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Linker Tools Error LNK2020

  • Article

unresolved token 'token'

Similar to an undefined external error, except that the reference is via metadata. In metadata, all functions and data must be defined.

To resolve:

  • Define the missing function or data, or

  • Include the object file or library in which the missing function or data is already defined.

Examples

The following sample generates LNK2020.

// LNK2020.cpp
// compile with: /clr /LD
ref struct A {
   A(int x);   // LNK2020
   static int f();   // LNK2020
};

// OK
ref struct B {
   B(int x) {}
   static int f() { return 0; }
};

LNK2020 will also occur if you create a variable of a managed template type, but do not also instantiate the type.

The following sample generates LNK2020.

// LNK2020_b.cpp
// compile with: /clr

template <typename T>
ref struct Base {
   virtual void f1() {};
};

template <typename T>
ref struct Base2 {
   virtual void f1() {};
};

int main() {
   Base<int>^ p;   // LNK2020
   Base2<int>^ p2 = gcnew Base2<int>();   // OK
};