Work around GCC 4.x constexpr failure in operator[]

Author: pdimov

include/boost/array.hpp

@@ -31,7 +31,8 @@
 #ifndef BOOST_ARRAY_HPP
 #define BOOST_ARRAY_HPP
 
-#include <boost/detail/workaround.hpp>
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>
 
 #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
 # pragma warning(push)
@@ -50,9 +51,6 @@
 #include <boost/throw_exception.hpp>
 #include <algorithm>
 
-// FIXES for broken compilers
-#include <boost/config.hpp>
-
 
 namespace boost {
 
@@ -117,7 +115,10 @@ namespace boost {
             return BOOST_ASSERT_MSG( i < N, "out of range" ), elems[i];
         }
 
-        BOOST_CONSTEXPR const_reference operator[](size_type i) const
+#if !BOOST_WORKAROUND(BOOST_GCC, < 50000)
+        BOOST_CONSTEXPR
+#endif
+        const_reference operator[](size_type i) const
         {
             return BOOST_ASSERT_MSG( i < N, "out of range" ), elems[i];
         }