Now that __alignof__ and alignof sometimes disagree it matters which one
we use. The standard says that std::alignment_of<T>::value equals
alignof(T), so we need to use that.
Change the only uses of alignment_of to use __alignof__ to avoid a
change in alignment.
PR libstdc++/88119
* include/ext/aligned_buffer.h (__aligned_membuf): Add comment.
(__aligned_buffer): Use __alignof__ instead of std::alignment_of.
* include/std/type_traits (alignment_of): Use alignof instead of
__alignof__.
* testsuite/20_util/alignment_of/value.cc: Fix test to check values
match alignof not __alignof__, as required by the standard.
From-SVN: r266613
PR libstdc++/66017
* include/bits/stl_tree.h (_Rb_tree_node): Use __aligned_membuf.
(_Rb_tree_iterator, _Rb_tree_const_iterator): Support construction
from _Base_ptr.
(_Rb_tree_const_iterator::_M_const_cast): Remove static_cast.
(_Rb_tree::begin, _Rb_tree::end): Remove static_cast.
* include/ext/aligned_buffer.h (__aligned_membuf): New type using
alignment of _Tp as a member subobject, not as a complete object.
* python/libstdcxx/v6/printers.py (StdRbtreeIteratorPrinter): Lookup
_Link_type manually as it might not be in the debug info.
From-SVN: r223745
