6 files changed, 53 insertions, 9 deletions
diff --git a/src/corelib/global/qcompilerdetection.h b/src/corelib/global/qcompilerdetection.h
index d8a44655dd..d759548fbc 100644
--- a/src/corelib/global/qcompilerdetection.h
+++ b/src/corelib/global/qcompilerdetection.h
@@ -1259,7 +1259,11 @@
  * "Weak overloads" - makes an otherwise confliciting overload weaker
  * (by making it a template)
  */
-#define Q_WEAK_OVERLOAD template <typename = void>
+#ifndef Q_CLANG_QDOC
+#  define Q_WEAK_OVERLOAD template <typename = void>
+#else
+#  define Q_WEAK_OVERLOAD
+#endif
 
 /*
  * Warning/diagnostic handling
diff --git a/src/corelib/global/qendian.h b/src/corelib/global/qendian.h
index a97776c761..e9e51c4b93 100644
--- a/src/corelib/global/qendian.h
+++ b/src/corelib/global/qendian.h
@@ -372,8 +372,8 @@ public:
     QLEInteger &operator ^=(T i);
     QLEInteger &operator ++();
     QLEInteger &operator --();
-    QLEInteger &operator ++(int);
-    QLEInteger &operator --(int);
+    QLEInteger operator ++(int);
+    QLEInteger operator --(int);
 
     static Q_DECL_CONSTEXPR QLEInteger max();
     static Q_DECL_CONSTEXPR QLEInteger min();
@@ -399,8 +399,8 @@ public:
     QBEInteger &operator ^=(T i);
     QBEInteger &operator ++();
     QBEInteger &operator --();
-    QBEInteger &operator ++(int);
-    QBEInteger &operator --(int);
+    QBEInteger operator ++(int);
+    QBEInteger operator --(int);
 
     static Q_DECL_CONSTEXPR QBEInteger max();
     static Q_DECL_CONSTEXPR QBEInteger min();
diff --git a/src/corelib/global/qflags.h b/src/corelib/global/qflags.h
index 4f46de5eaa..0fb0f8c6ae 100644
--- a/src/corelib/global/qflags.h
+++ b/src/corelib/global/qflags.h
@@ -192,6 +192,33 @@ typedef uint Flags;
 
 #endif /* Q_NO_TYPESAFE_FLAGS */
 
+// restore bit-wise enum-enum operators deprecated in C++20,
+// but used in a few places in the API
+#if __cplusplus > 201702L // assume compilers don't warn if in C++17 mode
+  // in C++20 mode, provide user-defined operators to override the deprecated operations:
+# define Q_DECLARE_MIXED_ENUM_OPERATOR(op, Ret, LHS, RHS) \
+    constexpr inline Ret operator op (LHS lhs, RHS rhs) noexcept \
+    { return static_cast<Ret>(std::underlying_type_t<LHS>(lhs) op std::underlying_type_t<RHS>(rhs)); } \
+    /* end */
+#else
+  // in C++11-17 mode, statically-assert that this compiler's result of the
+  // operation is the same that the C++20 version would produce:
+# define Q_DECLARE_MIXED_ENUM_OPERATOR(op, Ret, LHS, RHS) \
+    Q_STATIC_ASSERT((std::is_same<decltype(std::declval<LHS>() op std::declval<RHS>()), Ret>::value));
+#endif
+
+#define Q_DECLARE_MIXED_ENUM_OPERATORS(Ret, Flags, Enum) \
+    Q_DECLARE_MIXED_ENUM_OPERATOR(|, Ret, Flags, Enum) \
+    Q_DECLARE_MIXED_ENUM_OPERATOR(&, Ret, Flags, Enum) \
+    Q_DECLARE_MIXED_ENUM_OPERATOR(^, Ret, Flags, Enum) \
+    /* end */
+
+#define Q_DECLARE_MIXED_ENUM_OPERATORS_SYMMETRIC(Ret, Flags, Enum) \
+    Q_DECLARE_MIXED_ENUM_OPERATORS(Ret, Flags, Enum) \
+    Q_DECLARE_MIXED_ENUM_OPERATORS(Ret, Enum, Flags) \
+    /* end */
+
+
 QT_END_NAMESPACE
 
 #endif // QFLAGS_H
diff --git a/src/corelib/global/qglobal.cpp b/src/corelib/global/qglobal.cpp
index ac2e85c51e..5ad82c259d 100644
--- a/src/corelib/global/qglobal.cpp
+++ b/src/corelib/global/qglobal.cpp
@@ -3077,7 +3077,8 @@ QByteArray QSysInfo::machineUniqueId()
 {
 #if defined(Q_OS_DARWIN) && __has_include(<IOKit/IOKitLib.h>)
     char uuid[UuidStringLen + 1];
-    io_service_t service = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("IOPlatformExpertDevice"));
+    static const mach_port_t defaultPort = 0; // Effectively kIOMasterPortDefault/kIOMainPortDefault
+    io_service_t service = IOServiceGetMatchingService(defaultPort, IOServiceMatching("IOPlatformExpertDevice"));
     QCFString stringRef = (CFStringRef)IORegistryEntryCreateCFProperty(service, CFSTR(kIOPlatformUUIDKey), kCFAllocatorDefault, 0);
     CFStringGetCString(stringRef, uuid, sizeof(uuid), kCFStringEncodingMacRoman);
     return QByteArray(uuid);
@@ -3722,6 +3723,15 @@ bool qEnvironmentVariableIsSet(const char *varName) noexcept
 */
 bool qputenv(const char *varName, const QByteArray& value)
 {
+    // protect against non-NUL-terminated QByteArrays:
+    #define IS_RAW_DATA(d) ((d)->offset != sizeof(QByteArrayData)) // copied from qbytearray.cpp
+    if (IS_RAW_DATA(const_cast<QByteArray&>(value).data_ptr())) {
+        QByteArray copy(value);
+        copy.detach(); // ensures NUL termination
+        return qputenv(varName, copy);
+    }
+    #undef IS_RAW_DATA
+
     const auto locker = qt_scoped_lock(environmentMutex);
 #if defined(Q_CC_MSVC)
     return _putenv_s(varName, value.constData()) == 0;
diff --git a/src/corelib/global/qnamespace.h b/src/corelib/global/qnamespace.h
index ad4150b317..deab11f729 100644
--- a/src/corelib/global/qnamespace.h
+++ b/src/corelib/global/qnamespace.h
@@ -235,9 +235,7 @@ public:
 
         AlignCenter = AlignVCenter | AlignHCenter
     };
-
     Q_DECLARE_FLAGS(Alignment, AlignmentFlag)
-    Q_DECLARE_OPERATORS_FOR_FLAGS(Alignment)
 
     enum TextFlag {
         TextSingleLine = 0x0100,
@@ -260,6 +258,10 @@ public:
         , TextBypassShaping = 0x100000
 #endif
     };
+    Q_DECLARE_MIXED_ENUM_OPERATORS_SYMMETRIC(int, AlignmentFlag, TextFlag)
+    // *After* we've defined the mixed operators (or verified their sanity),
+    // otherwise the operators defined here mess with the mixed ones:
+    Q_DECLARE_OPERATORS_FOR_FLAGS(Alignment)
 
     enum TextElideMode {
         ElideLeft,
@@ -267,6 +269,7 @@ public:
         ElideMiddle,
         ElideNone
     };
+    Q_DECLARE_MIXED_ENUM_OPERATORS_SYMMETRIC(int, TextElideMode, TextFlag)
 
     enum WhiteSpaceMode {
         WhiteSpaceNormal,
diff --git a/src/corelib/global/qrandom.cpp b/src/corelib/global/qrandom.cpp
index 25f87c7e6a..0f0409976d 100644
--- a/src/corelib/global/qrandom.cpp
+++ b/src/corelib/global/qrandom.cpp
@@ -680,7 +680,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel
    position in the deterministic sequence as the \a other object was. Both
    objects will generate the same sequence from this point on.
 
-   For that reason, it is not adviseable to create a copy of
+   For that reason, it is not advisable to create a copy of
    QRandomGenerator::global(). If one needs an exclusive deterministic
    generator, consider instead using securelySeeded() to obtain a new object
    that shares no relationship with the QRandomGenerator::global().