resolve/metadata: Stop encoding macros as reexports

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -1077,6 +1077,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
                         res,
                         vis: ty::Visibility::Public,
                         span: ident.span,
+                        macro_rules: false,
                     });
                 }
             }
@@ -1088,17 +1089,19 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
             for child_index in children.decode((self, sess)) {
                 if let Some(ident) = self.opt_item_ident(child_index, sess) {
                     let kind = self.def_kind(child_index);
-                    if matches!(kind, DefKind::Macro(..)) {
-                        // FIXME: Macros are currently encoded twice, once as items and once as
-                        // reexports. We ignore the items here and only use the reexports.
-                        continue;
-                    }
                     let def_id = self.local_def_id(child_index);
                     let res = Res::Def(kind, def_id);
                     let vis = self.get_visibility(child_index);
                     let span = self.get_span(child_index, sess);
+                    let macro_rules = match kind {
+                        DefKind::Macro(..) => match self.kind(child_index) {
+                            EntryKind::MacroDef(_, macro_rules) => macro_rules,
+                            _ => unreachable!(),
+                        },
+                        _ => false,
+                    };
 
-                    callback(ModChild { ident, res, vis, span });
+                    callback(ModChild { ident, res, vis, span, macro_rules });
 
                     // For non-re-export structs and variants add their constructors to children.
                     // Re-export lists automatically contain constructors when necessary.
@@ -1110,7 +1113,13 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
                                 let ctor_res =
                                     Res::Def(DefKind::Ctor(CtorOf::Struct, ctor_kind), ctor_def_id);
                                 let vis = self.get_visibility(ctor_def_id.index);
-                                callback(ModChild { ident, res: ctor_res, vis, span });
+                                callback(ModChild {
+                                    ident,
+                                    res: ctor_res,
+                                    vis,
+                                    span,
+                                    macro_rules: false,
+                                });
                             }
                         }
                         DefKind::Variant => {
@@ -1135,7 +1144,13 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
                                     vis = ty::Visibility::Restricted(crate_def_id);
                                 }
                             }
-                            callback(ModChild { ident, res: ctor_res, vis, span });
+                            callback(ModChild {
+                                ident,
+                                res: ctor_res,
+                                vis,
+                                span,
+                                macro_rules: false,
+                            });
                         }
                         _ => {}
                     }

compiler/rustc_middle/src/metadata.rs

@@ -21,4 +21,6 @@ pub struct ModChild {
     pub vis: ty::Visibility,
     /// Span of the item.
     pub span: Span,
+    /// A proper `macro_rules` item (not a reexport).
+    pub macro_rules: bool,
 }

compiler/rustc_resolve/src/access_levels.rs

@@ -133,7 +133,7 @@ impl<'r, 'ast> Visitor<'ast> for AccessLevelsVisitor<'ast, 'r> {
             ast::ItemKind::Impl(..) => return,
 
             // Only exported `macro_rules!` items are public, but they always are
-            ast::ItemKind::MacroDef(..) => {
+            ast::ItemKind::MacroDef(ref macro_def) if macro_def.macro_rules => {
                 let is_macro_export =
                     item.attrs.iter().any(|attr| attr.has_name(sym::macro_export));
                 if is_macro_export { Some(AccessLevel::Public) } else { None }
@@ -155,7 +155,8 @@ impl<'r, 'ast> Visitor<'ast> for AccessLevelsVisitor<'ast, 'r> {
             | ast::ItemKind::Struct(..)
             | ast::ItemKind::Union(..)
             | ast::ItemKind::Trait(..)
-            | ast::ItemKind::TraitAlias(..) => {
+            | ast::ItemKind::TraitAlias(..)
+            | ast::ItemKind::MacroDef(..) => {
                 if item.vis.kind.is_pub() {
                     self.prev_level
                 } else {

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -940,7 +940,7 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
     /// Builds the reduced graph for a single item in an external crate.
     fn build_reduced_graph_for_external_crate_res(&mut self, child: ModChild) {
         let parent = self.parent_scope.module;
-        let ModChild { ident, res, vis, span } = child;
+        let ModChild { ident, res, vis, span, macro_rules } = child;
         let res = res.expect_non_local();
         let expansion = self.parent_scope.expansion;
         // Record primary definitions.
@@ -972,7 +972,9 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
                 _,
             ) => self.r.define(parent, ident, ValueNS, (res, vis, span, expansion)),
             Res::Def(DefKind::Macro(..), _) | Res::NonMacroAttr(..) => {
-                self.r.define(parent, ident, MacroNS, (res, vis, span, expansion))
+                if !macro_rules {
+                    self.r.define(parent, ident, MacroNS, (res, vis, span, expansion))
+                }
             }
             Res::Def(
                 DefKind::TyParam

compiler/rustc_resolve/src/imports.rs

@@ -1399,14 +1399,22 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
         let mut reexports = Vec::new();
 
         module.for_each_child(self.r, |_, ident, _, binding| {
-            // Filter away ambiguous imports and anything that has def-site hygiene.
+            // FIXME: Consider changing the binding inserted by `#[macro_export] macro_rules`
-            // FIXME: Implement actual cross-crate hygiene.
+            // into the crate root to actual `NameBindingKind::Import`.
-            let is_good_import =
+            if binding.is_import()
-                binding.is_import() && !binding.is_ambiguity() && !ident.span.from_expansion();
+                || matches!(binding.kind, NameBindingKind::Res(_, _is_macro_export @ true))
-            if is_good_import || binding.is_macro_def() {
+            {
                 let res = binding.res().expect_non_local();
-                if res != def::Res::Err {
+                // Ambiguous imports are treated as errors at this point and are
-                    reexports.push(ModChild { ident, res, vis: binding.vis, span: binding.span });
+                // not exposed to other crates (see #36837 for more details).
+                if res != def::Res::Err && !binding.is_ambiguity() {
+                    reexports.push(ModChild {
+                        ident,
+                        res,
+                        vis: binding.vis,
+                        span: binding.span,
+                        macro_rules: false,
+                    });
                 }
             }
         });

compiler/rustc_resolve/src/lib.rs

@@ -845,10 +845,6 @@ impl<'a> NameBinding<'a> {
         )
     }
 
-    fn is_macro_def(&self) -> bool {
-        matches!(self.kind, NameBindingKind::Res(Res::Def(DefKind::Macro(..), _), _))
-    }
-
     fn macro_kind(&self) -> Option<MacroKind> {
         self.res().macro_kind()
     }