1 files changed, 15 insertions, 5 deletions
diff --git a/boost/math/tools/big_constant.hpp b/boost/math/tools/big_constant.hpp
index 45f13ceef9..119063164a 100644
--- a/boost/math/tools/big_constant.hpp
+++ b/boost/math/tools/big_constant.hpp
@@ -11,15 +11,17 @@
 #include <boost/lexical_cast.hpp>
 #include <boost/type_traits/is_convertible.hpp>
 
-namespace boost{ namespace math{ namespace tools{
+namespace boost{ namespace math{ 
+
+namespace tools{
 
 template <class T>
-inline T make_big_value(long double v, const char*, mpl::true_ const&, mpl::false_ const&)
+inline BOOST_CONSTEXPR_OR_CONST T make_big_value(long double v, const char*, mpl::true_ const&, mpl::false_ const&)
 {
    return static_cast<T>(v);
 }
 template <class T>
-inline T make_big_value(long double v, const char*, mpl::true_ const&, mpl::true_ const&)
+inline BOOST_CONSTEXPR_OR_CONST T make_big_value(long double v, const char*, mpl::true_ const&, mpl::true_ const&)
 {
    return static_cast<T>(v);
 }
@@ -29,7 +31,7 @@ inline T make_big_value(long double, const char* s, mpl::false_ const&, mpl::fal
    return boost::lexical_cast<T>(s);
 }
 template <class T>
-inline const char* make_big_value(long double, const char* s, mpl::false_ const&, mpl::true_ const&)
+inline BOOST_CONSTEXPR const char* make_big_value(long double, const char* s, mpl::false_ const&, mpl::true_ const&)
 {
    return s;
 }
@@ -38,7 +40,15 @@ inline const char* make_big_value(long double, const char* s, mpl::false_ const&
 // For constants which might fit in a long double (if it's big enough):
 //
 #define BOOST_MATH_BIG_CONSTANT(T, D, x)\
-   boost::math::tools::make_big_value<T>(BOOST_JOIN(x, L), BOOST_STRINGIZE(x), mpl::bool_<D <= std::numeric_limits<long double>::digits>(), boost::is_convertible<const char*, T>())
+   boost::math::tools::make_big_value<T>(\
+      BOOST_JOIN(x, L), \
+      BOOST_STRINGIZE(x), \
+      mpl::bool_< (is_convertible<long double, T>::value) && \
+         ((D <= std::numeric_limits<long double>::digits) \
+          || is_floating_point<T>::value \
+          || (std::numeric_limits<T>::is_specialized && \
+             (std::numeric_limits<T>::digits10 <= std::numeric_limits<long double>::digits10))) >(), \
+      boost::is_convertible<const char*, T>())
 //
 // For constants too huge for any conceivable long double (and which generate compiler errors if we try and declare them as such):
 //