//! trybuild runner — exercises every derive macro across both
//! compile-pass (smoke tests) and compile-fail (error-message regression
//! guards) inputs.
//!
//! ## Regenerating expected stderr
//!
//! When stable rustc emits a different error format (rare), regenerate
//! the `.stderr` files alongside the same PR that bumps rustc:
//!
//! ```sh
//! TRYBUILD=overwrite cargo test -p gilt-derive --test trybuild
//! ```