go: runtime: in generic code, convert iface to type failed with "types from different scopes"

What version of Go are you using (`go version`)?

go version go1.18beta2 linux/amd64

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (`go env`)?

go env

GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/romain/.cache/go-build"
GOENV="/home/romain/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/romain/go/pkg/mod"
GONOPROXY="XXXXXXXXXXXXXXXXXXX"
GONOSUMDB="XXXXXXXXXXXXXXXXXXX"
GOOS="linux"
GOPATH="/home/romain/go"
GOPRIVATE="XXXXXXXXXXXXXXXXX"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/romain/sdk/go1.18beta2"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/romain/sdk/go1.18beta2/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.18beta2"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/romain/Documents/git/github/replicate-issue/types-from-different-scopes-issue/go.mod"
GOWORK=""
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-build838965849=/tmp/go-build -gno-record-gcc-switches"

What did you do?

Using generics and interface conversion, i get the following error at runtime :

panic: interface conversion: either.Either[go.shape.string_0,go.shape.interface {}_1] is either.right[github.com/rguilmont/types-from-different-scopes-issue/pkg/pkga.Test,interface {}], not either.right[github.com/rguilmont/types-from-different-scopes-issue/pkg/pkga.Test,interface {}] (types from different scopes)

goroutine 1 [running]:
github.com/rguilmont/types-from-different-scopes-issue/pkg/either.Fold[...]({0x4b2c00, 0xc00009e210}, 0x49c850, 0x49c858)
        /home/romain/Documents/git/github/replicate-issue/types-from-different-scopes-issue/pkg/either/either.go:42 +0xc5
main.main()
        /home/romain/Documents/git/github/replicate-issue/types-from-different-scopes-issue/pkg/cmd/main.go:13 +0x65

To check the code, here it is with instruction to replicate : https://github.com/rguilmont/types-from-different-scopes-issue

What did you expect to see?

It works! test

Thanks !

About this issue

Original URL
State: closed
Created 2 years ago
Comments: 15 (10 by maintainers)

Commits related to this issue

[release-branch.go1.18] cmd/compile: don't include instantiating types in type hash This CL is a bit overkill, but it is pretty safe for 1.18. We'll want to revisit for 1.19 so we can avoid the hash ... — committed to golang/go by randall77 2 years ago

Most upvoted comments

There is a CL that fixes this issue. I’m investigating a possibly better fix, should know one way or another by EOD.

randall77 on Mar 2, 2022

Reopening for cherry-picking into 1.18 release branch.

randall77 on Mar 3, 2022

Hm, looks like when compiling pkga, we make a symbol right["".Test,interface {}] in package either. But the "" in that symbol refers to pkga. But right is in package either, so we use either to substitute into the symbol name, which is not always right.

randall77 on Feb 24, 2022

Thanks for the report. I don’t know generics to say if this is expected or not, but I checked and this behavior reproduces with go1.18rc1 as well.

CC @findleyr, @mdempsky.

dmitshur on Feb 18, 2022