rustc-ap-rustc_feature 708.0.0

Automatically published version of the package `rustc_feature` in the rust-lang/rust repository from commit a4e595db8f12f9ee926256745d757004b850703f The publishing script for this crate lives at:

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/ at the moment.

Features are enabled in programs via the crate-level attributes of #![feature(...)] with a comma-separated list of features.

For the purpose of future feature-tracking, once a feature gate is added, even if it is stabilized or removed, do not remove it. Instead, move the symbol to the accepted or removed modules respectively.