encoding/binary: Read should document use of io.EOF vs io.ErrUnexpectedEOF

[joshlf]

Just like io.ReadFull, encoding/binary.Read will return io.EOF if the given reader returns EOF before any bytes are read, but will return io.ErrUnexpectedEOF if some (but not all) of the bytes are read before encountering EOF (binary.Read just calls io.ReadFull under the hood). IMO, this behavior should be documented so that a) callers know about it and, b) callers can rely on the behavior not changing in the future (whereas, currently, a change in this behavior wouldn't break the documented API).

This concern was originally raised here on golang-nuts.

• Version: 1.4.2
• OS/Arch: linux/amd64

[gopherbot]

CL https://golang.org/cl/15171 mentions this issue.