error[E0658]: mutable references are not allowed in constant functions --> $DIR/const_let_assign3.rs:6:18 | LL | const fn foo(&mut self, x: u32) { | ^^^^^^^^^ | = note: see issue #57349 for more information = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable error[E0658]: mutable references are not allowed in constants --> $DIR/const_let_assign3.rs:14:5 | LL | s.foo(3); | ^ | = note: see issue #57349 for more information = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable error[E0658]: mutable references are not allowed in constants --> $DIR/const_let_assign3.rs:20:13 | LL | let y = &mut x; | ^^^^^^ | = note: see issue #57349 for more information = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable error: aborting due to 3 previous errors For more information about this error, try `rustc --explain E0658`.