cmd/compile: internal compiler error: '(*Tree[go.shape.int]).RemoveParent.func1': value .dict (nil) incorrectly live at entry

[anupcshan]

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?

Reproduces with Go 1.20, but not with 1.19.4

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

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/codespace/.cache/go-build"
GOENV="/home/codespace/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/codespace/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/codespace/go:/home/codespace/src/server/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.20"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/workspaces/goissue/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 -fdebug-prefix-map=/tmp/go-build1991160894=/tmp/go-build -gno-record-gcc-switches"

What did you do?

main.go:

package main

func main() {
        _ = Tree[int]{}
}

type Tree[T comparable] struct {
        parent map[T]T
}

func (g *Tree[T]) RemoveParent(node T) {
        defer delete(g.parent, node)
        // To fix, remove "defer" from the above line, like below.
        // delete(g.parent, node)
}

What did you expect to see?

$ go build

What did you see instead?

$ go build
# goissue
./main.go:12:2: internal compiler error: '(*Tree[go.shape.int]).RemoveParent.func1': value .dict (nil) incorrectly live at entry

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

$ GOEXPERIMENT=nounified go build

#57778 shows the same error

[cuonglm]

It seems to me that GOEXPERIMENT=nounified build ok, but unified IR crashes.

[gopherbot]

Change https://go.dev/cl/466035 mentions this issue: cmd/compile: fix wrong ecsape analysis for go/defer generic calls

[cuonglm]

Seems we need to backport this? @mdempsky @randall77

[mdempsky]

@cuonglm Yes, I think so.

@gopherbot Please backport to Go 1.20.

[gopherbot]

Backport issue(s) opened: #58467 (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.

[mdempsky]

FWIW, as a workaround until a fix is included in a point release, if you change defer delete(m, k) into defer func() { delete(m, k) }(), it should work. The same applies to any other go/defer calls to builtin functions within a generic function/method.