for tuple constructors that construct from other tuples.
2015-09-25 Ville Voutilainen <ville.voutilainen@gmail.com>
Avoid creating dangling references in case of nested tuples
for tuple constructors that construct from other tuples.
* include/std/tuple (_TC::_NonNestedTuple): New.
* include/std/tuple (tuple::_TNTC): New.
* include/std/tuple (tuple(const tuple<_UElements...>&),
tuple(tuple<_UElements...>&&): Use _TNTC.
* testsuite/20_util/tuple/cons/nested_tuple_construct.cc: New.
From-SVN: r228134
