[libstdc++-v3 parallel mode] lack of __gnu_parallel::copy and inconvenience of transform overload

[Paolo Carlini]

Hi,
> While using __gnu_parallel, I could not guess nor find the reason not
> to have a __gnu_parallel::copy, which should be embarrassingly
> parallel for random iterators. I settled for __gnu_parallel::transform
> using an identity Op, which brings me to my second question/remark :
> given that the overload of std:transform (for 1 or 2 input sequences)
> interferes with the additional optional parameter for __gnu_parallel::
> algorithms, would it be possible to provide
> __gnu_parallel::transform1(...,__gnu_parallel::_Parallelism ) and
> __gnu_parallel::transform2(...,__gnu_parallel::_Parallelism ) to allow
> an easy selection of the parallelism of the transform algorithms over
> 1 and 2 input sequences ?
>   
Johannes, what do you think? Are you already aware of this kind of
request? Should we add it to libstdc++/38875?

Paolo.