用clang编译MSVC std lib。 在类范围内显式模板函数专门化

Question

I'm trying to compile the MSVC standard library using Clang. But it fails because the standard library uses explicit template function specialization at class scope.

This is a MS extension, and apparently not available in Clang.

Here's a simple example that compiles fine with MSVS, but not with Clang.

template<class T>
class A
{
public:
    A()
    {   
        foo((T)0, 0);
    }

    template<class T2>
    void foo(T2, void* p) {}

    template<>
    void foo<bool>(bool, void* p)
    {
        t = (T)p;
    }
    T t;
};

int main()
{
    A<bool> a;
    return 0;
}

What should I do to get this feature to work when using Clang, so I can compile the MSVC standard library?

This is the compile error I get:

warning: explicit specialization of 'foo' within class scope is a Microsoft extension [-Wmicrosoft]
void foo<bool>(bool, void* p)

error: expected ';' after expression
                t = (T)p;
                       ^
                   ;
error: no member named 'T' in 'A<bool>'
                t = (T)p;
                     ^

Answer 1

AFAIK you will have to extend clang to support explicit specialization within class scope. I don't think there is any way around it, unless you want to modify the library.

Answer 2

I think you'll have three possibilities:

1. Rewrite the MSVC library so it does not use that extension (could be fun, but time consuming...)
2. Fix that MS-extension in Clang (could be even more fun and time consuming...)
3. Do the sane thing: use each library with the compiler it was made for (how boring...)

---

Update from this testing code for Clang I assume that it is already implemented, but it does not expect an explicit template parameter:

template<>
void foo(bool, void* p)
{
    t = (T)p;
}

Its probably a bug in Clang's implementation of that extension.