Retreat ! go back to C++11 only code

This reverts commit b42de850314e7d76f873ddc7d64c5f7d2a30eb00.

1 files changed, 10 insertions, 7 deletions

diff --git a/src/flags.hh b/src/flags.hh
index f3562d95..2b68751b 100644
--- a/src/flags.hh
+++ b/src/flags.hh
@@ -10,18 +10,21 @@ template<typename Flags>
 struct WithBitOps : std::false_type {};
 
 template<typename Flags>
-using EnableIfWithBitOps = std::enable_if_t<WithBitOps<Flags>::value>;
+using UnderlyingType = typename std::underlying_type<Flags>::type;
+
+template<typename Flags>
+using EnableIfWithBitOps = typename std::enable_if<WithBitOps<Flags>::value>::type;
 
 template<typename Flags, typename = EnableIfWithBitOps<Flags>>
 constexpr Flags operator|(Flags lhs, Flags rhs)
 {
-    return (Flags)((std::underlying_type_t<Flags>) lhs | (std::underlying_type_t<Flags>) rhs);
+    return (Flags)((UnderlyingType<Flags>) lhs | (UnderlyingType<Flags>) rhs);
 }
 
 template<typename Flags, typename = EnableIfWithBitOps<Flags>>
 Flags& operator|=(Flags& lhs, Flags rhs)
 {
-    (std::underlying_type_t<Flags>&) lhs |= (std::underlying_type_t<Flags>) rhs;
+    (UnderlyingType<Flags>&) lhs |= (UnderlyingType<Flags>) rhs;
     return lhs;
 }
 
@@ -29,27 +32,27 @@ template<typename Flags>
 struct TestableFlags
 {
     Flags value;
-    constexpr operator bool() const { return (std::underlying_type_t<Flags>)value; }
+    constexpr operator bool() const { return (UnderlyingType<Flags>)value; }
     constexpr operator Flags() const { return value; }
 };
 
 template<typename Flags, typename = EnableIfWithBitOps<Flags>>
 constexpr TestableFlags<Flags> operator&(Flags lhs, Flags rhs)
 {
-    return { (Flags)((std::underlying_type_t<Flags>) lhs & (std::underlying_type_t<Flags>) rhs) };
+    return { (Flags)((UnderlyingType<Flags>) lhs & (UnderlyingType<Flags>) rhs) };
 }
 
 template<typename Flags, typename = EnableIfWithBitOps<Flags>>
 Flags& operator&=(Flags& lhs, Flags rhs)
 {
-    (std::underlying_type_t<Flags>&) lhs &= (std::underlying_type_t<Flags>) rhs;
+    (UnderlyingType<Flags>&) lhs &= (UnderlyingType<Flags>) rhs;
     return lhs;
 }
 
 template<typename Flags, typename = EnableIfWithBitOps<Flags>>
 constexpr Flags operator~(Flags lhs)
 {
-    return (Flags)(~(std::underlying_type_t<Flags>)lhs);
+    return (Flags)(~(UnderlyingType<Flags>)lhs);
 }
 
 }