Get rid of Q_COMPILER_CONSTEXPR checks

Is required now.

Change-Id: I62e95929d1649ea1390392230b619bd56d2a0349
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

src/corelib/global/qnamespace.h

@@ -1601,16 +1601,10 @@ namespace Qt {
         TitleBarArea    // For move
     };
 
-#if defined(Q_COMPILER_CONSTEXPR)
     enum class Initialization {
         Uninitialized
     };
-    [[maybe_unused]] static constexpr Initialization Uninitialized = Initialization::Uninitialized;
-#else
-    enum Initialization {
-        Uninitialized
-    };
-#endif
+    [[maybe_unused]] static inline constexpr Initialization Uninitialized = Initialization::Uninitialized;
 
     enum CoordinateSystem {
         DeviceCoordinates,

src/corelib/global/qrandom.cpp

@@ -361,15 +361,13 @@ struct QRandomGenerator::SystemAndGlobalGenerators
     SystemGenerator sys;
     alignas(64) std::aligned_storage<sizeof(QRandomGenerator64), 64>::type global_;
 
-#ifdef Q_COMPILER_CONSTEXPR
     constexpr SystemAndGlobalGenerators()
         : globalPRNGMutex{}, system_{0}, sys{}, global_{}
     {}
-#endif
 
     void confirmLiteral()
     {
-#if defined(Q_COMPILER_CONSTEXPR) && !defined(Q_CC_MSVC) && !defined(Q_OS_INTEGRITY)
+#if !defined(Q_CC_MSVC) && !defined(Q_OS_INTEGRITY)
         // Currently fails to compile with MSVC 2017, saying QBasicMutex is not
         // a literal type. Disassembly with MSVC 2013 and 2015 shows it is
         // actually a literal; MSVC 2017 has a bug relating to this, so we're

src/corelib/text/qlocale_p.h

@@ -504,7 +504,6 @@ constexpr inline bool ascii_isspace(uchar c)
     return c >= 1u && c <= 32u && (AsciiSpaceMask >> uint(c - 1)) & 1u;
 }
 
-#if defined(Q_COMPILER_CONSTEXPR)
 static_assert(ascii_isspace(' '));
 static_assert(ascii_isspace('\t'));
 static_assert(ascii_isspace('\n'));
@@ -518,7 +517,6 @@ static_assert(!ascii_isspace('\177'));
 static_assert(!ascii_isspace(uchar('\200')));
 static_assert(!ascii_isspace(uchar('\xA0')));
 static_assert(!ascii_isspace(uchar('\377')));
-#endif
 
 QT_END_NAMESPACE
 

src/corelib/thread/qatomic_cxx11.h

@@ -478,11 +478,7 @@ template <typename X> struct QAtomicOps
     }
 };
 
-#if defined(Q_COMPILER_CONSTEXPR)
 #  define Q_BASIC_ATOMIC_INITIALIZER(a)     { a }
-#else
-#  define Q_BASIC_ATOMIC_INITIALIZER(a)     { ATOMIC_VAR_INIT(a) }
-#endif
 
 QT_END_NAMESPACE
 

src/corelib/thread/qbasicatomic.h

@@ -49,7 +49,7 @@
 // If C++11 atomics are supported, use them!
 // Note that constexpr support is sometimes disabled in QNX or INTEGRITY builds,
 // but their libraries have <atomic>.
-#elif defined(Q_COMPILER_ATOMICS) && (defined(Q_COMPILER_CONSTEXPR) || defined(Q_OS_QNX) || defined(Q_OS_INTEGRITY))
+#elif defined(Q_COMPILER_ATOMICS)
 #  include <QtCore/qatomic_cxx11.h>
 
 // We only support one fallback: MSVC, because even on version 2015, it lacks full constexpr support
@@ -75,16 +75,7 @@ QT_END_NAMESPACE
 
 // New atomics
 
-#if defined(Q_COMPILER_CONSTEXPR)
-# if defined(Q_CC_CLANG) && Q_CC_CLANG < 303
-   /*
-      Do not define QT_BASIC_ATOMIC_HAS_CONSTRUCTORS for Clang before version 3.3.
-      For details about the bug: see http://llvm.org/bugs/show_bug.cgi?id=12670
-    */
-# else
-#  define QT_BASIC_ATOMIC_HAS_CONSTRUCTORS
-# endif
-#endif
+#define QT_BASIC_ATOMIC_HAS_CONSTRUCTORS
 
 template <typename T>
 class QBasicAtomicInteger

src/corelib/tools/qfreelist_p.h

@@ -207,9 +207,7 @@ public:
 template <typename T, typename ConstantsType>
 constexpr inline QFreeList<T, ConstantsType>::QFreeList()
     :
-#if defined(Q_COMPILER_CONSTEXPR)
       _v{}, // uniform initialization required
-#endif
       _next(ConstantsType::InitialNextValue)
 { }
 

src/gui/painting/qpixellayout.cpp

@@ -511,9 +511,7 @@ static void QT_FASTCALL rbSwap(uchar *dst, const uchar *src, int count)
     constexpr uchar gShift = greenShift<Format>();
     constexpr uchar bWidth = blueWidth<Format>();
     constexpr uchar bShift = blueShift<Format>();
-#ifdef Q_COMPILER_CONSTEXPR
     static_assert(rWidth == bWidth);
-#endif
     constexpr uint redBlueMask = (1 << rWidth) - 1;
     constexpr uint alphaGreenMask = (((1 << aWidth) - 1) << aShift)
                                     | (((1 << gWidth) - 1) << gShift);

src/widgets/widgets/qcalendarwidget.cpp

@@ -829,11 +829,7 @@ class StaticDayOfWeekAssociativeArray {
     static constexpr int day2idx(Qt::DayOfWeek day) noexcept { return int(day) - 1; } // alt: day % 7
 public:
     constexpr StaticDayOfWeekAssociativeArray() noexcept(noexcept(T()))
-#ifdef Q_COMPILER_CONSTEXPR
         : contained{}, data{}   // arrays require uniform initialization
-#else
-        : contained(), data()
-#endif
     {}
 
     constexpr bool contains(Qt::DayOfWeek day) const noexcept { return contained[day2idx(day)]; }

tests/auto/corelib/global/qflags/tst_qflags.cpp

@@ -105,7 +105,6 @@ constexpr Qt::MouseButtons testRelaxedConstExpr()
 
 void tst_QFlags::constExpr()
 {
-#ifdef Q_COMPILER_CONSTEXPR
     Qt::MouseButtons btn = Qt::LeftButton | Qt::RightButton;
     switch (btn) {
         case Qt::LeftButton: QVERIFY(false); break;
@@ -125,10 +124,7 @@ void tst_QFlags::constExpr()
 
     QVERIFY(!verifyConstExpr<Qt::RightButton>(~Qt::MouseButtons(Qt::LeftButton)));
 
-#if defined(__cpp_constexpr) &&  __cpp_constexpr-0 >= 201304
     QVERIFY(verifyConstExpr<uint(testRelaxedConstExpr())>(Qt::MiddleButton));
-#endif
-#endif
 }
 
 void tst_QFlags::signedness()

tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp

@@ -2182,7 +2182,6 @@ struct RegisterMetaTypeStruct<qRegisterMetaType< Name >()> \
     enum { Value = qRegisterMetaType< Name >() }; \
 };
 
-#if defined(Q_COMPILER_CONSTEXPR)
 QT_FOR_EACH_STATIC_TYPE(METATYPE_ID_STRUCT)
 QT_FOR_EACH_STATIC_TYPE(REGISTER_METATYPE_STRUCT)
 
@@ -2197,11 +2196,9 @@ struct RegisterMetaTypeStructDefaultTemplateValue
 {
   enum { Value };
 };
-#endif
 
 void tst_QMetaType::constexprMetaTypeIds()
 {
-#if defined(Q_COMPILER_CONSTEXPR)
     int id = 0;
     int metaType;
 
@@ -2217,9 +2214,6 @@ void tst_QMetaType::constexprMetaTypeIds()
     default:;
     }
     Q_UNUSED(metaType);
-#else
-    QSKIP("The test needs a compiler supporting constexpr");
-#endif
 }
 
 void tst_QMetaType::constRefs()
@@ -2228,9 +2222,7 @@ void tst_QMetaType::constRefs()
     QCOMPARE(::qMetaTypeId<const QString &>(), ::qMetaTypeId<QString>());
     QCOMPARE(::qMetaTypeId<const CustomMovable &>(), ::qMetaTypeId<CustomMovable>());
     QCOMPARE(::qMetaTypeId<const QList<CustomMovable> &>(), ::qMetaTypeId<QList<CustomMovable> >());
-#if defined(Q_COMPILER_CONSTEXPR)
     static_assert(::qMetaTypeId<const int &>() == ::qMetaTypeId<int>());
-#endif
 }
 
 struct CustomConvertibleType

tests/auto/corelib/text/qstringview/tst_qstringview.cpp

@@ -281,7 +281,6 @@ private:
 void tst_QStringView::constExpr() const
 {
     // compile-time checks
-#ifdef Q_COMPILER_CONSTEXPR
     {
         constexpr QStringView sv;
         static_assert(sv.size() == 0);
@@ -363,7 +362,6 @@ void tst_QStringView::constExpr() const
         static_assert(sv3.isEmpty());
         static_assert(sv3.size() == 0);
     }
-#endif
 }
 
 void tst_QStringView::basics() const

tests/auto/corelib/thread/qatomicint/tst_qatomicint.cpp

@@ -154,18 +154,11 @@ template <bool> inline void booleanHelper()
 template <typename Atomic>
 static void constexprFunctionsHelperTemplate()
 {
-#ifdef Q_COMPILER_CONSTEXPR
     // this is a compile-time test only
     booleanHelper<Atomic::isReferenceCountingWaitFree()>();
     booleanHelper<Atomic::isTestAndSetWaitFree()>();
     booleanHelper<Atomic::isFetchAndStoreWaitFree()>();
     booleanHelper<Atomic::isFetchAndAddWaitFree()>();
-#elif 0 // No longer constexpr
-    booleanHelper<Atomic::isReferenceCountingNative()>();
-    booleanHelper<Atomic::isTestAndSetNative()>();
-    booleanHelper<Atomic::isFetchAndStoreNative()>();
-    booleanHelper<Atomic::isFetchAndAddNative()>();
-#endif
 }
 
 void tst_QAtomicInt::warningFreeHelper()

tests/auto/corelib/thread/qatomicinteger/tst_qatomicinteger.cpp

@@ -196,18 +196,11 @@ void tst_QAtomicIntegerXX::static_checks()
     (void) QAtomicInteger<T>::isFetchAndAddNative();
     (void) QAtomicInteger<T>::isFetchAndAddWaitFree();
 
-#ifdef Q_COMPILER_CONSTEXPR
     // this is a compile-time test only
     booleanHelper<QAtomicInteger<T>::isReferenceCountingWaitFree()>();
     booleanHelper<QAtomicInteger<T>::isTestAndSetWaitFree()>();
     booleanHelper<QAtomicInteger<T>::isFetchAndStoreWaitFree()>();
     booleanHelper<QAtomicInteger<T>::isFetchAndAddWaitFree()>();
-#elif 0 // no longer constexpr
-    booleanHelper<QAtomicInteger<T>::isReferenceCountingNative()>();
-    booleanHelper<QAtomicInteger<T>::isTestAndSetNative()>();
-    booleanHelper<QAtomicInteger<T>::isFetchAndStoreNative()>();
-    booleanHelper<QAtomicInteger<T>::isFetchAndAddNative()>();
-#endif
 }
 
 void tst_QAtomicIntegerXX::addData()

tests/auto/gui/painting/qcolor/tst_qcolor.cpp

@@ -64,10 +64,8 @@ private slots:
 
     void globalColors_data();
     void globalColors();
-#if defined(Q_COMPILER_CONSTEXPR) & defined(Q_COMPILER_UNIFORM_INIT)
     void colorConstants_data();
     void colorConstants();
-#endif
 
     void setRed();
     void setGreen();
@@ -373,7 +371,6 @@ void tst_QColor::globalColors()
     QCOMPARE(color.rgba(), argb);
 }
 
-#if defined(Q_COMPILER_CONSTEXPR) & defined(Q_COMPILER_UNIFORM_INIT)
 void tst_QColor::colorConstants_data()
 {
     QTest::addColumn<QColor>("color");
@@ -556,7 +553,6 @@ void tst_QColor::colorConstants()
     QFETCH(QRgb, argb);
     QCOMPARE(color.rgba(), argb);
 }
-#endif // defined(Q_COMPILER_CONSTEXPR) & defined(Q_COMPILER_UNIFORM_INIT)
 
 /*
   CSS color names = SVG 1.0 color names + transparent (rgba(0,0,0,0))

tests/auto/network/ssl/qsslellipticcurve/tst_qsslellipticcurve.cpp

@@ -50,15 +50,11 @@ private Q_SLOTS:
 
 void tst_QSslEllipticCurve::constExpr()
 {
-#ifdef Q_COMPILER_CONSTEXPR
     // check that default ctor and op ==/!= are constexpr:
     char array1[QSslEllipticCurve() == QSslEllipticCurve() ?  1 : -1];
     char array2[QSslEllipticCurve() != QSslEllipticCurve() ? -1 :  1];
     Q_UNUSED(array1);
     Q_UNUSED(array2);
-#else
-    QSKIP("This test requires C++11 generalized constant expression support enabled in the compiler.");
-#endif
 }
 
 void tst_QSslEllipticCurve::construction()