cmd/compile: compilation error: prepwrite: bad off=... siz=8 s=main..stmp_0

Go version

go version go1.27-devel_85f838f46c Sun Apr 26 20:38:08 2026 -0700 linux/amd64

Output of go env in your module/workspace:

AR='ar'
CC='gcc'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='g++'
GCCGO='/research/compilers/gccgo'
GO111MODULE=''
GOAMD64='v1'
GOARCH='amd64'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/home/user/.cache/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/home/user/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build271633167=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/dev/null'
GOMODCACHE='/home/user/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/user/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/user/software/go/slot-a/src'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/user/.config/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/user/software/go/slot-a/src/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.27-devel_85f838f46c Sun Apr 26 20:38:08 2026 -0700'
GOWORK=''
PKG_CONFIG='pkg-config'

What did you do?

$ go build /tmp/bug.go
# command-line-arguments
/tmp/bug.go:3:5: type [100000000000001]string larger than address space
/tmp/bug.go:3:5: prepwrite: bad off=1600000000000000 siz=8 s=main..stmp_0

$ cat /tmp/bug.go
package main

var expected = []string {
        100000000000000: "a",
}

func main() {}

https://go.dev/play/p/usjNYeAeDMj

What did you see happen?

$ go build /tmp/bug.go
# command-line-arguments
/tmp/bug.go:3:5: type [100000000000001]string larger than address space
/tmp/bug.go:3:5: prepwrite: bad off=1600000000000000 siz=8 s=main..stmp_0

What did you expect to see?

symbol too large error, a more specific compiler frontend error "index too large" or some dynamic handling.

I have spent some time trying to analyze if this is a known problem/wontfix. This has strong similarities to an old bug report https://github.com/golang/go/issues/23781 which had a non-global int array with a too large index and was eventually fixed (that issue's code compiles without crash for me).

I cannot get this bug to manifest with an int array, only with an array of strings where the string at the index is non-empty.