metadata: Tweak the way in which declarative macros are encoded

To make the `macro_rules` flag more readily available without decoding everything else

Author: petrochenkov

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -5,6 +5,7 @@ use crate::rmeta::table::{FixedSizeEncoding, Table};
 use crate::rmeta::*;
 
 use rustc_ast as ast;
+use rustc_ast::ptr::P;
 use rustc_attr as attr;
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::FxHashMap;
@@ -1402,9 +1403,11 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
         tcx.arena.alloc_from_iter(self.root.exported_symbols.decode((self, tcx)))
     }
 
-    fn get_macro(self, id: DefIndex, sess: &Session) -> MacroDef {
+    fn get_macro(self, id: DefIndex, sess: &Session) -> ast::MacroDef {
         match self.kind(id) {
-            EntryKind::MacroDef(macro_def) => macro_def.decode((self, sess)),
+            EntryKind::MacroDef(mac_args, macro_rules) => {
+                ast::MacroDef { body: P(mac_args.decode((self, sess))), macro_rules }
+            }
             _ => bug!(),
         }
     }

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1407,7 +1407,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 EntryKind::Fn(self.lazy(data))
             }
             hir::ItemKind::Macro(ref macro_def, _) => {
-                EntryKind::MacroDef(self.lazy(macro_def.clone()))
+                EntryKind::MacroDef(self.lazy(&*macro_def.body), macro_def.macro_rules)
             }
             hir::ItemKind::Mod(ref m) => {
                 return self.encode_info_for_mod(item.def_id, m);

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -2,7 +2,7 @@ use decoder::Metadata;
 use def_path_hash_map::DefPathHashMapRef;
 use table::{Table, TableBuilder};
 
-use rustc_ast::{self as ast, MacroDef};
+use rustc_ast as ast;
 use rustc_attr as attr;
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::MetadataRef;
@@ -350,7 +350,7 @@ enum EntryKind {
     Fn(Lazy<FnData>),
     ForeignFn(Lazy<FnData>),
     Mod(Lazy<[ModChild]>),
-    MacroDef(Lazy<MacroDef>),
+    MacroDef(Lazy<ast::MacArgs>, /*macro_rules*/ bool),
     ProcMacro(MacroKind),
     Closure,
     Generator,