Rollup merge of rust-lang#30528 - michaelwoerister:fix-extern-def-paths, r=nikomatsakis

Avoid duplicating the last element of the def path which led to paths like "std::slice::into_vec::into_vec".

cc @rust-lang/compiler

Author: Manishearth

src/librustc/front/map/mod.rs

@@ -839,11 +839,10 @@ pub fn map_crate<'ast>(forest: &'ast mut Forest) -> Map<'ast> {
 }
 
 /// Used for items loaded from external crate that are being inlined into this
-/// crate.  The `path` should be the path to the item but should not include
-/// the item itself.
+/// crate.
 pub fn map_decoded_item<'ast, F: FoldOps>(map: &Map<'ast>,
-                                          path: Vec<PathElem>,
-                                          def_path: DefPath,
+                                          parent_path: Vec<PathElem>,
+                                          parent_def_path: DefPath,
                                           ii: InlinedItem,
                                           fold_ops: F)
                                           -> &'ast InlinedItem {
@@ -862,7 +861,7 @@ pub fn map_decoded_item<'ast, F: FoldOps>(map: &Map<'ast>,
     };
 
     let ii_parent = map.forest.inlined_items.alloc(InlinedParent {
-        path: path,
+        path: parent_path,
         ii: ii
     });
 
@@ -872,7 +871,7 @@ pub fn map_decoded_item<'ast, F: FoldOps>(map: &Map<'ast>,
             map.krate(),
             ii_parent,
             ii_parent_id,
-            def_path,
+            parent_def_path,
             mem::replace(&mut *map.map.borrow_mut(), vec![]),
             mem::replace(&mut *map.definitions.borrow_mut(), Definitions::new()));
     ii_parent.ii.visit(&mut collector);

src/librustc_metadata/astencode.rs

@@ -124,20 +124,20 @@ impl<'a, 'b, 'c, 'tcx> ast_map::FoldOps for &'a DecodeContext<'b, 'c, 'tcx> {
 /// ast-map.
 pub fn decode_inlined_item<'tcx>(cdata: &cstore::crate_metadata,
                                  tcx: &ty::ctxt<'tcx>,
-                                 path: Vec<ast_map::PathElem>,
-                                 def_path: ast_map::DefPath,
+                                 parent_path: Vec<ast_map::PathElem>,
+                                 parent_def_path: ast_map::DefPath,
                                  par_doc: rbml::Doc,
                                  orig_did: DefId)
                                  -> Result<&'tcx InlinedItem, (Vec<ast_map::PathElem>,
                                                                ast_map::DefPath)> {
     match par_doc.opt_child(c::tag_ast) {
-      None => Err((path, def_path)),
+      None => Err((parent_path, parent_def_path)),
       Some(ast_doc) => {
         let mut path_as_str = None;
         debug!("> Decoding inlined fn: {:?}::?",
         {
             // Do an Option dance to use the path after it is moved below.
-            let s = ast_map::path_to_string(path.iter().cloned());
+            let s = ast_map::path_to_string(parent_path.iter().cloned());
             path_as_str = Some(s);
             path_as_str.as_ref().map(|x| &x[..])
         });
@@ -152,8 +152,11 @@ pub fn decode_inlined_item<'tcx>(cdata: &cstore::crate_metadata,
             last_filemap_index: Cell::new(0)
         };
         let raw_ii = decode_ast(ast_doc);
-        let ii = ast_map::map_decoded_item(&dcx.tcx.map, path, def_path, raw_ii, dcx);
-
+        let ii = ast_map::map_decoded_item(&dcx.tcx.map,
+                                           parent_path,
+                                           parent_def_path,
+                                           raw_ii,
+                                           dcx);
         let name = match *ii {
             InlinedItem::Item(ref i) => i.name,
             InlinedItem::Foreign(ref i) => i.name,

src/librustc_metadata/decoder.rs

@@ -763,29 +763,54 @@ pub fn get_item_name(intr: &IdentInterner, cdata: Cmd, id: DefIndex) -> ast::Nam
 pub type DecodeInlinedItem<'a> =
     Box<for<'tcx> FnMut(Cmd,
                         &ty::ctxt<'tcx>,
-                        Vec<hir_map::PathElem>,
-                        hir_map::DefPath,
+                        Vec<hir_map::PathElem>, // parent_path
+                        hir_map::DefPath,       // parent_def_path
                         rbml::Doc,
                         DefId)
                         -> Result<&'tcx InlinedItem, (Vec<hir_map::PathElem>,
                                                       hir_map::DefPath)> + 'a>;
 
-pub fn maybe_get_item_ast<'tcx>(cdata: Cmd, tcx: &ty::ctxt<'tcx>, id: DefIndex,
+pub fn maybe_get_item_ast<'tcx>(cdata: Cmd,
+                                tcx: &ty::ctxt<'tcx>,
+                                id: DefIndex,
                                 mut decode_inlined_item: DecodeInlinedItem)
                                 -> FoundAst<'tcx> {
     debug!("Looking up item: {:?}", id);
     let item_doc = cdata.lookup_item(id);
     let item_did = item_def_id(item_doc, cdata);
-    let path = item_path(item_doc).split_last().unwrap().1.to_vec();
-    let def_path = def_path(cdata, id);
-    match decode_inlined_item(cdata, tcx, path, def_path, item_doc, item_did) {
+    let parent_path = {
+        let mut path = item_path(item_doc);
+        path.pop();
+        path
+    };
+    let parent_def_path = {
+        let mut def_path = def_path(cdata, id);
+        def_path.pop();
+        def_path
+    };
+    match decode_inlined_item(cdata,
+                              tcx,
+                              parent_path,
+                              parent_def_path,
+                              item_doc,
+                              item_did) {
         Ok(ii) => FoundAst::Found(ii),
-        Err((path, def_path)) => {
+        Err((mut parent_path, mut parent_def_path)) => {
             match item_parent_item(cdata, item_doc) {
-                Some(did) => {
-                    let parent_item = cdata.lookup_item(did.index);
-                    match decode_inlined_item(cdata, tcx, path, def_path, parent_item, did) {
-                        Ok(ii) => FoundAst::FoundParent(did, ii),
+                Some(parent_did) => {
+                    // Remove the last element from the paths, since we are now
+                    // trying to inline the parent.
+                    parent_path.pop();
+                    parent_def_path.pop();
+
+                    let parent_item = cdata.lookup_item(parent_did.index);
+                    match decode_inlined_item(cdata,
+                                              tcx,
+                                              parent_path,
+                                              parent_def_path,
+                                              parent_item,
+                                              parent_did) {
+                        Ok(ii) => FoundAst::FoundParent(parent_did, ii),
                         Err(_) => FoundAst::NotFound
                     }
                 }