Upgrade to Go 1.22 to avoid scoping bugs with closures in for loops?

[dmcardle]

The associated forum post URL from https://forum.rclone.org

N/a

What is the problem you are having with rclone?

Version of Go prior to 1.22 contain a footgun related to closures in for loops: https://go.dev/blog/loopvar-preview

Release notes for Go 1.22

I've run into this twice so far:

• cmd/gitannex: Add layout modes for compatibility #7754 (comment)

• rclone/cmd/gitannex/gitannex_test.go

  Lines 865 to 868 in 2c76800

  	// TODO: Remove this when rclone requires a Go version >= 1.22. Future
  	// versions of Go fix the semantics of capturing a range variable.
  	// https://go.dev/blog/loopvar-preview
  	testCase := testCase

What is your rclone version (output from rclone version)

HEAD, currently 2c76800

Which OS you are using and how many bits (e.g. Windows 7, 64 bit)

N/a, the language semantics are cross-platform

Which cloud storage system are you using? (e.g. Google Drive)

N/a

The command you were trying to run (e.g. rclone copy /tmp remote:tmp)

N/a

A log from the command with the -vv flag (e.g. output from rclone -vv copy /tmp remote:tmp)

N/a

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[Animosity022]

1.66 already has Go 1.22

https://forum.rclone.org/t/rclone-v1-66-release/44987

 rclone version
rclone v1.66.0
- os/version: darwin 14.4.1 (64 bit)
- os/kernel: 23.4.0 (arm64)
- os/type: darwin
- os/arch: arm64 (ARMv8 compatible)
- go/version: go1.22.1
- go/linking: dynamic
- go/tags: cmount

[dmcardle]

Oh, I was going based on the go.mod file, which still says 1.20.

rclone/go.mod

Line 3 in 2c76800

go 1.20

[dmcardle]

Aha, I guess the minimum version is still 1.20, and the CI still tests go1.20. Nothing to do here. Thanks, @Animosity022!

[ncw]

@dmcardle we try to support current go and two previous versions, so currently that is go1.22, go1.21, go1.20.

However in two go versions time that support will look like go1.24, go1.23, go1.22 so at that point we can remove those unnecessary lines of code so you can re-open that issue then if you want!

Eg this (might not be all of them if we renamed the var too).

$ git grep -P '\b(\w+) := \1(\s|$)'
backend/azureblob/azureblob.go:         v := v
backend/b2/upload.go:           part := part // for the closure
backend/b2/upload.go:           part := part // for the closure
backend/combine/combine.go:             upstream := upstream
backend/combine/combine.go:             u := u
backend/combine/combine.go:             u := u
backend/drive/metadata.go:                              permissionID := permissionID
backend/s3/s3.go:               partNum := partNum // for closure
backend/union/policy/epff.go:           u := u // Closure
backend/union/union.go:         i := i
cmd/gitannex/gitannex_test.go:                          lineEnding := lineEnding
cmd/gitannex/gitannex_test.go:          testCase := testCase
cmd/gitannex/gitannex_test.go:          testCase := testCase
fs/config/rc.go:                name := name
fs/operations/multithread.go:           chunk := chunk
fs/operations/operations.go:                    dir := dir
fs/operations/rc.go:            copy := copy
fs/operations/rc.go:            op := op
fs/sync/rc.go:          name := name
fs/sync/sync.go:                        item := item
lib/encoder/filename/encode.go:         org := org
lib/multipart/multipart.go:             partNum := partNum