Restrict operator<< for SymEngine auxiliary classes.

diff --git a/include/deal.II/differentiation/sd/symengine_optimizer.h b/include/deal.II/differentiation/sd/symengine_optimizer.h
index 74a088c0fac6f6c05ecce50ffa6d25a16b14c02c..9da2b5543720863dbd9933846d621a22a696abdd 100644 (file)
--- a/include/deal.II/differentiation/sd/symengine_optimizer.h
+++ b/include/deal.II/differentiation/sd/symengine_optimizer.h
@@ -45,6 +45,7 @@
 #  include <boost/type_traits.hpp>
 
 #  include <algorithm>
+#  include <iosfwd>
 #  include <map>
 #  include <memory>
 #  include <type_traits>
@@ -114,9 +115,8 @@ namespace Differentiation
     /**
      * Output operator that outputs the selected optimizer type.
      */
-    template <typename StreamType>
-    inline StreamType &
-    operator<<(StreamType &s, OptimizerType o)
+    inline std::ostream &
+    operator<<(std::ostream &s, OptimizerType o)
     {
       if (o == OptimizerType::dictionary)
         s << "dictionary";
@@ -266,9 +266,8 @@ namespace Differentiation
      * Output operator that outputs optimization flags as a set of or'd
      * text values.
      */
-    template <typename StreamType>
-    inline StreamType &
-    operator<<(StreamType &s, OptimizationFlags o)
+    inline std::ostream &
+    operator<<(std::ostream &s, OptimizationFlags o)
     {
       s << " OptimizationFlags|";
       if (static_cast<unsigned int>(o & OptimizationFlags::optimize_cse))