libstdc++: Revert change to __bitwise_relocatable

This reverts r15-6060-ge4a0157c2397c9 so that __is_bitwise_relocatable
depends only on is_trivial. To avoid the deprecation warnings for C++26,
use the __is_trivial built-in directly instead of std::is_trivial.

We need to be sure that the type is trivially copyable, not just
trivially constructible and trivially assignable. Otherwise we get
-Wclass-memaccess diagnostics for e.g. std::vector<std::pair<A*, B*>>.
We could add is_trivially_copyable to the conditions, but this isn't
really an appropriate change for stage 3 anyway (it affects all modes
from C++11 upwards). Just revert to using is_trivial, and we can revisit
the condition for GCC 16.

libstdc++-v3/ChangeLog:

	* include/bits/stl_uninitialized.h (__is_bitwise_relocatable):
	Revert to depending on is_trivial.

diff --git a/libstdc++-v3/include/bits/stl_uninitialized.h b/libstdc++-v3/include/bits/stl_uninitialized.h
index 916288352d705e3a8f188e371a5d25092e5fec4f..b7e65eb3ca06fde89dec64f4d64d245f156ba2f7 100644 (file)
--- a/libstdc++-v3/include/bits/stl_uninitialized.h
+++ b/libstdc++-v3/include/bits/stl_uninitialized.h
@@ -1248,7 +1248,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   // Also known as is_trivially_relocatable.
   template<typename _Tp, typename = void>
     struct __is_bitwise_relocatable
-    : __and_<is_trivially_move_constructible<_Tp>, is_trivially_destructible<_Tp>> { };
+    : __bool_constant<__is_trivial(_Tp)>
+    { };
 
   template <typename _InputIterator, typename _ForwardIterator,
            typename _Allocator>