if b.Pos == src.NoXPos {
		s.Fatalf("Block %s should have a position", b)
	}
	bestPos := src.NoXPos
	for _, e := range b.Preds {
		p := e.Block()
		if !p.LackingPos() {
			continue
		}
		if bestPos == src.NoXPos {
			bestPos = b.Pos
			for _, v := range b.Values {
				if v.LackingPos() {
					continue
				}
				if v.Pos != src.NoXPos {

pkg syscall (netbsd-arm64-cgo), const O_NOSIGPIPE = 16777216
pkg syscall (netbsd-arm64-cgo), const O_NOSIGPIPE ideal-int
pkg syscall (netbsd-arm64-cgo), const OPOST = 1
pkg syscall (netbsd-arm64-cgo), const OPOST ideal-int
pkg syscall (netbsd-arm64-cgo), const O_RSYNC = 131072
pkg syscall (netbsd-arm64-cgo), const O_RSYNC ideal-int
pkg syscall (netbsd-arm64-cgo), const O_SHLOCK = 16