Adding constexpr qualifier for cross product

glm/detail/func_geometric.inl

@@ -67,7 +67,7 @@ namespace detail
 	template<typename T, qualifier Q, bool Aligned>
 	struct compute_cross
 	{
-		GLM_FUNC_QUALIFIER static vec<3, T, Q> call(vec<3, T, Q> const& x, vec<3, T, Q> const& y)
+		GLM_FUNC_QUALIFIER GLM_CONSTEXPR static vec<3, T, Q> call(vec<3, T, Q> const& x, vec<3, T, Q> const& y)
 		{
 			GLM_STATIC_ASSERT(std::numeric_limits<T>::is_iec559, "'cross' accepts only floating-point inputs");
 
@@ -172,7 +172,7 @@ namespace detail
 
 	// cross
 	template<typename T, qualifier Q>
-	GLM_FUNC_QUALIFIER vec<3, T, Q> cross(vec<3, T, Q> const& x, vec<3, T, Q> const& y)
+	GLM_FUNC_QUALIFIER GLM_CONSTEXPR vec<3, T, Q> cross(vec<3, T, Q> const& x, vec<3, T, Q> const& y)
 	{
 		return detail::compute_cross<T, Q, detail::is_aligned<Q>::value>::call(x, y);
 	}

glm/geometric.hpp

@@ -56,7 +56,7 @@ namespace glm
 	/// @see <a href="http://www.opengl.org/sdk/docs/manglsl/xhtml/cross.xml">GLSL cross man page</a>
 	/// @see <a href="http://www.opengl.org/registry/doc/GLSLangSpec.4.20.8.pdf">GLSL 4.20.8 specification, section 8.5 Geometric Functions</a>
 	template<typename T, qualifier Q>
-	GLM_FUNC_DECL vec<3, T, Q> cross(vec<3, T, Q> const& x, vec<3, T, Q> const& y);
+	GLM_FUNC_DECL GLM_CONSTEXPR vec<3, T, Q> cross(vec<3, T, Q> const& x, vec<3, T, Q> const& y);
 
 	/// Returns a vector in the same direction as x but with length of 1.
 	/// According to issue 10 GLSL 1.10 specification, if length(x) == 0 then result is undefined and generate an error.