1 error[E0428]: the name `a` is defined multiple times
2 --> $DIR/issue-3099-b.rs:13:1
5 | --------- previous definition of the module `a` here
7 LL | pub mod a {} //~ ERROR the name `a` is defined multiple times
8 | ^^^^^^^^^ `a` redefined here
10 = note: `a` must be defined only once in the type namespace of this module
12 error: aborting due to previous error
14 For more information about this error, try `rustc --explain E0428`.