a98cb1..83a7dc800c 100644
--- a/src/winmain/qtmain_winrt.cpp
+++ b/src/winmain/qtmain_winrt.cpp
@@ -307,7 +307,7 @@ private:
         if (develMode) {
             // Write a PID file to help runner
             const QString pidFileName = QDir(QStandardPaths::writableLocation(QStandardPaths::DataLocation))
-                    .absoluteFilePath(QString::number(uint(GetCurrentProcessId())) + QStringLiteral(".pid"));
+                    .absoluteFilePath(QString::asprintf("%u.pid", uint(GetCurrentProcessId())));
             CREATEFILE2_EXTENDED_PARAMETERS params = {
                 sizeof(CREATEFILE2_EXTENDED_PARAMETERS),
                 FILE_ATTRIBUTE_NORMAL
diff --git a/src/xml/sax/qxml.cpp b/src/xml/sax/qxml.cpp
index d4c8519d67..1724076b84 100644
--- a/src/xml/sax/qxml.cpp
+++ b/src/xml/sax/qxml.cpp
@@ -1295,7 +1295,7 @@ static QString extractEncodingDecl(const QString &text, bool *needMoreText)
     *needMoreText = false;
 
     int l = text.length();
-    QString snip = QString::fromLatin1("<?xml").left(l);
+    const QLatin1String snip("<?xml", std::min(l, 5));
     if (l > 0 && !text.startsWith(snip))
         return QString();