rustfmt will format comment even not covered by file-lines option

[BusyJay]

Consider following file

struct A {
t: i64
}

#[cfg(test)]
mod tests {
    #[test]
    fn it_works() {
                                         // test
    }
}

If I format it using command rustfmt --write-mode=diff --file-lines '[{"file": "src/lib.rs", "range": [0, 2]}]' src/lib.rs, only first two lines should be formatted, but I got these output:

Warning: Extra file listed in file_lines option '/tmp/testfmt/src/lib.rs'
Diff in src/lib.rs at line 1:
 struct A {⏎
-t: i64⏎
+    t: i64,⏎
 }⏎
 ⏎
 #[cfg(test)]⏎
Diff in src/lib.rs at line 6:
 mod tests {⏎
     #[test]⏎
     fn it_works() {⏎
-                                         // test⏎
+        // test⏎
     }⏎
 }⏎

It tries to format the comment at L9 too.

[kamalmarhubi]

As mentioned in #1514 (comment) I'm not so sure this is a bug as much as incomplete implementation. I had named the flag --experimental-file-lines but changed it to --file-lines during review.

[fintelia]

No, rustfmt shouldn't try to format code blatantly outside of file_lines. However, I believe this issue was resolved by #1510.

[topecongiro]

Closed via #1510.