error[E0308]: mismatched types
  --> $DIR/closure-no-fn-1.rs:6:29
   |
LL |     let foo: fn(u8) -> u8 = |v: u8| { a += v; a };
   |                             ^^^^^^^^^^^^^^^^^^^^^ expected fn pointer, found closure
   |
   = note: expected type `fn(u8) -> u8`
              found type `[closure@$DIR/closure-no-fn-1.rs:6:29: 6:50 a:_]`

error: aborting due to previous error

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