diff --git a/sprout/pit/pit.hpp b/sprout/pit/pit.hpp
index 1f1eb599..2afb51f8 100644
--- a/sprout/pit/pit.hpp
+++ b/sprout/pit/pit.hpp
@@ -47,31 +47,31 @@ namespace sprout {
 		value_type elem;
 	public:
 		pit() = default;
-		void swap(pit& other)
+		SPROUT_CXX14_CONSTEXPR void swap(pit& other)
 		SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(sprout::swap(elem, other.elem)))
 		{
 			sprout::swap(elem, other.elem);
 		}
 		// iterators:
-		iterator begin() {
+		SPROUT_CXX14_CONSTEXPR iterator begin() {
 			return iterator(elem, enumerable_size);
 		}
 		SPROUT_CONSTEXPR const_iterator begin() const {
 			return const_iterator(elem, enumerable_size);
 		}
-		iterator end() SPROUT_NOEXCEPT {
+		SPROUT_CXX14_CONSTEXPR iterator end() SPROUT_NOEXCEPT {
 			return iterator(elem, 0);
 		}
 		SPROUT_CONSTEXPR const_iterator end() const SPROUT_NOEXCEPT {
 			return const_iterator(elem, 0);
 		}
-		reverse_iterator rbegin() SPROUT_NOEXCEPT {
+		SPROUT_CXX14_CONSTEXPR reverse_iterator rbegin() SPROUT_NOEXCEPT {
 			return reverse_iterator(end());
 		}
 		SPROUT_CONSTEXPR const_reverse_iterator rbegin() const SPROUT_NOEXCEPT {
 			return const_reverse_iterator(end());
 		}
-		reverse_iterator rend() SPROUT_NOEXCEPT {
+		SPROUT_CXX14_CONSTEXPR reverse_iterator rend() SPROUT_NOEXCEPT {
 			return reverse_iterator(begin());
 		}
 		SPROUT_CONSTEXPR const_reverse_iterator rend() const SPROUT_NOEXCEPT {
@@ -100,13 +100,13 @@ namespace sprout {
 			return enumerable_size == 0;
 		}
 		// element access:
-		reference operator[](size_type) {
+		SPROUT_CXX14_CONSTEXPR reference operator[](size_type) {
 			return elem;
 		}
 		SPROUT_CONSTEXPR const_reference operator[](size_type) const {
 			return elem;
 		}
-		reference at(size_type i) {
+		SPROUT_CXX14_CONSTEXPR reference at(size_type i) {
 			return i < size()
 				? elem
 				: (throw std::out_of_range("pit<>: index out of range"), elem)
@@ -118,20 +118,20 @@ namespace sprout {
 				: (throw std::out_of_range("pit<>: index out of range"), elem)
 				;
 		}
-		reference front() {
+		SPROUT_CXX14_CONSTEXPR reference front() {
 			return elem;
 		}
 		SPROUT_CONSTEXPR const_reference front() const {
 			return elem;
 		}
-		reference back() {
+		SPROUT_CXX14_CONSTEXPR reference back() {
 			return elem;
 		}
 		SPROUT_CONSTEXPR const_reference back() const {
 			return elem;
 		}
 		// others:
-		void rangecheck(size_type i) const {
+		SPROUT_CXX14_CONSTEXPR void rangecheck(size_type i) const {
 			if (i >= size()) {
 				throw std::out_of_range("pit<>: index out of range");
 			}
@@ -144,7 +144,7 @@ namespace sprout {
 	// swap
 	//
 	template<typename Container>
-	inline void
+	inline SPROUT_CXX14_CONSTEXPR void
 	swap(sprout::pit<Container>& lhs, sprout::pit<Container>& rhs)
 	SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(lhs.swap(rhs)))
 	{
diff --git a/sprout/random/random_result.hpp b/sprout/random/random_result.hpp
index b6a17042..2ca8701a 100644
--- a/sprout/random/random_result.hpp
+++ b/sprout/random/random_result.hpp
@@ -84,31 +84,31 @@ namespace sprout {
 			SPROUT_CONSTEXPR random_result operator()() const {
 				return distribution_(engine_);
 			}
-			result_type& result() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR result_type& result() SPROUT_NOEXCEPT {
 				return result_;
 			}
 			SPROUT_CONSTEXPR result_type const& result() const SPROUT_NOEXCEPT {
 				return result_;
 			}
-			result_type& generated_value() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR result_type& generated_value() SPROUT_NOEXCEPT {
 				return result_;
 			}
 			SPROUT_CONSTEXPR result_type const& generated_value() const SPROUT_NOEXCEPT {
 				return result_;
 			}
-			engine_type& engine() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR engine_type& engine() SPROUT_NOEXCEPT {
 				return engine_;
 			}
 			SPROUT_CONSTEXPR engine_type const& engine() const SPROUT_NOEXCEPT {
 				return engine_;
 			}
-			random_result& next_generator() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR random_result& next_generator() SPROUT_NOEXCEPT {
 				return *this;
 			}
 			SPROUT_CONSTEXPR random_result const& next_generator() const SPROUT_NOEXCEPT {
 				return *this;
 			}
-			distribution_type& distribution() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR distribution_type& distribution() SPROUT_NOEXCEPT {
 				return distribution_;
 			}
 			SPROUT_CONSTEXPR distribution_type const& distribution() const SPROUT_NOEXCEPT {
@@ -126,7 +126,7 @@ namespace sprout {
 			SPROUT_CONSTEXPR result_type max() const SPROUT_NOEXCEPT {
 				return distribution_.max();
 			}
-			void swap(random_result& other)
+			SPROUT_CXX14_CONSTEXPR void swap(random_result& other)
 			SPROUT_NOEXCEPT_EXPR(
 				SPROUT_NOEXCEPT_EXPR(sprout::swap(result_, other.result_))
 				&& SPROUT_NOEXCEPT_EXPR(sprout::swap(engine_, other.engine_))
@@ -152,12 +152,12 @@ namespace sprout {
 			SPROUT_CONSTEXPR pointer operator->() const SPROUT_NOEXCEPT {
 				return &result_;
 			}
-			random_result& operator++() {
+			SPROUT_CXX14_CONSTEXPR random_result& operator++() {
 				random_result temp((*this)());
 				temp.swap(*this);
 				return *this;
 			}
-			random_result operator++(int) {
+			SPROUT_CXX14_CONSTEXPR random_result operator++(int) {
 				random_result result(*this);
 				++*this;
 				return result;
@@ -215,25 +215,25 @@ namespace sprout {
 			SPROUT_CONSTEXPR random_result operator()() const {
 				return engine_();
 			}
-			result_type& result() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR result_type& result() SPROUT_NOEXCEPT {
 				return result_;
 			}
 			SPROUT_CONSTEXPR result_type const& result() const SPROUT_NOEXCEPT {
 				return result_;
 			}
-			result_type& generated_value() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR result_type& generated_value() SPROUT_NOEXCEPT {
 				return result_;
 			}
 			SPROUT_CONSTEXPR result_type const& generated_value() const SPROUT_NOEXCEPT {
 				return result_;
 			}
-			engine_type& engine() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR engine_type& engine() SPROUT_NOEXCEPT {
 				return engine_;
 			}
 			SPROUT_CONSTEXPR engine_type const& engine() const SPROUT_NOEXCEPT {
 				return engine_;
 			}
-			random_result& next_generator() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR random_result& next_generator() SPROUT_NOEXCEPT {
 				return *this;
 			}
 			SPROUT_CONSTEXPR random_result const& next_generator() const SPROUT_NOEXCEPT {
@@ -274,12 +274,12 @@ namespace sprout {
 			SPROUT_CONSTEXPR pointer operator->() const SPROUT_NOEXCEPT {
 				return &result_;
 			}
-			random_result& operator++() {
+			SPROUT_CXX14_CONSTEXPR random_result& operator++() {
 				random_result temp((*this)());
 				temp.swap(*this);
 				return *this;
 			}
-			random_result operator++(int) {
+			SPROUT_CXX14_CONSTEXPR random_result operator++(int) {
 				random_result result(*this);
 				random_result temp((*this)());
 				temp.swap(*this);
@@ -291,7 +291,7 @@ namespace sprout {
 		// swap
 		//
 		template<typename Engine, typename Distribution>
-		inline void
+		inline SPROUT_CXX14_CONSTEXPR void
 		swap(sprout::random::random_result<Engine, Distribution>& lhs, sprout::random::random_result<Engine, Distribution>& rhs)
 		SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(lhs.swap(rhs)))
 		{
diff --git a/sprout/rational/rational.hpp b/sprout/rational/rational.hpp
index 2d835cab..3792b1c1 100644
--- a/sprout/rational/rational.hpp
+++ b/sprout/rational/rational.hpp
@@ -96,11 +96,15 @@ namespace sprout {
 			: base_type(n, d, normalize_g(n, d))
 		{}
 
-		rational& operator=(rational const&) = default;
-		rational& operator=(param_type n) SPROUT_NOEXCEPT {
+		SPROUT_CXX14_CONSTEXPR rational& operator=(rational const& rhs) SPROUT_NOEXCEPT {
+			rational temp(rhs);
+			sprout::swap(temp, *this);
+			return *this;
+		}
+		SPROUT_CXX14_CONSTEXPR rational& operator=(param_type n) SPROUT_NOEXCEPT {
 			return assign(n, 1);
 		}
-		rational& assign(param_type n, param_type d) {
+		SPROUT_CXX14_CONSTEXPR rational& assign(param_type n, param_type d) {
 			rational temp(n, d);
 			sprout::swap(temp, *this);
 			return *this;
@@ -113,7 +117,7 @@ namespace sprout {
 			return den_;
 		}
 
-		rational& operator+=(rational const& rhs) {
+		SPROUT_CXX14_CONSTEXPR rational& operator+=(rational const& rhs) {
 			IntType g = sprout::gcd(den_, rhs.den_);
 			den_ /= g;
 			num_ = num_ * (rhs.den_ / g) + rhs.num_ * den_;
@@ -122,7 +126,7 @@ namespace sprout {
 			den_ *= rhs.den_ / g;
 			return *this;
 		}
-		rational& operator-=(rational const& rhs) {
+		SPROUT_CXX14_CONSTEXPR rational& operator-=(rational const& rhs) {
 			IntType g = sprout::gcd(den_, rhs.den_);
 			den_ /= g;
 			num_ = num_ * (rhs.den_ / g) - rhs.num_ * den_;
@@ -131,14 +135,14 @@ namespace sprout {
 			den_ *= rhs.den_ / g;
 			return *this;
 		}
-		rational& operator*=(rational const& rhs) {
+		SPROUT_CXX14_CONSTEXPR rational& operator*=(rational const& rhs) {
 			IntType gcd1 = sprout::gcd(num_, rhs.den_);
 			IntType gcd2 = sprout::gcd(rhs.num_, den_);
 			num_ =(num_ / gcd1) * (rhs.num_ / gcd2);
 			den_ =(den_ / gcd2) * (rhs.den_ / gcd1);
 			return *this;
 		}
-		rational& operator/=(rational const& rhs) {
+		SPROUT_CXX14_CONSTEXPR rational& operator/=(rational const& rhs) {
 			if (rhs.num_ == IntType(0)) {
 				throw sprout::bad_rational();
 			}
@@ -155,33 +159,33 @@ namespace sprout {
 			}
 			return *this;
 		}
-		rational& operator+=(param_type rhs) {
+		SPROUT_CXX14_CONSTEXPR rational& operator+=(param_type rhs) {
 			return *this += rational(rhs);
 		}
-		rational& operator-=(param_type rhs) {
+		SPROUT_CXX14_CONSTEXPR rational& operator-=(param_type rhs) {
 			return *this -= rational(rhs);
 		}
-		rational& operator*=(param_type rhs) {
+		SPROUT_CXX14_CONSTEXPR rational& operator*=(param_type rhs) {
 			return *this *= rational(rhs);
 		}
-		rational& operator/=(param_type rhs) {
+		SPROUT_CXX14_CONSTEXPR rational& operator/=(param_type rhs) {
 			return *this /= rational(rhs);
 		}
 
-		rational& operator++() SPROUT_NOEXCEPT {
+		SPROUT_CXX14_CONSTEXPR rational& operator++() SPROUT_NOEXCEPT {
 			num_ += den_;
 			return *this;
 		}
-		rational& operator--() SPROUT_NOEXCEPT {
+		SPROUT_CXX14_CONSTEXPR rational& operator--() SPROUT_NOEXCEPT {
 			num_ -= den_;
 			return *this;
 		}
-		rational operator++(int) SPROUT_NOEXCEPT {
+		SPROUT_CXX14_CONSTEXPR rational operator++(int) SPROUT_NOEXCEPT {
 			rational result(*this);
 			++*this;
 			return result;
 		}
-		rational operator--(int) SPROUT_NOEXCEPT {
+		SPROUT_CXX14_CONSTEXPR rational operator--(int) SPROUT_NOEXCEPT {
 			rational result(*this);
 			--*this;
 			return result;
diff --git a/sprout/sub_array/sub_array.hpp b/sprout/sub_array/sub_array.hpp
index 5d52ac5f..ac998241 100644
--- a/sprout/sub_array/sub_array.hpp
+++ b/sprout/sub_array/sub_array.hpp
@@ -243,11 +243,11 @@ namespace sprout {
 				)
 		{}
 
-		void fill(const_reference value) {
+		SPROUT_CXX14_CONSTEXPR void fill(const_reference value) {
 			std::fill_n(begin(), size(), value);
 		}
 		template<typename Container2>
-		void swap(sub_array<Container2>& other)
+		SPROUT_CXX14_CONSTEXPR void swap(sub_array<Container2>& other)
 		SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(sprout::swap(other.array_, array_)))
 		{
 			sprout::swap(other.array_, array_);
@@ -255,13 +255,13 @@ namespace sprout {
 			sprout::swap(other.to_last_, to_last_);
 		}
 		// iterators:
-		iterator begin() {
+		SPROUT_CXX14_CONSTEXPR iterator begin() {
 			return sprout::next(sprout::begin(get_array()), to_first_);
 		}
 		SPROUT_CONSTEXPR const_iterator begin() const {
 			return sprout::next(sprout::begin(get_array()), to_first_);
 		}
-		iterator end() {
+		SPROUT_CXX14_CONSTEXPR iterator end() {
 			return sprout::next(sprout::begin(get_array()), to_last_);
 		}
 		SPROUT_CONSTEXPR const_iterator end() const {
@@ -284,13 +284,13 @@ namespace sprout {
 			return to_first_ == to_last_;
 		}
 		// element access:
-		reference operator[](size_type i) {
+		SPROUT_CXX14_CONSTEXPR reference operator[](size_type i) {
 			return *sprout::next(sprout::begin(get_array()), to_first_ + i);
 		}
 		SPROUT_CONSTEXPR const_reference operator[](size_type i) const {
 			return *sprout::next(sprout::begin(get_array()), to_first_ + i);
 		}
-		reference at(size_type i) {
+		SPROUT_CXX14_CONSTEXPR reference at(size_type i) {
 			return i < size() ? *sprout::next(sprout::begin(get_array()), to_first_ + i)
 				: (throw std::out_of_range("sub_array<>: index out of range"), *sprout::next(sprout::begin(get_array()), to_first_ + i))
 				;
@@ -300,20 +300,20 @@ namespace sprout {
 				: (throw std::out_of_range("sub_array<>: index out of range"), *sprout::next(sprout::begin(get_array()), to_first_ + i))
 				;
 		}
-		reference front() {
+		SPROUT_CXX14_CONSTEXPR reference front() {
 			return *sprout::next(sprout::begin(get_array()), to_first_);
 		}
 		SPROUT_CONSTEXPR const_reference front() const {
 			return *sprout::next(sprout::begin(get_array()), to_first_);
 		}
-		reference back() {
+		SPROUT_CXX14_CONSTEXPR reference back() {
 			return *sprout::next(sprout::begin(get_array()), to_last_ - 1);
 		}
 		SPROUT_CONSTEXPR const_reference back() const {
 			return *sprout::next(sprout::begin(get_array()), to_last_ - 1);
 		}
 
-		pointer data() {
+		SPROUT_CXX14_CONSTEXPR pointer data() {
 			return get_array().data() + to_first_;
 		}
 		SPROUT_CONSTEXPR const_pointer data() const {
@@ -321,32 +321,35 @@ namespace sprout {
 		}
 		// others:
 		template<typename Container2>
-		sub_array& operator=(sub_array<Container2> const& rhs) {
+		SPROUT_CXX14_CONSTEXPR sub_array& operator=(sub_array<Container2> const& rhs) {
 			array_ = rhs.array_;
 			to_first_ = rhs.to_first_;
 			to_last_ = rhs.to_last_;
 			return *this;
 		}
 		template<typename Container2>
-		sub_array& operator=(sub_array<Container2>&& rhs) {
+		SPROUT_CXX14_CONSTEXPR sub_array& operator=(sub_array<Container2>&& rhs) {
 			array_ = std::move(rhs.array_);
 			to_first_ = std::move(rhs.to_first_);
 			to_last_ = std::move(rhs.to_last_);
 			return *this;
 		}
-		pointer c_array() {
+		SPROUT_CXX14_CONSTEXPR pointer c_array() {
 			return data();
 		}
-		void assign(const_reference value) {
+		SPROUT_CONSTEXPR const_pointer c_array() const {
+			return data();
+		}
+		SPROUT_CXX14_CONSTEXPR void assign(const_reference value) {
 			fill(value);
 		}
-		void rangecheck(size_type i) const {
+		SPROUT_CXX14_CONSTEXPR void rangecheck(size_type i) const {
 			if (i >= size()) {
 				throw std::out_of_range("sub_array<>: index out of range");
 			}
 		}
 
-		param_type get_internal() {
+		SPROUT_CXX14_CONSTEXPR param_type get_internal() {
 			return impl_type::template to_param<Container>(array_);
 		}
 		SPROUT_CONSTEXPR const_param_type get_internal() const {
@@ -378,7 +381,7 @@ namespace sprout {
 	// swap
 	//
 	template<typename Container>
-	inline void
+	inline SPROUT_CXX14_CONSTEXPR void
 	swap(sprout::sub_array<Container>& lhs, sprout::sub_array<Container>& rhs)
 	SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(lhs.swap(rhs)))
 	{
diff --git a/sprout/uuid/uuid.hpp b/sprout/uuid/uuid.hpp
index 2350992c..399db609 100644
--- a/sprout/uuid/uuid.hpp
+++ b/sprout/uuid/uuid.hpp
@@ -81,47 +81,47 @@ namespace sprout {
 		public:
 			value_type elems[static_size];
 		public:
-			void fill(const_reference value) {
+			SPROUT_CXX14_CONSTEXPR void fill(const_reference value) {
 				std::fill_n(begin(), size(), value);
 			}
-			void swap(uuid& other) SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR void swap(uuid& other) SPROUT_NOEXCEPT {
 				std::swap_ranges(other.begin(), other.end(), begin());
 			}
 			// iterators:
 #if SPROUT_USE_INDEX_ITERATOR_IMPLEMENTATION
-			iterator begin() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR iterator begin() SPROUT_NOEXCEPT {
 				return iterator(*this, 0);
 			}
 			SPROUT_CONSTEXPR const_iterator begin() const SPROUT_NOEXCEPT {
 				return const_iterator(*this, 0);
 			}
-			iterator end() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR iterator end() SPROUT_NOEXCEPT {
 				return iterator(*this, size());
 			}
 			SPROUT_CONSTEXPR const_iterator end() const SPROUT_NOEXCEPT {
 				return const_iterator(*this, size());
 			}
 #else
-			iterator begin() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR iterator begin() SPROUT_NOEXCEPT {
 				return &elems[0];
 			}
 			SPROUT_CONSTEXPR const_iterator begin() const SPROUT_NOEXCEPT {
 				return &elems[0];
 			}
-			iterator end() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR iterator end() SPROUT_NOEXCEPT {
 				return &elems[0] + size();
 			}
 			SPROUT_CONSTEXPR const_iterator end() const SPROUT_NOEXCEPT {
 				return &elems[0] + size();
 			}
 #endif
-			reverse_iterator rbegin() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR reverse_iterator rbegin() SPROUT_NOEXCEPT {
 				return reverse_iterator(end());
 			}
 			SPROUT_CONSTEXPR const_reverse_iterator rbegin() const SPROUT_NOEXCEPT {
 				return const_reverse_iterator(end());
 			}
-			reverse_iterator rend() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR reverse_iterator rend() SPROUT_NOEXCEPT {
 				return reverse_iterator(begin());
 			}
 			SPROUT_CONSTEXPR const_reverse_iterator rend() const SPROUT_NOEXCEPT {
@@ -159,13 +159,13 @@ namespace sprout {
 				return size() == 0;
 			}
 			// element access:
-			reference operator[](size_type i) {
+			SPROUT_CXX14_CONSTEXPR reference operator[](size_type i) {
 				return elems[i];
 			}
 			SPROUT_CONSTEXPR const_reference operator[](size_type i) const {
 				return elems[i];
 			}
-			reference at(size_type i) {
+			SPROUT_CXX14_CONSTEXPR reference at(size_type i) {
 				return i < size()
 					? elems[i]
 					: (throw std::out_of_range("uuid: index out of range"), elems[i])
@@ -177,20 +177,20 @@ namespace sprout {
 					: (throw std::out_of_range("uuid: index out of range"), elems[i])
 					;
 			}
-			reference front() {
+			SPROUT_CXX14_CONSTEXPR reference front() {
 				return elems[0];
 			}
 			SPROUT_CONSTEXPR const_reference front() const {
 				return elems[0];
 			}
-			reference back() {
+			SPROUT_CXX14_CONSTEXPR reference back() {
 				return elems[size() - 1];
 			}
 			SPROUT_CONSTEXPR const_reference back() const {
 				return elems[size() - 1];
 			}
 
-			pointer data() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR pointer data() SPROUT_NOEXCEPT {
 				return &elems[0];
 			}
 			SPROUT_CONSTEXPR const_pointer data() const SPROUT_NOEXCEPT {
@@ -198,13 +198,16 @@ namespace sprout {
 			}
 
 			// others:
-			pointer c_array() SPROUT_NOEXCEPT {
+			SPROUT_CXX14_CONSTEXPR pointer c_array() SPROUT_NOEXCEPT {
 				return &elems[0];
 			}
-			void assign(const_reference value) {
+			SPROUT_CONSTEXPR const_pointer c_array() SPROUT_NOEXCEPT {
+				return &elems[0];
+			}
+			SPROUT_CXX14_CONSTEXPR void assign(const_reference value) {
 				fill(value);
 			}
-			void rangecheck(size_type i) const {
+			SPROUT_CXX14_CONSTEXPR void rangecheck(size_type i) const {
 				if (i >= size()) {
 					throw std::out_of_range("uuid: index out of range");
 				}
@@ -267,7 +270,7 @@ namespace sprout {
 		//
 		// swap
 		//
-		inline void
+		inline SPROUT_CXX14_CONSTEXPR void
 		swap(sprout::uuids::uuid& lhs, sprout::uuids::uuid& rhs)
 		SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(lhs.swap(rhs)))
 		{
diff --git a/sprout/variant/variant.hpp b/sprout/variant/variant.hpp
index 729c7c21..d310f800 100644
--- a/sprout/variant/variant.hpp
+++ b/sprout/variant/variant.hpp
@@ -63,7 +63,7 @@ namespace sprout {
 				static_assert(Index::value < sizeof...(Types), "variant<>: invalid operand");
 			}
 		public:
-			void swap(variant_impl& other)
+			SPROUT_CXX14_CONSTEXPR void swap(variant_impl& other)
 			SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(sprout::swap(tuple_, other.tuple_)))
 			{
 				sprout::swap(tuple_, other.tuple_);
@@ -238,23 +238,23 @@ namespace sprout {
 				)
 		{}
 		// modifiers
-		void swap(variant& other)
+		SPROUT_CXX14_CONSTEXPR void swap(variant& other)
 		SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(std::declval<impl_type&>().swap(other)))
 		{
 			impl_type::swap(other);
 		}
-		variant& operator=(variant const& rhs) {
+		SPROUT_CXX14_CONSTEXPR variant& operator=(variant const& rhs) {
 			static_cast<impl_type&>(*this) = rhs;
 			return *this;
 		}
-		variant& operator=(variant&& rhs)
+		SPROUT_CXX14_CONSTEXPR variant& operator=(variant&& rhs)
 		SPROUT_NOEXCEPT_EXPR(std::is_nothrow_move_assignable<impl_type>::value)
 		{
 			static_cast<impl_type&>(*this) = sprout::move(rhs);
 			return *this;
 		}
 		template<typename T>
-		variant& operator=(T&& rhs) {
+		SPROUT_CXX14_CONSTEXPR variant& operator=(T&& rhs) {
 			static_cast<impl_type&>(*this) = variant(sprout::forward<T>(rhs));
 			return *this;
 		}
@@ -302,7 +302,7 @@ namespace sprout {
 				;
 		}
 		template<std::size_t I>
-		typename std::enable_if<
+		SPROUT_CXX14_CONSTEXPR typename std::enable_if<
 			I != sizeof...(Types),
 			typename sprout::tuples::tuple_element<I, tuple_type>::type&
 		>::type get_at() {
@@ -318,7 +318,7 @@ namespace sprout {
 			return get_at<sprout::types::find_index<tuple_type, U>::value>();
 		}
 		template<typename U>
-		typename std::enable_if<
+		SPROUT_CXX14_CONSTEXPR typename std::enable_if<
 			sprout::types::find_index<tuple_type, U>::value != sizeof...(Types),
 			U&
 		>::type get() {
@@ -334,7 +334,7 @@ namespace sprout {
 				;
 		}
 		template<typename Visitor>
-		typename visitor_result<typename std::remove_reference<Visitor>::type, variant>::type
+		SPROUT_CXX14_CONSTEXPR typename visitor_result<typename std::remove_reference<Visitor>::type, variant>::type
 		apply_visitor(Visitor&& visitor) {
 			typedef typename visitor_result<typename std::remove_reference<Visitor>::type, variant>::type result_type;
 			return SPROUT_ASSERT(0 <= which_ && sprout::math::less(which_, sizeof...(Types))),
@@ -347,7 +347,7 @@ namespace sprout {
 	// swap
 	//
 	template<typename... Types>
-	inline void
+	inline SPROUT_CXX14_CONSTEXPR void
 	swap(sprout::variant<Types...>& lhs, sprout::variant<Types...>& rhs)
 	SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(lhs.swap(rhs)))
 	{