Fast IEnumerable<enum1> to List<enum2> convertation

I have two same enums that have the same names of members, but they are in different namespaces so they are "different types", but in fact namespace1.enum1 {a,b,c,d,e,f} and namespace2.enum2 {a,b,c,d,e,f}

How is the easiest way to convert IEnumerable<enum1> to List<enum2> without using loops?

Well something's going to loop somewhere, but it doesn't have to be in your code. Just a LINQ Select will be fine:

var result = original.Select(x => (Enum2) x).ToList();

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