error[E0015]: cannot call non-const closure in constants --> $DIR/invalid-inline-const-in-match-arm.rs:5:17 | LL | const { (|| {})() } => {} | ^^^^^^^^^ | = note: closures need an RFC before allowed to be called in constants = note: calls in constants are limited to constant functions, tuple structs and tuple variants help: add `#![feature(const_trait_impl)]` to the crate attributes to enable | LL + #![feature(const_trait_impl)] | error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0015`.