Also arena-allocate ast::MacroDef to make Item: Copy

compiler/rustc_ast_lowering/src/item.rs

@@ -443,7 +443,8 @@ fn lower_item_kind(
             ItemKind::MacroDef(MacroDef { body, macro_rules }) => {
                 let body = P(self.lower_delim_args(body));
                 let macro_kind = self.resolver.decl_macro_kind(self.local_def_id(id));
-                hir::ItemKind::Macro(ast::MacroDef { body, macro_rules: *macro_rules }, macro_kind)
+                let macro_def = self.arena.alloc(ast::MacroDef { body, macro_rules: *macro_rules });
+                hir::ItemKind::Macro(macro_def, macro_kind)
             }
             ItemKind::MacCall(..) => {
                 panic!("`TyMac` should have been expanded by now")

compiler/rustc_hir/src/arena.rs

@@ -8,10 +8,10 @@ macro_rules! arena_types {
             [] hir_krate: rustc_hir::Crate<'tcx>,
             [] asm_template: rustc_ast::InlineAsmTemplatePiece,
             [] attribute: rustc_ast::Attribute,
-            [] item: rustc_hir::Item<'tcx>,
             [] owner_info: rustc_hir::OwnerInfo<'tcx>,
             [] use_path: rustc_hir::UsePath<'tcx>,
             [] lit: rustc_hir::Lit,
+            [] macro_def: rustc_ast::MacroDef,
         ]);
     )
 }

compiler/rustc_hir/src/hir.rs

@@ -3063,7 +3063,7 @@ pub fn hir_id(&self) -> HirId {
 /// An item
 ///
 /// The name might be a dummy name in case of anonymous items
-#[derive(Debug, HashStable_Generic)]
+#[derive(Debug, Clone, Copy, HashStable_Generic)]
 pub struct Item<'hir> {
     pub ident: Ident,
     pub owner_id: OwnerId,
@@ -3271,7 +3271,7 @@ pub fn is_unsafe(&self) -> bool {
     }
 }
 
-#[derive(Debug, HashStable_Generic)]
+#[derive(Debug, Clone, Copy, HashStable_Generic)]
 pub enum ItemKind<'hir> {
     /// An `extern crate` item, with optional *original* crate name if the crate was renamed.
     ///
@@ -3292,7 +3292,7 @@ pub enum ItemKind<'hir> {
     /// A function declaration.
     Fn(FnSig<'hir>, &'hir Generics<'hir>, BodyId),
     /// A MBE macro definition (`macro_rules!` or `macro`).
-    Macro(ast::MacroDef, MacroKind),
+    Macro(&'hir ast::MacroDef, MacroKind),
     /// A module.
     Mod(&'hir Mod<'hir>),
     /// An external module, e.g. `extern { .. }`.