鑒于以下代碼：
class DummyOK {
public:
template <typename U, typename... Args>
class AThing {
public:
};
public:
template <typename U, typename... Args>
AThing<U, Args...> GetAThing();
};
template <typename U, typename... Args>
typename DummyOK::template AThing<U, Args...> DummyOK::GetAThing() {
return AThing<U, Args...>{};
}
template <typename T>
class DummyKO {
public:
template <typename U, typename... Args>
class AThing {
public:
};
public:
template <typename U, typename... Args>
AThing<U, Args...> GetAThing();
template <typename U, typename... Args>
AThing<U, Args...> AnOtherGetAThing() {
return AThing<U, Args...>{};
}
};
template <typename T>
template <typename U, typename... Args>
typename DummyKO<T>::template AThing<U, Args...> DummyKO<T>::GetAThing() {
return AThing<U, Args...>{};
}
int main() {
DummyOK{}.GetAThing<char, unsigned, float>();
DummyKO<int>{}.GetAThing<char, unsigned, float>();
DummyKO<int>{}.AnOtherGetAThing<char, unsigned, float>();
return 0;
}
也可以在這里找到：https : //godbolt.org/z/8747rj77K
為什么它在 clang/gcc 上編譯而不是在 msvc 上編譯。為什么 AnOtherGetAThing() 編譯而不是 GetAThing()（在 msvc 上）。
msvc回傳的錯誤是：
<source>(39): error C2244: 'DummyKO<T>::GetAThing': unable to match function definition to an existing declaration
<source>(39): note: see declaration of 'DummyKO<T>::GetAThing'
<source>(39): note: definition
<source>(39): note: 'DummyKO<T>::AThing<U,Args...> DummyKO<T>::GetAThing(void)'
<source>(39): note: existing declarations
<source>(39): note: 'DummyKO<T>::AThing<U,Args...> DummyKO<T>::GetAThing(void)'
謝謝
uj5u.com熱心網友回復：
我會說 msvc 錯誤，
作為解決方法，您可以使用尾隨回傳型別：
template <typename T>
template <typename U, typename... Args>
auto DummyKO<T>::GetAThing() -> AThing<U, Args...>
{
// ...
}
演示
轉載請註明出處，本文鏈接：https://www.uj5u.com/caozuo/346193.html