rename rustc_attr to rustc_attr_parsing and create rustc_attr_data_structures

compiler/rustc_attr_parsing/src/lib.rs

@@ -0,0 +1,22 @@
+//! Functions and types dealing with attributes and meta items.
+//!
+//! FIXME(Centril): For now being, much of the logic is still in `rustc_ast::attr`.
+//! The goal is to move the definition of `MetaItem` and things that don't need to be in `syntax`
+//! to this crate.
+
+// tidy-alphabetical-start
+#![allow(internal_features)]
+#![doc(rust_logo)]
+#![feature(let_chains)]
+#![feature(rustdoc_internals)]
+#![warn(unreachable_pub)]
+// tidy-alphabetical-end
+
+mod attributes;
+mod session_diagnostics;
+
+pub use attributes::*;
+pub use rustc_attr_data_structures::*;
+pub use util::{find_crate_name, is_builtin_attr, parse_version};
+
+rustc_fluent_macro::fluent_messages! { "../messages.ftl" }