error: only one #[error(...)] attribute is allowed
 --> tests/ui/duplicate-fmt.rs:5:1
  |
5 | #[error("...")]
  | ^^^^^^^^^^^^^^^

error: duplicate #[error(fmt = ...)] attribute
  --> tests/ui/duplicate-fmt.rs:10:1
   |
10 | #[error(fmt = core::fmt::LowerHex::fmt)]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: cannot have both #[error(transparent)] and #[error(fmt = ...)]
  --> tests/ui/duplicate-fmt.rs:14:1
   |
14 | #[error(fmt = core::fmt::Octal::fmt)]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: cannot have both #[error(fmt = ...)] and a format arguments attribute
  --> tests/ui/duplicate-fmt.rs:20:1
   |
20 | #[error("...")]
   | ^^^^^^^^^^^^^^^