fixed defaulted moves on older compilers

Author: akrzemi1

doc/1A_on_performance.qbk

@@ -19,7 +19,7 @@ Lifetime of the `T` inside `_storage` is manually controlled with placement-`new
     T _storage;
   };
 
-We call it a ['direct] storage. This makes `optional<T>` a trivially-copyable type for scalar `T`s. This only works for compilers that support defaulted functions. On compilers without defaulted functions we still use the direct storage, but `optional<T>` is no longer recognized as trivially-copyable. Apart from scalar types, we leave the programmer a way of customizing her type, so that it is reconized by `optional` as candidate for optimized storage, by specializing type trait `boost::opitonal_config::optional_uses_direct_storage_for`:
+We call it a ['direct] storage. This makes `optional<T>` a trivially-copyable type for scalar `T`s. This only works for compilers that support defaulted functions (including defaulted move assignment and constructor). On compilers without defaulted functions we still use the direct storage, but `optional<T>` is no longer recognized as trivially-copyable. Apart from scalar types, we leave the programmer a way of customizing her type, so that it is reconized by `optional` as candidate for optimized storage, by specializing type trait `boost::opitonal_config::optional_uses_direct_storage_for`:
 
   struct X // not trivial
   {

include/boost/optional/detail/optional_config.hpp

@@ -114,14 +114,16 @@
 #endif
 
 
-// Detection of correctly implemented defaulted functions
+// Detect suport for defaulting move operations
+// (some older compilers implement rvalue references,
+// defaulted funcitons but move operations are not special members and cannot be defaulted)
 
 #ifdef BOOST_NO_CXX11_DEFAULTED_FUNCTIONS
-# define BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_FUNCTIONS
+# define BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_MOVE_FUNCTIONS
 #elif BOOST_WORKAROUND(BOOST_MSVC, < 1900)
-// on MSVC 12.0 move constructor and move assignment are not reconized as special functions
-// and they cannot be defaulted 
-# define BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_FUNCTIONS
+# define BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_MOVE_FUNCTIONS
+#elif BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40600)
+# define BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_MOVE_FUNCTIONS
 #endif
 
 

test/optional_test_experimental_traits.cpp

@@ -20,7 +20,7 @@
 #include "boost/type_traits/is_base_of.hpp"
 #include "boost/optional/detail/experimental_traits.hpp"
 
-#ifndef BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_FUNCTIONS
+#ifndef BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_MOVE_FUNCTIONS
 
 struct PrivDefault
 {
@@ -144,7 +144,7 @@ void test_trivial_copyability()
 
 int main()
 {
-#ifndef BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_FUNCTIONS
+#ifndef BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_MOVE_FUNCTIONS
   test_type_traits();
   test_trivial_copyability();
 #endif

test/optional_test_static_properties.cpp

@@ -20,7 +20,7 @@
 #include "boost/type_traits/is_base_of.hpp"
 #include "boost/optional/detail/experimental_traits.hpp"
 
-#ifndef BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_FUNCTIONS
+#ifndef BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_MOVE_FUNCTIONS
 
 struct PrivDefault
 {
@@ -138,7 +138,7 @@ void test_trivial_copyability()
 
 int main()
 {
-#ifndef BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_FUNCTIONS
+#ifndef BOOST_OPTIONAL_DETAIL_NO_DEFAULTED_MOVE_FUNCTIONS
   test_type_traits();
   test_trivial_copyability();
 #endif