From 0992a8e18968600c6b22de601bc37caadd64e7f2 Mon Sep 17 00:00:00 2001
From: Jean-Paul Pelteret <jppelteret@gmail.com>
Date: Sat, 9 Jan 2016 00:26:28 +0100
Subject: [PATCH] Tensor::operator<< for dim==0 now accesses values by
 reference.

This is done instead of making a copy, and is useful when non-trivial
number types (e.g. auto-differentiable) are stored.
---
 doc/news/changes.h            | 4 +++-
 include/deal.II/base/tensor.h | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/doc/news/changes.h b/doc/news/changes.h
index 372805040d..7e93d38360 100644
--- a/doc/news/changes.h
+++ b/doc/news/changes.h
@@ -199,7 +199,9 @@ inconvenience this causes.
 <h3>General</h3>
 <ol>
   <li> Fixed: Tensor::operator[] that takes TableIndices as a parameter no
-  longer returns by value, but rather by reference.
+  longer returns by value, but rather by reference. Tensor::operator<< for
+  dim==0 now accesses values by reference instead of making a copy. This is
+  useful when non-trivial number types are stored.
   <br>
   (Jean-Paul Pelteret, 2016/01/08)
   </li>
diff --git a/include/deal.II/base/tensor.h b/include/deal.II/base/tensor.h
index 7aa7c52fc5..3a240f5d53 100644
--- a/include/deal.II/base/tensor.h
+++ b/include/deal.II/base/tensor.h
@@ -1192,7 +1192,7 @@ template <int dim, typename Number>
 inline
 std::ostream &operator << (std::ostream &out, const Tensor<0,dim,Number> &p)
 {
-  out << static_cast<Number>(p);
+  out << static_cast<const Number &>(p);
   return out;
 }
 
-- 
2.39.5