error[E0010]: allocations are not allowed in statics --> $DIR/issue-7364.rs:16:37 | LL | static boxed: Box> = box RefCell::new(0); | ^^^^^^^^^^^^^^^^^^^ allocation not allowed in statics error[E0277]: `std::cell::RefCell` cannot be shared between threads safely --> $DIR/issue-7364.rs:16:1 | LL | static boxed: Box> = box RefCell::new(0); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `std::cell::RefCell` cannot be shared between threads safely | = help: the trait `std::marker::Sync` is not implemented for `std::cell::RefCell` = note: required because of the requirements on the impl of `std::marker::Sync` for `std::ptr::Unique>` = note: required because it appears within the type `std::boxed::Box>` = note: shared static variables must have a type that implements `Sync` error: aborting due to 2 previous errors Some errors occurred: E0010, E0277. For more information about an error, try `rustc --explain E0010`.