errors, fmt: revert rejected changes for Go 1.13

Reverts the following changes:

  https://go.googlesource.com/go/+/1f90d081391d4f5911960fd28d81d7ea5e554a8f
  https://go.googlesource.com/go/+/8bf18b56a47a98b9dd2fa03beb358312237a8c76
  https://go.googlesource.com/go/+/5402854c3557f87fa2741a52ffc15dfb1ef333cc
  https://go.googlesource.com/go/+/37f84817247d3b8e687a701ccb0d6bc7ffe3cb78
  https://go.googlesource.com/go/+/6be6f114e0d483a233101a67c9644cd72bd3ae7a

Partially reverts the followinng change, removing the errors.Opaque
function and the errors.Wrapper type definition:

  https://go.googlesource.com/go/+/62f5e8156ef56fa61e6af56f4ccc633bde1a9120

Updates documentation referencing the Wrapper type.

Change-Id: Ia622883e39cafb06809853e3fd90b21441124534
Reviewed-on: https://go-review.googlesource.com/c/go/+/176997
Run-TryBot: Damien Neil <dneil@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>

1 files changed, 0 insertions, 34 deletions

diff --git a/src/errors/format.go b/src/errors/format.go
deleted file mode 100644
index 12deed3cf7..0000000000
--- a/src/errors/format.go
+++ /dev/null
@@ -1,34 +0,0 @@
-// Copyright 2018 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package errors
-
-// A Formatter formats error messages.
-type Formatter interface {
-	error
-
-	// FormatError prints the receiver's first error and returns the next error in
-	// the error chain, if any.
-	FormatError(p Printer) (next error)
-}
-
-// A Printer formats error messages.
-//
-// The most common implementation of Printer is the one provided by package fmt
-// during Printf. Localization packages such as golang.org/x/text/message
-// typically provide their own implementations.
-type Printer interface {
-	// Print appends args to the message output.
-	Print(args ...interface{})
-
-	// Printf writes a formatted string.
-	Printf(format string, args ...interface{})
-
-	// Detail reports whether error detail is requested.
-	// After the first call to Detail, all text written to the Printer
-	// is formatted as additional detail, or ignored when
-	// detail has not been requested.
-	// If Detail returns false, the caller can avoid printing the detail at all.
-	Detail() bool
-}