encoding/json: retrieving underlying reader offset in UnmarshalJSON()?

[Julio-Guerra]

I am using big json configuration files and trying to produce useful user error messages, at least including the current line in the file.

So my question is: is there any way to retrieve the underlying reader's offset from UnmarshalJSON() to be able to return parsing or validation errors including it?

go version go1.8.3 linux/amd64

[ianlancetaylor]

We don't use the issue tracker to ask questions. Please see https://golang.org/wiki/Questions . Thanks.

You can check whether the returned error value is a json.UnmarshalTypeError, which has an Offset field. See https://golang.org/pkg/encoding/json/#UnsupportedTypeError .

Closing because there is no bug here.