Avoid embedded preprocessor directives in __tree

[dim]

Summary

When I compile <map> as part of clang, with -pedantic enabled, I get the
following warnings:

In file included from /usr/include/c++/v1/map:442:
/usr/include/c++/v1/__tree:874:2: warning: embedding a directive within macro arguments has undefined behavior [-Wembedded-directive]
#if _LIBCPP_STD_VER <= 11
 ^
/usr/include/c++/v1/__tree:877:2: warning: embedding a directive within macro arguments has undefined behavior [-Wembedded-directive]
#endif
 ^
/usr/include/c++/v1/__tree:1392:2: warning: embedding a directive within macro arguments has undefined behavior [-Wembedded-directive]
#if _LIBCPP_STD_VER <= 11
 ^
/usr/include/c++/v1/__tree:1395:2: warning: embedding a directive within macro arguments has undefined behavior [-Wembedded-directive]
#endif
 ^

This is because the #ifs are within the parameter list of a
_NOEXCEPT_() macro invocation. EricWF fixed something similar in
rL242623, by moving the #if outside the macro invocation.

[EricWF]

LGTM. Thanks

[vitalybuka]

PPC bots are broken by this patch
http://lab.llvm.org:8011/builders/sanitizer-ppc64be-linux/builds/3547
http://lab.llvm.org:8011/builders/sanitizer-ppc64le-linux/builds/2353

[dim]

In D23961#527284, @vitalybuka wrote:

PPC bots are broken by this patch
http://lab.llvm.org:8011/builders/sanitizer-ppc64be-linux/builds/3547
http://lab.llvm.org:8011/builders/sanitizer-ppc64le-linux/builds/2353

I saw some mails about it, but also that the failures were all in timing-related tests. The next runs seem to have succeeded, so these were false positives.

libcxx/trunk/include/__tree

#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
 
     _LIBCPP_INLINE_VISIBILITY
     size_type max_size() const _NOEXCEPT
         {return __node_traits::max_size(__node_alloc());}
 
     void clear() _NOEXCEPT;
 
     void swap(__tree& __t)
+#if _LIBCPP_STD_VER <= 11
         _NOEXCEPT_(
             __is_nothrow_swappable<value_compare>::value
-#if _LIBCPP_STD_VER <= 11
             && (!__node_traits::propagate_on_container_swap::value ||
                  __is_nothrow_swappable<__node_allocator>::value)
-#endif
             );
-
+#else
+        _NOEXCEPT_(__is_nothrow_swappable<value_compare>::value);
+#endif
 
 #ifndef _LIBCPP_CXX03_LANG
     template <class _Key, class ..._Args>
     pair<iterator, bool>
     __emplace_unique_key_args(_Key const&, _Args&&... __args);
     template <class _Key, class ..._Args>
     iterator
     __emplace_hint_unique_key_args(const_iterator, _Key const&, _Args&&...);
if (__nd != nullptr)
         __node_traits::destroy(__na, _NodeTypes::__get_ptr(__nd->__value_));
         __node_traits::deallocate(__na, __nd, 1);
     }
 }
 
 template <class _Tp, class _Compare, class _Allocator>
 void
 __tree<_Tp, _Compare, _Allocator>::swap(__tree& __t)
+#if _LIBCPP_STD_VER <= 11
         _NOEXCEPT_(
             __is_nothrow_swappable<value_compare>::value
-#if _LIBCPP_STD_VER <= 11
             && (!__node_traits::propagate_on_container_swap::value ||
                  __is_nothrow_swappable<__node_allocator>::value)
-#endif
             )
+#else
+        _NOEXCEPT_(__is_nothrow_swappable<value_compare>::value)
+#endif
 {
     using _VSTD::swap;
     swap(__begin_node_, __t.__begin_node_);
     swap(__pair1_.first(), __t.__pair1_.first());
     __swap_allocator(__node_alloc(), __t.__node_alloc());
     __pair3_.swap(__t.__pair3_);
     if (size() == 0)
         __begin_node() = __end_node();