PSTL algos in <numeric> need to move the __init variables

[jwakely]

All of reduce, transform_reduce, exclusive_scan, and inclusive_scan, transform_exclusive_scan, and transform_inclusive_scan only have a precondition on the type of init that it meets the Cpp17MoveConstructible requirements, so when passing it to the next internal function it needs to be moved, not copied:

     return transform_inclusive_scan(std::forward<_ExecutionPolicy>(__exec), __first, __last, __result, __binary_op,
-                                    __pstl::__internal::__no_op(), __init);
+                                    __pstl::__internal::__no_op(), std::move(__init));

e.g.

llvm-project/pstl/include/pstl/internal/glue_numeric_impl.h

Line 33 in e0ae779

return transform_reduce(std::forward<_ExecutionPolicy>(__exec), __first, __last, __init, __binary_op,

[jwakely]

And they need to move when returning init as well:

-    return std::make_pair(__result, __init);
+    return std::make_pair(__result, std::move(__init));

e.g.

llvm-project/pstl/include/pstl/internal/numeric_impl.h

Line 169 in fdd09e9

return std::make_pair(__result, __init);

[frederick-vs-ja]

This seems resolved. libc++'s own implementation correctly uses std::move, and the old PSTL implementation was removed by #143717.

[jwakely]

Yeah let's close it. The problem was fixed downstream in libstdc++ and reported upstream to PSTL.