cmd/compile: panic on conversion to anonymous interface when 2 versions of library are built

[jirfag]

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

$ go version
go version go1.11.4 darwin/amd64

Does this issue reproduce with the latest release?

yes it does

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

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/denis/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/denis/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
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 -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/nl/54f5x38s4m53mkzzj92zsj340000gn/T/go-build581161643=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

Run

git clone https://github.com/golangci/test4.git
go run main.go

and got

panic: interface conversion: *ssa.Call is not interface { ssa.setNum(int) }: missing method setNum

goroutine 1 [running]:
github.com/golangci/test2/ssa.Panics(0x105cde0, 0xc000064020, 0x2)
        /Users/denis/go/pkg/mod/github.com/golangci/test2@v0.0.0-20190108121323-b241e05eddb2/ssa/func.go:6 +0x82
main.main()
        /Users/denis/go/src/github.com/golangci/test4/main.go:14 +0xa0
exit status 2

What did you expect to see?

No panic with anonymous interface cast.

What did you see instead?

Panic.

[mvdan]

Unless I'm missing something, this is a run-time panic, not a compiler panic. Any reason you assigned this to cmd/compile?

Also, were you able to reproduce this with a smaller package or Go program?

[jirfag]

sorry, suggest more appropriate component, please. I set cmd/compile because it looks like a compiler bug and #24547 had such component.

I will try to reproduce it with a smaller program.

[jirfag]

I could reproduce it with much smaller program

[mvdan]

sorry, suggest more appropriate component, please.

Oh, I don't know if the compiler has a bug here - certainly possible, but I was wondering if you had dug up the cause.

If you can reproduce the crash with a smaller self-contained program, please share it. That will make debugging the problem faster.

[jirfag]

I have already changed the description of the issue with the smaller test case:

git clone https://github.com/golangci/test4.git
go run main.go

[mvdan]

Sorry, but that repo is a 404. Can you just share the file on play.golang.org?