Don't return dummy MacroData in get_macro

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -204,7 +204,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
     pub(crate) fn get_macro(&self, res: Res) -> Option<&'ra MacroData> {
         match res {
             Res::Def(DefKind::Macro(..), def_id) => Some(self.get_macro_by_def_id(def_id)),
-            Res::NonMacroAttr(_) => Some(self.non_macro_attr),
             _ => None,
         }
     }

compiler/rustc_resolve/src/lib.rs

@@ -1392,7 +1392,7 @@ pub struct Resolver<'ra, 'tcx> {
     extern_macro_map: CacheRefCell<FxHashMap<DefId, &'ra MacroData>>,
     dummy_ext_bang: Arc<SyntaxExtension>,
     dummy_ext_derive: Arc<SyntaxExtension>,
-    non_macro_attr: &'ra MacroData,
+    non_macro_attr: Arc<SyntaxExtension>,
     local_macro_def_scopes: FxHashMap<LocalDefId, LocalModule<'ra>> = default::fx_hash_map(),
     ast_transform_scopes: FxHashMap<LocalExpnId, LocalModule<'ra>> = default::fx_hash_map(),
     unused_macros: FxIndexMap<LocalDefId, (NodeId, Ident)>,
@@ -1812,8 +1812,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             extern_macro_map: Default::default(),
             dummy_ext_bang: Arc::new(SyntaxExtension::dummy_bang(edition)),
             dummy_ext_derive: Arc::new(SyntaxExtension::dummy_derive(edition)),
-            non_macro_attr: arenas
-                .alloc_macro(MacroData::new(Arc::new(SyntaxExtension::non_macro_attr(edition)))),
+            non_macro_attr: Arc::new(SyntaxExtension::non_macro_attr(edition)),
             unused_macros: Default::default(),
             unused_macro_rules: Default::default(),
             single_segment_macro_resolutions: Default::default(),
@@ -1984,7 +1983,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         match macro_kind {
             MacroKind::Bang => Arc::clone(&self.dummy_ext_bang),
             MacroKind::Derive => Arc::clone(&self.dummy_ext_derive),
-            MacroKind::Attr => Arc::clone(&self.non_macro_attr.ext),
+            MacroKind::Attr => Arc::clone(&self.non_macro_attr),
         }
     }
 

compiler/rustc_resolve/src/macros.rs

@@ -869,21 +869,25 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         };
 
         let res = res?;
-        let ext = match deleg_impl {
-            Some((impl_def_id, star_span)) => match res {
-                Res::Def(DefKind::Trait, def_id) => {
-                    let edition = self.tcx.sess.edition();
-                    Some(Arc::new(SyntaxExtension::glob_delegation(
-                        def_id,
-                        impl_def_id,
-                        star_span,
-                        edition,
-                    )))
-                }
-                _ => None,
-            },
-            None => self.get_macro(res).map(|macro_data| Arc::clone(&macro_data.ext)),
+        let ext = match res {
+            Res::Def(DefKind::Macro(..), def_id) => {
+                let md = self.get_macro_by_def_id(def_id);
+                Some(Arc::clone(&md.ext))
+            }
+            Res::Def(DefKind::Trait, def_id) if let Some((impl_def_id, star_span)) = deleg_impl => {
+                let edition = self.tcx.sess.edition();
+                Some(Arc::new(SyntaxExtension::glob_delegation(
+                    def_id,
+                    impl_def_id,
+                    star_span,
+                    edition,
+                )))
+            }
+            // Avoid ICE-ing on tool attributes in weird positions like `rustfmt::skip!()`
+            Res::NonMacroAttr(_) => Some(Arc::clone(&self.non_macro_attr)),
+            _ => None,
         };
+
         Ok((ext, res))
     }