Fix a compilation issue with LLVMs libc++

Due to more restrictive include policy template<class T1, class T2> struct pair
is not already defined in std at this point. Unfortunately, a forward
declaration is invalid because it doesn't allow for instantiations:

  "error: implicit instantiation of undefined template"

Furthermore, ISO/IEC C++ 2011 Standard, section 17.6.4.2.1 prohibits such
manipulation of the namespace std.

git-svn-id: https://svn.dealii.org/trunk@30210 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/include/deal.II/grid/tria_accessor.h b/deal.II/include/deal.II/grid/tria_accessor.h
index e0524d229185cf8487dab551b2bb97c251ffa530..7ff6297f2cf46c040cc5a56280ec0345b2b86e62 100644 (file)
--- a/deal.II/include/deal.II/grid/tria_accessor.h
+++ b/deal.II/include/deal.II/grid/tria_accessor.h
@@ -26,12 +26,8 @@
 #include <deal.II/grid/tria_iterator_selector.h>
 #include <deal.II/grid/cell_id.h>
 
+#include <utility>
 
-namespace std
-{
-  template<class T1, class T2>
-  struct pair;
-}
 
 DEAL_II_NAMESPACE_OPEN