Compare text length for plain text in the diffing.

src/compare/diff.rs

@@ -915,6 +915,18 @@ fn compare_plain_text<'s>(
     let mut this_status = DiffStatus::Good;
     let mut message = None;
     let text = emacs.as_text()?;
+    let emacs_text_length = {
+        let start_ind: usize = text.properties.get(0).expect("Should have start index.").as_atom()?.parse()?;
+        let end_ind: usize = text.properties.get(1).expect("Should have end index.").as_atom()?.parse()?;
+        end_ind - start_ind
+    };
+    if rust.source.len() != emacs_text_length {
+        this_status = DiffStatus::Bad;
+        message = Some(format!(
+            "(emacs len != rust len) {:?} != {:?}",
+            emacs_text_length, rust.source.len()
+        ));
+    }
     let unquoted_text = text.unquote()?;
     if unquoted_text != rust.source {
         this_status = DiffStatus::Bad;