error[E0015]: cannot call non-const closure in constant functions --> $DIR/issue-56164.rs:1:18 | LL | const fn foo() { (||{})() } | ^^^^^^^^ | = note: closures need an RFC before allowed to be called in constant functions = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants = help: add `#![feature(const_trait_impl)]` to the crate attributes to enable error: function pointer calls are not allowed in constant functions --> $DIR/issue-56164.rs:5:5 | LL | input() | ^^^^^^^ note: erroneous constant used --> $DIR/issue-56164.rs:1:18 | LL | const fn foo() { (||{})() } | ^^^^^^ note: erroneous constant used --> $DIR/issue-56164.rs:1:18 | LL | const fn foo() { (||{})() } | ^^^^^^ error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0015`.