QT6和类特异性操作员的编译问题新

Question

考虑一个具有自定义操作员新的课程。

class BaseClass {
  void* operator new(size_t size);
  void operator delete(void* p);
};

class MyClass : public BaseClass {
public:
  MyClass(int);
};

然后使用myClass作为信号的参数和QT中的

qt5 slot，但使用QT6使用QT6在使用Visual Studio 2019时在qmetatype中生成深度的汇编错误，而无法找到特定于类的类别myClass的新位置。

vs 2019的汇编错误（更改为隐藏特定路径和类名称）：

...QtCore\qmetatype.h(2313): error C2660: 'BaseClass::operator new': function does not take 3 arguments
: note: see declaration of 'BaseClass::operator new'
...QtCore\qmetatype.h(2310): note: while compiling class template member function 'QtPrivate::QMetaTypeInterface::CopyCtrFn QtPrivate::QMetaTypeForType<T>::getCopyCtr(void)'
        with
        [
            T=Ty
        ]
...QtCore\qmetatype.h(2370): note: see reference to class template instantiation 'QtPrivate::QMetaTypeForType<T>' being compiled
        with
        [
            T=Ty
        ]
...QtCore\qmetatype.h(2494): note: see reference to class template instantiation 'QtPrivate::QMetaTypeInterfaceWrapper<Ty>' being compiled
...QtCore\qmetatype.h(2537): note: see reference to function template instantiation 'const QtPrivate::QMetaTypeInterface *QtPrivate::qTryMetaTypeInterfaceForType<Unique,QtPrivate::TypeAndForceComplete<MyClass &,std::false_type>>(void)' being compiled
    with
    [
        Unique=qt_meta_stringdata_..._t
    ]
moc_xxx.cpp(286): note: see reference to variable template 'const QtPrivate::QMetaTypeInterface *const qt_incomplete_metaTypeArray<qt_meta_stringdata_ModelBrowser_t,QtPrivate::TypeAndForceComplete<ModelBrowser,std::integral_constant<bool,1> >,QtPrivate::TypeAndForceComplete<void,std::integral_constant<bool,0> >,QtPrivate::TypeAndForceComplete<void,std::integral_constant<bool,0> >,QtPrivate::TypeAndForceComplete<MyClass &,std::integral_constant<bool,0> >,QtPrivate::TypeAndForceComplete<void,std::integral_constant<bool,0> >,QtPrivate::TypeAndForceComplete<MyClass &,std::integral_constant<bool,0> >,QtPrivate::TypeAndForceComplete<void,std::integral_constant<bool,0> >,...[58]' being compiled

尝试添加通用类特定的位置新（也就是void* operator* operator new new（size_t size，std :: align_val_t，void*），void*））似乎可能是可能的，但根据标准和其他编译器中的失败而不是。

Answer 1

以下只是一个解决方案，它并不总是有效 - 但这很琐碎：

class MyClass : public BaseClass {
public:
  MyClass(int);

  MyClass()=delete;
  MyClass(const MyClass&)=delete;
}

其起作用的原因是Qmetatype通过std :: IS_DEFAULT_CONSTRUCTIBLE_V和std守护了有问题的调用:: is_copy_constructible_v。