error: cannot find derive macro `x3300` in this scope
  --> $DIR/issue-43106-gating-of-derive-2.rs:12:14
   |
LL |     #[derive(x3300)]
   |              ^^^^^

error: cannot find derive macro `x3300` in this scope
  --> $DIR/issue-43106-gating-of-derive-2.rs:8:14
   |
LL |     #[derive(x3300)]
   |              ^^^^^

error: cannot find derive macro `x3300` in this scope
  --> $DIR/issue-43106-gating-of-derive-2.rs:4:14
   |
LL |     #[derive(x3300)]
   |              ^^^^^

error: aborting due to 3 previous errors