Why does PipeWriter.CloseWithError pretend to return an error?

[Glen Mailer]

Hi everyone,

We got bitten by a bug recently when using PipeWriter.CloseWithError. We incorrectly assumed it would pass-through the error it was passed.

The docs do say that it will always return `nil`, but does anyone know why it has an `error` return type at all?

I can't see an interface that it has to match, and couldn't think of any other reason.

Cheers

Glen

[Ian Lance Taylor]

I think it's an unfortunate accident due to how the API was developed.
When CloseWithError was first introduced
(https://go.googlesource.com/go/+/6defc25c8383ab326e8c11af0c78de8a394dca84,
before the open source release) it could return an error. The API has
shifted a lot since then, and now it always returns a nil error. We
could have cleaned it up for Go 1, but nobody noticed.

Ian