cmd/link/internal/ld: linker problem with shared libraries

[kiap]

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

1.16rc1

Does this issue reproduce with the latest release?

Yes

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

go env Output

tested on CentOS 7 and RHEL8
$ go env

GO111MODULE=""

GOARCH="amd64"

GOBIN=""

GOCACHE="/usr/src/.cache"

GOENV="/root/.config/go/env"

GOEXE=""

GOFLAGS=""

GOHOSTARCH="amd64"

GOHOSTOS="linux"

GOINSECURE=""

GOMODCACHE="/usr/src/it.dev/pkg/mod"

GONOPROXY=""

GONOSUMDB=""

GOOS="linux"

GOPATH="/usr/src/it.dev"

GOPRIVATE=""

GOPROXY="https://proxy.golang.org,direct"

GOROOT="/usr/src/go"

GOSUMDB="sum.golang.org"

GOTMPDIR=""

GOTOOLDIR="/usr/src/go/pkg/tool/linux_amd64"

GOVCS=""

GOVERSION="devel +4436114 Fri Jan 29 19:48:48 2021 +0000"

GCCGO="gccgo"

AR="ar"

CC="gcc"

CXX="g++"

CGO_ENABLED="1"

GOMOD="/usr/src/it.dev/src/hello/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-build561658131=/tmp/go-build -gno-record-gcc-switches"

What did you do?

We have problem with shared library linking of new ld in 1.16rc1, I recreated the problem using standard library, we originally had the issue with our own developed libraries

I have chosen the following based on their dependencies hierarchy

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib runtime sync

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib runtime/race

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib unicode

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib unicode/utf8

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib unicode/utf16

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib math/bits

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib math

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib internal/unsafeheader

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib internal/reflectlite

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib internal/testlog

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib container/list

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib container/ring

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib crypto/internal/subtle

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib crypto/subtle

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib vendor/golang.org/x/crypto/cryptobyte/asn1

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib internal/nettrace

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib vendor/golang.org/x/crypto/internal/subtle

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib encoding

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib internal/goversion

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib hash/maphash

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib image/color

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib internal/cfg

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib image/color/palette

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib math/cmplx

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib runtime/metrics

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib internal/singleflight

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib internal/sysinfo

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib math/rand

go install -v -ldflags '-s -w' -gcflags '-trimpath /usr/src/go' -buildmode=shared -linkshared -pkgdir /usr/src/lib errors

What did you expect to see?

shared libraries built and placed into /usr/src/lib

/usr/src/lib/libcontainer-list.so
/usr/src/lib/libcontainer-ring.so
/usr/src/lib/libcrypto-internal-subtle.so
/usr/src/lib/libcrypto-subtle.so
/usr/src/lib/libencoding.so
/usr/src/lib/libhash-maphash.so
/usr/src/lib/libimage-color-palette.so
/usr/src/lib/libimage-color.so
/usr/src/lib/libinternal-cfg.so
/usr/src/lib/libinternal-goversion.so
/usr/src/lib/libinternal-nettrace.so
/usr/src/lib/libinternal-reflectlite.so
/usr/src/lib/libinternal-singleflight.so
/usr/src/lib/libinternal-sysinfo.so
/usr/src/lib/libinternal-testlog.so
/usr/src/lib/libinternal-unsafeheader.so
/usr/src/lib/libmath-bits.so
/usr/src/lib/libmath-cmplx.so
/usr/src/lib/libmath-rand.so
/usr/src/lib/libmath.so
/usr/src/lib/libruntime-metrics.so
/usr/src/lib/libruntime-race.so
/usr/src/lib/libruntime,sync.so
/usr/src/lib/libunicode.so
/usr/src/lib/libunicode-utf16.so
/usr/src/lib/libunicode-utf8.so
/usr/src/lib/libvendor-golang.org-x-crypto-cryptobyte-asn1.so
/usr/src/lib/libvendor-golang.org-x-crypto-internal-subtle.so
/usr/src/lib/liberrors.so

What did you see instead?

All shared libraries created except for liberrors.so

Attention it is possible to replicate this with strings, bufio, and so many other libraries, as well as our properietary libraries, older versions worked just fine)

/tmp/go-build3363267740/b011/liberrors.so

panic: runtime error: index out of range [23] with length 0

goroutine 1 [running]:
cmd/link/internal/ld.decodetypeKind(...)
/usr/src/go/src/cmd/link/internal/ld/decodesym.go:52
cmd/link/internal/ld.(*deadcodePass).decodeIfaceMethod(0xc000112c50, 0xc00009c000, 0x87f340, 0xc8, 0x68, 0x8b, 0xc0000be000, 0xc00009c000)
/usr/src/go/src/cmd/link/internal/ld/deadcode.go:391 +0x247
cmd/link/internal/ld.(*deadcodePass).flood(0xc000112c50)
/usr/src/go/src/cmd/link/internal/ld/deadcode.go:169 +0x5bb
cmd/link/internal/ld.deadcode(0xc000152000)
/usr/src/go/src/cmd/link/internal/ld/deadcode.go:308 +0xa9
cmd/link/internal/ld.Main(0x87f340, 0x20, 0x20, 0x1, 0x7, 0x10, 0x0, 0x0, 0x6e8658, 0x1b, ...)
/usr/src/go/src/cmd/link/internal/ld/main.go:247 +0xdf6
main.main()
/usr/src/go/src/cmd/link/main.go:68 +0x258

[thanm]

I'll take a look at this.

[gopherbot]

Change https://golang.org/cl/288496 mentions this issue: cmd/link: don't decode type symbol in deadcode when linkShared

[thanm]

Whoops, looks like Cherry is already working on it.