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? false

What 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 ~[]E

What did you expect to see?

Do not take action on this situation.

Comment From: gopherbot

Change https://go.dev/cl/693879 mentions this issue: gopls/internal/analysis/modernize: fix the compilation error caused

Comment From: gabyhelp

Related Issues

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

Comment From: findleyr

Thanks for the report. We've fixed similar issues in the past -- was this with gopls@v0.20.0?

Nevertheless, we should fix this for the next release.

Comment From: cuishuang

Thanks for the report. We've fixed similar issues in the past -- was this with gopls@v0.20.0?

Nevertheless, we should fix this for the next release.

Thanks.

Comment From: findleyr

@cuishuang sorry, why did you close this? Is it already fixed?

I meant that we should make sure it's fixed in the next release. AFAIK, it's not fixed yet.

Comment From: cuishuang

@cuishuang sorry, why did you close this? Is it already fixed?

I meant that we should make sure it's fixed in the next release. AFAIK, it's not fixed yet.

Sorry for the delayed response.

As I mentioned in CL693879,

I did some testing and found that it was likely because the code I used locally to compile the binary is not the latest version. Sorry for the inconvenience.

Using the latest code should prevent this issue from occurring.

So I think this issue can be closed. Thank you for your response.

Comment From: mvdan

I just ran into this problem as well today, with modernize at version v0.0.0-20250905165647-bd1ee09fe80a, so I don't think the bug is resolved.

See https://review.gerrithub.io/c/cue-lang/cue/+/1222171 at patchset 1 - the change to encoding/json broke the build. This can be reproduced on https://github.com/cue-lang/cue at commit 20531e1837bf21fd9b38f83610d1a47d663fe2fc:

$ go build ./encoding/json; echo ==; modernize -fix -slicescontains ./encoding/json; go build ./encoding/json
==
# cuelang.org/go/encoding/json
encoding/json/json.go:195:27: in call to slices.ContainsFunc, S (type []ast.Expr) does not satisfy ~[]E