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// Copyright 2020 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.
// +build !go1.13
package errors
import "reflect"
// Is is a copy of Go 1.13's errors.Is for use with older Go versions.
func Is(err, target error) bool {
if target == nil {
return err == target
}
isComparable := reflect.TypeOf(target).Comparable()
for {
if isComparable && err == target {
return true
}
if x, ok := err.(interface{ Is(error) bool }); ok && x.Is(target) {
return true
}
if err = unwrap(err); err == nil {
return false
}
}
}
func unwrap(err error) error {
u, ok := err.(interface {
Unwrap() error
})
if !ok {
return nil
}
return u.Unwrap()
}
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