From befe29adf075ed4a29235662335571a26c5e909a Mon Sep 17 00:00:00 2001
From: bolero-MURAKAMI <bolero.murakami@gmail.com>
Date: Mon, 6 Apr 2015 00:21:34 +0900
Subject: [PATCH] fix CXX14_CONSTEXPR config

---
 sprout/config/compiler/gcc.hpp     | 9 +++++++--
 sprout/random/mersenne_twister.hpp | 8 ++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/sprout/config/compiler/gcc.hpp b/sprout/config/compiler/gcc.hpp
index ab7e01a5..46f9b723 100644
--- a/sprout/config/compiler/gcc.hpp
+++ b/sprout/config/compiler/gcc.hpp
@@ -60,7 +60,12 @@
 #	define SPROUT_HAS_CONSTEXPR_BIT_OPERATION
 #endif
 
-#define SPROUT_NO_CXX14_CONSTEXPR
-#define SPROUT_NO_CXX14_VARIABLE_TEMPLATES
+#if !defined(__cpp_constexpr) || (__cpp_constexpr < 201304)
+#  define SPROUT_NO_CXX14_CONSTEXPR
+#endif
+
+#if !defined(__cpp_variable_templates) || (__cpp_variable_templates < 201304)
+#  define SPROUT_NO_CXX14_VARIABLE_TEMPLATES
+#endif
 
 #endif	// #ifndef SPROUT_CONFIG_COMPILER_GCC_HPP
diff --git a/sprout/random/mersenne_twister.hpp b/sprout/random/mersenne_twister.hpp
index b0d714aa..321f94d2 100644
--- a/sprout/random/mersenne_twister.hpp
+++ b/sprout/random/mersenne_twister.hpp
@@ -464,12 +464,20 @@ namespace sprout {
 				z ^= (z >> l);
 				return z;
 			}
+#ifndef SPROUT_CONFIG_DISABLE_CXX14_CONSTEXPR
+			SPROUT_CXX14_CONSTEXPR sprout::random::random_result<mersenne_twister_engine> const operator()() const {
+				mersenne_twister_engine eng(*this);
+				result_type value = eng();
+				return sprout::random::random_result<mersenne_twister_engine>(value, eng);
+			}
+#else	// #ifndef SPROUT_CONFIG_DISABLE_CXX14_CONSTEXPR
 			SPROUT_CONSTEXPR sprout::random::random_result<mersenne_twister_engine> const operator()() const {
 				return i_ == n
 					? twist().generate()
 					: generate()
 					;
 			}
+#endif	// #ifndef SPROUT_CONFIG_DISABLE_CXX14_CONSTEXPR
 #ifndef SPROUT_CONFIG_DISABLE_CXX14_CONSTEXPR
 			friend SPROUT_CXX14_CONSTEXPR bool operator==(mersenne_twister_engine const& lhs, mersenne_twister_engine const& rhs) SPROUT_NOEXCEPT {
 				return lhs.i_ < rhs.i_