Remove extern crate rustc_macros from numerous crates.

compiler/rustc_ast/src/ast.rs

@@ -32,7 +32,7 @@ use rustc_data_structures::packed::Pu128;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_data_structures::sync::Lrc;
-use rustc_macros::HashStable_Generic;
+use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_span::source_map::{respan, Spanned};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{ErrorGuaranteed, Span, DUMMY_SP};

compiler/rustc_ast/src/expand/allocator.rs

@@ -1,3 +1,4 @@
+use rustc_macros::HashStable_Generic;
 use rustc_span::symbol::{sym, Symbol};
 
 #[derive(Clone, Debug, Copy, Eq, PartialEq, HashStable_Generic)]

compiler/rustc_ast/src/expand/mod.rs

@@ -1,5 +1,6 @@
 //! Definitions shared by macros / syntax extensions and e.g. `rustc_middle`.
 
+use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_span::{def_id::DefId, symbol::Ident};
 
 use crate::MetaItem;

compiler/rustc_ast/src/format.rs

@@ -1,6 +1,7 @@
 use crate::ptr::P;
 use crate::Expr;
 use rustc_data_structures::fx::FxHashMap;
+use rustc_macros::{Decodable, Encodable};
 use rustc_span::symbol::{Ident, Symbol};
 use rustc_span::Span;
 

compiler/rustc_ast/src/lib.rs

@@ -20,9 +20,6 @@
 #![feature(negative_impls)]
 #![feature(stmt_expr_attributes)]
 
-#[macro_use]
-extern crate rustc_macros;
-
 #[macro_use]
 extern crate tracing;
 

compiler/rustc_ast/src/token.rs

@@ -9,7 +9,7 @@ use crate::util::case::Case;
 
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::Lrc;
-use rustc_macros::HashStable_Generic;
+use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_span::symbol::{kw, sym};
 #[allow(clippy::useless_attribute)] // FIXME: following use of `hidden_glob_reexports` incorrectly triggers `useless_attribute` lint.
 #[allow(hidden_glob_reexports)]

compiler/rustc_ast/src/tokenstream.rs

@@ -20,7 +20,7 @@ use crate::AttrVec;
 
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::{self, Lrc};
-use rustc_macros::HashStable_Generic;
+use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_serialize::{Decodable, Encodable};
 use rustc_span::{sym, Span, SpanDecoder, SpanEncoder, Symbol, DUMMY_SP};
 use smallvec::{smallvec, SmallVec};