Template instantiation problems

[Lewis Baker]

I am having some template problems in VC7.1
The following code should compile fine but I get the error:
'warning C4667: 'void F(Traits<T>::P)' : no function
template defined that matches forced instantiation'


However if I instantiate the function implicitly by using
it in some code then everything seems to work.


Any clues or is this a compiler bug?


Regards,
Lewis


---- Code below ----


// Traits class
template<class T>
class Traits
{
public:
typedef T* P;
};


// Template function declaration
template<class T> void F( typename Traits<T>::P );


// Template function definition
template<class T>
void F( typename Traits<T>::P X )
{
Traits<T>::P x = X;
}


// Explicitly instantiate function
template void F( Traits<int>::P ); // <-- Error here


// Implicitly instantiate function
void UseF()
{
int a;
F<int>( &a ); // <-- No problems
}

[Carl Daniel [VC++ MVP]]

Lewis Baker wrote:

I am having some template problems in VC7.1
The following code should compile fine but I get the error:
The code should not compile, according to the C++ standard.
'warning C4667: 'void F(Traits<T>::P)' : no function
template defined that matches forced instantiation'

However if I instantiate the function implicitly by using
it in some code then everything seems to work.

Any clues or is this a compiler bug?
The code's not required to compile.

Regards,

Lewis

---- Code below ----
// Traits class
template<class T>
class Traits
{
public:
typedef T* P;
};

// Template function declaration
template<class T> void F( typename Traits<T>::P );

// Template function definition
template<class T>
void F( typename Traits<T>::P X )
{
Traits<T>::P x = X;
This should be

typename Traits<T>::P x = X;
}

// Explicitly instantiate function
template void F( Traits<int>::P ); // <-- Error here
This is a non-deduced context. The compiler is unable to deduce the
template arguments based on these formal types.

// Implicitly instantiate function
void UseF()
{
int a;
F<int>( &a ); // <-- No problems
}

-cd