代码：

#include<iostream>

using namespace std;
struct S1{};
struct S2{};
struct S3{};
template<class T1>
class X
{    
    public:
    template<class T2>
    void print(T2 &v){};
};


template<class T1>
template<>
void X<T1>::print<S1>(S1 &v)
{
    cout<<"S1"<<endl;
}


template<class T1>
template<>
void X<T1>::print<S2>(S2 &v)
{
    cout<<"S2"<<endl;
}

template<class T1>
template<>
void X<T1>::print<S3>(S3 &v)
{
    cout<<"S3"<<endl;
}

int main()
{
    S1 s1;
    S2 s2;
    S3 s3;
    X<int> x;
    x.print(s1);
    x.print(s2);
    x;print(s3);
    return(0);
    
}

编译失败,gcc:
$ g++ test_template.cpp
test_template.cpp:17:10: 错误：invalid explicit specialization before ‘>’ token
   17 | template<>
      |          ^
test_template.cpp:17:10: 错误：所包含的类模板并未被显式特例化
test_template.cpp:25:10: 错误：invalid explicit specialization before ‘>’ token
   25 | template<>
      |          ^
test_template.cpp:25:10: 错误：所包含的类模板并未被显式特例化
test_template.cpp:32:10: 错误：invalid explicit specialization before ‘>’ token
   32 | template<>
      |          ^
test_template.cpp:32:10: 错误：所包含的类模板并未被显式特例化
test_template.cpp: 在函数‘int main()’中:
test_template.cpp:46:4: 错误：‘print’ was not declared in this scope; did you mean ‘printf’?
   46 |  x;print(s3);
      |    ^~~~~
--
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