error: `member_name` should be set only once
 --> tests/ui/errors/attr.tuples.unique.member-name.rs:7:15
  |
7 |     #[tuples::member_name(B)]
  |               ^^^^^^^^^^^

error: the first definition was here
 --> tests/ui/errors/attr.tuples.unique.member-name.rs:6:15
  |
6 |     #[tuples::member_name(A)]
  |               ^^^^^^^^^^^