reflect: Value.NumMethod and Type.NumMethod doesn't seem to agree on exported methods

[mvdan]

On e7d5857, I see:

// NumMethod returns the number of exported methods in the value's method set.
func (v Value) NumMethod() int {
    if v.typ == nil {
        panic(&ValueError{"reflect.Value.NumMethod", Invalid})
    }
    if v.flag&flagMethod != 0 {
        return 0
    }
    return v.typ.NumMethod()
}

Note that Value.NumMethod is documented to only return the number of exported methods. It calls Type.NumMethod, which is documented as:

// NumMethod returns the number of methods accessible using Method.
//
// Note that NumMethod counts unexported methods only for interface types.

Am I misreading the docs, or do they seem to disagree when it comes to interface types?

cc @dsnet
cc @ianlancetaylor @mdempsky given some past changes regarding NumMethods and exported methods

[ianlancetaylor]

I think you're right and that we should update the documentation for Value.NumMethod.

[cuonglm]

FYI, https://go-review.googlesource.com/c/go/+/264357