error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `gen` --> $DIR/feature-gate-gen_blocks.rs:12:11 | LL | async gen {}; | ^^^ expected one of 8 possible tokens error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `gen` --> $DIR/feature-gate-gen_blocks.rs:25:11 | LL | async gen {}; | ^^^ expected one of 8 possible tokens error[E0422]: cannot find struct, variant or union type `gen` in this scope --> $DIR/feature-gate-gen_blocks.rs:5:5 | LL | gen {}; | ^^^ not found in this scope error: aborting due to 3 previous errors For more information about this error, try `rustc --explain E0422`.