This is a thing that can be seen in Rust error messages:
error[E0382]: use of moved value: `a`
--> src/main.rs:5:5
|
2 | let a = String::from("aa");
| - move occurs because `a` has type `String`, which does not implement the `Copy` trait
3 | let b = a;
| - value moved here
4 | println!("{}", b);
5 | a
| ^ value used here after move
I think it would be fun (and quite useful) to create a visual representation of these errors in the editor.
Basically, a "gutter rail" is a "rail" on the gutter, which is simply a vertical line spanning from the first line where the error occurs, to the last line where the error's children messages end.
liquidev
commented
3 years ago 
This is a thing that can be seen in Rust error messages:
I think it would be fun (and quite useful) to create a visual representation of these errors in the editor.
Basically, a "gutter rail" is a "rail" on the gutter, which is simply a vertical line spanning from the first line where the error occurs, to the last line where the error's children messages end.