x/tools/gopls: modernize x/exp/maps.Clear for Go >= 1.21

[BieHDC]

gopls version

Build info

golang.org/x/tools/gopls v0.16.2
golang.org/x/tools/gopls@v0.16.2 h1:K1z03MlikHfaMTtG01cUeL5FAOTJnITuNe0TWOcg8tM=
github.com/BurntSushi/toml@v1.2.1 h1:9F2/+DoOYIOksmaJFPw1tGFy1eDnIJXg+UHjuD8lTak=
github.com/google/go-cmp@v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
golang.org/x/exp/typeparams@v0.0.0-20221212164502-fae10dda9338 h1:2O2DON6y3XMJiQRAS1UWU+54aec2uopH3x7MAiqGW6Y=
golang.org/x/mod@v0.20.0 h1:utOm6MM3R3dnawAiJgn0y+xvuYRsm1RKM/4giyfDgV0=
golang.org/x/sync@v0.8.0 h1:3NFvSEYkUoMifnESzZl15y791HH1qU2xm6eCJU5ZPXQ=
golang.org/x/telemetry@v0.0.0-20240829154258-f29ab539cc98 h1:Wm3cG5X6sZ0RSVRc/H1/sciC4AT6HAKgLCSH2lbpR/c=
golang.org/x/text@v0.16.0 h1:a94ExnEXNtEwYLGJSIUxnWoxoRz/ZcCsV63ROupILh4=
golang.org/x/tools@v0.22.1-0.20240829175637-39126e24d653 h1:6bJEg2w2kUHWlfdJaESYsmNfI1LKAZQi6zCa7LUn7eI=
golang.org/x/vuln@v1.0.4 h1:SP0mPeg2PmGCu03V+61EcQiOjmpri2XijexKdzv8Z1I=
honnef.co/go/tools@v0.4.7 h1:9MDAWxMoSnB6QoSqiVr7P5mtkT9pOc1kSxchzPCnqJs=
mvdan.cc/gofumpt@v0.6.0 h1:G3QvahNDmpD+Aek/bNOLrFR2XC6ZAdo62dZu65gmwGo=
mvdan.cc/xurls/v2@v2.5.0 h1:lyBNOm8Wo71UknhUs4QTFUNNMyxy2JEIaKKo0RWOh+8=
go: go1.23.4

go env

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/REDACTED/.cache/go-build'
GOENV='/home/REDACTED/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/REDACTED/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/REDACTED/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/lib/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/lib/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.23.4'
GODEBUG=''
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/REDACTED/.config/go/telemetry'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/dev/null'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build637431612=/tmp/go-build -gno-record-gcc-switches'

What did you do?

I was using maps.Clear() in my code where the go version in the go.mod file is >1.21. I later figured out by coincidence that since Go 1.21 the built in clear() method does that task.

What did you see happen?

Nothing.

What did you expect to see?

gopls suggesting to replace the call to maps.Clear() with the built in clear() method when the go.mod go version is >= 1.21.

Editor and settings

Kate

Logs

No response

[gabyhelp]

Related Issues

• x/tools/gopls: references doesn't work properly. #60676 (closed)
• x/tools/gopls: #52425 (closed)
• x/tools/gopls: disable code actions from gopls #68783 (closed)
• x/tools/gopls: missing semantic tokens for function parameters in block #56257 (closed)
• x/tools/gopls: suggest go.mod go version update if generics code is found #51086 (closed)
• x/tools/gopls: Error for version 0.14.0 with "gopls version" command #63803 (closed)
• x/tools/gopls: negated build flag causes error #59346
• x/tools/gopls: go.mod: Please provide completions for package versions #58769
• x/tools/gopls: broken hovering in the builtin file #68026 (closed)

Related Code Changes

• cmd/go: support -json flag in go version

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[findleyr]

You're using x/exp/maps? The standard library maps package does not have Clear.

We'd like to support this type of modernizer, but probably wouldn't add one for a package in x/exp.

[BieHDC]

You're using x/exp/maps? The standard library maps package does not have Clear.

Yes. I searxed the internet when looking for this functionality and it said "maps.Clear", i typed this in my editor and the auto import organisation put up that package.

[findleyr]

Thanks @BieHDC for describing your use-case. I think there are some actionable improvements we can make here:

1. Avoid deprecated symbols and/or packages in import resolution.
2. Deprecate x/exp/maps.

Looking at x/exp/maps, which has over 5000 importers, maybe we should use this opportunity to offer API modernizers to transition users to the standard library maps package.

The way I would imagine this working is as follows: define API wrappers for every x/exp/maps function, which delegate to either the standard library package or clear builtin, and then offer quick fixes, both over the x/exp import and over each call site, to modernize the API usage via inlining the synthetic wrappers.

Unlike normal inlining, which is in the refactoring menu, this would be in the quickfix menu, which would be more visible.

CC @adonovan

[adonovan]

BTW: maps.Clear is generic, and our inliner still can't handle generic functions yet. (It shouldn't be a huge task, but @findleyr tackled it recently and discovered that it was trickier than it looked.)

[gopherbot]

Change https://go.dev/cl/634919 mentions this issue: internal/refactor/inline/analyzer: use "//go:fix inline" annotation

[findleyr]

BTW: maps.Clear is generic, and our inliner still can't handle generic functions yet. (It shouldn't be a huge task, but @findleyr tackled it recently and discovered that it was trickier than it looked.)

It wasn't that much trickier! The tricky part was just writing out type expressions for caller types that may not have previously been explicitly imported. I will get it working soon...

[adonovan]

See also:

• x/tools/gopls/internal/analysis: add "modernizer" analyzers #70815

[gopherbot]

Change https://go.dev/cl/635678 mentions this issue: gopls/internal/analysis/modernize: maps.Clear -> clear(m)

[gopherbot]

Change https://go.dev/cl/635680 mentions this issue: slices,maps: delegate to go1.21 functions of the same name

[adonovan]

I've closed this issue because https://go.dev/cl/635680 reduces maps.Clear to the same status as all the other exp/maps functions: wrappers around the std maps package. In the near future, if proposal #32816 is accepted, we can simply annotate such functions as candidates for auto-inlining and let the tools take care of it. This work is tracked as part of #70815.