clang-16: Incorrect "must explicitly initialize the member" error in function-local class #62559
Description
See https://godbolt.org/z/zoxs4nae4 for a self-contained example.
Both GCC and Clang 15 accept the code. Clang 16 and Clang trunk reject it.
For
#include<memory>
class TypeErased {
public:
virtual ~TypeErased();
};
template <typename T, typename... Args>
std::unique_ptr<TypeErased> make_type_erased(Args&&... args) {
struct TypeErasureWrapper : public TypeErased {
T content;
TypeErasureWrapper(Args&&... args) : content{std::forward<Args>(args)...} {}
~TypeErasureWrapper() override {}
};
return std::make_unique<TypeErasureWrapper>(std::forward<Args>(args)...);
}
class NoDefaultConstructor {
public:
NoDefaultConstructor(int);
};
auto testNoDefaultConstructor() {
return make_type_erased<NoDefaultConstructor>(1);
}The error message from Clang 16 does not make sense to me:
<source>:12:7: error: constructor for 'TypeErasureWrapper' must explicitly initialize the member 'content' which does not have a default constructor
TypeErasureWrapper(Args&&... args) : content{std::forward<Args>(args)...} {}
^ ^Clang is complaining that we would not initialize content, but on the very same line we are actually initializing it.
The error does not occur if the class has a default constructor or if I define TypeErasureWrapper outside the function, as shown in https://godbolt.org/z/YYzhWPnKx