Auto merge of #46540 - euclio:import-parents, r=nrc

save-analysis: add parents to imports

This PR populates the `parent` field added to `Import` in `rls-data` 0.14.

I'm not quite sure if I handled nested imports' parents correctly: this is a new feature to me.

r? @nrc

cc rust-dev-tools/rls-analysis#123

Author: bors

src/Cargo.lock

@@ -15,7 +15,7 @@ rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_typeck = { path = "../librustc_typeck" }
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }
-rls-data = "0.13"
+rls-data = "0.14"
 rls-span = "0.4"
 # FIXME(#40527) should move rustc serialize out of tree
 rustc-serialize = "0.3"

src/librustc_save_analysis/Cargo.toml

@@ -1231,13 +1231,26 @@ impl<'l, 'tcx: 'l, 'll, O: DumpOutput + 'll> DumpVisitor<'l, 'tcx, 'll, O> {
         }
     }
 
+    /// Dumps imports in a use tree recursively.
+    ///
+    /// A use tree is an import that may contain nested braces (RFC 2128). The `use_tree` parameter
+    /// is the current use tree under scrutiny, while `id` and `prefix` are its corresponding node
+    /// id and path. `root_item` is the topmost use tree in the hierarchy.
+    ///
+    /// If `use_tree` is a simple or glob import, it is dumped into the analysis data. Otherwise,
+    /// each child use tree is dumped recursively.
     fn process_use_tree(&mut self,
                          use_tree: &'l ast::UseTree,
                          id: NodeId,
-                         parent_item: &'l ast::Item,
+                         root_item: &'l ast::Item,
                          prefix: &ast::Path) {
         let path = &use_tree.prefix;
-        let access = access_from!(self.save_ctxt, parent_item);
+        let access = access_from!(self.save_ctxt, root_item);
+
+        // The parent def id of a given use tree is always the enclosing item.
+        let parent = self.save_ctxt.tcx.hir.opt_local_def_id(id)
+            .and_then(|id| self.save_ctxt.tcx.parent_def_id(id))
+            .map(::id_from_def_id);
 
         match use_tree.kind {
             ast::UseTreeKind::Simple(ident) => {
@@ -1276,6 +1289,7 @@ impl<'l, 'tcx: 'l, 'll, O: DumpOutput + 'll> DumpVisitor<'l, 'tcx, 'll, O> {
                         span,
                         name: ident.to_string(),
                         value: String::new(),
+                        parent,
                     });
                 }
                 self.write_sub_paths_truncated(&path);
@@ -1311,6 +1325,7 @@ impl<'l, 'tcx: 'l, 'll, O: DumpOutput + 'll> DumpVisitor<'l, 'tcx, 'll, O> {
                         span,
                         name: "*".to_owned(),
                         value: names.join(", "),
+                        parent,
                     });
                 }
                 self.write_sub_paths(&path);
@@ -1325,7 +1340,7 @@ impl<'l, 'tcx: 'l, 'll, O: DumpOutput + 'll> DumpVisitor<'l, 'tcx, 'll, O> {
                     span: path.span,
                 };
                 for &(ref tree, id) in nested_items {
-                    self.process_use_tree(tree, id, parent_item, &prefix);
+                    self.process_use_tree(tree, id, root_item, &prefix);
                 }
             }
         }
@@ -1389,6 +1404,9 @@ impl<'l, 'tcx: 'l, 'll, O: DumpOutput + 'll> Visitor<'l> for DumpVisitor<'l, 'tc
                 if !self.span.filter_generated(alias_span, item.span) {
                     let span =
                         self.span_from_span(alias_span.expect("No span found for extern crate"));
+                    let parent = self.save_ctxt.tcx.hir.opt_local_def_id(item.id)
+                        .and_then(|id| self.save_ctxt.tcx.parent_def_id(id))
+                        .map(::id_from_def_id);
                     self.dumper.import(
                         &Access {
                             public: false,
@@ -1400,6 +1418,7 @@ impl<'l, 'tcx: 'l, 'll, O: DumpOutput + 'll> Visitor<'l> for DumpVisitor<'l, 'tc
                             span,
                             name: item.ident.to_string(),
                             value: String::new(),
+                            parent,
                         },
                     );
                 }