rustc-ap-rustc_attr 642.0.0

Automatically published version of the package `rustc_attr` in the rust-lang/rust repository from commit a29424a2265411dda7d7446516ac5fd7499e2b55 The publishing script for this crate lives at: https://github.com/alexcrichton/rustc-auto-publish

Documentation

Functions and types dealing with attributes and meta items.

FIXME(Centril): For now being, much of the logic is still in syntax::attr. The goal is to move the definition of MetaItem and things that don't need to be in syntax to this crate.