cmd/compile: internal compiler error: Type.Elem UNION

[ClarkQAQ]

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

$ go version
go version go1.20 linux/amd64

Does this issue reproduce with the latest release?

Yes, but it works in go1.19

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

go env Output

$ go env
GO111MODULE="auto"
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/clark/.cache/go-build"
GOENV="/home/clark/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/clark/.go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/clark/.go"
GOPRIVATE=""
GOPROXY="https://goproxy.cn,direct"
GOROOT="/usr/lib/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.20"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
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 -fdebug-prefix-map=/tmp/go-build3340342221=/tmp/go-build -gno-record-gcc-switches"

What did you do?

GoPlay: https://go.dev/play/p/DfmO9bKkKal

go run main.go

What did you expect to see?

[clark@ArchOxO issus]$ go run main.go 
true

What did you see instead?

[clark@ArchOxO issus]$ go run main.go 
# command-line-arguments
./main.go:3:5: internal compiler error: Type.Elem UNION

Please file a bug report including a short program that triggers the error.
https://go.dev/issue/new

[cuonglm]

CL 458619 fixes this issue for unified IR.

Should we backport? cc @mdempsky

[gopherbot]

Change https://go.dev/cl/465455 mentions this issue: test: add test for issue 58345

[mdempsky]

@cuonglm Yeah, I think backporting that CL to 1.20 seems appropriate and reasonable. Thanks.

[dr2chase]

@gopherbot please consider backport this to 1.20.

[gopherbot]

Backport issue(s) opened: #58413 (for 1.20).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases.

[cuonglm]

Backport CL is created, closing.