Clippy fix for unwrap_or(T::default()) in the absence of type inference.

I ran clippy --fix on:

fn main() {
    let s = None.unwrap_or(String::default());
    let x = s.len();
    println!("{}", x);
}

This fixes to

fn main() {
    let s = None.unwrap_or_default();
    let x = s.len();
    println!("{}", x);
}

But now we've lost the type information and it no longer compiles. It should fix to

fn main() {
    let s: String = None.unwrap_or_default();
    let x = s.len();
    println!("{}", x);
}

Meta

• cargo clippy -V: clippy 0.1.51 (2fd73fab 2021-03-23)
• rustc -Vv:

  rustc 1.51.0 (2fd73fabe 2021-03-23)
  binary: rustc
  commit-hash: 2fd73fabe469357a12c2c974c140f67e7cdd76d0
  commit-date: 2021-03-23
  host: x86_64-apple-darwin
  release: 1.51.0
  LLVM version: 11.0.1