rustdoc: Track macro_rules scopes during early doc link resolution

This way links referring to `macro_rules` items are resolved correctly

compiler/rustc_resolve/src/lib.rs

@@ -145,7 +145,7 @@ enum ScopeSet<'a> {
 pub struct ParentScope<'a> {
     pub module: Module<'a>,
     expansion: LocalExpnId,
-    macro_rules: MacroRulesScopeRef<'a>,
+    pub macro_rules: MacroRulesScopeRef<'a>,
     derives: &'a [ast::Path],
 }
 
@@ -990,6 +990,8 @@ pub struct Resolver<'a> {
     /// `macro_rules` scopes *produced* by expanding the macro invocations,
     /// include all the `macro_rules` items and other invocations generated by them.
     output_macro_rules_scopes: FxHashMap<LocalExpnId, MacroRulesScopeRef<'a>>,
+    /// `macro_rules` scopes produced by `macro_rules` item definitions.
+    macro_rules_scopes: FxHashMap<LocalDefId, MacroRulesScopeRef<'a>>,
     /// Helper attributes that are in scope for the given expansion.
     helper_attrs: FxHashMap<LocalExpnId, Vec<Ident>>,
     /// Ready or in-progress results of resolving paths inside the `#[derive(...)]` attribute
@@ -1361,6 +1363,7 @@ impl<'a> Resolver<'a> {
             non_macro_attr: Lrc::new(SyntaxExtension::non_macro_attr(session.edition())),
             invocation_parent_scopes: Default::default(),
             output_macro_rules_scopes: Default::default(),
+            macro_rules_scopes: Default::default(),
             helper_attrs: Default::default(),
             derive_data: Default::default(),
             local_macro_def_scopes: FxHashMap::default(),
@@ -1919,6 +1922,11 @@ impl<'a> Resolver<'a> {
         }
     }
 
+    /// For rustdoc.
+    pub fn macro_rules_scope(&self, def_id: LocalDefId) -> MacroRulesScopeRef<'a> {
+        *self.macro_rules_scopes.get(&def_id).expect("not a `macro_rules` item")
+    }
+
     /// Retrieves the span of the given `DefId` if `DefId` is in the local crate.
     #[inline]
     pub fn opt_span(&self, def_id: DefId) -> Option<Span> {