It is a bit confusing, but the compiler is doing the right thing here. In the first code snippet, value == 0 is false because value has concrete type uint, but 0 has type int. For interfaces to compare equal, both their type and their concrete value must be the same.

Two other ways to write this program to avoid this problem:

• https://play.golang.org/p/dKwBkV0T_d -- compare to uint(0), not plain 0)
• https://play.golang.org/p/a_d97KPZUn -- make value be a concrete type, not an interface, so the compiler treats 0 as type uint to match the type of value

I think in general you probably want to use the second form.

Thanks you for explanation! But I still think that at least go vet should notify about this pitfall.

The more common way to write such a switch is to introduce a variable with the type switch: https://play.golang.org/p/93shxyhA_Z and then the code is less surprising.

@griesemer thank you for advice! It's definitely good advice to avoid such cases!