resolve: Do not rely on default transparency when detecting proc macro derives

Author: petrochenkov

src/librustc_resolve/build_reduced_graph.rs

@@ -145,7 +145,7 @@ impl<'a> Resolver<'a> {
         }
     }
 
-    fn get_macro_by_def_id(&mut self, def_id: DefId) -> Option<Lrc<SyntaxExtension>> {
+    crate fn get_macro_by_def_id(&mut self, def_id: DefId) -> Option<Lrc<SyntaxExtension>> {
         if let Some(ext) = self.macro_map.get(&def_id) {
             return Some(ext.clone());
         }

src/librustc_resolve/lib.rs

@@ -1647,10 +1647,14 @@ impl<'a> Resolver<'a> {
             if module.expansion != parent.expansion &&
             module.expansion.is_descendant_of(parent.expansion) {
                 // The macro is a proc macro derive
-                if module.expansion.looks_like_proc_macro_derive() {
-                    if parent.expansion.outer_expn_is_descendant_of(span.ctxt()) {
-                        *poisoned = Some(node_id);
-                        return module.parent;
+                if let Some(&def_id) = self.macro_defs.get(&module.expansion) {
+                    if let Some(ext) = self.get_macro_by_def_id(def_id) {
+                        if !ext.is_builtin && ext.macro_kind() == MacroKind::Derive {
+                            if parent.expansion.outer_expn_is_descendant_of(span.ctxt()) {
+                                *poisoned = Some(node_id);
+                                return module.parent;
+                            }
+                        }
                     }
                 }
             }

src/libsyntax_pos/hygiene.rs

@@ -119,18 +119,6 @@ impl ExpnId {
     pub fn outer_expn_is_descendant_of(self, ctxt: SyntaxContext) -> bool {
         HygieneData::with(|data| data.is_descendant_of(self, data.outer_expn(ctxt)))
     }
-
-    // Used for enabling some compatibility fallback in resolve.
-    #[inline]
-    pub fn looks_like_proc_macro_derive(self) -> bool {
-        HygieneData::with(|data| {
-            let expn_data = data.expn_data(self);
-            if let ExpnKind::Macro(MacroKind::Derive, _) = expn_data.kind {
-                return expn_data.default_transparency == Transparency::Opaque;
-            }
-            false
-        })
-    }
 }
 
 #[derive(Debug)]