error: This config is already set.
 --> tests/compile_fail/config/already_set.rs:6:23
  |
6 |     #[function = "a", function = "b"]
  |                       ^^^^^^^^^^^^^^

error: Value for config `function` is already set here.
 --> tests/compile_fail/config/already_set.rs:6:18
  |
6 |     #[function = "a", function = "b"]
  |                  ^^^

error: This config is already set.
 --> tests/compile_fail/config/already_set.rs:7:7
  |
7 |     #[function = "c"]
  |       ^^^^^^^^^^^^^^