cmd/link: index out of range at cmd/link/internal/ld.decodetypeKind

[johejo]

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

$ go version
go version devel go1.22-a9859a7df7 Fri Aug 18 23:45:44 2023 +0000 linux/amd64

Does this issue reproduce with the latest release?

no, tip only

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

go env Output

$ go env
GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/mitsuoheijo/.cache/go-build'
GOENV='/home/mitsuoheijo/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/mitsuoheijo/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/mitsuoheijo/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/mitsuoheijo/repos/github.com/golang/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/mitsuoheijo/repos/github.com/golang/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='devel go1.22-a9859a7df7 Fri Aug 18 23:45:44 2023 +0000'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/home/mitsuoheijo/repos/github.com/osrg/gobgp/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-build811026688=/tmp/go-build -gno-record-gcc-switches'

What did you do?

git clone https://github.com/osrg/gobgp.git
cd gobgp/
git checkout v3.17.0
go build ./cmd/gobgpd

What did you expect to see?

build succeeds

What did you see instead?

# github.com/osrg/gobgp/v3/cmd/gobgpd
type:func([]github.com/osrg/gobgp/v3/pkg/packet/bgp.ExtendedCommunityInterface) []github.com/osrg/gobgp/v3/pkg/packet/bgp.ExtendedCommunityInterface: missing type
panic: runtime error: index out of range [23] with length 0

goroutine 1 [running]:
cmd/link/internal/ld.decodetypeKind(...)
        /home/mitsuoheijo/repos/github.com/golang/go/src/cmd/link/internal/ld/decodesym.go:42
cmd/link/internal/ld.(*dwctxt).newtype(0xc001ef6948, 0x7a245)
        /home/mitsuoheijo/repos/github.com/golang/go/src/cmd/link/internal/ld/dwarf.go:546 +0x228a
cmd/link/internal/ld.(*dwctxt).defgotype(0xc001ef6948, 0x7a245)
        /home/mitsuoheijo/repos/github.com/golang/go/src/cmd/link/internal/ld/dwarf.go:534 +0x119
cmd/link/internal/ld.(*dwctxt).importInfoSymbol(0xc001ef6948, 0x4a00e)
        /home/mitsuoheijo/repos/github.com/golang/go/src/cmd/link/internal/ld/dwarf.go:1143 +0x345
cmd/link/internal/ld.(*dwctxt).dwarfVisitFunction(0xc001ef6948, 0x6?, 0xc0000b7040)
        /home/mitsuoheijo/repos/github.com/golang/go/src/cmd/link/internal/ld/dwarf.go:1723 +0x41f
cmd/link/internal/ld.dwarfGenerateDebugInfo(0xc00011e200)
        /home/mitsuoheijo/repos/github.com/golang/go/src/cmd/link/internal/ld/dwarf.go:1882 +0x148e
cmd/link/internal/ld.Main(_, {0x20, 0x20, 0x1, 0x7, 0x10, 0x0, {0xc000012469, 0x1, 0x1}, ...})
        /home/mitsuoheijo/repos/github.com/golang/go/src/cmd/link/internal/ld/main.go:356 +0x1332
main.main()
        /home/mitsuoheijo/repos/github.com/golang/go/src/cmd/link/main.go:72 +0xdfb

If disabling DWARF with -ldflags='-w' the link succeeds.

[dmitshur]

Thanks for reporting.

CC @mdempsky, @cuonglm.

[mdempsky]

Bisect identifies ca858a4.

[gopherbot]

Change https://go.dev/cl/521155 mentions this issue: Revert "cmd/compile/internal/gc: steps towards work-queue"

[mdempsky]

Confirmed that reverting that CL fixes the gobgpd build.

I'm fine with reverting and then rolling forward once the failure case is understood.

[mdempsky]

The issue here is that DWARF generation can also produce references to runtime type descriptors, which need to be written out too. So that also needs to go into the work queue. Whee.

[mdempsky]

Minimal repro:

package a

type iface interface{ m() }

func F() {
	f := func(rt []iface) []iface {
		return append([]iface{}, rt...)
	}
	f(nil)
}

package main

import "test/a"

func main() {
	a.F()
}

[johejo]

Fixed in https://go-review.googlesource.com/c/go/+/522339