structcheck returns false positives for embedded structs

[valyala]

Thank you for creating the issue!

• Yes, I'm using a binary release within 2 latest major releases. Only such installations are supported.
• Yes, I've searched similar issues on GitHub and didn't find any.
• Yes, I've included all information below (version, config, etc).

Please include the following information:

Version of golangci-lint

$ golangci-lint --version
golangci-lint has version v1.21.0 built from (unknown, mod sum: "h1:HxAxpR8Z0M8omihvQdsD3PF0qPjlqYqp2vMJzstoKeI=") on (unknown)

Config file

$ cat .golangci.yml
cat: .golangci.yml: No such file or directory

Go environment

$ go version && go env
go version go1.13.1 linux/amd64
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/valyala/.cache/go-build"
GOENV="/home/valyala/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/valyala/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/valyala/work/go-src"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/valyala/work/go-src/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/valyala/work/VictoriaMetrics/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build974883207=/tmp/go-build -gno-record-gcc-switches"

See false positives here: https://github.com/VictoriaMetrics/VictoriaMetrics/commit/97ce4e03a57825a783a28e25fc88b9a9e9e09c3c/checks?check_suite_id=269491276

[kortschak]

We see the same thing in gonum/gonum. Locally, this looks like this:

~/src/gonum.org/v1/gonum/graph/encoding/dot [master*]$ golangci-lint run
decode.go:152:2: `graphAttr` is unused (structcheck)
	graphAttr, nodeAttr, edgeAttr encoding.AttributeSetter
	^

This field is used embedded.

[rillig]

Self-contained example, extracted from https://github.com/rillig/pkglint:

package main

import "fmt"

type Autofix struct {
	autofixShortTerm // embedded with implicit name
}

type autofixShortTerm struct {
	actions []string
}

func (a *Autofix) PrintActions() {
	for _, action := range a.actions { // obviously used
		fmt.Println(action)
	}
}

func main() {
	fix := Autofix{}
	fix.actions = append(fix.actions, "action") // obviously used as well
	fix.PrintActions()
}

Output:

$ golangci-lint.exe run
demo.go:10:2: `actions` is unused (structcheck)
        actions []string

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[rillig]

Still reproducible:

$ golangci-lint.exe --version
golangci-lint has version v1.45.2 built from (unknown, mod sum: "h1:9I3PzkvscJkFAQpTQi5Ga0V4qWdJERajX1UZ7QqkW+I=") on (unknown)

$ golangci-lint.exe run ./main.go 
main.go:10:2: `actions` is unused (structcheck)
        actions []string
        ^

[byashimov]

Hey.
Please reopen. This happens with >=1.53.0
1.52 is not affected.

Run @rillig example:

demo.go:10:2: `actions` is unused (structcheck)
        actions []string
        ^
➜  ✗ golangci-lint --version            
golangci-lint has version 1.53.2 built with go1.20.4 from 59a7aaf7 on 2023-06-03T15:04:31Z

A real example.

[ldez]

structcheck is deprecated, please stop using it.

https://golangci-lint.run/usage/linters/