panic when range-func return nil

[dungdm93]

Go version

go version go1.23.0 linux/amd64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/dungdm93/.cache/go-build'
GOENV='/home/dungdm93/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/dungdm93/go/pkg/mod'
GONOPROXY='example.com/example/*'
GONOSUMDB='example.com/example/*'
GOOS='linux'
GOPATH='/home/dungdm93/go'
GOPRIVATE='example.com/example/*'
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.23.0'
GODEBUG=''
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/dungdm93/.config/go/telemetry'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/dev/null'
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-build883436730=/tmp/go-build -gno-record-gcc-switches'

What did you do?

package main

import "iter"

func Seq() iter.Seq[string] {
	return nil
}

func main() {
	var l []any = nil
	for _, v := range l { // run normally
		println(v)
	}

	var m map[string]any = nil
	for k, v := range m { // run normally
		println(k, v)
	}

	for e := range Seq() { // panic: runtime error: nil pointer dereference
		println(e)
	}
}

What did you see happen?

panic: runtime error: nil pointer dereference when iter.Seq is nil

What did you expect to see?

Run successfully, as the same way as range over nil map and list

[gabyhelp]

Related Issues and Documentation

• proposal: spec: range over nil function values should not panic #65629 (closed)
• iter: `iter.Seq` returns incorrect values for subsequent next calls #64646 (closed)
• Len(slice) returns a non-zero positive number, but accessing first element results in panic #42037 (closed)
• cmd/compile: ICE compiling rangefunc for < 1.23 in combination with Cgo #67497 (closed)
• General function call #50712 (closed)
• runtime: panic in mapaccess2_faststr (suspected data race) #65115 (closed)
• cmd/compile: internal compiler error: panic: runtime error: index out of range [0] with length 0 #51765 (closed)
• net: mapErr causes panic #60029 (closed)
• runtime: endless traceback when panic in generics funtion #58513 (closed)
• proposal: iter: Allow nil iterators #68931 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[cuonglm]

Duplicated of #65629