error[E0764]: mutable references are not allowed in the final value of constants
  --> $DIR/issue-76510.rs:3:29
   |
LL | const S: &'static mut str = &mut " hello ";
   |                             ^^^^^^^^^^^^^^

error[E0658]: mutation through a reference is not allowed in constants
  --> $DIR/issue-76510.rs:3:29
   |
LL | const S: &'static mut str = &mut " hello ";
   |                             ^^^^^^^^^^^^^^
   |
   = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0658, E0764.
For more information about an error, try `rustc --explain E0658`.