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Compiler Error C2942

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'class' : type-class-id redefined as a formal argument of a function

You can't use a generic or template class as a formal argument. You cannot pass an argument directly to the constructor of a generic or template class.

This error is obsolete in Visual Studio 2022 and later versions.

The following sample generates C2942:

// C2942.cpp
// compile with: /c
template<class T>
struct TC {};
void f(int TC<int>) {}   // C2942

// OK
struct TC2 {};
void f(TC2 i) {}

C2942 can also occur when using generics:

// C2942b.cpp
// compile with: /clr /c
generic<class T>
ref struct GC {};
void f(int GC<int>) {}   // C2942
ref struct GC2 { };
void f(int GC2) {}