Il 19/07/20 20:42, Thiago Macieira ha scritto:
In that sense, Peppe's suggestion of C++17 offsetof is better.
To clarify, I was proposing to do something like this:
Type Klass::_qt_property_api_propertyName::value() const
{
/*1*/ const size_t propertyMemberOffset =
reinterpret_cast<size_t>(&(static_cast<Klass *>(nullptr)->propertyName));
/*2*/ const auto *thisPtr = reinterpret_cast<const Klass
*>(reinterpret_cast<const char *>(this) - propertyMemberOffset);
return thisPtr->d_func()->property.value();
}
* change /*1*/ become offsetof(Klass, propertyName);* change /*2*/ to use ASM. We know the ABI of the platforms we support and we know how to calculate the correct pointer value, we just need to stop C/C++ from reason about it and flagging it as possible UB. Yes, it's a crude hack... :(
My 2 c, -- Giuseppe D'Angelo | giuseppe.dang...@kdab.com | Senior Software Engineer KDAB (France) S.A.S., a KDAB Group company Tel. France +33 (0)4 90 84 08 53, http://www.kdab.com KDAB - The Qt, C++ and OpenGL Experts
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