error: cannot find macro `__build_diagnostic_array!` in this scope
  --> $DIR/feature-gate-rustc-diagnostic-macros.rs:22:1
   |
LL | __build_diagnostic_array!(DIAGNOSTICS);
   | ^^^^^^^^^^^^^^^^^^^^^^^^

error: cannot find macro `__register_diagnostic!` in this scope
  --> $DIR/feature-gate-rustc-diagnostic-macros.rs:14:1
   |
LL | __register_diagnostic!(E0001);
   | ^^^^^^^^^^^^^^^^^^^^^

error: cannot find macro `__diagnostic_used!` in this scope
  --> $DIR/feature-gate-rustc-diagnostic-macros.rs:18:5
   |
LL |     __diagnostic_used!(E0001);
   |     ^^^^^^^^^^^^^^^^^

error: aborting due to 3 previous errors