error[E0531]: cannot find tuple struct or tuple variant `a` in this scope
  --> $DIR/enums-pats-not-idents.rs:2:9
   |
LL |     let a(1) = 13;
   |         ^ not found in this scope

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0531`.