build failed by rustc 1.38.0

[zhang-ray]

error[E0425]: cannot find function `lookup_host` in module `net`
   --> src/main.rs:315:38
    |
315 |                 let addr = try!(net::lookup_host(name)).filter_map(|addr| {
    |                                      ^^^^^^^^^^^ not found in `net`

error[E0554]: `#![feature]` may not be used on the stable release channel
 --> src/main.rs:1:1
  |
1 | #![feature(lookup_host)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^