error[E0015]: cannot call non-const closure in constants
  --> $DIR/issue-28113.rs:4:5
   |
LL |     || -> u8 { 5 }()
   |     ^^^^^^^^^^^^^^^^
   |
   = note: closures need an RFC before allowed to be called in constants
   = note: calls in constants are limited to constant functions, tuple structs and tuple variants

error: aborting due to previous error

For more information about this error, try `rustc --explain E0015`.