It seems that the patch is causing *first to be moved twice into the same
position.
*first is already moved in the __stable_partition_adaptive function:
if (__len <= __buffer_size)
{
_ForwardIterator __result1 = __first;
_Pointer __result2 = __buffer;
// The precondition guarantees that !__pred(__first), so
// move that element to the buffer before starting the loop.
// This ensures that we only call __pred once per element.
*__result2 = _GLIBCXX_MOVE(*__first); <--- moved here
And your patch moves the same element when creating buffer:
#if __glibcxx_constexpr_algorithms >= 202306L // >= C++26
if consteval {
_ValueType __buf = std::move(*__first);
return std::__stable_partition_adaptive(__first, __last, __pred,
__len,
&__buf,
_DistanceType(1));
}
+#endif
Given that we have constexpr allocations now, do we really need to avoid
allocating temporary buffers, and using very slow implementation?
On Sat, Mar 15, 2025 at 9:15 PM Giuseppe D'Angelo <giuseppe.dang...@kdab.com>
wrote:
> Hello,
>
> I'm attaching the patch for constexpr stable_partition.
>
> Thank you,
> --
> Giuseppe D'Angelo
>
