Refactor away `CrateLoader::load_macros`.

src/librustc/middle/cstore.rs

@@ -423,7 +423,7 @@ pub enum LoadedMacros {
 }
 
 pub trait CrateLoader {
-    fn load_macros(&mut self, extern_crate: &ast::Item) -> LoadedMacros;
-    fn process_item(&mut self, item: &ast::Item, defs: &Definitions);
+    fn process_item(&mut self, item: &ast::Item, defs: &Definitions, load_macros: bool)
+                    -> Option<LoadedMacros>;
     fn postprocess(&mut self, krate: &ast::Crate);
 }

src/librustc_metadata/creader.rs

@@ -23,7 +23,7 @@
 use rustc::middle;
 use rustc::middle::cstore::{CrateStore, validate_crate_name, ExternCrate};
 use rustc::util::nodemap::{FnvHashMap, FnvHashSet};
-use rustc::hir::map as hir_map;
+use rustc::hir::map::Definitions;
 
 use std::cell::{RefCell, Cell};
 use std::ops::Deref;
@@ -631,8 +631,6 @@ fn load_derive_macros(&mut self, item: &ast::Item, index: DefIndex, svh: Svh, pa
         use rustc_back::dynamic_lib::DynamicLibrary;
         use syntax_ext::deriving::custom::CustomDerive;
 
-        self.cstore.add_used_for_derive_macros(item);
-
         // Make sure the path contains a / or the linker will search for it.
         let path = env::current_dir().unwrap().join(path);
         let lib = match DynamicLibrary::open(Some(&path)) {
@@ -1020,13 +1018,19 @@ fn postprocess(&mut self, krate: &ast::Crate) {
         self.register_statically_included_foreign_items();
     }
 
-    fn process_item(&mut self, item: &ast::Item, definitions: &hir_map::Definitions) {
+    fn process_item(&mut self, item: &ast::Item, definitions: &Definitions, load_macros: bool)
+                    -> Option<LoadedMacros> {
         match item.node {
             ast::ItemKind::ExternCrate(_) => {}
-            ast::ItemKind::ForeignMod(ref fm) => return self.process_foreign_mod(item, fm),
-            _ => return,
+            ast::ItemKind::ForeignMod(ref fm) => {
+                self.process_foreign_mod(item, fm);
+                return None;
+            }
+            _ => return None,
         }
 
+        let loaded_macros = if load_macros { Some(self.read_macros(item)) } else { None };
+
         // If this `extern crate` item has `#[macro_use]` then we can safely skip it.
         // These annotations were processed during macro expansion and are already loaded
         // (if necessary) into our crate store.
@@ -1034,15 +1038,13 @@ fn process_item(&mut self, item: &ast::Item, definitions: &hir_map::Definitions)
         // Note that it's important we *don't* fall through below as some `#[macro_use]`
         // crates are explicitly not linked (e.g. macro crates) so we want to ensure
         // we avoid `resolve_crate` with those.
-        if attr::contains_name(&item.attrs, "macro_use") {
-            if self.cstore.was_used_for_derive_macros(item) {
-                return
-            }
+        if let Some(LoadedMacros::CustomDerives(..)) = loaded_macros {
+            return loaded_macros;
         }
 
         if let Some(info) = self.extract_crate_info(item) {
             if !info.should_link {
-                return;
+                return loaded_macros;
             }
 
             let (cnum, ..) = self.resolve_crate(
@@ -1058,9 +1060,7 @@ fn process_item(&mut self, item: &ast::Item, definitions: &hir_map::Definitions)
 
             self.cstore.add_extern_mod_stmt_cnum(info.id, cnum);
         }
-    }
 
-    fn load_macros(&mut self, extern_crate: &ast::Item) -> LoadedMacros {
-        self.read_macros(extern_crate)
+        loaded_macros
     }
 }

src/librustc_metadata/cstore.rs

@@ -21,14 +21,13 @@
 use rustc::middle::cstore::ExternCrate;
 use rustc_back::PanicStrategy;
 use rustc_data_structures::indexed_vec::IndexVec;
-use rustc::util::nodemap::{FnvHashMap, NodeMap, NodeSet, DefIdMap, FnvHashSet};
+use rustc::util::nodemap::{FnvHashMap, NodeMap, NodeSet, DefIdMap};
 
 use std::cell::{RefCell, Cell};
 use std::rc::Rc;
 use std::path::PathBuf;
 use flate::Bytes;
-use syntax::ast::{self, Ident};
-use syntax::attr;
+use syntax::{ast, attr};
 use syntax_pos;
 
 pub use rustc::middle::cstore::{NativeLibraryKind, LinkagePreference};
@@ -105,7 +104,6 @@ pub struct CStore {
     pub inlined_item_cache: RefCell<DefIdMap<Option<CachedInlinedItem>>>,
     pub defid_for_inlined_node: RefCell<NodeMap<DefId>>,
     pub visible_parent_map: RefCell<DefIdMap<DefId>>,
-    pub used_for_derive_macro: RefCell<FnvHashSet<Ident>>,
 }
 
 impl CStore {
@@ -121,7 +119,6 @@ pub fn new(dep_graph: &DepGraph) -> CStore {
             visible_parent_map: RefCell::new(FnvHashMap()),
             inlined_item_cache: RefCell::new(FnvHashMap()),
             defid_for_inlined_node: RefCell::new(FnvHashMap()),
-            used_for_derive_macro: RefCell::new(FnvHashSet()),
         }
     }
 
@@ -277,14 +274,6 @@ pub fn do_extern_mod_stmt_cnum(&self, emod_id: ast::NodeId) -> Option<CrateNum>
     {
         self.extern_mod_crate_map.borrow().get(&emod_id).cloned()
     }
-
-    pub fn was_used_for_derive_macros(&self, i: &ast::Item) -> bool {
-        self.used_for_derive_macro.borrow().contains(&i.ident)
-    }
-
-    pub fn add_used_for_derive_macros(&self, i: &ast::Item) {
-        self.used_for_derive_macro.borrow_mut().insert(i.ident);
-    }
 }
 
 impl CrateMetadata {

src/librustc_resolve/build_reduced_graph.rs

@@ -215,12 +215,11 @@ fn build_reduced_graph_for_item(&mut self, item: &Item, expansion: Mark) {
                 }
 
                 let loaded_macros = if legacy_imports != LegacyMacroImports::default() {
-                    Some(self.crate_loader.load_macros(item))
+                    self.crate_loader.process_item(item, &self.definitions, true)
                 } else {
-                    None
+                    self.crate_loader.process_item(item, &self.definitions, false)
                 };
 
-                self.crate_loader.process_item(item, &self.definitions);
                 // n.b. we don't need to look at the path option here, because cstore already did
                 let crate_id = self.session.cstore.extern_mod_stmt_cnum(item.id);
                 let module = if let Some(crate_id) = crate_id {
@@ -270,7 +269,9 @@ fn build_reduced_graph_for_item(&mut self, item: &Item, expansion: Mark) {
                 self.current_module = module;
             }
 
-            ItemKind::ForeignMod(..) => self.crate_loader.process_item(item, &self.definitions),
+            ItemKind::ForeignMod(..) => {
+                self.crate_loader.process_item(item, &self.definitions, false);
+            }
 
             // These items live in the value namespace.
             ItemKind::Static(_, m, _) => {