1 error[E0428]: the name `A` is defined multiple times
2 --> $DIR/define-two.rs:15:21
4 LL | #[proc_macro_derive(A)]
5 | - previous definition of the macro `A` here
7 LL | #[proc_macro_derive(A)]
10 = note: `A` must be defined only once in the macro namespace of this module
12 error: aborting due to previous error
14 For more information about this error, try `rustc --explain E0428`.