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Support Go 1.20 Unwrap() []error (#69)
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Go 1.20 includes native support for wrapping multiple errors.
Errors which wrap multiple other errors must implement,

    Unwrap() []error

If an error implements this method, `errors.Is` and `errors.As`
will descend into the list and continue matching.

Versions of Go prior to 1.20, however, still need the old
`Is` and `As` method implementations on the error object
to get a similar behavior.

This change adds the `Unwrap() []error` method
gated by a build constraint requiring Go 1.20 or higher.
It similarly moves the existing `Is` and `As` methods
to a file that is ignored on Go 1.20 or higher.

Once Go 1.21 is released and 1.19 is no longer supported,
the pre-go1.20 file may be deleted and the build constraints removed.

For details, see also the section,
"How should existing multierror types adopt the new interface?"
of the [multiple errors proposal][1].

  [1]: golang/go#53435

Refs #64
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abhinav committed Feb 10, 2023
1 parent 39ca40c commit 55bc553
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4 changes: 2 additions & 2 deletions .github/workflows/go.yml
Original file line number Diff line number Diff line change
Expand Up @@ -13,9 +13,9 @@ jobs:
runs-on: ubuntu-latest
strategy:
matrix:
go: ["1.18.x", "1.19.x"]
go: ["1.19.x", "1.20.x"]
include:
- go: 1.19.x
- go: 1.20.x
latest: true

steps:
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5 changes: 5 additions & 0 deletions CHANGELOG.md
Original file line number Diff line number Diff line change
@@ -1,6 +1,11 @@
Releases
========

v1.10.0 (unreleased)
====================

- Comply with Go 1.20's multiple-error interface.

v1.9.0 (2022-12-12)
===================

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30 changes: 1 addition & 29 deletions error.go
Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
// Copyright (c) 2017-2021 Uber Technologies, Inc.
// Copyright (c) 2017-2023 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
Expand Down Expand Up @@ -142,7 +142,6 @@ package multierr // import "go.uber.org/multierr"

import (
"bytes"
"errors"
"fmt"
"io"
"strings"
Expand Down Expand Up @@ -239,33 +238,6 @@ func (merr *multiError) Errors() []error {
return merr.errors
}

// As attempts to find the first error in the error list that matches the type
// of the value that target points to.
//
// This function allows errors.As to traverse the values stored on the
// multierr error.
func (merr *multiError) As(target interface{}) bool {
for _, err := range merr.Errors() {
if errors.As(err, target) {
return true
}
}
return false
}

// Is attempts to match the provided error against errors in the error list.
//
// This function allows errors.Is to traverse the values stored on the
// multierr error.
func (merr *multiError) Is(target error) bool {
for _, err := range merr.Errors() {
if errors.Is(err, target) {
return true
}
}
return false
}

func (merr *multiError) Error() string {
if merr == nil {
return ""
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29 changes: 29 additions & 0 deletions error_post_go120.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,29 @@
// Copyright (c) 2017-2023 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

//go:build go1.20
// +build go1.20

package multierr

// Unwrap returns a list of errors wrapped by this multierr.
func (merr *multiError) Unwrap() []error {
return merr.Errors()
}
59 changes: 59 additions & 0 deletions error_pre_go120.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,59 @@
// Copyright (c) 2017-2023 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

//go:build !go1.20
// +build !go1.20

package multierr

import "errors"

// Versions of Go before 1.20 did not support the Unwrap() []error method.
// This provides a similar behavior by implementing the Is(..) and As(..)
// methods.
// See the errors.Join proposal for details:
// https://github.com/golang/go/issues/53435

// As attempts to find the first error in the error list that matches the type
// of the value that target points to.
//
// This function allows errors.As to traverse the values stored on the
// multierr error.
func (merr *multiError) As(target interface{}) bool {
for _, err := range merr.Errors() {
if errors.As(err, target) {
return true
}
}
return false
}

// Is attempts to match the provided error against errors in the error list.
//
// This function allows errors.Is to traverse the values stored on the
// multierr error.
func (merr *multiError) Is(target error) bool {
for _, err := range merr.Errors() {
if errors.Is(err, target) {
return true
}
}
return false
}
14 changes: 7 additions & 7 deletions tools/go.mod
Original file line number Diff line number Diff line change
Expand Up @@ -3,14 +3,14 @@ module go.uber.org/multierr/tools
go 1.18

require (
golang.org/x/lint v0.0.0-20201208152925-83fdc39ff7b5
honnef.co/go/tools v0.3.3
golang.org/x/lint v0.0.0-20210508222113-6edffad5e616
honnef.co/go/tools v0.4.0
)

require (
github.com/BurntSushi/toml v1.0.0 // indirect
golang.org/x/exp/typeparams v0.0.0-20220314205449-43aec2f8a4e7 // indirect
golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4 // indirect
golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f // indirect
golang.org/x/tools v0.1.12 // indirect
github.com/BurntSushi/toml v1.2.1 // indirect
golang.org/x/exp/typeparams v0.0.0-20221208152030-732eee02a75a // indirect
golang.org/x/mod v0.7.0 // indirect
golang.org/x/sys v0.4.0 // indirect
golang.org/x/tools v0.5.0 // indirect
)
29 changes: 15 additions & 14 deletions tools/go.sum
Original file line number Diff line number Diff line change
@@ -1,25 +1,26 @@
github.com/BurntSushi/toml v1.0.0 h1:dtDWrepsVPfW9H/4y7dDgFc2MBUSeJhlaDtK13CxFlU=
github.com/BurntSushi/toml v1.0.0/go.mod h1:CxXYINrC8qIiEnFrOxCa7Jy5BFHlXnUU2pbicEuybxQ=
github.com/BurntSushi/toml v1.2.1 h1:9F2/+DoOYIOksmaJFPw1tGFy1eDnIJXg+UHjuD8lTak=
github.com/BurntSushi/toml v1.2.1/go.mod h1:CxXYINrC8qIiEnFrOxCa7Jy5BFHlXnUU2pbicEuybxQ=
golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
golang.org/x/exp/typeparams v0.0.0-20220314205449-43aec2f8a4e7 h1:mzVEuUhnztMdHb426A1o6cjz5ha6YV3t6zFTBXqSon4=
golang.org/x/exp/typeparams v0.0.0-20220314205449-43aec2f8a4e7/go.mod h1:AbB0pIl9nAr9wVwH+Z2ZpaocVmF5I4GyWCDIsVjR0bk=
golang.org/x/lint v0.0.0-20201208152925-83fdc39ff7b5 h1:2M3HP5CCK1Si9FQhwnzYhXdG6DXeebvUHFpre8QvbyI=
golang.org/x/lint v0.0.0-20201208152925-83fdc39ff7b5/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
golang.org/x/exp/typeparams v0.0.0-20221208152030-732eee02a75a h1:Jw5wfR+h9mnIYH+OtGT2im5wV1YGGDora5vTv/aa5bE=
golang.org/x/exp/typeparams v0.0.0-20221208152030-732eee02a75a/go.mod h1:AbB0pIl9nAr9wVwH+Z2ZpaocVmF5I4GyWCDIsVjR0bk=
golang.org/x/lint v0.0.0-20210508222113-6edffad5e616 h1:VLliZ0d+/avPrXXH+OakdXhpJuEoBZuwh1m2j7U6Iug=
golang.org/x/lint v0.0.0-20210508222113-6edffad5e616/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4 h1:6zppjxzCulZykYSLyVDYbneBfbaBIQPYMevg0bEwv2s=
golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
golang.org/x/mod v0.7.0 h1:LapD9S96VoQRhi/GrNTqeBJFrUjs5UHCAtTlgwA5oZA=
golang.org/x/mod v0.7.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.1.0 h1:wsuoTGHzEhffawBOhz5CYhcrV4IdKZbEyZjBMuTp12o=
golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f h1:v4INt8xihDGvnrfjMDVXGxw9wrfxYyCjk0KbXjhR55s=
golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/sys v0.4.0 h1:Zr2JFtRQNX3BCZ8YtxRE9hNJYC8J6I1MVbMg6owUp18=
golang.org/x/sys v0.4.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
golang.org/x/tools v0.1.12 h1:VveCTK38A2rkS8ZqFY25HIDFscX5X9OoEhJd3quQmXU=
golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
golang.org/x/tools v0.5.0 h1:+bSpV5HIeWkuvgaMfI3UmKRThoTA5ODJTUd8T17NO+4=
golang.org/x/tools v0.5.0/go.mod h1:N+Kgy78s5I24c24dU8OfWNEotWjutIs8SnJvn5IDq+k=
golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
honnef.co/go/tools v0.3.3 h1:oDx7VAwstgpYpb3wv0oxiZlxY+foCpRAwY7Vk6XpAgA=
honnef.co/go/tools v0.3.3/go.mod h1:jzwdWgg7Jdq75wlfblQxO4neNaFFSvgc1tD5Wv8U0Yw=
honnef.co/go/tools v0.4.0 h1:lyXVV1c8wUBJRKqI8JgIpT8TW1VDagfYYaxbKa/HoL8=
honnef.co/go/tools v0.4.0/go.mod h1:36ZgoUOrqOk1GxwHhyryEkq8FQWkUO2xGuSMhUCcdvA=

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