error[E0658]: `become` expression is experimental --> $DIR/feature-gate-explicit_tail_calls.rs:2:5 | LL | become bottom(); | ^^^^^^^^^^^^^^^ | = note: see issue #112788 for more information = help: add `#![feature(explicit_tail_calls)]` to the crate attributes to enable error[E0658]: `become` expression is experimental --> $DIR/feature-gate-explicit_tail_calls.rs:6:5 | LL | become you(); | ^^^^^^^^^^^^ | = note: see issue #112788 for more information = help: add `#![feature(explicit_tail_calls)]` to the crate attributes to enable error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0658`.