error[E0277]: the size for values of type `(dyn Fn() -> u32 + 'static)` cannot be known at compilation time --> $DIR/issue-24446.rs:2:17 | LL | static foo: dyn Fn() -> u32 = || -> u32 { | ^^^^^^^^^^^^^^^ doesn't have a size known at compile-time | = help: the trait `Sized` is not implemented for `(dyn Fn() -> u32 + 'static)` error[E0277]: `(dyn Fn() -> u32 + 'static)` cannot be shared between threads safely --> $DIR/issue-24446.rs:2:17 | LL | static foo: dyn Fn() -> u32 = || -> u32 { | ^^^^^^^^^^^^^^^ `(dyn Fn() -> u32 + 'static)` cannot be shared between threads safely | = help: the trait `Sync` is not implemented for `(dyn Fn() -> u32 + 'static)` = note: shared static variables must have a type that implements `Sync` error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0277`.