这个问题是来自Software Engineering Stack Exchange的migrated，因为它可以在Stack Overflow上回答。Migrated 8天前.
下面的代码：

#include <iostream>

class Test {
   public:
    Test() {std::cout << "I am called\n";};

    template <typename T>
    Test(T t);
};

template <typename T> Test::Test(T t){ std::cout << t << "\n";};

// Explicit template instantiation
template Test::Test<int>(int);
template Test::Test<double>(double);

int main() {
    Test test;
    Test test2(12342);
    Test test3(3.1415);
    return 0;
}

字符串
这段代码可以很好地与GCC（我的版本是13.2）一起编译和工作。输出如我所料：

I am called
12342
3.1415

型
Clang（我的版本是16.0.0）抛出错误，代码无法编译：

<source>:14:16: error: qualified reference to 'Test' is a constructor name rather than a type in this context
template Test::Test<int>(int);
               ^
<source>:14:20: error: expected unqualified-id
template Test::Test<int>(int);
                   ^
<source>:15:16: error: qualified reference to 'Test' is a constructor name rather than a type in this context
template Test::Test<double>(double);
               ^
<source>:15:20: error: expected unqualified-id
template Test::Test<double>(double);
                   ^
4 errors generated.

型
有人能帮助我理解这个问题或指导我找到来源吗？