x/tools/gopls: completion gives wrong lambda suggestion for pointer receivers of a generic type

[lixin9311]

gopls version

$ gopls -v version
Build info
----------
golang.org/x/tools/gopls v0.12.4
    golang.org/x/tools/[email protected] h1:nce5etAamR46d9oNGxop1aRK5rDQ0NqcY/SHIcyfEKY=
    github.com/BurntSushi/[email protected] h1:9F2/+DoOYIOksmaJFPw1tGFy1eDnIJXg+UHjuD8lTak=
    github.com/google/[email protected] h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
    github.com/sergi/[email protected] h1:we8PVUC3FE2uYfodKH/nBHMSetSfHDR6scGdBi+erh0=
    golang.org/x/[email protected] h1:+WEEuIdZHnUeJJmEUjyYC2gfUMj69yZXw17EnHg/otA=
    golang.org/x/exp/[email protected] h1:2O2DON6y3XMJiQRAS1UWU+54aec2uopH3x7MAiqGW6Y=
    golang.org/x/[email protected] h1:bUO06HqtnRcc/7l71XBe4WcqTZ+3AH1J59zWDDwLKgU=
    golang.org/x/[email protected] h1:ftCYgMx6zT/asHUrPw8BLLscYtGznsLAnjq5RH9P66E=
    golang.org/x/[email protected] h1:KS/R3tvhPqvJvwcKfnBHJwwthS11LRhmM5D59eEXa0s=
    golang.org/x/[email protected] h1:UpjohKhiEgNc0CSauXmwYftY1+LlaC75SJwh0SgCX58=
    golang.org/x/[email protected] h1:5PWemM67wMSPpO0Y3lOPlyvgO3z56YkZRxPFcdd300g=
    golang.org/x/[email protected] h1:A9kONVi4+AnuOr1dopsibH6hLi1Huy54cbeJxnq4vmU=
    honnef.co/go/[email protected] h1:6qXr+R5w+ktL5UkwEbPp+fEvfyoMPche6GkOpGHZcLc=
    mvdan.cc/[email protected] h1:JVf4NN1mIpHogBj7ABpgOyZc65/UUOkKQFkoURsz4MM=
    mvdan.cc/xurls/[email protected] h1:tzxjVAj+wSBmDcF6zBB7/myTy3gX9xvi8Tyr28AuQgc=
go: go1.20.4

go env

$ go env
GO111MODULE=""
GOARCH="arm64"
GOBIN=""
GOCACHE="/Users/reducted/Library/Caches/go-build"
GOENV="/Users/reducted/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/reducted/go/pkg/mod"
GONOPROXY="reducted"
GONOSUMDB="reducted"
GOOS="darwin"
GOPATH="/Users/reducted/go"
GOPRIVATE="reducted"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/opt/homebrew/Cellar/go/1.20.4/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/opt/homebrew/Cellar/go/1.20.4/libexec/pkg/tool/darwin_arm64"
GOVCS=""
GOVERSION="go1.20.4"
GCCGO="gccgo"
AR="ar"
CC="cc"
CXX="c++"
CGO_ENABLED="1"
GOMOD="reducted"
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 -fdebug-prefix-map=/var/folders/6_/msm1_r211ds7gwg7dv3zw8j40000gn/T/go-build420238562=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

A bugged snippet:

package main

type Helloer interface {
	Hello() string
}

type Bob struct{}
func (b *Bob) Hello() string {
	return "Hello, I'm Bob"
}

type GreetingMachine[T Helloer] struct {
	Greeter T
}
func (gm *GreetingMachine[T]) GreetFunc(f func(T)) { // pointer receiver here
	f(gm.Greeter)
}


func main() {
	gm := &GreetingMachine[*Bob]{
		Greeter: &Bob{},
	}
	// try autocomplete on `gm.GreetFunc(f)`
	gm.GreetFunc(func(t T) {})  // autocomplete here gives `func(t T) {}`
}

A working version:

package main

type Helloer interface {
	Hello() string
}

type Bob struct{}
func (b *Bob) Hello() string {
	return "Hello, I'm Bob"
}

type GreetingMachine[T Helloer] struct {
	Greeter T
}
func (gm GreetingMachine[T]) GreetFunc(f func(T)) {  // change to a value receiver
	f(gm.Greeter)
}


func main() {
	gm := &GreetingMachine[*Bob]{
		Greeter: &Bob{},
	}
	// try autocomplete on `gm.GreetFunc(f)`
	gm.GreetFunc(func(b *Bob) {})  // autocomplete here gives `func(b *Bob) {}`
}

What did you expect to see?

See the comment on the snippet code above.

What did you see instead?

See the comment on the snippet code above.

Editor and settings

VSCode

Logs

Nothing useful...

[findleyr]

Thanks!

This is clearly a bug. Prioritizing for [email protected].

[gopherbot]

Change https://go.dev/cl/539677 mentions this issue: gopls/internal/lsp/source: fix signatureHelp with pointer receivers