if len(cidrs) != 1 {
		t.Errorf("Expected exactly one CIDR: %v", cidrs.StringSlice())
	}
	cidrs = checkOK("192.168.0.1/32,192.168.0.1/32")
	if len(cidrs) != 1 {
		t.Errorf("Expected exactly one CIDR (after de-dup): %v", cidrs.StringSlice())
	}
	cidrs = checkOK("192.168.0.1/32,192.168.0.2/32")
	if len(cidrs) != 2 {
		t.Errorf("Expected two CIDRs: %v", cidrs.StringSlice())
	}
	cidrs = checkOK("  192.168.0.1/32 , 192.168.0.2/32   ")

)

// Implemented in runtime package.
func runtime_BeforeFork()
func runtime_AfterFork()
func runtime_AfterForkInChild()

// Fork, dup fd onto 0..len(fd), and exec(argv0, argvv, envv) in child.
// If a dup or exec fails, write the errno error to pipe.
// (Pipe is close-on-exec so if exec succeeds, it will be closed.)
// In the child, this function must not acquire any locks, because

	goCmd(nil, "build", "-buildmode=plugin", "./plugin2")
	so, err := os.ReadFile("plugin2.so")
	if err != nil {
		log.Panic(err)
	}
	if err := os.WriteFile("plugin2-dup.so", so, 0444); err != nil {
		log.Panic(err)
	}
	prettyPrintf("cp plugin2.so plugin2-dup.so\n")

	goCmd(nil, "build", "-buildmode=plugin", "-o=sub/plugin1.so", "./sub/plugin1")
	goCmd(nil, "build", "-buildmode=plugin", "-o=unnamed1.so", "./unnamed1/main.go")

	upgradeTo := make(map[string]string, len(upgrade))
	for _, u := range upgrade {
		if !pathInList[u.Path] {
			list = append(list, module.Version{Path: u.Path, Version: "none"})
		}
		if prev, dup := upgradeTo[u.Path]; dup {
			upgradeTo[u.Path] = reqs.Max(u.Path, prev, u.Version)
		} else {
			upgradeTo[u.Path] = u.Version
		}
	}

	lsa, _ := lrsa.Sockaddr()
	rsa, _ := rrsa.Sockaddr()

	netfd.setAddr(netfd.addrFunc()(lsa), netfd.addrFunc()(rsa))
	return netfd, nil
}

// Unimplemented functions.

func (fd *netFD) dup() (*os.File, error) {
	// TODO: Implement this, perhaps using internal/poll.DupCloseOnExec.
	return nil, syscall.EWINDOWS

            LinkedHashMap<String, String> dup = new LinkedHashMap<>(inherited.size() + overrides.size());
            dup.putAll(inherited);
            dup.putAll(overrides);
            return dup;
        }

        private void mergeConfigurations(ModuleRevisionId sourceMrid, Configuration[] configurations) {

	}
	r0, _, e1 := Syscall(SYS_CHDIR, uintptr(unsafe.Pointer(_p0)), 0, 0)
	if int32(r0) == -1 {
		err = e1
	}
	return
}

// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT

func Dup(oldfd int, newfd int) (fd int, err error) {
	r0, _, e1 := Syscall(SYS_DUP, uintptr(oldfd), uintptr(newfd), 0)
	fd = int(r0)
	if int32(r0) == -1 {
		err = e1
	}
	return
}

	}
	r0, _, e1 := Syscall(SYS_CHDIR, uintptr(unsafe.Pointer(_p0)), 0, 0)
	if int32(r0) == -1 {
		err = e1
	}
	return
}

// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT

func Dup(oldfd int, newfd int) (fd int, err error) {
	r0, _, e1 := Syscall(SYS_DUP, uintptr(oldfd), uintptr(newfd), 0)
	fd = int(r0)
	if int32(r0) == -1 {
		err = e1
	}
	return
}

}

func (ln *TCPListener) close() error {
	return ln.fd.Close()
}

func (ln *TCPListener) file() (*os.File, error) {
	f, err := ln.fd.dup()
	if err != nil {
		return nil, err
	}
	return f, nil
}

func (sl *sysListener) listenTCP(ctx context.Context, laddr *TCPAddr) (*TCPListener, error) {
	return sl.listenTCPProto(ctx, laddr, 0)
}

//sys	Chmod(path string, mode uint32) (err error)
//sys	Chown(path string, uid int, gid int) (err error)
//sys	Chroot(path string) (err error)
//sys	Close(fd int) (err error)
//sys	Dup(fd int) (nfd int, err error)
//sys	Dup2(from int, to int) (err error)
//sys	dup3(from int, to int, flags int) (err error)
//sys	Fchdir(fd int) (err error)
//sys	Fchflags(fd int, flags int) (err error)