x/tools/gopls: use common package name aliases in unimported completion and goimports

[jhendrixMSFT]

What version of Go, VS Code & VS Code Go extension are you using?

Version Information

go version go1.21.0 windows/amd64
golang.org/x/tools/gopls v0.13.2
vscode version 1.81.1 x64
vscode go extension version 0.39.1
Checking configured tools....
GOBIN: undefined
toolsGopath:
gopath: C:\Users\jhendrix\go
GOROOT: C:\Program Files\Go
PATH: C:\Program Files\PowerShell\7;C:\Program Files\Common Files\Oracle\Java\javapath;C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\wbin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0;C:\WINDOWS\System32\OpenSSH;C:\Program Files\dotnet;C:\Program Files\nodejs;C:\Program Files\PowerShell\7;C:\Program Files\Git\cmd;C:\Program Files\Docker\Docker\resources\bin;C:\Program Files\Go\bin;C:\Users\jhendrix\AppData\Local\Microsoft\WindowsApps;C:\Users\jhendrix\AppData\Local\Programs\Microsoft VS Code\bin;C:\Users\jhendrix\go\bin;C:\Users\jhendrix\AppData\Local\Programs\Fiddler;C:\Program Files\Graphviz\bin;C:\Users\jhendrix.dotnet\tools;C:\Users\jhendrix\AppData\Roaming\npm;C:\Users\jhendrix\go\bin

go:	C:\Program Files\Go\bin\go.exe: go version go1.21.0 windows/amd64

gotests:	C:\Users\jhendrix\go\bin\gotests.exe	(version: v1.6.0 built with go: go1.21.0)
gomodifytags:	C:\Users\jhendrix\go\bin\gomodifytags.exe	(version: v1.16.0 built with go: go1.21.0)
impl:	C:\Users\jhendrix\go\bin\impl.exe	(version: v1.1.0 built with go: go1.21.0)
goplay:	C:\Users\jhendrix\go\bin\goplay.exe	(version: v1.0.0 built with go: go1.21.0)
dlv:	C:\Users\jhendrix\go\bin\dlv.exe	(version: v1.21.0 built with go: go1.21.0)
staticcheck:	C:\Users\jhendrix\go\bin\staticcheck.exe	(version: v0.4.3 built with go: go1.21.0)
gopls:	C:\Users\jhendrix\go\bin\gopls.exe	(version: v0.13.2 built with go: go1.21.0)

go env
Workspace Folder (autocompleterepro): c:\git\jhendrixMSFT\autocompleterepro
set GO111MODULE=
set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\jhendrix\AppData\Local\go-build
set GOENV=C:\Users\jhendrix\AppData\Roaming\go\env
set GOEXE=.exe
set GOEXPERIMENT=
set GOFLAGS=
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOINSECURE=
set GOMODCACHE=C:\Users\jhendrix\go\pkg\mod
set GONOPROXY=
set GONOSUMDB=
set GOOS=windows
set GOPATH=C:\Users\jhendrix\go
set GOPRIVATE=
set GOPROXY=https://proxy.golang.org,direct
set GOROOT=C:\Program Files\Go
set GOSUMDB=sum.golang.org
set GOTMPDIR=C:\Users\jhendrix\go\tmp
set GOTOOLCHAIN=auto
set GOTOOLDIR=C:\Program Files\Go\pkg\tool\windows_amd64
set GOVCS=
set GOVERSION=go1.21.0
set GCCGO=gccgo
set GOAMD64=v1
set AR=ar
set CC=gcc
set CXX=g++
set CGO_ENABLED=0
set GOMOD=c:\git\jhendrixMSFT\autocompleterepro\go.mod
set GOWORK=
set CGO_CFLAGS=-O2 -g
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-O2 -g
set CGO_FFLAGS=-O2 -g
set CGO_LDFLAGS=-O2 -g
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=C:\Users\jhendrix\go\tmp\go-build1620475247=/tmp/go-build -gno-record-gcc-switches

using default Go setting, nothing added/edited

Describe the bug

Using autocomplete to create a stub definition of a func within a struct, the aliased package names for the dependent types aren't preserved. Instead, the non-aliased package names are used.

Steps to reproduce the behavior:

Clone https://github.com/jhendrixMSFT/autocompleterepro
On line 12, note that the package names for resp and errResp are incorrect. They should be azfake but are fake.
To repro, just delete line 12 then recreate it, using the autocomplete prompt to create the stub definition for Get.

[findleyr]

Thank you very much for the issue, and for the repro. Aliases are notoriously problematic in tools/gopls (primarily because they are not represented properly in go/types). With that said, we have various workarounds, and should apply them here.

Transferring to the gopls issue tracker.

[findleyr]

Milestoning this for gopls@v0.15.0 because I think the situation with aliases may be improved in go/types as part of Go 1.22. We'll no more by gopls@v0.15.0.

[findleyr]

This should be fixed in Go 1.23, when go/types produces Alias information by default. In the meantime, we should verify the fix in a future version of gopls (v0.16.0 or v0.17.).