I encountered this too. Should be easy enough to teach it to recognise type conversions; will give it a go.

Change https://golang.org/cl/85015 mentions this issue: cmd/stringer: support X = T(iota)

Instead, just write

const (
   One Num = iota
   Two
)

Stringer doesn't need to support the full language.

I initially thought it would be better for stringer to be more lax in what it accepts, since in a user's code both X T = iota and X = T(iota) make sense. And, limiting ourselves to this case, the added code to stringer is not much.

However, I do see that this can lead to a certain slippery slope. And I struggle to think of a reason why rewriting to the simpler (AST-wise) X T = iota would ever be a problem. It could certainly confuse users such as @josharian and myself, but perhaps then we just need to clarify the docs or give a better error message.

I'm convinced now that we shouldn't do this. If anyone feels like there is a compelling reason to support this form, feel free to reopen this discussion at a later time.

I think this can be addressed for simple cases (e.g. a plain type conversion) with less code than https://golang.org/cl/85015 was proposing. I'm going to send an alternate change.

Note that while X T = iota and X = T(iota) are equivalent and both easy, if you aren't using iota then it becomes a lot messier when the value you are using is a constant of a different type.

https://go-review.googlesource.com/c/146577 has been merged and I think this issue can be closed. (the referenced issue in the Fixes line is Fixes #11581).

Good point, closing.