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Compiler Error C3855

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'class': type parameter 'param' is incompatible with the declaration

The compiler found nontype template or generic parameters with different names. This can occur when a specified template parameter in the definition of a template specialization is incompatible with its declaration.

The following sample generates C3855:

// C3855.cpp
template <int N>
struct C {
   void f();
};

template <char N>
void C<N>::f() {}   // C3855

Possible resolution:

// C3855b.cpp
// compile with: /c
template <int N>
struct C {
   void f();
};

template <int N>
void C<N>::f() {}

C3855 can also occur when using generics:

// C3855c.cpp
// compile with: /clr
generic <class T>
ref struct GC1 {
   generic <class U>
   ref struct GC2;
};

generic <class T>
generic <class U>
generic <class V>
ref struct GC1<T>::GC2 { };   // C3855

Possible resolution:

// C3855d.cpp
// compile with: /clr /c
generic <class T>
ref struct GC1 {
   generic <class U>
   ref struct GC2;
};

generic <class T>
generic <class U>
ref struct GC1<T>::GC2 { };