//! # Feature gates
//!
//! This crate declares the set of past and present unstable features in the compiler.
-//! Feature gate checking itself is done in `librustc_ast_passes/feature_gate.rs`
+//! Feature gate checking itself is done in `rustc_ast_passes/src/feature_gate.rs`
//! at the moment.
//!
//! Features are enabled in programs via the crate-level attributes of