Use tidy to sort crate attributes for all compiler crates.

We already do this for a number of crates, e.g. `rustc_middle`,
`rustc_span`, `rustc_metadata`, `rustc_span`, `rustc_errors`.

For the ones we don't, in many cases the attributes are a mess.
- There is no consistency about order of attribute kinds (e.g.
  `allow`/`deny`/`feature`).
- Within attribute kind groups (e.g. the `feature` attributes),
  sometimes the order is alphabetical, and sometimes there is no
  particular order.
- Sometimes the attributes of a particular kind aren't even grouped
  all together, e.g. there might be a `feature`, then an `allow`, then
  another `feature`.

This commit extends the existing sorting to all compiler crates,
increasing consistency. If any new attribute line is added there is now
only one place it can go -- no need for arbitrary decisions.

Exceptions:
- `rustc_log`, `rustc_next_trait_solver` and `rustc_type_ir_macros`,
  because they have no crate attributes.
- `rustc_codegen_gcc`, because it's quasi-external to rustc (e.g. it's
  ignored in `rustfmt.toml`).

compiler/rustc_abi/src/lib.rs

@@ -1,7 +1,9 @@
-#![cfg_attr(feature = "nightly", feature(step_trait))]
+// tidy-alphabetical-start
 #![cfg_attr(feature = "nightly", allow(internal_features))]
 #![cfg_attr(feature = "nightly", doc(rust_logo))]
 #![cfg_attr(feature = "nightly", feature(rustdoc_internals))]
+#![cfg_attr(feature = "nightly", feature(step_trait))]
+// tidy-alphabetical-end
 
 use std::fmt;
 use std::num::{NonZeroUsize, ParseIntError};

compiler/rustc_arena/src/lib.rs

@@ -7,23 +7,25 @@
 //!
 //! This crate implements several kinds of arena.
 
+// tidy-alphabetical-start
+#![allow(clippy::mut_from_ref)] // Arena allocators are one place where this pattern is fine.
+#![allow(internal_features)]
+#![cfg_attr(test, feature(test))]
+#![deny(unsafe_op_in_unsafe_fn)]
 #![doc(
     html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/",
     test(no_crate_inject, attr(deny(warnings)))
 )]
 #![doc(rust_logo)]
-#![feature(rustdoc_internals)]
 #![feature(core_intrinsics)]
+#![feature(decl_macro)]
 #![feature(dropck_eyepatch)]
-#![feature(new_uninit)]
 #![feature(maybe_uninit_slice)]
-#![feature(decl_macro)]
+#![feature(new_uninit)]
 #![feature(rustc_attrs)]
-#![cfg_attr(test, feature(test))]
+#![feature(rustdoc_internals)]
 #![feature(strict_provenance)]
-#![deny(unsafe_op_in_unsafe_fn)]
-#![allow(internal_features)]
-#![allow(clippy::mut_from_ref)] // Arena allocators are one of the places where this pattern is fine.
+// tidy-alphabetical-end
 
 use smallvec::SmallVec;
 

compiler/rustc_ast/src/lib.rs

@@ -4,20 +4,22 @@
 //!
 //! This API is completely unstable and subject to change.
 
+// tidy-alphabetical-start
+#![allow(internal_features)]
 #![doc(
     html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/",
     test(attr(deny(warnings)))
 )]
 #![doc(rust_logo)]
-#![allow(internal_features)]
-#![feature(rustdoc_internals)]
 #![feature(associated_type_defaults)]
 #![feature(box_patterns)]
 #![feature(if_let_guard)]
 #![feature(let_chains)]
-#![feature(never_type)]
 #![feature(negative_impls)]
+#![feature(never_type)]
+#![feature(rustdoc_internals)]
 #![feature(stmt_expr_attributes)]
+// tidy-alphabetical-end
 
 pub mod util {
     pub mod case;

compiler/rustc_ast_ir/src/lib.rs

@@ -1,6 +1,8 @@
+// tidy-alphabetical-start
+#![cfg_attr(feature = "nightly", allow(internal_features))]
 #![cfg_attr(feature = "nightly", feature(never_type))]
 #![cfg_attr(feature = "nightly", feature(rustc_attrs))]
-#![cfg_attr(feature = "nightly", allow(internal_features))]
+// tidy-alphabetical-end
 
 #[cfg(feature = "nightly")]
 use rustc_macros::{Decodable, Encodable, HashStable_NoContext};

compiler/rustc_ast_lowering/src/lib.rs

@@ -30,12 +30,14 @@
 //! get confused if the spans from leaf AST nodes occur in multiple places
 //! in the HIR, especially for multiple identifiers.
 
+// tidy-alphabetical-start
 #![allow(internal_features)]
-#![feature(rustdoc_internals)]
 #![doc(rust_logo)]
 #![feature(assert_matches)]
 #![feature(box_patterns)]
 #![feature(let_chains)]
+#![feature(rustdoc_internals)]
+// tidy-alphabetical-end
 
 use crate::errors::{AssocTyParentheses, AssocTyParenthesesSub, MisplacedImplTrait};
 use rustc_ast::node_id::NodeMap;

compiler/rustc_ast_passes/src/lib.rs

@@ -4,13 +4,15 @@
 //!
 //! The crate also contains other misc AST visitors, e.g. `node_count` and `show_span`.
 
+// tidy-alphabetical-start
 #![allow(internal_features)]
 #![doc(rust_logo)]
-#![feature(rustdoc_internals)]
 #![feature(box_patterns)]
 #![feature(if_let_guard)]
 #![feature(iter_is_partitioned)]
 #![feature(let_chains)]
+#![feature(rustdoc_internals)]
+// tidy-alphabetical-end
 
 pub mod ast_validation;
 mod errors;

compiler/rustc_ast_pretty/src/lib.rs

@@ -1,7 +1,9 @@
+// tidy-alphabetical-start
 #![allow(internal_features)]
-#![feature(rustdoc_internals)]
 #![doc(rust_logo)]
 #![feature(box_patterns)]
+#![feature(rustdoc_internals)]
+// tidy-alphabetical-end
 
 mod helpers;
 pub mod pp;

compiler/rustc_attr/src/lib.rs

@@ -4,10 +4,12 @@
 //! 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)]
-#![feature(rustdoc_internals)]
 #![doc(rust_logo)]
 #![feature(let_chains)]
+#![feature(rustdoc_internals)]
+// tidy-alphabetical-end
 
 mod builtin;
 mod session_diagnostics;

compiler/rustc_baked_icu_data/src/lib.rs

@@ -20,10 +20,12 @@
 //! --cldr-tag latest --icuexport-tag latest -o src/data
 //! ```
 
+// tidy-alphabetical-start
+#![allow(elided_lifetimes_in_paths)]
 #![allow(internal_features)]
-#![feature(rustdoc_internals)]
 #![doc(rust_logo)]
-#![allow(elided_lifetimes_in_paths)]
+#![feature(rustdoc_internals)]
+// tidy-alphabetical-end
 
 mod data {
     include!("data/mod.rs");

compiler/rustc_borrowck/src/lib.rs

@@ -1,7 +1,7 @@
 //! This query borrow-checks the MIR to (further) ensure it is not broken.
 
+// tidy-alphabetical-start
 #![allow(internal_features)]
-#![feature(rustdoc_internals)]
 #![doc(rust_logo)]
 #![feature(assert_matches)]
 #![feature(box_patterns)]
@@ -10,8 +10,10 @@
 #![feature(min_specialization)]
 #![feature(never_type)]
 #![feature(rustc_attrs)]
+#![feature(rustdoc_internals)]
 #![feature(stmt_expr_attributes)]
 #![feature(try_blocks)]
+// tidy-alphabetical-end
 
 #[macro_use]
 extern crate tracing;

compiler/rustc_builtin_macros/src/lib.rs

@@ -1,12 +1,12 @@
 //! This crate contains implementations of built-in macros and other code generating facilities
 //! injecting code into the crate before it is lowered to HIR.
 
+// tidy-alphabetical-start
 #![allow(internal_features)]
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![allow(rustc::untranslatable_diagnostic)]
-#![feature(rustdoc_internals)]
-#![doc(rust_logo)]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
+#![doc(rust_logo)]
 #![feature(assert_matches)]
 #![feature(box_patterns)]
 #![feature(decl_macro)]
@@ -15,7 +15,9 @@
 #![feature(lint_reasons)]
 #![feature(proc_macro_internals)]
 #![feature(proc_macro_quote)]
+#![feature(rustdoc_internals)]
 #![feature(try_blocks)]
+// tidy-alphabetical-end
 
 extern crate proc_macro;
 

compiler/rustc_codegen_cranelift/src/lib.rs

@@ -1,13 +1,16 @@
+// tidy-alphabetical-start
+#![allow(rustc::diagnostic_outside_of_impl)]
+#![allow(rustc::untranslatable_diagnostic)]
 #![cfg_attr(doc, allow(internal_features))]
-#![cfg_attr(doc, feature(rustdoc_internals))]
 #![cfg_attr(doc, doc(rust_logo))]
+#![cfg_attr(doc, feature(rustdoc_internals))]
+// Note: please avoid adding other feature gates where possible
 #![feature(rustc_private)]
 // Note: please avoid adding other feature gates where possible
-#![allow(rustc::diagnostic_outside_of_impl)]
-#![allow(rustc::untranslatable_diagnostic)]
 #![warn(rust_2018_idioms)]
-#![warn(unused_lifetimes)]
 #![warn(unreachable_pub)]
+#![warn(unused_lifetimes)]
+// tidy-alphabetical-end
 
 extern crate jobserver;
 #[macro_use]

compiler/rustc_codegen_llvm/src/lib.rs

@@ -4,16 +4,18 @@
 //!
 //! This API is completely unstable and subject to change.
 
+// tidy-alphabetical-start
 #![allow(internal_features)]
-#![feature(rustdoc_internals)]
-#![doc(rust_logo)]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
+#![doc(rust_logo)]
 #![feature(exact_size_is_empty)]
 #![feature(extern_types)]
 #![feature(hash_raw_entry)]
+#![feature(impl_trait_in_assoc_type)]
 #![feature(iter_intersperse)]
 #![feature(let_chains)]
-#![feature(impl_trait_in_assoc_type)]
+#![feature(rustdoc_internals)]
+// tidy-alphabetical-end
 
 use back::owned_target_machine::OwnedTargetMachine;
 use back::write::{create_informational_target_machine, create_target_machine};

compiler/rustc_codegen_ssa/src/lib.rs

@@ -1,15 +1,17 @@
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
-#![doc(rust_logo)]
-#![feature(rustdoc_internals)]
+// tidy-alphabetical-start
 #![allow(internal_features)]
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![allow(rustc::untranslatable_diagnostic)]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
+#![doc(rust_logo)]
 #![feature(box_patterns)]
 #![feature(if_let_guard)]
 #![feature(let_chains)]
 #![feature(negative_impls)]
+#![feature(rustdoc_internals)]
 #![feature(strict_provenance)]
 #![feature(try_blocks)]
+// tidy-alphabetical-end
 
 //! This crate contains codegen code that is used by all codegen backends (LLVM and others).
 //! The backend-agnostic functions of this crate use functions defined in various traits that

compiler/rustc_const_eval/src/lib.rs

@@ -1,18 +1,20 @@
+// tidy-alphabetical-start
 #![allow(internal_features)]
 #![allow(rustc::diagnostic_outside_of_impl)]
-#![feature(rustdoc_internals)]
 #![doc(rust_logo)]
 #![feature(assert_matches)]
 #![feature(box_patterns)]
 #![feature(decl_macro)]
+#![feature(if_let_guard)]
 #![feature(let_chains)]
+#![feature(never_type)]
+#![feature(rustdoc_internals)]
 #![feature(slice_ptr_get)]
 #![feature(strict_provenance)]
-#![feature(never_type)]
 #![feature(trait_alias)]
 #![feature(try_blocks)]
 #![feature(yeet_expr)]
-#![feature(if_let_guard)]
+// tidy-alphabetical-end
 
 pub mod check_consts;
 pub mod const_eval;

compiler/rustc_driver/src/lib.rs

@@ -1,8 +1,10 @@
 // This crate is intentionally empty and a re-export of `rustc_driver_impl` to allow the code in
 // `rustc_driver_impl` to be compiled in parallel with other crates.
 
+// tidy-alphabetical-start
 #![allow(internal_features)]
-#![feature(rustdoc_internals)]
 #![doc(rust_logo)]
+#![feature(rustdoc_internals)]
+// tidy-alphabetical-end
 
 pub use rustc_driver_impl::*;

compiler/rustc_driver_impl/src/lib.rs

@@ -4,16 +4,18 @@
 //!
 //! This API is completely unstable and subject to change.
 
+// tidy-alphabetical-start
+#![allow(internal_features)]
 #![allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
-#![feature(rustdoc_internals)]
-#![allow(internal_features)]
 #![feature(decl_macro)]
 #![feature(let_chains)]
 #![feature(panic_backtrace_config)]
 #![feature(panic_update_hook)]
 #![feature(result_flattening)]
+#![feature(rustdoc_internals)]
+// tidy-alphabetical-end
 
 use rustc_ast as ast;
 use rustc_codegen_ssa::{traits::CodegenBackend, CodegenErrors, CodegenResults};

compiler/rustc_error_codes/src/lib.rs

@@ -1,10 +1,12 @@
 //! This library is used to gather all error codes into one place, to make
 //! their maintenance easier.
 
+// tidy-alphabetical-start
 #![allow(internal_features)]
-#![feature(rustdoc_internals)]
-#![doc(rust_logo)]
 #![deny(rustdoc::invalid_codeblock_attributes)]
+#![doc(rust_logo)]
+#![feature(rustdoc_internals)]
+// tidy-alphabetical-end
 
 // This higher-order macro defines the error codes that are in use. It is used
 // in the `rustc_errors` crate. Removed error codes are listed in the comment

compiler/rustc_error_messages/src/lib.rs

@@ -1,8 +1,10 @@
+// tidy-alphabetical-start
+#![allow(internal_features)]
 #![doc(rust_logo)]
-#![feature(rustdoc_internals)]
 #![feature(rustc_attrs)]
+#![feature(rustdoc_internals)]
 #![feature(type_alias_impl_trait)]
-#![allow(internal_features)]
+// tidy-alphabetical-end
 
 use fluent_bundle::FluentResource;
 use fluent_syntax::parser::ParserError;

compiler/rustc_feature/src/lib.rs

@@ -11,9 +11,11 @@
 //! even if it is stabilized or removed, *do not remove it*. Instead, move the
 //! symbol to the `accepted` or `removed` modules respectively.
 
+// tidy-alphabetical-start
 #![allow(internal_features)]
-#![feature(rustdoc_internals)]
 #![doc(rust_logo)]
+#![feature(rustdoc_internals)]
+// tidy-alphabetical-end
 
 mod accepted;
 mod builtin_attrs;

compiler/rustc_fluent_macro/src/lib.rs

@@ -1,10 +1,12 @@
+// tidy-alphabetical-start
+#![allow(internal_features)]
+#![allow(rustc::default_hash_types)]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
-#![allow(internal_features)]
-#![feature(rustdoc_internals)]
 #![feature(proc_macro_diagnostic)]
 #![feature(proc_macro_span)]
-#![allow(rustc::default_hash_types)]
+#![feature(rustdoc_internals)]
+// tidy-alphabetical-end
 
 use proc_macro::TokenStream;
 

compiler/rustc_fs_util/src/lib.rs

@@ -1,7 +1,9 @@
+// tidy-alphabetical-start
 use std::ffi::CString;
 use std::fs;
 use std::io;
 use std::path::{absolute, Path, PathBuf};
+// tidy-alphabetical-end
 
 // Unfortunately, on windows, it looks like msvcrt.dll is silently translating
 // verbatim paths under the hood to non-verbatim paths! This manifests itself as