warning: unnecessary parentheses around assigned value
  --> $DIR/issue-54752-async-block.rs:6:22
   |
LL | fn main() { let _a = (async { }); }
   |                      ^         ^
   |
   = note: `#[warn(unused_parens)]` on by default
help: remove these parentheses
   |
LL - fn main() { let _a = (async { }); }
LL + fn main() { let _a = async { }; }
   |

warning: 1 warning emitted