Merge remote-tracking branch 'origin/5.14' into 5.15

 Conflicts:
	tests/auto/network/kernel/qnetworkinterface/BLACKLIST

Change-Id: I1e8866c63b54bcd95fc2a044276ee15b7f60e79a

31 files changed, 156 insertions, 140 deletions

diff --git a/src/corelib/global/qcompilerdetection.h b/src/corelib/global/qcompilerdetection.h
index aab5625d00..b1fcf09e92 100644
--- a/src/corelib/global/qcompilerdetection.h
+++ b/src/corelib/global/qcompilerdetection.h
@@ -505,6 +505,39 @@
 #endif
 
 /*
+ * SG10's SD-6 feature detection and some useful extensions from Clang and GCC
+ * https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations
+ * http://clang.llvm.org/docs/LanguageExtensions.html#feature-checking-macros
+ * Not using wrapper macros, per http://eel.is/c++draft/cpp.cond#7.sentence-2
+ */
+#ifndef __has_builtin
+#  define __has_builtin(x)             0
+#endif
+#ifndef __has_feature
+#  define __has_feature(x)             0
+#endif
+#ifndef __has_attribute
+#  define __has_attribute(x)           0
+#endif
+#ifndef __has_cpp_attribute
+#  define __has_cpp_attribute(x)       0
+#endif
+#ifndef __has_include
+#  define __has_include(x)             0
+#endif
+#ifndef __has_include_next
+#  define __has_include_next(x)        0
+#endif
+
+// Kept around until all submodules have transitioned
+#define QT_HAS_BUILTIN(x)        __has_builtin(x)
+#define QT_HAS_FEATURE(x)        __has_feature(x)
+#define QT_HAS_ATTRIBUTE(x)      __has_attribute(x)
+#define QT_HAS_CPP_ATTRIBUTE(x)  __has_cpp_attribute(x)
+#define QT_HAS_INCLUDE(x)        __has_include(x)
+#define QT_HAS_INCLUDE_NEXT(x)   __has_include_next(x)
+
+/*
  * C++11 support
  *
  *  Paper           Macro                               SD-6 macro
@@ -1031,37 +1064,6 @@
 #endif
 
 /*
- * SG10's SD-6 feature detection and some useful extensions from Clang and GCC
- * https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations
- * http://clang.llvm.org/docs/LanguageExtensions.html#feature-checking-macros
- */
-#ifdef __has_builtin
-#  define QT_HAS_BUILTIN(x)             __has_builtin(x)
-#else
-#  define QT_HAS_BUILTIN(x)             0
-#endif
-#ifdef __has_attribute
-#  define QT_HAS_ATTRIBUTE(x)           __has_attribute(x)
-#else
-#  define QT_HAS_ATTRIBUTE(x)           0
-#endif
-#ifdef __has_cpp_attribute
-#  define QT_HAS_CPP_ATTRIBUTE(x)       __has_cpp_attribute(x)
-#else
-#  define QT_HAS_CPP_ATTRIBUTE(x)       0
-#endif
-#ifdef __has_include
-#  define QT_HAS_INCLUDE(x)             __has_include(x)
-#else
-#  define QT_HAS_INCLUDE(x)             0
-#endif
-#ifdef __has_include_next
-#  define QT_HAS_INCLUDE_NEXT(x)        __has_include_next(x)
-#else
-#  define QT_HAS_INCLUDE_NEXT(x)        0
-#endif
-
-/*
  * C++11 keywords and expressions
  */
 #ifdef Q_COMPILER_NULLPTR
@@ -1137,7 +1139,7 @@
 #  define Q_DECL_ALIGN(n)   alignas(n)
 #endif
 
-#if QT_HAS_CPP_ATTRIBUTE(nodiscard) && !defined(Q_CC_CLANG)         // P0188R1
+#if __has_cpp_attribute(nodiscard) && !defined(Q_CC_CLANG)         // P0188R1
 // Can't use [[nodiscard]] with Clang, see https://bugs.llvm.org/show_bug.cgi?id=33518
 #  undef Q_REQUIRED_RESULT
 #  define Q_REQUIRED_RESULT [[nodiscard]]
@@ -1239,11 +1241,6 @@
 #ifndef QT_MAKE_CHECKED_ARRAY_ITERATOR
 #  define QT_MAKE_CHECKED_ARRAY_ITERATOR(x, N) (x)
 #endif
-#ifdef __has_feature
-#  define QT_HAS_FEATURE(x)             __has_feature(x)
-#else
-#  define QT_HAS_FEATURE(x)             0
-#endif
 
 /*
  * Warning/diagnostic handling
@@ -1334,11 +1331,11 @@
     } while (false)
 
 #if defined(__cplusplus)
-#if QT_HAS_CPP_ATTRIBUTE(clang::fallthrough)
+#if __has_cpp_attribute(clang::fallthrough)
 #    define Q_FALLTHROUGH() [[clang::fallthrough]]
-#elif QT_HAS_CPP_ATTRIBUTE(gnu::fallthrough)
+#elif __has_cpp_attribute(gnu::fallthrough)
 #    define Q_FALLTHROUGH() [[gnu::fallthrough]]
-#elif QT_HAS_CPP_ATTRIBUTE(fallthrough)
+#elif __has_cpp_attribute(fallthrough)
 #  define Q_FALLTHROUGH() [[fallthrough]]
 #endif
 #endif
diff --git a/src/corelib/global/qconfig-bootstrapped.h b/src/corelib/global/qconfig-bootstrapped.h
index 81bf6f95ce..b62c1a4d35 100644
--- a/src/corelib/global/qconfig-bootstrapped.h
+++ b/src/corelib/global/qconfig-bootstrapped.h
@@ -77,13 +77,13 @@
 #define QT_FEATURE_binaryjson -1
 #define QT_FEATURE_cborstream -1
 #define QT_CRYPTOGRAPHICHASH_ONLY_SHA1
-#define QT_FEATURE_cxx11_random (QT_HAS_INCLUDE(<random>) ? 1 : -1)
+#define QT_FEATURE_cxx11_random (__has_include(<random>) ? 1 : -1)
 #define QT_NO_DATASTREAM
 #define QT_FEATURE_datestring 1
 #define QT_FEATURE_datetimeparser -1
 #define QT_FEATURE_easingcurve -1
 #define QT_FEATURE_etw -1
-#define QT_FEATURE_getauxval (QT_HAS_INCLUDE(<sys/auxv.h>) ? 1 : -1)
+#define QT_FEATURE_getauxval (__has_include(<sys/auxv.h>) ? 1 : -1)
 #define QT_FEATURE_getentropy -1
 #define QT_NO_GEOM_VARIANT
 #define QT_FEATURE_hijricalendar -1
diff --git a/src/corelib/global/qendian.h b/src/corelib/global/qendian.h
index 5cd9d3160b..257efbbdbe 100644
--- a/src/corelib/global/qendian.h
+++ b/src/corelib/global/qendian.h
@@ -66,7 +66,7 @@ template <typename T> Q_ALWAYS_INLINE void qToUnaligned(const T src, void *dest)
     // Using sizeof(T) inside memcpy function produces internal compiler error with
     // MSVC2008/ARM in tst_endian -> use extra indirection to resolve size of T.
     const size_t size = sizeof(T);
-#if QT_HAS_BUILTIN(__builtin_memcpy)
+#if __has_builtin(__builtin_memcpy)
     __builtin_memcpy
 #else
     memcpy
@@ -78,7 +78,7 @@ template <typename T> Q_ALWAYS_INLINE T qFromUnaligned(const void *src)
 {
     T dest;
     const size_t size = sizeof(T);
-#if QT_HAS_BUILTIN(__builtin_memcpy)
+#if __has_builtin(__builtin_memcpy)
     __builtin_memcpy
 #else
     memcpy
diff --git a/src/corelib/global/qglobal.cpp b/src/corelib/global/qglobal.cpp
index f46313d9d5..025ec4ee33 100644
--- a/src/corelib/global/qglobal.cpp
+++ b/src/corelib/global/qglobal.cpp
@@ -92,7 +92,7 @@
 #  include <sys/systeminfo.h>
 #endif
 
-#if defined(Q_OS_DARWIN) && QT_HAS_INCLUDE(<IOKit/IOKitLib.h>)
+#if defined(Q_OS_DARWIN) && __has_include(<IOKit/IOKitLib.h>)
 #  include <IOKit/IOKitLib.h>
 #  include <private/qcore_mac_p.h>
 #endif
@@ -3051,7 +3051,7 @@ enum {
 */
 QByteArray QSysInfo::machineUniqueId()
 {
-#if defined(Q_OS_DARWIN) && QT_HAS_INCLUDE(<IOKit/IOKitLib.h>)
+#if defined(Q_OS_DARWIN) && __has_include(<IOKit/IOKitLib.h>)
     char uuid[UuidStringLen + 1];
     io_service_t service = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("IOPlatformExpertDevice"));
     QCFString stringRef = (CFStringRef)IORegistryEntryCreateCFProperty(service, CFSTR(kIOPlatformUUIDKey), kCFAllocatorDefault, 0);
diff --git a/src/corelib/global/qglobal.h b/src/corelib/global/qglobal.h
index 1e26e9453a..e335916eac 100644
--- a/src/corelib/global/qglobal.h
+++ b/src/corelib/global/qglobal.h
@@ -769,7 +769,7 @@ inline void qt_noop(void) {}
 
 #if !defined(QT_NO_EXCEPTIONS)
 #  if !defined(Q_MOC_RUN)
-#    if (defined(Q_CC_CLANG) && !defined(Q_CC_INTEL) && !QT_HAS_FEATURE(cxx_exceptions)) || \
+#    if (defined(Q_CC_CLANG) && !defined(Q_CC_INTEL) && !__has_feature(cxx_exceptions)) || \
         (defined(Q_CC_GNU) && !defined(__EXCEPTIONS))
 #      define QT_NO_EXCEPTIONS
 #    endif
diff --git a/src/corelib/global/qglobal_p.h b/src/corelib/global/qglobal_p.h
index 58bc8b7bf3..5ab84fa8be 100644
--- a/src/corelib/global/qglobal_p.h
+++ b/src/corelib/global/qglobal_p.h
@@ -74,7 +74,7 @@ Q_CORE_EXPORT time_t qMkTime(struct tm *when);
 
 QT_END_NAMESPACE
 
-#if !QT_HAS_BUILTIN(__builtin_available)
+#if !__has_builtin(__builtin_available)
 #include <initializer_list>
 #include <QtCore/qoperatingsystemversion.h>
 #include <QtCore/qversionnumber.h>
@@ -142,7 +142,7 @@ QT_END_NAMESPACE
     QT_BUILTIN_AVAILABLE1, \
     QT_BUILTIN_AVAILABLE0, )
 #define __builtin_available(...) QT_BUILTIN_AVAILABLE_CHOOSER(__VA_ARGS__)(__VA_ARGS__)
-#endif // !QT_HAS_BUILTIN(__builtin_available)
+#endif // !__has_builtin(__builtin_available)
 #endif // defined(__cplusplus)
 
 #endif // QGLOBAL_P_H
diff --git a/src/corelib/global/qlogging.cpp b/src/corelib/global/qlogging.cpp
index c9209bd8e3..c1a45476f9 100644
--- a/src/corelib/global/qlogging.cpp
+++ b/src/corelib/global/qlogging.cpp
@@ -70,7 +70,7 @@
 #if QT_CONFIG(slog2)
 #include <sys/slog2.h>
 #endif
-#if QT_HAS_INCLUDE(<paths.h>)
+#if __has_include(<paths.h>)
 #include <paths.h>
 #endif
 
@@ -106,7 +106,7 @@
 #    if __UCLIBC_HAS_BACKTRACE__
 #      define QLOGGING_HAVE_BACKTRACE
 #    endif
-#  elif (defined(__GLIBC__) && defined(__GLIBCXX__)) || (QT_HAS_INCLUDE(<cxxabi.h>) && QT_HAS_INCLUDE(<execinfo.h>))
+#  elif (defined(__GLIBC__) && defined(__GLIBCXX__)) || (__has_include(<cxxabi.h>) && __has_include(<execinfo.h>))
 #    define QLOGGING_HAVE_BACKTRACE
 #  endif
 #endif
@@ -116,7 +116,7 @@ extern char *__progname;
 #endif
 
 #ifndef QT_BOOTSTRAPPED
-#if defined(Q_OS_LINUX) && (defined(__GLIBC__) || QT_HAS_INCLUDE(<sys/syscall.h>))
+#if defined(Q_OS_LINUX) && (defined(__GLIBC__) || __has_include(<sys/syscall.h>))
 #  include <sys/syscall.h>
 
 # if defined(Q_OS_ANDROID) && !defined(SYS_gettid)
@@ -1276,7 +1276,7 @@ void QMessagePattern::setPattern(const QString &pattern)
 #if defined(QLOGGING_HAVE_BACKTRACE) && !defined(QT_BOOTSTRAPPED)
 // make sure the function has "Message" in the name so the function is removed
 
-#if ((defined(Q_CC_GNU) && defined(QT_COMPILER_SUPPORTS_SIMD_ALWAYS)) || QT_HAS_ATTRIBUTE(optimize)) \
+#if ((defined(Q_CC_GNU) && defined(QT_COMPILER_SUPPORTS_SIMD_ALWAYS)) || __has_attribute(optimize)) \
     && !defined(Q_CC_INTEL) && !defined(Q_CC_CLANG)
 // force skipping the frame pointer, to save the backtrace() function some work
 __attribute__((optimize("omit-frame-pointer")))
diff --git a/src/corelib/global/qnumeric_p.h b/src/corelib/global/qnumeric_p.h
index 86e7997680..fdfcbda6ca 100644
--- a/src/corelib/global/qnumeric_p.h
+++ b/src/corelib/global/qnumeric_p.h
@@ -249,7 +249,7 @@ QT_WARNING_POP
 // size_t. Implementations for 8- and 16-bit types will work but may not be as
 // efficient. Implementations for 64-bit may be missing on 32-bit platforms.
 
-#if (defined(Q_CC_GNU) && (Q_CC_GNU >= 500) || (defined(Q_CC_INTEL) && !defined(Q_OS_WIN))) || QT_HAS_BUILTIN(__builtin_add_overflow)
+#if (defined(Q_CC_GNU) && (Q_CC_GNU >= 500) || (defined(Q_CC_INTEL) && !defined(Q_OS_WIN))) || __has_builtin(__builtin_add_overflow)
 // GCC 5, ICC 18, and Clang 3.8 have builtins to detect overflows
 
 template <typename T> inline
diff --git a/src/corelib/io/qfilesystemengine_unix.cpp b/src/corelib/io/qfilesystemengine_unix.cpp
index 2e81f93bcf..3bbebc7fe9 100644
--- a/src/corelib/io/qfilesystemengine_unix.cpp
+++ b/src/corelib/io/qfilesystemengine_unix.cpp
@@ -55,7 +55,7 @@
 #include <stdio.h>
 #include <errno.h>
 
-#if QT_HAS_INCLUDE(<paths.h>)
+#if __has_include(<paths.h>)
 # include <paths.h>
 #endif
 #ifndef _PATH_TMP           // from <paths.h>
diff --git a/src/corelib/io/qprocess.cpp b/src/corelib/io/qprocess.cpp
index ad2e7fb6b8..816026a36c 100644
--- a/src/corelib/io/qprocess.cpp
+++ b/src/corelib/io/qprocess.cpp
@@ -100,7 +100,7 @@ QT_END_NAMESPACE
 #include <private/qcore_unix_p.h>
 #endif
 
-#if QT_HAS_INCLUDE(<paths.h>)
+#if __has_include(<paths.h>)
 #include <paths.h>
 #endif
 
diff --git a/src/corelib/io/qstandardpaths.cpp b/src/corelib/io/qstandardpaths.cpp
index 02adda3d6c..bca454fc7a 100644
--- a/src/corelib/io/qstandardpaths.cpp
+++ b/src/corelib/io/qstandardpaths.cpp
@@ -48,7 +48,7 @@
 #include <qcoreapplication.h>
 #endif
 
-#if QT_HAS_INCLUDE(<paths.h>)
+#if __has_include(<paths.h>)
 #include <paths.h>
 #endif
 
diff --git a/src/corelib/io/qstorageinfo_unix.cpp b/src/corelib/io/qstorageinfo_unix.cpp
index 1e72241e68..37b8a60c37 100644
--- a/src/corelib/io/qstorageinfo_unix.cpp
+++ b/src/corelib/io/qstorageinfo_unix.cpp
@@ -108,7 +108,7 @@
 #  endif // QT_LARGEFILE_SUPPORT
 #endif // Q_OS_BSD4
 
-#if QT_HAS_INCLUDE(<paths.h>)
+#if __has_include(<paths.h>)
 #  include <paths.h>
 #endif
 #ifndef _PATH_MOUNTED
diff --git a/src/corelib/kernel/qdeadlinetimer.h b/src/corelib/kernel/qdeadlinetimer.h
index 9dd92481d2..99e09eb31f 100644
--- a/src/corelib/kernel/qdeadlinetimer.h
+++ b/src/corelib/kernel/qdeadlinetimer.h
@@ -52,7 +52,7 @@
 
 #include <limits>
 
-#if QT_HAS_INCLUDE(<chrono>)
+#if __has_include(<chrono>)
 #  include <chrono>
 #endif
 
@@ -120,7 +120,7 @@ public:
     QDeadlineTimer &operator-=(qint64 msecs)
     { *this = *this + (-msecs); return *this; }
 
-#if QT_HAS_INCLUDE(<chrono>) || defined(Q_CLANG_QDOC)
+#if __has_include(<chrono>) || defined(Q_CLANG_QDOC)
     template <class Clock, class Duration>
     QDeadlineTimer(std::chrono::time_point<Clock, Duration> deadline_,
                    Qt::TimerType type_ = Qt::CoarseTimer) : t2(0)
diff --git a/src/corelib/kernel/qobject.h b/src/corelib/kernel/qobject.h
index 540b8b32c1..f5d7c22e3a 100644
--- a/src/corelib/kernel/qobject.h
+++ b/src/corelib/kernel/qobject.h
@@ -55,7 +55,7 @@
 
 #include <QtCore/qobject_impl.h>
 
-#if QT_HAS_INCLUDE(<chrono>)
+#if __has_include(<chrono>)
 #  include <chrono>
 #endif
 
@@ -160,7 +160,7 @@ public:
     void moveToThread(QThread *thread);
 
     int startTimer(int interval, Qt::TimerType timerType = Qt::CoarseTimer);
-#if QT_HAS_INCLUDE(<chrono>)
+#if __has_include(<chrono>)
     Q_ALWAYS_INLINE
     int startTimer(std::chrono::milliseconds time, Qt::TimerType timerType = Qt::CoarseTimer)
     {
diff --git a/src/corelib/kernel/qtimer.h b/src/corelib/kernel/qtimer.h
index eb7185c12d..6bbfd741d9 100644
--- a/src/corelib/kernel/qtimer.h
+++ b/src/corelib/kernel/qtimer.h
@@ -47,7 +47,7 @@
 #include <QtCore/qbasictimer.h> // conceptual inheritance
 #include <QtCore/qobject.h>
 
-#if QT_HAS_INCLUDE(<chrono>)
+#if __has_include(<chrono>)
 #  include <chrono>
 #endif
 
@@ -177,7 +177,7 @@ Q_SIGNALS:
     void timeout(QPrivateSignal);
 
 public:
-#if QT_HAS_INCLUDE(<chrono>) || defined(Q_QDOC)
+#if __has_include(<chrono>) || defined(Q_QDOC)
     void setInterval(std::chrono::milliseconds value)
     {
         setInterval(int(value.count()));
@@ -223,7 +223,7 @@ private:
     static void singleShotImpl(int msec, Qt::TimerType timerType,
                                const QObject *receiver, QtPrivate::QSlotObjectBase *slotObj);
 
-#if QT_HAS_INCLUDE(<chrono>)
+#if __has_include(<chrono>)
     static Qt::TimerType defaultTypeFor(std::chrono::milliseconds interval)
     { return defaultTypeFor(int(interval.count())); }
 
diff --git a/src/corelib/kernel/qvariant.h b/src/corelib/kernel/qvariant.h
index 6e27c9bf1f..f48419c934 100644
--- a/src/corelib/kernel/qvariant.h
+++ b/src/corelib/kernel/qvariant.h
@@ -53,7 +53,7 @@
 #include <QtCore/qbytearraylist.h>
 #endif
 
-#if QT_HAS_INCLUDE(<variant>) && __cplusplus >= 201703L
+#if __has_include(<variant>) && __cplusplus >= 201703L
 #include <variant>
 #elif defined(Q_CLANG_QDOC)
 namespace std { template<typename...> struct variant; }
@@ -370,7 +370,7 @@ class Q_CORE_EXPORT QVariant
     static inline QVariant fromValue(const T &value)
     { return QVariant(qMetaTypeId<T>(), &value, QTypeInfo<T>::isPointer); }
 
-#if (QT_HAS_INCLUDE(<variant>) && __cplusplus >= 201703L) || defined(Q_CLANG_QDOC)
+#if (__has_include(<variant>) && __cplusplus >= 201703L) || defined(Q_CLANG_QDOC)
     template<typename... Types>
     static inline QVariant fromStdVariant(const std::variant<Types...> &value)
     {
@@ -546,7 +546,7 @@ inline QVariant QVariant::fromValue(const QVariant &value)
     return value;
 }
 
-#if QT_HAS_INCLUDE(<variant>) && __cplusplus >= 201703L
+#if __has_include(<variant>) && __cplusplus >= 201703L
 template<>
 inline QVariant QVariant::fromValue(const std::monostate &)
 {
diff --git a/src/corelib/serialization/qcborarray.h b/src/corelib/serialization/qcborarray.h
index e06544f245..fe06b8630f 100644
--- a/src/corelib/serialization/qcborarray.h
+++ b/src/corelib/serialization/qcborarray.h
@@ -214,7 +214,7 @@ public:
     bool contains(const QCborValue &value) const;
 
     int compare(const QCborArray &other) const noexcept Q_DECL_PURE_FUNCTION;
-#if 0 && QT_HAS_INCLUDE(<compare>)
+#if 0 && __has_include(<compare>)
     std::strong_ordering operator<=>(const QCborArray &other) const
     {
         int c = compare(other);
diff --git a/src/corelib/serialization/qcbormap.h b/src/corelib/serialization/qcbormap.h
index 4aea901eef..6636ce776a 100644
--- a/src/corelib/serialization/qcbormap.h
+++ b/src/corelib/serialization/qcbormap.h
@@ -245,7 +245,7 @@ public:
     { const_iterator it = find(key); return it != end(); }
 
     int compare(const QCborMap &other) const noexcept Q_DECL_PURE_FUNCTION;
-#if 0 && QT_HAS_INCLUDE(<compare>)
+#if 0 && __has_include(<compare>)
     std::strong_ordering operator<=>(const QCborMap &other) const
     {
         int c = compare(other);
diff --git a/src/corelib/serialization/qcborvalue.h b/src/corelib/serialization/qcborvalue.h
index 9c613dfcfb..071213e83a 100644
--- a/src/corelib/serialization/qcborvalue.h
+++ b/src/corelib/serialization/qcborvalue.h
@@ -59,7 +59,7 @@
 #  undef False
 #endif
 
-#if 0 && QT_HAS_INCLUDE(<compare>)
+#if 0 && __has_include(<compare>)
 #  include <compare>
 #endif
 
@@ -265,7 +265,7 @@ public:
     QCborValueRef operator[](const QString & key);
 
     int compare(const QCborValue &other) const;
-#if 0 && QT_HAS_INCLUDE(<compare>)
+#if 0 && __has_include(<compare>)
     std::strong_ordering operator<=>(const QCborValue &other) const
     {
         int c = compare(other);
@@ -421,7 +421,7 @@ public:
 
     int compare(const QCborValue &other) const
     { return concrete().compare(other); }
-#if 0 && QT_HAS_INCLUDE(<compare>)
+#if 0 && __has_include(<compare>)
     std::strong_ordering operator<=>(const QCborValue &other) const
     {
         int c = compare(other);
diff --git a/src/corelib/serialization/qcborvalue_p.h b/src/corelib/serialization/qcborvalue_p.h
index 590c2d6e05..48818e4c63 100644
--- a/src/corelib/serialization/qcborvalue_p.h
+++ b/src/corelib/serialization/qcborvalue_p.h
@@ -196,8 +196,7 @@ public:
         if (value.container)
             return replaceAt_complex(e, value, disp);
 
-        e.value = value.value_helper();
-        e.type = value.type();
+        e = { value.value_helper(), value.type() };
         if (value.isContainer())
             e.container = nullptr;
     }
diff --git a/src/corelib/text/qbytearray.cpp b/src/corelib/text/qbytearray.cpp
index 5a61d7f70d..94d22e288e 100644
--- a/src/corelib/text/qbytearray.cpp
+++ b/src/corelib/text/qbytearray.cpp
@@ -334,7 +334,7 @@ int qstricmp(const char *str1, const char *str2)
         return int(Incomplete);
     };
 
-#if defined(__SSE4_1__) && !(defined(__SANITIZE_ADDRESS__) || QT_HAS_FEATURE(address_sanitizer))
+#if defined(__SSE4_1__) && !(defined(__SANITIZE_ADDRESS__) || __has_feature(address_sanitizer))
     enum { PageSize = 4096, PageMask = PageSize - 1 };
     const __m128i zero = _mm_setzero_si128();
     forever {
diff --git a/src/corelib/text/qbytearray.h b/src/corelib/text/qbytearray.h
index 4fa17cf58b..36cf580cd9 100644
--- a/src/corelib/text/qbytearray.h
+++ b/src/corelib/text/qbytearray.h
@@ -264,7 +264,7 @@ public:
     void chop(int n);
 
 #if defined(Q_COMPILER_REF_QUALIFIERS) && !defined(QT_COMPILING_QSTRING_COMPAT_CPP) && !defined(Q_CLANG_QDOC)
-#  if defined(Q_CC_GNU) && !defined(Q_CC_CLANG) && !defined(Q_CC_INTEL) && !QT_HAS_CPP_ATTRIBUTE(nodiscard)
+#  if defined(Q_CC_GNU) && !defined(Q_CC_CLANG) && !defined(Q_CC_INTEL) && !__has_cpp_attribute(nodiscard)
     // required due to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61941
 #    pragma push_macro("Q_REQUIRED_RESULT")
 #    undef Q_REQUIRED_RESULT
diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
index 51aa0b7512..4d83f19db7 100644
--- a/src/corelib/text/qstring.cpp
+++ b/src/corelib/text/qstring.cpp
@@ -146,6 +146,9 @@ qsizetype qFindStringBoyerMoore(QStringView haystack, qsizetype from, QStringVie
 static inline qsizetype qFindChar(QStringView str, QChar ch, qsizetype from, Qt::CaseSensitivity cs) noexcept;
 template <typename Haystack>
 static inline qsizetype qLastIndexOf(Haystack haystack, QChar needle, qsizetype from, Qt::CaseSensitivity cs) noexcept;
+template <>
+inline qsizetype qLastIndexOf(QString haystack, QChar needle,
+                              qsizetype from, Qt::CaseSensitivity cs) noexcept = delete; // unwanted, would detach
 static inline qsizetype qt_string_count(QStringView haystack, QStringView needle, Qt::CaseSensitivity cs);
 static inline qsizetype qt_string_count(QStringView haystack, QChar needle, Qt::CaseSensitivity cs);
 
@@ -3817,7 +3820,7 @@ int QString::indexOf(const QStringRef &str, int from, Qt::CaseSensitivity cs) co
 int QString::lastIndexOf(const QString &str, int from, Qt::CaseSensitivity cs) const
 {
     // ### Qt6: qsizetype
-    return int(QtPrivate::lastIndexOf(*this, from, str, cs));
+    return int(QtPrivate::lastIndexOf(QStringView(*this), from, str, cs));
 }
 
 #endif // QT_STRINGVIEW_LEVEL < 2
@@ -3856,7 +3859,7 @@ int QString::lastIndexOf(QLatin1String str, int from, Qt::CaseSensitivity cs) co
 int QString::lastIndexOf(QChar ch, int from, Qt::CaseSensitivity cs) const
 {
     // ### Qt6: qsizetype
-    return int(qLastIndexOf(*this, ch, from, cs));
+    return int(qLastIndexOf(QStringView(*this), ch, from, cs));
 }
 
 #if QT_STRINGVIEW_LEVEL < 2
diff --git a/src/corelib/text/qstring.h b/src/corelib/text/qstring.h
index 5def2c81a1..1669d7c94a 100644
--- a/src/corelib/text/qstring.h
+++ b/src/corelib/text/qstring.h
@@ -487,7 +487,7 @@ public:
     Q_REQUIRED_RESULT QString rightJustified(int width, QChar fill = QLatin1Char(' '), bool trunc = false) const;
 
 #if defined(Q_COMPILER_REF_QUALIFIERS) && !defined(QT_COMPILING_QSTRING_COMPAT_CPP) && !defined(Q_CLANG_QDOC)
-#  if defined(Q_CC_GNU) && !defined(Q_CC_CLANG) && !defined(Q_CC_INTEL) && !QT_HAS_CPP_ATTRIBUTE(nodiscard)
+#  if defined(Q_CC_GNU) && !defined(Q_CC_CLANG) && !defined(Q_CC_INTEL) && !__has_cpp_attribute(nodiscard)
     // required due to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61941
 #    pragma push_macro("Q_REQUIRED_RESULT")
 #    undef Q_REQUIRED_RESULT
diff --git a/src/corelib/thread/qfutex_p.h b/src/corelib/thread/qfutex_p.h
index 7bec4554b7..f287b752d7 100644
--- a/src/corelib/thread/qfutex_p.h
+++ b/src/corelib/thread/qfutex_p.h
@@ -81,7 +81,7 @@ QT_END_NAMESPACE
 // if not defined in linux/futex.h
 #  define FUTEX_PRIVATE_FLAG        128         // added in v2.6.22
 
-#  if QT_HAS_FEATURE(thread_sanitizer) || defined(__SANITIZE_THREAD__)
+#  if __has_feature(thread_sanitizer) || defined(__SANITIZE_THREAD__)
 #    include <sanitizer/tsan_interface.h>
 inline void _q_tsan_acquire(void *addr, void *addr2)
 {
@@ -98,7 +98,7 @@ inline void _q_tsan_release(void *addr, void *addr2)
 #  else
 inline void _q_tsan_acquire(void *, void *) {}
 inline void _q_tsan_release(void *, void *) {}
-#  endif // QT_HAS_FEATURE(thread_sanitizer) || defined(__SANITIZE_THREAD__)
+#  endif // __has_feature(thread_sanitizer) || defined(__SANITIZE_THREAD__)
 
 QT_BEGIN_NAMESPACE
 namespace QtLinuxFutex {
diff --git a/src/corelib/thread/qmutex.h b/src/corelib/thread/qmutex.h
index c693ff65d8..93c4bf23e8 100644
--- a/src/corelib/thread/qmutex.h
+++ b/src/corelib/thread/qmutex.h
@@ -44,7 +44,7 @@
 #include <QtCore/qatomic.h>
 #include <new>
 
-#if QT_HAS_INCLUDE(<chrono>)
+#if __has_include(<chrono>)
 #  include <chrono>
 #  include <limits>
 #endif
@@ -147,7 +147,7 @@ public:
     // Lockable concept
     bool try_lock() QT_MUTEX_LOCK_NOEXCEPT { return tryLock(); }
 
-#if QT_HAS_INCLUDE(<chrono>) || defined(Q_CLANG_QDOC)
+#if __has_include(<chrono>) || defined(Q_CLANG_QDOC)
     // TimedLockable concept
     template <class Rep, class Period>
     bool try_lock_for(std::chrono::duration<Rep, Period> duration)
@@ -175,7 +175,7 @@ private:
     friend class QRecursiveMutex;
     friend class ::tst_QMutex;
 
-#if QT_HAS_INCLUDE(<chrono>)
+#if __has_include(<chrono>)
     template<class Rep, class Period>
     static int convertToMilliseconds(std::chrono::duration<Rep, Period> duration)
     {
@@ -213,7 +213,7 @@ public:
     using QMutex::tryLock;
     using QMutex::unlock;
     using QMutex::try_lock;
-#if QT_HAS_INCLUDE(<chrono>)
+#if __has_include(<chrono>)
     using QMutex::try_lock_for;
     using QMutex::try_lock_until;
 #endif
@@ -295,7 +295,7 @@ public:
     inline void unlock() noexcept {}
     inline bool isRecursive() const noexcept { return true; }
 
-#if QT_HAS_INCLUDE(<chrono>)
+#if __has_include(<chrono>)
     template <class Rep, class Period>
     inline bool try_lock_for(std::chrono::duration<Rep, Period> duration) noexcept
     {
diff --git a/src/corelib/time/qdatetime.cpp b/src/corelib/time/qdatetime.cpp
index 979b8c9aeb..d2d09ceee6 100644
--- a/src/corelib/time/qdatetime.cpp
+++ b/src/corelib/time/qdatetime.cpp
@@ -127,7 +127,7 @@ static const char qt_shortMonthNames[][4] = {
     "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
 };
 
-static int qt_monthNumberFromShortName(QStringRef shortName)
+static int qt_monthNumberFromShortName(QStringView shortName)
 {
     for (unsigned int i = 0; i < sizeof(qt_shortMonthNames) / sizeof(qt_shortMonthNames[0]); ++i) {
         if (shortName == QLatin1String(qt_shortMonthNames[i], 3))
@@ -136,9 +136,9 @@ static int qt_monthNumberFromShortName(QStringRef shortName)
     return -1;
 }
 static int qt_monthNumberFromShortName(const QString &shortName)
-{ return qt_monthNumberFromShortName(QStringRef(&shortName)); }
+{ return qt_monthNumberFromShortName(QStringView(shortName)); }
 
-static int fromShortMonthName(const QStringRef &monthName, int year)
+static int fromShortMonthName(QStringView monthName, int year)
 {
     // Assume that English monthnames are the default
     int month = qt_monthNumberFromShortName(monthName);
@@ -207,7 +207,7 @@ static QString toOffsetString(Qt::DateFormat format, int offset)
 
 #if QT_CONFIG(datestring)
 // Parse offset in [+-]HH[[:]mm] format
-static int fromOffsetString(const QStringRef &offsetString, bool *valid) noexcept
+static int fromOffsetString(QStringView offsetString, bool *valid) noexcept
 {
     *valid = false;
 
@@ -228,22 +228,23 @@ static int fromOffsetString(const QStringRef &offsetString, bool *valid) noexcep
         return 0;
 
     // Split the hour and minute parts
-    const QStringRef time = offsetString.mid(1);
-    int hhLen = time.indexOf(QLatin1Char(':'));
-    int mmIndex;
+    const QStringView time = offsetString.mid(1);
+    qsizetype hhLen = time.indexOf(QLatin1Char(':'));
+    qsizetype mmIndex;
     if (hhLen == -1)
         mmIndex = hhLen = 2; // [+-]HHmm or [+-]HH format
     else
         mmIndex = hhLen + 1;
 
-    const QStringRef hhRef = time.left(hhLen);
+    const QLocale C = QLocale::c();
+    const QStringView hhRef = time.left(qMin(hhLen, time.size()));
     bool ok = false;
-    const int hour = hhRef.toInt(&ok);
+    const int hour = C.toInt(hhRef, &ok);
     if (!ok)
         return 0;
 
-    const QStringRef mmRef = time.mid(mmIndex);
-    const int minute = mmRef.isEmpty() ? 0 : mmRef.toInt(&ok);
+    const QStringView mmRef = time.mid(qMin(mmIndex, time.size()));
+    const int minute = mmRef.isEmpty() ? 0 : C.toInt(mmRef, &ok);
     if (!ok || minute < 0 || minute > 59)
         return 0;
 
@@ -2324,7 +2325,7 @@ int QTime::msecsTo(const QTime &t) const
 
 #if QT_CONFIG(datestring)
 
-static QTime fromIsoTimeString(const QStringRef &string, Qt::DateFormat format, bool *isMidnight24)
+static QTime fromIsoTimeString(QStringView string, Qt::DateFormat format, bool *isMidnight24)
 {
     if (isMidnight24)
         *isMidnight24 = false;
@@ -2333,11 +2334,12 @@ static QTime fromIsoTimeString(const QStringRef &string, Qt::DateFormat format,
     if (size < 5)
         return QTime();
 
+    const QLocale C(QLocale::c());
     bool ok = false;
-    int hour = string.mid(0, 2).toInt(&ok);
+    int hour = C.toInt(string.mid(0, 2), &ok);
     if (!ok)
         return QTime();
-    const int minute = string.mid(3, 2).toInt(&ok);
+    const int minute = C.toInt(string.mid(3, 2), &ok);
     if (!ok)
         return QTime();
     int second = 0;
@@ -2358,11 +2360,11 @@ static QTime fromIsoTimeString(const QStringRef &string, Qt::DateFormat format,
         // seconds is 4. E.g. 12:34,99999 will expand to 12:34:59.9994. The milliseconds
         // will then be rounded up AND clamped to 999.
 
-        const QStringRef minuteFractionStr = string.mid(6, 5);
-        const long minuteFractionInt = minuteFractionStr.toLong(&ok);
+        const QStringView minuteFractionStr = string.mid(6, qMin(qsizetype(5), string.size() - 6));
+        const long minuteFractionInt = C.toLong(minuteFractionStr, &ok);
         if (!ok)
             return QTime();
-        const float minuteFraction = double(minuteFractionInt) / (std::pow(double(10), minuteFractionStr.count()));
+        const float minuteFraction = double(minuteFractionInt) / (std::pow(double(10), minuteFractionStr.size()));
 
         const float secondWithMs = minuteFraction * 60;
         const float secondNoMs = std::floor(secondWithMs);
@@ -2371,15 +2373,20 @@ static QTime fromIsoTimeString(const QStringRef &string, Qt::DateFormat format,
         msec = qMin(qRound(secondFraction * 1000.0), 999);
     } else {
         // HH:mm:ss or HH:mm:ss.zzz
-        second = string.mid(6, 2).toInt(&ok);
+        second = C.toInt(string.mid(6, qMin(qsizetype(2), string.size() - 6)), &ok);
         if (!ok)
             return QTime();
         if (size > 8 && (string.at(8) == QLatin1Char(',') || string.at(8) == QLatin1Char('.'))) {
-            const QStringRef msecStr(string.mid(9, 4));
-            int msecInt = msecStr.isEmpty() ? 0 : msecStr.toInt(&ok);
+            QStringView msecStr(string.mid(9, qMin(qsizetype(4), string.size() - 9)));
+            // toInt() ignores leading spaces, so catch them before calling it
+            if (!msecStr.isEmpty() && !msecStr.at(0).isDigit())
+                return QTime();
+            // We do, however, want to ignore *trailing* spaces.
+            msecStr = msecStr.trimmed();
+            int msecInt = msecStr.isEmpty() ? 0 : C.toInt(msecStr, &ok);
             if (!ok)
                 return QTime();
-            const double secondFraction(msecInt / (std::pow(double(10), msecStr.count())));
+            const double secondFraction(msecInt / (std::pow(double(10), msecStr.size())));
             msec = qMin(qRound(secondFraction * 1000.0), 999);
         }
     }
@@ -2428,7 +2435,7 @@ QTime QTime::fromString(const QString &string, Qt::DateFormat format)
     case Qt::ISODateWithMs:
     case Qt::TextDate:
     default:
-        return fromIsoTimeString(QStringRef(&string), format, nullptr);
+        return fromIsoTimeString(QStringView(string), format, nullptr);
     }
 }
 
@@ -3410,6 +3417,7 @@ inline qint64 QDateTimePrivate::zoneMSecsToEpochMSecs(qint64 zoneMSecs, const QT
                                                       DaylightStatus hint,
                                                       QDate *zoneDate, QTime *zoneTime)
 {
+    Q_ASSERT(zone.isValid());
     // Get the effective data from QTimeZone
     QTimeZonePrivate::Data data = zone.d->dataForLocalTime(zoneMSecs, int(hint));
     // Docs state any time before 1970-01-01 will *not* have any DST applied
@@ -3799,8 +3807,9 @@ QTimeZone QDateTime::timeZone() const
     case Qt::OffsetFromUTC:
         return QTimeZone(d->m_offsetFromUtc);
     case Qt::TimeZone:
-        Q_ASSERT(d->m_timeZone.isValid());
-        return d->m_timeZone;
+        if (d->m_timeZone.isValid())
+            return d->m_timeZone;
+        break;
     case Qt::LocalTime:
         return QTimeZone::systemTimeZone();
     }
@@ -3884,6 +3893,7 @@ QString QDateTime::timeZoneAbbreviation() const
 #if !QT_CONFIG(timezone)
         break;
 #else
+        Q_ASSERT(d->m_timeZone.isValid());
         return d->m_timeZone.d->abbreviation(toMSecsSinceEpoch());
 #endif // timezone
     case Qt::LocalTime:  {
@@ -3920,6 +3930,7 @@ bool QDateTime::isDaylightTime() const
 #if !QT_CONFIG(timezone)
         break;
 #else
+        Q_ASSERT(d->m_timeZone.isValid());
         return d->m_timeZone.d->isDaylightTime(toMSecsSinceEpoch());
 #endif // timezone
     case Qt::LocalTime: {
@@ -4044,6 +4055,10 @@ void QDateTime::setTimeZone(const QTimeZone &toZone)
 */
 qint64 QDateTime::toMSecsSinceEpoch() const
 {
+    // Note: QDateTimeParser relies on this producing a useful result, even when
+    // !isValid(), at least when the invalidity is a time in a fall-back (that
+    // we'll have adjusted to lie outside it, but marked invalid because it's
+    // not what was asked for). Other things may be doing similar.
     switch (getSpec(d)) {
     case Qt::UTC:
         return getMSecs(d);
@@ -4058,12 +4073,13 @@ qint64 QDateTime::toMSecsSinceEpoch() const
     }
 
     case Qt::TimeZone:
-#if !QT_CONFIG(timezone)
-        return 0;
-#else
-        return QDateTimePrivate::zoneMSecsToEpochMSecs(d->m_msecs, d->m_timeZone,
-                                                       extractDaylightStatus(getStatus(d)));
+#if QT_CONFIG(timezone)
+        if (d->m_timeZone.isValid()) {
+            return QDateTimePrivate::zoneMSecsToEpochMSecs(d->m_msecs, d->m_timeZone,
+                                                           extractDaylightStatus(getStatus(d)));
+        }
 #endif
+        return 0;
     }
     Q_UNREACHABLE();
     return 0;
@@ -4158,9 +4174,11 @@ void QDateTime::setMSecsSinceEpoch(qint64 msecs)
     case Qt::TimeZone:
         Q_ASSERT(!d.isShort());
 #if QT_CONFIG(timezone)
+        d.detach();
+        if (!d->m_timeZone.isValid())
+            break;
         // Docs state any LocalTime before 1970-01-01 will *not* have any DST applied
         // but all affected times afterwards will have DST applied.
-        d.detach();
         if (msecs >= 0) {
             status = mergeDaylightStatus(status,
                                          d->m_timeZone.d->isDaylightTime(msecs)
@@ -4433,7 +4451,7 @@ static inline void massageAdjustedDateTime(const QDateTimeData &d, QDate *date,
         QDateTimePrivate::DaylightStatus status = QDateTimePrivate::UnknownDaylightTime;
         localMSecsToEpochMSecs(timeToMSecs(*date, *time), &status, date, time);
 #if QT_CONFIG(timezone)
-    } else if (spec == Qt::TimeZone) {
+    } else if (spec == Qt::TimeZone && d->m_timeZone.isValid()) {
         QDateTimePrivate::zoneMSecsToEpochMSecs(timeToMSecs(*date, *time),
                                                 d->m_timeZone,
                                                 QDateTimePrivate::UnknownDaylightTime,
@@ -5094,7 +5112,8 @@ QDateTime QDateTime::fromMSecsSinceEpoch(qint64 msecs, const QTimeZone &timeZone
 {
     QDateTime dt;
     dt.setTimeZone(timeZone);
-    dt.setMSecsSinceEpoch(msecs);
+    if (timeZone.isValid())
+        dt.setMSecsSinceEpoch(msecs);
     return dt;
 }
 
@@ -5197,16 +5216,17 @@ QDateTime QDateTime::fromString(const QString &string, Qt::DateFormat format)
         if (!date.isValid())
             return QDateTime();
         if (size == 10)
-            return QDateTime(date);
+            return date.startOfDay();
 
         Qt::TimeSpec spec = Qt::LocalTime;
-        QStringRef isoString(&string);
-        isoString = isoString.mid(10); // trim "yyyy-MM-dd"
+        QStringView isoString = QStringView(string).mid(10); // trim "yyyy-MM-dd"
 
-        // Must be left with T and at least one digit for the hour:
+        // Must be left with T (or space) and at least one digit for the hour:
         if (isoString.size() < 2
-            || !(isoString.startsWith(QLatin1Char('T'))
-                 // FIXME: QSql relies on QVariant::toDateTime() accepting a space here:
+            || !(isoString.startsWith(QLatin1Char('T'), Qt::CaseInsensitive)
+                 // RFC 3339 (section 5.6) allows a space here.  (It actually
+                 // allows any separator one considers more readable, merely
+                 // giving space as an example - but let's not go wild !)
                  || isoString.startsWith(QLatin1Char(' ')))) {
             return QDateTime();
         }
@@ -5214,7 +5234,7 @@ QDateTime QDateTime::fromString(const QString &string, Qt::DateFormat format)
 
         int offset = 0;
         // Check end of string for Time Zone definition, either Z for UTC or [+-]HH:mm for Offset
-        if (isoString.endsWith(QLatin1Char('Z'))) {
+        if (isoString.endsWith(QLatin1Char('Z'), Qt::CaseInsensitive)) {
             spec = Qt::UTC;
             isoString.chop(1); // trim 'Z'
         } else {
@@ -5345,7 +5365,7 @@ QDateTime QDateTime::fromString(const QString &string, Qt::DateFormat format)
         if (parts.count() == 5)
             return QDateTime(date, time, Qt::LocalTime);
 
-        QStringRef tz = parts.at(5);
+        QStringView tz = parts.at(5);
         if (!tz.startsWith(QLatin1String("GMT"), Qt::CaseInsensitive))
             return QDateTime();
         tz = tz.mid(3);
diff --git a/src/corelib/time/qdatetimeparser.cpp b/src/corelib/time/qdatetimeparser.cpp
index a487534528..fa0884c827 100644
--- a/src/corelib/time/qdatetimeparser.cpp
+++ b/src/corelib/time/qdatetimeparser.cpp
@@ -1363,7 +1363,7 @@ QDateTimeParser::scanString(const QDateTime &defaultValue,
     // given date (which might be a spring-forward, skipping an hour).
     if (parserType == QVariant::DateTime && !(isSet & HourSectionMask) && !when.isValid()) {
         qint64 msecs = when.toMSecsSinceEpoch();
-        // Fortunately, that gets a useful answer ...
+        // Fortunately, that gets a useful answer, even though when is invalid ...
         const QDateTime replace =
 #if QT_CONFIG(timezone)
             tspec == Qt::TimeZone
diff --git a/src/corelib/time/qtimezoneprivate.cpp b/src/corelib/time/qtimezoneprivate.cpp
index 7d6ef0a404..facdf6661d 100644
--- a/src/corelib/time/qtimezoneprivate.cpp
+++ b/src/corelib/time/qtimezoneprivate.cpp
@@ -381,18 +381,15 @@ QTimeZonePrivate::Data QTimeZonePrivate::dataForLocalTime(qint64 forLocalMSecs,
                   On the first pass, the case we consider is what hint told us to expect
                   (except when hint was -1 and didn't actually tell us what to expect),
                   so it's likely right.  We only get a second pass if the first failed,
-                  by which time the second case, that we're trying, is likely right.  If
-                  an overwhelming majority of calls have hint == -1, the Q_LIKELY here
-                  shall be wrong half the time; otherwise, its errors shall be rarer
-                  than that.
+                  by which time the second case, that we're trying, is likely right.
                 */
                 if (nextFirst ? i == 0 : i) {
                     Q_ASSERT(nextStart != invalidMSecs());
-                    if (Q_LIKELY(nextStart <= nextTran.atMSecsSinceEpoch))
+                    if (nextStart <= nextTran.atMSecsSinceEpoch)
                         return nextTran;
                 } else {
                     // If next is invalid, nextFirst is false, to route us here first:
-                    if (nextStart == invalidMSecs() || Q_LIKELY(nextStart > tran.atMSecsSinceEpoch))
+                    if (nextStart == invalidMSecs() || nextStart > tran.atMSecsSinceEpoch)
                         return tran;
                 }
             }
@@ -421,7 +418,7 @@ QTimeZonePrivate::Data QTimeZonePrivate::dataForLocalTime(qint64 forLocalMSecs,
 
     int early = offsetFromUtc(recent);
     int late = offsetFromUtc(imminent);
-    if (Q_LIKELY(early == late)) { // > 99% of the time
+    if (early == late) { // > 99% of the time
         utcEpochMSecs = forLocalMSecs - early * 1000;
     } else {
         // Close to a DST transition: early > late is near a fall-back,
@@ -433,7 +430,7 @@ QTimeZonePrivate::Data QTimeZonePrivate::dataForLocalTime(qint64 forLocalMSecs,
         const qint64 forStd = forLocalMSecs - offsetInStd * 1000;
         // Best guess at the answer:
         const qint64 hinted = hint > 0 ? forDst : forStd;
-        if (Q_LIKELY(offsetFromUtc(hinted) == (hint > 0 ? offsetInDst : offsetInStd))) {
+        if (offsetFromUtc(hinted) == (hint > 0 ? offsetInDst : offsetInStd)) {
             utcEpochMSecs = hinted;
         } else if (hint <= 0 && offsetFromUtc(forDst) == offsetInDst) {
             utcEpochMSecs = forDst;
diff --git a/src/corelib/tools/qalgorithms.h b/src/corelib/tools/qalgorithms.h
index b01ce0db58..aa79e0d4a9 100644
--- a/src/corelib/tools/qalgorithms.h
+++ b/src/corelib/tools/qalgorithms.h
@@ -535,7 +535,7 @@ QT_DEPRECATED_X("Use std::binary_search") Q_OUTOFLINE_TEMPLATE RandomAccessItera
 #  define QT_HAS_BUILTIN_CTZS
 Q_DECL_CONSTEXPR Q_ALWAYS_INLINE uint qt_builtin_ctzs(quint16 v) noexcept
 {
-#  if QT_HAS_BUILTIN(__builtin_ctzs)
+#  if __has_builtin(__builtin_ctzs)
     return __builtin_ctzs(v);
 #  else
     return __builtin_ctz(v);
@@ -544,7 +544,7 @@ Q_DECL_CONSTEXPR Q_ALWAYS_INLINE uint qt_builtin_ctzs(quint16 v) noexcept
 #define QT_HAS_BUILTIN_CLZS
 Q_DECL_CONSTEXPR Q_ALWAYS_INLINE uint qt_builtin_clzs(quint16 v) noexcept
 {
-#  if QT_HAS_BUILTIN(__builtin_clzs)
+#  if __has_builtin(__builtin_clzs)
     return __builtin_clzs(v);
 #  else
     return __builtin_clz(v) - 16U;
diff --git a/src/corelib/tools/qscopeguard.h b/src/corelib/tools/qscopeguard.h
index 45c3f93da4..40d2747b1d 100644
--- a/src/corelib/tools/qscopeguard.h
+++ b/src/corelib/tools/qscopeguard.h
@@ -51,7 +51,7 @@ template <typename F> QScopeGuard<F> qScopeGuard(F f);
 
 template <typename F>
 class
-#if QT_HAS_CPP_ATTRIBUTE(nodiscard)
+#if __has_cpp_attribute(nodiscard)
 // Q_REQUIRED_RESULT can be defined as __warn_unused_result__ or as [[nodiscard]]
 // but the 1st one has some limitations for example can be placed only on functions.
 Q_REQUIRED_RESULT
@@ -91,7 +91,7 @@ private:
 
 
 template <typename F>
-#if QT_HAS_CPP_ATTRIBUTE(nodiscard)
+#if __has_cpp_attribute(nodiscard)
 Q_REQUIRED_RESULT
 #endif
 QScopeGuard<F> qScopeGuard(F f)