On-demandify extern_crate

src/librustc/middle/cstore.rs

@@ -254,7 +254,6 @@ pub trait CrateStore {
     fn is_compiler_builtins(&self, cnum: CrateNum) -> bool;
     fn is_sanitizer_runtime(&self, cnum: CrateNum) -> bool;
     fn panic_strategy(&self, cnum: CrateNum) -> PanicStrategy;
-    fn extern_crate(&self, cnum: CrateNum) -> Option<ExternCrate>;
     /// The name of the crate as it is referred to in source code of the current
     /// crate.
     fn crate_name(&self, cnum: CrateNum) -> Symbol;
@@ -374,7 +373,6 @@ impl CrateStore for DummyCrateStore {
     fn panic_strategy(&self, cnum: CrateNum) -> PanicStrategy {
         bug!("panic_strategy")
     }
-    fn extern_crate(&self, cnum: CrateNum) -> Option<ExternCrate> { bug!("extern_crate") }
     fn crate_name(&self, cnum: CrateNum) -> Symbol { bug!("crate_name") }
     fn original_crate_name(&self, cnum: CrateNum) -> Symbol {
         bug!("original_crate_name")

src/librustc/ty/item_path.rs

@@ -100,7 +100,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                 //
                 // Returns `None` for the local crate.
                 if cnum != LOCAL_CRATE {
-                    let opt_extern_crate = self.sess.cstore.extern_crate(cnum);
+                    let opt_extern_crate = self.extern_crate(cnum);
                     let opt_extern_crate = opt_extern_crate.and_then(|extern_crate| {
                         if extern_crate.direct {
                             Some(extern_crate.def_id)
@@ -136,8 +136,8 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             // If `cur_def` is a direct or injected extern crate, push the path to the crate
             // followed by the path to the item within the crate and return.
             if cur_def.index == CRATE_DEF_INDEX {
-                match self.sess.cstore.extern_crate(cur_def.krate) {
-                    Some(extern_crate) if extern_crate.direct => {
+                match *self.extern_crate(cur_def.krate) {
+                    Some(ref extern_crate) if extern_crate.direct => {
                         self.push_item_path(buffer, extern_crate.def_id);
                         cur_path.iter().rev().map(|segment| buffer.push(&segment.as_str())).count();
                         return true;

src/librustc/ty/maps.rs

@@ -13,7 +13,7 @@ use hir::def_id::{CrateNum, CRATE_DEF_INDEX, DefId, LOCAL_CRATE};
 use hir::def::Def;
 use hir;
 use middle::const_val;
-use middle::cstore::LinkagePreference;
+use middle::cstore::{ExternCrate, LinkagePreference};
 use middle::privacy::AccessLevels;
 use middle::region::RegionMaps;
 use mir;
@@ -501,6 +501,12 @@ impl<'tcx> QueryDescription for queries::is_panic_runtime<'tcx> {
     }
 }
 
+impl<'tcx> QueryDescription for queries::extern_crate<'tcx> {
+    fn describe(_: TyCtxt, _: CrateNum) -> String {
+        "getting crate's ExternCrateData".to_string()
+    }
+}
+
 macro_rules! define_maps {
     (<$tcx:tt>
      $($(#[$attr:meta])*
@@ -963,6 +969,8 @@ define_maps! { <'tcx>
 
     [] is_allocator: MetaDataByCrateNum(CrateNum) -> bool,
     [] is_panic_runtime: MetaDataByCrateNum(CrateNum) -> bool,
+
+    [] extern_crate: MetaDataByCrateNum(CrateNum) -> Rc<Option<ExternCrate>>,
 }
 
 fn type_param_predicates((item_id, param_id): (DefId, DefId)) -> DepConstructor {

src/librustc_metadata/cstore_impl.rs

@@ -14,7 +14,7 @@ use schema;
 
 use rustc::dep_graph::DepTrackingMapConfig;
 use rustc::middle::cstore::{CrateStore, CrateSource, LibSource, DepKind,
-                            ExternCrate, NativeLibrary, MetadataLoader, LinkMeta,
+                            NativeLibrary, MetadataLoader, LinkMeta,
                             LinkagePreference, LoadedMacro, EncodedMetadata};
 use rustc::hir::def;
 use rustc::middle::lang_items;
@@ -156,6 +156,7 @@ provide! { <'tcx> tcx, def_id, cdata, cnum,
         dylib_dependency_formats => { Rc::new(cdata.get_dylib_dependency_formats(&tcx.dep_graph)) }
         is_allocator => { cdata.is_allocator(&tcx.dep_graph) }
         is_panic_runtime => { cdata.is_panic_runtime(&tcx.dep_graph) }
+        extern_crate => { Rc::new(cdata.extern_crate.get()) }
     }
 }
 
@@ -283,11 +284,6 @@ impl CrateStore for cstore::CStore {
         self.get_crate_data(cnum).name()
     }
 
-    fn extern_crate(&self, cnum: CrateNum) -> Option<ExternCrate>
-    {
-        self.get_crate_data(cnum).extern_crate.get()
-    }
-
     fn crate_hash(&self, cnum: CrateNum) -> Svh
     {
         self.get_crate_hash(cnum)

src/librustc_save_analysis/lib.rs

@@ -107,7 +107,7 @@ impl<'l, 'tcx: 'l> SaveContext<'l, 'tcx> {
         let mut result = Vec::new();
 
         for n in self.tcx.sess.cstore.crates() {
-            let span = match self.tcx.sess.cstore.extern_crate(n) {
+            let span = match *self.tcx.extern_crate(n) {
                 Some(ref c) => c.span,
                 None => {
                     debug!("Skipping crate {}, no data", n);