Use Q_DECL_CONSTEXPR in QFlags

Change-Id: I851e0b1c3f80a7b33a38cb1ab2665dc0f3c73adc
Reviewed-on: http://codereview.qt.nokia.com/1248
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Gabriel de Dietrich <gabriel.dietrich-de@nokia.com>
(cherry picked from commit c0c6dd2b022cfd667f32b8a48bcac86ac07d3880)

2 files changed, 43 insertions, 15 deletions

diff --git a/src/corelib/global/qglobal.h b/src/corelib/global/qglobal.h
index 1f5f537..892ae73 100644
--- a/src/corelib/global/qglobal.h
+++ b/src/corelib/global/qglobal.h
@@ -2267,9 +2267,9 @@ class QFlags
     int i;
 public:
     typedef Enum enum_type;
-    inline QFlags(const QFlags &f) : i(f.i) {}
-    inline QFlags(Enum f) : i(f) {}
-    inline QFlags(Zero = 0) : i(0) {}
+    Q_DECL_CONSTEXPR inline QFlags(const QFlags &f) : i(f.i) {}
+    Q_DECL_CONSTEXPR inline QFlags(Enum f) : i(f) {}
+    Q_DECL_CONSTEXPR inline QFlags(Zero = 0) : i(0) {}
     inline QFlags(QFlag f) : i(f) {}
 
     inline QFlags &operator=(const QFlags &f) { i = f.i; return *this; }
@@ -2280,18 +2280,18 @@ public:
     inline QFlags &operator^=(QFlags f) { i ^= f.i; return *this; }
     inline QFlags &operator^=(Enum f) { i ^= f; return *this; }
 
-    inline operator int() const { return i; }
+    Q_DECL_CONSTEXPR  inline operator int() const { return i; }
 
-    inline QFlags operator|(QFlags f) const { QFlags g; g.i = i | f.i; return g; }
-    inline QFlags operator|(Enum f) const { QFlags g; g.i = i | f; return g; }
-    inline QFlags operator^(QFlags f) const { QFlags g; g.i = i ^ f.i; return g; }
-    inline QFlags operator^(Enum f) const { QFlags g; g.i = i ^ f; return g; }
-    inline QFlags operator&(int mask) const { QFlags g; g.i = i & mask; return g; }
-    inline QFlags operator&(uint mask) const { QFlags g; g.i = i & mask; return g; }
-    inline QFlags operator&(Enum f) const { QFlags g; g.i = i & f; return g; }
-    inline QFlags operator~() const { QFlags g; g.i = ~i; return g; }
+    Q_DECL_CONSTEXPR inline QFlags operator|(QFlags f) const { return QFlags(Enum(i | f.i)); }
+    Q_DECL_CONSTEXPR inline QFlags operator|(Enum f) const { return QFlags(Enum(i | f)); }
+    Q_DECL_CONSTEXPR inline QFlags operator^(QFlags f) const { return QFlags(Enum(i ^ f.i)); }
+    Q_DECL_CONSTEXPR inline QFlags operator^(Enum f) const { return QFlags(Enum(i ^ f)); }
+    Q_DECL_CONSTEXPR inline QFlags operator&(int mask) const { return QFlags(Enum(i & mask)); }
+    Q_DECL_CONSTEXPR inline QFlags operator&(uint mask) const { return QFlags(Enum(i & mask)); }
+    Q_DECL_CONSTEXPR inline QFlags operator&(Enum f) const { return QFlags(Enum(i & f)); }
+    Q_DECL_CONSTEXPR inline QFlags operator~() const { return QFlags(Enum(~i)); }
 
-    inline bool operator!() const { return !i; }
+    Q_DECL_CONSTEXPR inline bool operator!() const { return !i; }
 
     inline bool testFlag(Enum f) const { return (i & f) == f && (f != 0 || i == int(f) ); }
 };
@@ -2304,9 +2304,9 @@ inline QIncompatibleFlag operator|(Flags::enum_type f1, int f2) \
 { return QIncompatibleFlag(int(f1) | f2); }
 
 #define Q_DECLARE_OPERATORS_FOR_FLAGS(Flags) \
-inline QFlags<Flags::enum_type> operator|(Flags::enum_type f1, Flags::enum_type f2) \
+Q_DECL_CONSTEXPR inline QFlags<Flags::enum_type> operator|(Flags::enum_type f1, Flags::enum_type f2) \
 { return QFlags<Flags::enum_type>(f1) | f2; } \
-inline QFlags<Flags::enum_type> operator|(Flags::enum_type f1, QFlags<Flags::enum_type> f2) \
+Q_DECL_CONSTEXPR inline QFlags<Flags::enum_type> operator|(Flags::enum_type f1, QFlags<Flags::enum_type> f2) \
 { return f2 | f1; } Q_DECLARE_INCOMPATIBLE_FLAGS(Flags)
 
 
diff --git a/tests/auto/qflags/tst_qflags.cpp b/tests/auto/qflags/tst_qflags.cpp
index 87025b6..85e64a6 100644
--- a/tests/auto/qflags/tst_qflags.cpp
+++ b/tests/auto/qflags/tst_qflags.cpp
@@ -47,6 +47,7 @@ private slots:
     void testFlag() const;
     void testFlagZeroFlag() const;
     void testFlagMultiBits() const;
+    void constExpr();
 };
 
 void tst_QFlags::testFlag() const
@@ -96,5 +97,32 @@ void tst_QFlags::testFlagMultiBits() const
     }
 }
 
+template <int N, typename T> bool verifyConstExpr(T n) { return n == N; }
+
+void tst_QFlags::constExpr()
+{
+#ifdef Q_COMPILER_CONSTEXPR
+    Qt::MouseButtons btn = Qt::LeftButton | Qt::RightButton;
+    switch (btn) {
+        case Qt::LeftButton: QVERIFY(false); break;
+        case Qt::RightButton: QVERIFY(false); break;
+        case Qt::LeftButton | Qt::RightButton: QVERIFY(true); break;
+        default: QVERIFY(false);
+    }
+
+    QVERIFY(verifyConstExpr<(Qt::LeftButton | Qt::RightButton) & Qt::LeftButton>(Qt::LeftButton));
+    QVERIFY(verifyConstExpr<(Qt::LeftButton | Qt::RightButton) & Qt::MiddleButton>(0));
+    QVERIFY(verifyConstExpr<(Qt::LeftButton | Qt::RightButton) | Qt::MiddleButton>(Qt::LeftButton | Qt::RightButton | Qt::MiddleButton));
+    QVERIFY(verifyConstExpr<~(Qt::LeftButton | Qt::RightButton)>(~(Qt::LeftButton | Qt::RightButton)));
+    QVERIFY(verifyConstExpr<Qt::MouseButtons(Qt::LeftButton) ^ Qt::RightButton>(Qt::LeftButton ^ Qt::RightButton));
+    QVERIFY(verifyConstExpr<Qt::MouseButtons(0)>(0));
+    QVERIFY(verifyConstExpr<Qt::MouseButtons(Qt::RightButton) & 0xff>(Qt::RightButton));
+    QVERIFY(verifyConstExpr<Qt::MouseButtons(Qt::RightButton) | 0xff>(0xff));
+
+    QVERIFY(!verifyConstExpr<Qt::RightButton>(!Qt::MouseButtons(Qt::LeftButton)));
+#endif
+}
+
+
 QTEST_MAIN(tst_QFlags)
 #include "tst_qflags.moc"