reuse original symbols for inlined items

When inlining an item from another crate, use the original symbol from that
crate's metadata instead of generating a new symbol using the `ast::NodeId` of
the inlined copy.  This requires exporting symbols in the crate metadata in a
few additional cases.  Having predictable symbols for inlined items will be
useful later to avoid generating duplicate object code for inlined items.

src/librustc/metadata/encoder.rs

@@ -892,7 +892,8 @@ fn encode_info_for_method(ecx: &EncodeContext,
                                 IITraitItemRef(local_def(parent_id),
                                                RequiredInlinedTraitItemRef(
                                                    &*ast_method)));
-        } else {
+        }
+        if !any_types {
             encode_symbol(ecx, rbml_w, m.def_id.node);
         }
         encode_method_argument_names(rbml_w, &*ast_method.pe_fn_decl());
@@ -1047,7 +1048,8 @@ fn encode_info_for_item(ecx: &EncodeContext,
         encode_attributes(rbml_w, item.attrs.as_slice());
         if tps_len > 0u || should_inline(item.attrs.as_slice()) {
             encode_inlined_item(ecx, rbml_w, IIItemRef(item));
-        } else {
+        }
+        if tps_len == 0 {
             encode_symbol(ecx, rbml_w, item.id);
         }
         encode_visibility(rbml_w, vis);
@@ -1411,9 +1413,8 @@ fn encode_info_for_foreign_item(ecx: &EncodeContext,
         encode_name(rbml_w, nitem.ident.name);
         if abi == abi::RustIntrinsic {
             encode_inlined_item(ecx, rbml_w, IIForeignRef(nitem));
-        } else {
-            encode_symbol(ecx, rbml_w, nitem.id);
         }
+        encode_symbol(ecx, rbml_w, nitem.id);
       }
       ForeignItemStatic(_, mutbl) => {
         if mutbl {

src/librustc/middle/trans/base.rs

@@ -2554,6 +2554,15 @@ pub fn create_entry_wrapper(ccx: &CrateContext,
 
 fn exported_name(ccx: &CrateContext, id: ast::NodeId,
                  ty: ty::t, attrs: &[ast::Attribute]) -> String {
+    match ccx.external_srcs().borrow().find(&id) {
+        Some(&did) => {
+            let sym = csearch::get_symbol(&ccx.sess().cstore, did);
+            debug!("found item {} in other crate...", sym);
+            return sym;
+        }
+        None => {}
+    }
+
     match attr::first_attr_value_str_by_name(attrs, "export_name") {
         // Use provided name
         Some(name) => name.get().to_string(),
@@ -2597,16 +2606,7 @@ pub fn get_item_val(ccx: &CrateContext, id: ast::NodeId) -> ValueRef {
                     // using the current crate's name/version
                     // information in the hash of the symbol
                     debug!("making {}", sym);
-                    let (sym, is_local) = {
-                        match ccx.external_srcs().borrow().find(&i.id) {
-                            Some(&did) => {
-                                debug!("but found in other crate...");
-                                (csearch::get_symbol(&ccx.sess().cstore,
-                                                     did), false)
-                            }
-                            None => (sym, true)
-                        }
-                    };
+                    let is_local = !ccx.external_srcs().borrow().contains_key(&id);
 
                     // We need the translated value here, because for enums the
                     // LLVM type is not fully determined by the Rust type.