warning: the feature `unsafe_fields` is incomplete and may not be safe to use and/or cause compiler crashes
  --> $DIR/feature-gate-unsafe_fields.rs:5:32
   |
LL | #![cfg_attr(with_gate, feature(unsafe_fields))]
   |                                ^^^^^^^^^^^^^
   |
   = note: see issue #132922 <https://github.com/rust-lang/rust/issues/132922> for more information
   = note: `#[warn(incomplete_features)]` on by default

warning: 1 warning emitted