x/tools/gopls: Add refactor "move to a new file"

[golopot]

gopls version

Build info ---------- golang.org/x/tools/gopls v0.14.2 golang.org/x/tools/gopls@v0.14.2 h1:sIw6vjZiuQ9S7s0auUUkHlWgsCkKZFWDHmrge8LYsnc= github.com/BurntSushi/toml@v1.2.1 h1:9F2/+DoOYIOksmaJFPw1tGFy1eDnIJXg+UHjuD8lTak= github.com/google/go-cmp@v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38= github.com/sergi/go-diff@v1.1.0 h1:we8PVUC3FE2uYfodKH/nBHMSetSfHDR6scGdBi+erh0= golang.org/x/exp/typeparams@v0.0.0-20221212164502-fae10dda9338 h1:2O2DON6y3XMJiQRAS1UWU+54aec2uopH3x7MAiqGW6Y= golang.org/x/mod@v0.14.0 h1:dGoOF9QVLYng8IHTm7BAyWqCqSheQ5pYWGhzW00YJr0= golang.org/x/sync@v0.4.0 h1:zxkM55ReGkDlKSM+Fu41A+zmbZuaPVbGMzvvdUPznYQ= golang.org/x/sys@v0.14.0 h1:Vz7Qs629MkJkGyHxUlRHizWJRG2j8fbQKjELVSNhy7Q= golang.org/x/telemetry@v0.0.0-20231114163143-69313e640400 h1:brbkEFfGwNGAEkykUOcryE/JiHUMMJouzE0fWWmz/QU= golang.org/x/text@v0.13.0 h1:ablQoSUd0tRdKxZewP80B+BaqeKJuVhuRxj/dkrun3k= golang.org/x/tools@v0.14.1-0.20231114185516-c9d3e7de13fd h1:Oku7E+OCrXHyst1dG1z10etCTxewCHXNFLRlyMPbh3w= golang.org/x/vuln@v1.0.1 h1:KUas02EjQK5LTuIx1OylBQdKKZ9jeugs+HiqO5HormU= honnef.co/go/tools@v0.4.5 h1:YGD4H+SuIOOqsyoLOpZDWcieM28W47/zRO7f+9V3nvo= mvdan.cc/gofumpt@v0.4.0 h1:JVf4NN1mIpHogBj7ABpgOyZc65/UUOkKQFkoURsz4MM= mvdan.cc/xurls/v2@v2.4.0 h1:tzxjVAj+wSBmDcF6zBB7/myTy3gX9xvi8Tyr28AuQgc= go: go1.21.6

go env

go env
GO111MODULE=''
GOARCH='arm64'
GOBIN=''
GOCACHE='/Users/chiawenchen/Library/Caches/go-build'
GOENV='/Users/chiawenchen/Library/Application Support/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='arm64'
GOHOSTOS='darwin'
GOINSECURE=''
GOMODCACHE='/Users/chiawenchen/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='darwin'
GOPATH='/Users/chiawenchen/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/opt/homebrew/Cellar/go/1.21.6/libexec'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/opt/homebrew/Cellar/go/1.21.6/libexec/pkg/tool/darwin_arm64'
GOVCS=''
GOVERSION='go1.21.6'
GCCGO='gccgo'
AR='ar'
CC='cc'
CXX='c++'
CGO_ENABLED='1'
GOMOD='/Users/chiawenchen/testgopls/go.mod'
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 -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -ffile-prefix-map=/var/folders/ls/sjfzwn0x09g0_ckr_7m5ybpc0000gn/T/go-build2538955256=/tmp/go-build -gno-record-gcc-switches -fno-common'

What did you do?

.

What did you see happen?

.

What did you expect to see?

When selecting severals lines containing functions, types, etc, offer a refactor for moving these things to a new file in the same package. The exact changes this refactor does is:

1. Create a new file in the the same package. The name of the new file will be the name of the first entity selected. If a file of the same name already exists, append underscores until it doesn't.
2. Add line "package packagename" to the new file
3. Add selected lines to new file
4. Add needed imports for the new file
5. Remove selected lines from the old file
6. Remove redundant imports from the source file

Editor and settings

No response

Logs

No response

[findleyr]

I agree this is a good and simple refactoring to apply. However we should fix AST comment handling (#20744) first -- something that we have on our radar for this year.

CC @adonovan @suzmue

[golopot]

However we should fix AST comment handling (#20744) first

Is this issue somewhat depended on AST comment handling changes, or is it just a priority issue? in that case I can do the implementation.

[adonovan]

The feature is unlikely to work well until comment support is improved, but comment support will improve this year, so I don't think it should stop you from contributing this feature in the meantime, if that's something you're interested in doing.

[gopherbot]

Change https://go.dev/cl/565895 mentions this issue: gopls/internal: add code action "move to a new file"