Add support for trait associated items

Author: GuillaumeGomez

src/librustdoc/html/render/span_map.rs

@@ -231,6 +231,24 @@ impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
         self.handle_pat(p);
     }
 
+    fn visit_qpath(&mut self, qpath: &QPath<'tcx>, id: HirId, span: Span) {
+        match *qpath {
+            QPath::TypeRelative(qself, segment) => {
+                self.infer_id(segment.hir_id, Some(id), span);
+
+                rustc_ast::visit::try_visit!(self.visit_ty(qself));
+                self.visit_path_segment(segment);
+            }
+            QPath::Resolved(maybe_qself, path) => {
+                self.handle_path(path);
+
+                rustc_ast::visit::visit_opt!(self, visit_ty, maybe_qself);
+                self.visit_path(path, id)
+            }
+            _ => {}
+        }
+    }
+
     fn visit_mod(&mut self, m: &'tcx Mod<'tcx>, span: Span, id: HirId) {
         // To make the difference between "mod foo {}" and "mod foo;". In case we "import" another
         // file, we want to link to it. Otherwise no need to create a link.

tests/rustdoc/jump-to-def-assoc-items.rs

@@ -0,0 +1,15 @@
+//@ compile-flags: -Zunstable-options --generate-link-to-definition
+
+#![crate_name = "foo"]
+
+pub enum Ty {
+    Var,
+}
+
+//@ has 'src/foo/jump-to-def-assoc-items.rs.html'
+//@ has - '//a[@href="#6"]' 'Self::Var'
+impl Ty {
+    fn f() {
+        let _ = Self::Var;
+    }
+}