[WIP] Partial bot skeleton, non-functional though

vendor/github.com/cockroachdb/errors/errbase/formatter.go

@@ -0,0 +1,99 @@
+// Copyright 2019 The Cockroach Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+// implied. See the License for the specific language governing
+// permissions and limitations under the License.
+
+// This file is taken from golang.org/x/xerrors,
+// at commit 3ee3066db522c6628d440a3a91c4abdd7f5ef22f (2019-05-10).
+// From the original code:
+// 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 errbase
+
+// A Formatter formats error messages.
+//
+// NB: Consider implementing SafeFormatter instead. This will ensure
+// that error displays can distinguish bits that are PII-safe.
+type Formatter interface {
+	error
+
+	// FormatError prints the receiver's first error.
+	// The return value decides what happens in the case
+	// FormatError() is used to produce a "short" message,
+	// eg. when it is used to implement Error():
+	//
+	// - if it returns nil, then the short message
+	//   contains no more than that produced for this error,
+	//   even if the error has a further causal chain.
+	//
+	// - if it returns non-nil, then the short message
+	//   contains the value printed by this error,
+	//   followed by that of its causal chain.
+	//   (e.g. thiserror: itscause: furthercause)
+	//
+	// Note that all the causal chain is reported in verbose reports in
+	// any case.
+	FormatError(p Printer) (next error)
+}
+
+// SafeFormatter is implemented by error leaf or wrapper types that want
+// to separate safe and non-safe information when printed out.
+//
+// When multiple errors are chained (e.g. via errors.Wrap), intermediate
+// layers in the error that do not implement SafeError are considered
+// “unsafe”
+type SafeFormatter interface {
+	// SafeFormatError prints the receiver's first error.
+	//
+	// The provided Printer behaves like a redact.SafePrinter its
+	// Print() and Printf() methods conditionally add redaction markers
+	// around unsafe bits.
+	//
+	// The return value of SafeFormatError() decides what happens in the
+	// case the method is used to produce a "short" message, eg. when it
+	// is used to implement Error():
+	//
+	// - if it returns nil, then the short message
+	//   contains no more than that produced for this error,
+	//   even if the error has a further causal chain.
+	//
+	// - if it returns non-nil, then the short message
+	//   contains the value printed by this error,
+	//   followed by that of its causal chain.
+	//   (e.g. thiserror: itscause: furthercause)
+	//
+	// Note that all the causal chain is reported in verbose reports in
+	// any case.
+	SafeFormatError(p Printer) (next error)
+}
+
+// A Printer formats error messages.
+//
+// The most common implementation of Printer is the one provided by package fmt
+// during Printf (as of Go 1.13). 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
+}