Compiler Error CS1637

Iterators cannot have unsafe parameters or yield types

Check the argument list of the iterator and the type of any yield statements to verify that you are not using any unsafe types.

Example

The following sample generates CS1637:

// CS1637.cs
// compile with: /unsafe
using System.Collections;

public unsafe class C
{
    public IEnumerator Iterator1(int* p)  // CS1637
    {
        yield return null;
    }
}