[PATCH] D23961: Avoid embedded preprocessor directives in __tree

[Dimitry Andric via cfe-commits]

dim created this revision.
dim added reviewers: mclow.lists, EricWF.
dim added subscribers: emaste, cfe-commits.

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

https://reviews.llvm.org/D23961

Files:
  include/__tree

Index: include/__tree
===================================================================
--- include/__tree
+++ include/__tree
@@ -1111,14 +1111,15 @@
     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>
@@ -1797,13 +1798,15 @@
 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_);


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