<algorithm>: ranges::inplace_merge accidentally constructed remove_cvref_t<iter_rvalue_reference_t<I>>

[hewillk]

This is basically a sibling of #4102.

STL/stl/inc/algorithm

Lines 7614 to 7630 in 1c59a20

	template <bidirectional_iterator _It>
	void _Rotate_one_right(_It _First, _It _Mid, _It _Last) {
	// exchanges the range [_First, _Mid) with [_Mid, _Last)
	_STL_INTERNAL_CHECK(_RANGES next(_Mid) == _Last);
	auto _Temp = _RANGES iter_move(_Mid);
	_RANGES _Move_backward_common(_First, _STD move(_Mid), _STD move(_Last));
	*_First = _STD move(_Temp);
	}
	template <bidirectional_iterator _It>
	void _Rotate_one_left(_It _First, _It _Mid, _It _Last) {
	// exchanges the range [_First, _Mid) with [_Mid, _Last)
	_STL_INTERNAL_CHECK(_RANGES next(_First) == _Mid);
	auto _Temp = _RANGES iter_move(_First);
	auto _Result = _RANGES _Move_unchecked(_STD move(_Mid), _STD move(_Last), _STD move(_First));
	*_Result.out = _STD move(_Temp);
	}

auto _Temp = _RANGES iter_move(_Mid) unexpectedly constructed remove_cvref_t<iter_reference_t<I>>.

Contrived testcase: https://godbolt.org/z/b7YqKPMej

[frederick-vs-ja]

It seems that we should use iter_value_t<_It> _Temp(_RANGES iter_move(_First));.

[StephanTLavavej]

Agreed. As in #4102 (comment) this also indicates missing test coverage.