go/scanner: report specific error for UCS-2 encoded files
Windows text files may be encoded as UCS-2 (i.e. 2-byte UTF-16).
This CL causes the scanner to emit a better error when it reads
a file in this encoding.
+ test
Fixes #71950
Change-Id: Ia65bbf9a60e36984b0f3e4865591aa6978d2bde2
Reviewed-on: https://go-review.googlesource.com/c/go/+/652515
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Alan Donovan <adonovan@google.com>
Commit-Queue: Alan Donovan <adonovan@google.com>