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authorMarc Mutz <marc.mutz@kdab.com>2012-07-10 15:27:48 +0200
committerQt by Nokia <qt-info@nokia.com>2012-08-26 14:29:49 +0200
commit7e0fa2fc75a9c9ca3466d0a3fb6c9f302fc22a62 (patch)
tree47c8dfa207ad76815e82b51d75e42587e1a374b1
parent9090e0d9c6b8e16b206a2e0ed9ddbc3e1d0c2c68 (diff)
QVariant: make the HasIsNullMethod check work across all compilers (maybe)
Currently, we have a C++11 version that requires Q_COMPILER_DECLTYPE support, and can deal with final classes, and a C++98 version that doesn't require any C++11 features, but fails on final classes. What we're missing is a version that works for MSVC v8 and v9 (2005 and 2008), which sport the 'sealed' non-standard keywords but lack decltype support. So far, we tried to solve the problem by making class-level final special (Q_DECL_FINAL_CLASS), not defining that macro for these two compilers, even though we did define Q_DECL_FINAL, the method-level keyword. This new formulation, taken from http://stackoverflow.com/a/9655327/134841 supposedly supports all compilers with a minor #ifdef for MSVC which doesn't like applying sizeof() the way we do. However, testing has shown this to blow up on OSX. So we use the less intrusive approach: add this variant as a third version, only used by VC 2005 and 2008. Change-Id: If1945f8a6e9ed36cb68212fa781d5e29eb2a082d Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
-rw-r--r--src/corelib/kernel/qvariant_p.h12
1 files changed, 12 insertions, 0 deletions
diff --git a/src/corelib/kernel/qvariant_p.h b/src/corelib/kernel/qvariant_p.h
index 6b778f3fb2..c680297854 100644
--- a/src/corelib/kernel/qvariant_p.h
+++ b/src/corelib/kernel/qvariant_p.h
@@ -224,6 +224,18 @@ class QVariantIsNull
public:
static const bool Value = (sizeof(test<T>(0)) == sizeof(Yes));
};
+#elif defined(Q_CC_MSVC) && _MSC_VER >= 1400 // MSVC 2005, 2008 version: no decltype, but 'sealed' classes (>=2010 has decltype)
+ template<typename T>
+ class HasIsNullMethod {
+ struct Yes { char unused[1]; };
+ struct No { char unused[2]; };
+ Q_STATIC_ASSERT(sizeof(Yes) != sizeof(No));
+
+ template<class C> static Yes test(char (*)[(&C::isNull == 0) + 1]);
+ template<class C> static No test(...);
+ public:
+ static const bool Value = (sizeof(test<T>(0)) == sizeof(Yes));
+ };
#else // C++98 version (doesn't work for final classes)
template<typename T, bool IsClass = QTypeInfo<T>::isComplex>
class HasIsNullMethod