error[E0658]: the `#[coroutines]` attribute is an experimental feature
  --> $DIR/gen_block.rs:20:13
   |
LL |     let _ = #[coroutine] || yield true;
   |             ^^^^^^^^^^^^
   |
   = note: see issue #43122 <https://github.com/rust-lang/rust/issues/43122> for more information
   = help: add `#![feature(coroutines)]` to the crate attributes to enable
   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error[E0658]: the `#[coroutines]` attribute is an experimental feature
  --> $DIR/gen_block.rs:24:13
   |
LL |     let _ = #[coroutine] || {};
   |             ^^^^^^^^^^^^
   |
   = note: see issue #43122 <https://github.com/rust-lang/rust/issues/43122> for more information
   = help: add `#![feature(coroutines)]` to the crate attributes to enable
   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error[E0658]: yield syntax is experimental
  --> $DIR/gen_block.rs:16:16
   |
LL |     let _ = || yield true;
   |                ^^^^^^^^^^
   |
   = note: see issue #43122 <https://github.com/rust-lang/rust/issues/43122> for more information
   = help: add `#![feature(coroutines)]` to the crate attributes to enable
   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error: `yield` can only be used in `#[coroutine]` closures, or `gen` blocks
  --> $DIR/gen_block.rs:16:16
   |
LL |     let _ = || yield true;
   |                ^^^^^^^^^^
   |
help: use `#[coroutine]` to make this closure a coroutine
   |
LL |     let _ = #[coroutine] || yield true;
   |             ++++++++++++

error[E0658]: yield syntax is experimental
  --> $DIR/gen_block.rs:20:29
   |
LL |     let _ = #[coroutine] || yield true;
   |                             ^^^^^^^^^^
   |
   = note: see issue #43122 <https://github.com/rust-lang/rust/issues/43122> for more information
   = help: add `#![feature(coroutines)]` to the crate attributes to enable
   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error[E0282]: type annotations needed
  --> $DIR/gen_block.rs:7:13
   |
LL |     let x = gen {};
   |             ^^^^^^ cannot infer type

error: aborting due to 6 previous errors

Some errors have detailed explanations: E0282, E0658.
For more information about an error, try `rustc --explain E0282`.