rustc_errors: remove unused code

compiler/rustc_error_messages/src/lib.rs

@@ -1,8 +1,3 @@
-// tidy-alphabetical-start
-#![allow(internal_features)]
-#![feature(rustc_attrs)]
-// tidy-alphabetical-end
-
 use std::borrow::Cow;
 
 pub use fluent_bundle::types::FluentType;
@@ -29,7 +24,6 @@ pub fn register_functions<R, M>(bundle: &mut fluent_bundle::bundle::FluentBundle
 ///
 /// Intended to be removed once diagnostics are entirely translatable.
 #[derive(Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable, StableHash)]
-#[rustc_diagnostic_item = "DiagMessage"]
 pub enum DiagMessage {
     /// Non-translatable diagnostic message or a message that has been translated eagerly.
     ///

compiler/rustc_errors/src/diagnostic.rs

@@ -8,7 +8,6 @@ use std::path::PathBuf;
 use std::thread::panicking;
 
 use rustc_ast::attr::version::RustcVersion;
-use rustc_data_structures::sync::{DynSend, DynSync};
 use rustc_error_messages::{DiagArgMap, DiagArgName, DiagArgValue, IntoDiagArg};
 use rustc_lint_defs::{Applicability, LintExpectationId};
 use rustc_macros::{Decodable, Encodable};
@@ -102,7 +101,6 @@ impl EmissionGuarantee for rustc_span::fatal_error::FatalError {
 ///   rather than the `Diagnostic` impl.
 /// - Derived impls are always generic, and it's good for the hand-written
 ///   impls to be consistent with them.
-#[rustc_diagnostic_item = "Diagnostic"]
 pub trait Diagnostic<'a, G: EmissionGuarantee = ErrorGuaranteed> {
     /// Write out as a diagnostic out of `DiagCtxt`.
     #[must_use]
@@ -120,16 +118,6 @@ where
     }
 }
 
-impl<'a> Diagnostic<'a, ()>
-    for Box<
-        dyn for<'b> FnOnce(DiagCtxtHandle<'b>, Level) -> Diag<'b, ()> + DynSync + DynSend + 'static,
-    >
-{
-    fn into_diag(self, dcx: DiagCtxtHandle<'a>, level: Level) -> Diag<'a, ()> {
-        self(dcx, level)
-    }
-}
-
 /// Type used to emit diagnostic through a closure instead of implementing the `Diagnostic` trait.
 pub struct DiagDecorator<F: FnOnce(&mut Diag<'_, ()>)>(pub F);
 
@@ -143,7 +131,6 @@ impl<'a, F: FnOnce(&mut Diag<'_, ()>)> Diagnostic<'a, ()> for DiagDecorator<F> {
 
 /// Trait implemented by error types. This should not be implemented manually. Instead, use
 /// `#[derive(Subdiagnostic)]` -- see [rustc_macros::Subdiagnostic].
-#[rustc_diagnostic_item = "Subdiagnostic"]
 pub trait Subdiagnostic {
     /// Add a subdiagnostic to an existing diagnostic.
     fn add_to_diag<G: EmissionGuarantee>(self, diag: &mut Diag<'_, G>);

compiler/rustc_errors/src/lib.rs

@@ -3,14 +3,11 @@
 //! This module contains the code for creating and emitting diagnostics.
 
 // tidy-alphabetical-start
-#![allow(internal_features)]
-#![allow(rustc::direct_use_of_rustc_type_ir)]
 #![feature(associated_type_defaults)]
 #![feature(default_field_values)]
 #![feature(macro_metavar_expr_concat)]
 #![feature(negative_impls)]
 #![feature(never_type)]
-#![feature(rustc_attrs)]
 // tidy-alphabetical-end
 
 extern crate self as rustc_errors;