error[E0658]: parentheses in patterns are unstable (see issue #51087)
  --> $DIR/feature-gate-pattern_parentheses.rs:13:9
   |
LL |         (pat) => {} //~ ERROR parentheses in patterns are unstable
   |         ^^^^^
   |
   = help: add #![feature(pattern_parentheses)] to the crate attributes to enable

error: aborting due to previous error

For more information about this error, try `rustc --explain E0658`.