`gochecksumtype`: works only inside one package

Author: maratoriCreated Oct 24, 2023Updated Aug 29, 2026

Labelsbugdependencies

Welcome

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 read the typecheck section of the FAQ (https://golangci-lint.run/usage/faq/#why-do-you-have-typecheck-errors).
Yes, I've tried with the standalone linter if available (e.g., gocritic, go vet, etc.). (https://golangci-lint.run/usage/linters/)

Description of the problem

gochecksumtype doesn't report missing cases if the sum type is declared in one package and the type switch is in a different package (see https://github.com/golangci/golangci-lint/pull/3671#discussion_r1370424897).

Version of golangci-lint

bash

$ golangci-lint --version
golangci-lint has version v1.55.0 built with go1.21.3 from de1c3919 on 2023-10-20T11:56:32Z

Configuration

bash

# paste configuration file or CLI flags here

Go environment

bash

$ go version && go env
go version go1.21.3 linux/amd64
GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/root/.cache/go-build'
GOENV='/root/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='local'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.21.3'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/app/go.mod'
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 -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build2772357518=/tmp/go-build -gno-record-gcc-switches'

Verbose output of running

bash

$ golangci-lint cache clean
$ golangci-lint run -v
# paste output here

A minimal reproducible example or link to a public repository

/decl/decl.go

package decl

//sumtype:decl
type MySumType interface {
        sealed()
}

type VariantA struct{}

func (*VariantA) sealed() {}

type VariantB struct{}

func (*VariantB) sealed() {}

/usage/usage.go

package usage

import "decl"

func DoSomething(x decl.MySumType) {
        switch x.(type) { // <-- here is expected a report about missing VariantB
        case *decl.VariantA:
        }
}

Validation

Yes, I've included all information above (version, config, etc.).

Source: golangci/golangci-lint

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