message: Remove Hash for File
  Summary: It wasn't used, which is good, because while the Hash took the hash of the span, the equality used the pointer, so these weren't going to be remotely compatible.
diff: @@ -39,7 +39,7 @@ use gazebo::prelude::*;
  use std::{
  cmp,
  fmt::{self, Display},
  - hash::{Hash, Hasher},
  + hash::Hash,
  ops::{Add, Deref, Sub},
  sync::Arc,
  };
  @@ -320,12 +320,6 @@ impl PartialEq for File {
  impl Eq for File {}
  -impl Hash for File {
  - fn hash<H: Hasher>(&self, hasher: &mut H) {
  - self.span.hash(hasher);
  - }
  -}
  -
  /// A line and column.
  #[derive(Copy, Clone, Dupe, Hash, Eq, PartialEq, Debug)]
  pub struct LineCol {
  