error[E0658]: references in constants may only refer to immutable values
  --> $DIR/E0017.rs:5:30
   |
LL | const CR: &'static mut i32 = &mut C;
   |                              ^^^^^^ constants require immutable values
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable

error[E0019]: static contains unimplemented expression type
  --> $DIR/E0017.rs:6:39
   |
LL | static STATIC_REF: &'static mut i32 = &mut X;
   |                                       ^^^^^^

error[E0658]: references in statics may only refer to immutable values
  --> $DIR/E0017.rs:6:39
   |
LL | static STATIC_REF: &'static mut i32 = &mut X;
   |                                       ^^^^^^ statics require immutable values
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable

error[E0596]: cannot borrow immutable static item `X` as mutable
  --> $DIR/E0017.rs:6:39
   |
LL | static STATIC_REF: &'static mut i32 = &mut X;
   |                                       ^^^^^^ cannot borrow as mutable

error[E0658]: references in statics may only refer to immutable values
  --> $DIR/E0017.rs:9:38
   |
LL | static CONST_REF: &'static mut i32 = &mut C;
   |                                      ^^^^^^ statics require immutable values
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable

error[E0658]: references in statics may only refer to immutable values
  --> $DIR/E0017.rs:10:52
   |
LL | static STATIC_MUT_REF: &'static mut i32 = unsafe { &mut M };
   |                                                    ^^^^^^ statics require immutable values
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable

error: aborting due to 6 previous errors

Some errors have detailed explanations: E0019, E0596, E0658.
For more information about an error, try `rustc --explain E0019`.