Works for me:

  #[derive(Debug)]
  struct Input<'a>{
      words: Vec<&'a str>,
      phrase: &'a str,
  }

  fn main() {
    let s="foo bar baz";
    let input = Input {
        words: s.split_whitespace().collect(),
        phrase: s,
    };
    dbg!(input);
  }

   Compiling playground v0.0.1 (/playground)
    Finished dev [unoptimized + debuginfo] target(s) in 1.15s
     Running `target/debug/playground`
  [src/main.rs:13] input = Input {
    words: [
        "foo",
        "bar",
        "baz",
    ],
    phrase: "foo bar baz",
  }