QTypeInfo: use C++11 type traits to deduce if a type is static or complex

All types that can be trivially copied and destructed are by definition
relocatable, and we should apply those semantics when moving them in
memory.

Types that are trivial, are by definition not complex and should be
treated as such.

[ChangeLog][QtCore] Qt Containers and meta type system now use C++11
type traits (std::is_trivial, std::is_trivially_copyable and
std::is_trivially_destructible) to detect the class of a type not
explicitly set by Q_DECLARE_TYPEINFO. (Q_DECLARE_TYPEINFO is still
needed for QList.)

Done-with: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
Change-Id: Iebb87ece425ea919e86169d06cd509c54a074282
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 20 insertions, 8 deletions

diff --git a/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp b/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp
index 0c328dff58..fb11e4c522 100644
--- a/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp
+++ b/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp
@@ -342,6 +342,7 @@ struct Bar
             ++failureCount;
         }
     }
+    ~Bar() {}
 
 public:
     static int failureCount;
@@ -458,7 +459,7 @@ void tst_QMetaType::threadSafety()
 
 namespace TestSpace
 {
-    struct Foo { double d; };
+    struct Foo { double d; public: ~Foo() {} };
     struct QungTfu {};
 }
 Q_DECLARE_METATYPE(TestSpace::Foo)
@@ -515,11 +516,17 @@ void tst_QMetaType::properties()
 }
 
 template <typename T>
-struct Whity { T t; };
+struct Whity { T t; Whity() {} };
 
 Q_DECLARE_METATYPE( Whity < int > )
 Q_DECLARE_METATYPE(Whity<double>)
 
+#if !defined(Q_CC_CLANG) && defined(Q_CC_GNU) && Q_CC_GNU < 501
+QT_BEGIN_NAMESPACE
+Q_DECLARE_TYPEINFO(Whity<double>, Q_MOVABLE_TYPE);
+QT_END_NAMESPACE
+#endif
+
 void tst_QMetaType::normalizedTypes()
 {
     int WhityIntId = ::qMetaTypeId<Whity<int> >();
@@ -818,10 +825,13 @@ void tst_QMetaType::sizeOfStaticLess()
     QCOMPARE(size_t(QMetaType(type).sizeOf()), size);
 }
 
-struct CustomMovable {};
+struct CustomMovable { CustomMovable() {} };
+#if !defined(Q_CC_CLANG) && defined(Q_CC_GNU) && Q_CC_GNU < 501
 QT_BEGIN_NAMESPACE
 Q_DECLARE_TYPEINFO(CustomMovable, Q_MOVABLE_TYPE);
 QT_END_NAMESPACE
+#endif
+
 Q_DECLARE_METATYPE(CustomMovable);
 
 class CustomObject : public QObject
@@ -850,13 +860,15 @@ public:
 };
 Q_DECLARE_METATYPE(CustomMultiInheritanceObject*);
 
-class C { char _[4]; };
-class M { char _[4]; };
+class C { char _[4]; public: C() = default; C(const C&) {} };
+class M { char _[4]; public: M() {} };
 class P { char _[4]; };
 
 QT_BEGIN_NAMESPACE
+#if defined(Q_CC_GNU) && Q_CC_GNU < 501
 Q_DECLARE_TYPEINFO(M, Q_MOVABLE_TYPE);
 Q_DECLARE_TYPEINFO(P, Q_PRIMITIVE_TYPE);
+#endif
 QT_END_NAMESPACE
 
 // avoid the comma:
@@ -902,7 +914,7 @@ QT_FOR_EACH_STATIC_PRIMITIVE_POINTER(ADD_METATYPE_TEST_ROW)
 QT_FOR_EACH_STATIC_CORE_POINTER(ADD_METATYPE_TEST_ROW)
 #undef ADD_METATYPE_TEST_ROW
     QTest::newRow("TestSpace::Foo") << ::qMetaTypeId<TestSpace::Foo>() << false << true << false << false;
-    QTest::newRow("Whity<double>") << ::qMetaTypeId<Whity<double> >() << false << true << false << false;
+    QTest::newRow("Whity<double>") << ::qMetaTypeId<Whity<double> >() << true << true << false << false;
     QTest::newRow("CustomMovable") << ::qMetaTypeId<CustomMovable>() << true << true << false << false;
     QTest::newRow("CustomObject*") << ::qMetaTypeId<CustomObject*>() << true << false << true << false;
     QTest::newRow("CustomMultiInheritanceObject*") << ::qMetaTypeId<CustomMultiInheritanceObject*>() << true << false << true << false;
diff --git a/tests/auto/corelib/tools/qpair/tst_qpair.cpp b/tests/auto/corelib/tools/qpair/tst_qpair.cpp
index 1d5f7536c8..dedc353e67 100644
--- a/tests/auto/corelib/tools/qpair/tst_qpair.cpp
+++ b/tests/auto/corelib/tools/qpair/tst_qpair.cpp
@@ -41,8 +41,8 @@ private Q_SLOTS:
     void taskQTBUG_48780_pairContainingCArray();
 };
 
-class C { char _[4]; };
-class M { char _[4]; };
+class C { C() {} char _[4]; };
+class M { M() {} char _[4]; };
 class P { char _[4]; };
 
 QT_BEGIN_NAMESPACE