| error[E0658]: `concat_idents` is not stable enough for use and is subject to change (see issue #29599) | |
| --> $DIR/feature-gate-concat_idents2.rs:14:5 | |
| | | |
| LL | concat_idents!(a, b); //~ ERROR `concat_idents` is not stable enough | |
| | ^^^^^^^^^^^^^^^^^^^^^ | |
| | | |
| = help: add #![feature(concat_idents)] to the crate attributes to enable | |
| error: aborting due to previous error | |
| For more information about this error, try `rustc --explain E0658`. |