error[E0425]: cannot find value `asdf_fdsa` in this scope
  --> $DIR/syntax-extension-minor.rs:20:13
   |
LL |     assert!(concat_idents!(asd, f_f, dsa) == "<.<".to_string());
   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not found in this scope

error: aborting due to previous error

For more information about this error, try `rustc --explain E0425`.