x/tools/gopls/internal/analysis/modernize: slicescontains analyzer suggests invalid refactoring when function parameter type doesn't match slice element type #74938
Description
Go version
go1.24.3
Output of go env in your module/workspace:
AR='ar'
CC='cc'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='c++'
GCCGO='gccgo'
GO111MODULE=''
GOARCH='arm64'
GOARM64='v8.0'
GOAUTH='netrc'
GOBIN='/Users/mac/go/bin'
GOCACHE='/Users/mac/Library/Caches/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/Users/mac/Library/Application Support/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -ffile-prefix-map=/var/folders/tq/m955dwkd1519phkp2hwpv9_80000gn/T/go-build2400307511=/tmp/go-build -gno-record-gcc-switches -fno-common'
GOHOSTARCH='arm64'
GOHOSTOS='darwin'
GOINSECURE=''
GOMOD='/dev/null'
GOMODCACHE='/Users/mac/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='darwin'
GOPATH='/Users/mac/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/Users/mac/Library/Application Support/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/darwin_arm64'
GOVCS=''
GOVERSION='go1.24.3'
GOWORK=''
PKG_CONFIG='pkg-config'What did you do?
package main
import "fmt"
type Expression interface{}
type Column struct {
UniqueID int64
}
func (col *Column) EqualColumn(expr Expression) bool {
other, ok := expr.(*Column)
if !ok {
return false
}
return col.UniqueID == other.UniqueID
}
func (col *Column) InColumnArray(cols []*Column) bool {
for _, c := range cols {
if col.EqualColumn(c) { // c is *Column, but EqualColumn expects Expression
return true
}
}
return false
}
func main() {
cols := []*Column{
{UniqueID: 1},
{UniqueID: 2},
{UniqueID: 3},
}
colToCheck := &Column{UniqueID: 2}
fmt.Println("Is column in array?", colToCheck.InColumnArray(cols)) // true
colToCheck2 := &Column{UniqueID: 5}
fmt.Println("Is column in array?", colToCheck2.InColumnArray(cols)) // false
}The Output:
Is column in array? true
Is column in array? falseWhat did you see happen?
After executing modernize -fix -test ./..., it will become.
package main
import "slices"
import "fmt"
type Expression interface{}
type Column struct {
UniqueID int64
}
func (col *Column) EqualColumn(expr Expression) bool {
other, ok := expr.(*Column)
if !ok {
return false
}
return col.UniqueID == other.UniqueID
}
func (col *Column) InColumnArray(cols []*Column) bool {
return slices.ContainsFunc(cols, col.EqualColumn)
}
func main() {
cols := []*Column{
{UniqueID: 1},
{UniqueID: 2},
{UniqueID: 3},
}
colToCheck := &Column{UniqueID: 2}
fmt.Println("Is column in array?", colToCheck.InColumnArray(cols)) // true
colToCheck2 := &Column{UniqueID: 5}
fmt.Println("Is column in array?", colToCheck2.InColumnArray(cols)) // false
}Output:
# command-line-arguments
./main2.go:22:28: in call to slices.ContainsFunc, S (type []*Column) does not satisfy ~[]EWhat did you expect to see?
Do not take action on this situation.