env GOSSAFUNC=keys go build for_keys_go_issue2.go

for_keys_go_issue2.go

package main

import "fmt"

type S struct {
	b [8]byte
}

func keys(m map[S]struct{}) [][]byte {
	var z [][]byte
	for k := range m {
		z = append(z, k.b[:])
	}
	return z
}

func main() {
	fmt.Println(keys(map[S]struct{}{
		S{b: [8]byte{1}}: struct{}{},
		S{b: [8]byte{2}}: struct{}{},
	}))
}