How to check assignability of types at runtime in C#?

Question

The Type class has a method IsAssignableFrom() that almost works. Unfortunately it only returns true if the two types are the same or the first is in

Answer 1

This one almost works... it's using Linq expressions:

public static bool IsReallyAssignableFrom(this Type type, Type otherType)
{
    if (type.IsAssignableFrom(otherType))
        return true;

    try
    {
        var v = Expression.Variable(otherType);
        var expr = Expression.Convert(v, type);
        return expr.Method == null || expr.Method.Name == "op_Implicit";
    }
    catch(InvalidOperationException ex)
    {
        return false;
    }
}

The only case that doesn't work is for built-in conversions for primitive types: it incorrectly returns true for conversions that should be explicit (e.g. int to short). I guess you could handle those cases manually, as there is a finite (and rather small) number of them.

I don't really like having to catch an exception to detect invalid conversions, but I don't see any other simple way to do it...