Make verbose query description more useful.

Author: cjgillot

compiler/rustc_query_impl/src/plumbing.rs

@@ -309,7 +309,7 @@ pub(crate) fn create_query_frame<
         ty::print::with_forced_impl_filename_line!(do_describe(tcx.tcx, key))
     );
     let description =
-        if tcx.sess.verbose() { format!("{} [{}]", description, name) } else { description };
+        if tcx.sess.verbose() { format!("{} [{:?}]", description, name) } else { description };
     let span = if kind == dep_graph::DepKind::def_span {
         // The `def_span` query is used to calculate `default_span`,
         // so exit to avoid infinite recursion.