Compiler Error C2881

'namespace1' : is already used as an alias for 'namespace2'

You tried to use a namespace as an alias, but it is already in use as an alias to another namespace.

For example, the following code uses namespace C as an alias for both namespace A and namespace B.

namespace A {
   int k;
}

namespace B {
   int i;
}

namespace C = A;
namespace C = B; // C2881, C is already an alias for A