error[E0308]: mismatched types
  --> $DIR/closure-no-fn-2.rs:6:27
   |
LL |     let bar: fn() -> u8 = || { b };
   |              ----------   ^^^^^^^^ expected fn pointer, found closure
   |              |
   |              expected due to this
   |
   = note: expected fn pointer `fn() -> u8`
                 found closure `{closure@$DIR/closure-no-fn-2.rs:6:27: 6:29}`
note: closures can only be coerced to `fn` types if they do not capture any variables
  --> $DIR/closure-no-fn-2.rs:6:32
   |
LL |     let bar: fn() -> u8 = || { b };
   |                                ^ `b` captured here

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0308`.