diff options
author | Marc Mutz <marc.mutz@kdab.com> | 2012-07-10 15:27:48 +0200 |
---|---|---|
committer | Qt by Nokia <qt-info@nokia.com> | 2012-08-26 14:29:49 +0200 |
commit | 7e0fa2fc75a9c9ca3466d0a3fb6c9f302fc22a62 (patch) | |
tree | 47c8dfa207ad76815e82b51d75e42587e1a374b1 /src | |
parent | 9090e0d9c6b8e16b206a2e0ed9ddbc3e1d0c2c68 (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>
Diffstat (limited to 'src')
-rw-r--r-- | src/corelib/kernel/qvariant_p.h | 12 |
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 |