message: Don't expose File
  Summary: Only used internally in one place, so make it pub(crate)
diff: @@ -168,7 +168,7 @@ impl CodeMap {
  }
  /// Looks up a `File`
  - pub fn get_file(&self) -> &Arc<File> {
  + pub(crate) fn get_file(&self) -> &Arc<File> {
  &self.file
  }
  @@ -198,7 +198,7 @@ impl CodeMap {
  }
  /// A `CodeMap`'s record of a source file.
  -pub struct File {
  +pub(crate) struct File {
  /// The span representing the entire file.
  span: Span,
  