error[E0658]: repr with 128-bit type is unstable (see issue #35118)
  --> $DIR/feature-gate-repr128.rs:12:1
   |
12 | / enum A { //~ ERROR repr with 128-bit type is unstable
13 | |     A(u64)
14 | | }
   | |_^
   |
   = help: add #![feature(repr128)] to the crate attributes to enable

error: aborting due to previous error