From: Jean-Paul Pelteret <jppelteret@gmail.com>
Date: Fri, 8 Jan 2016 23:26:28 +0000 (+0100)
Subject: Tensor::operator<< for dim==0 now accesses values by reference.
X-Git-Tag: v8.4.0-rc2~104^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F2047%2Fhead;p=dealii.git

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.
---

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;
 }