std::allocator functions and typedefs deprecated in C++17

[brycelelbach]

With MSVC 2017:

C:/dvs/p4/build/sw/gpgpu/thrust\thrust/detail/allocator/allocator_traits.inl(87): error #1444-D: function "std::allocator<_Ty>::construct(_Objty *, _Types &&...) [with _Ty=vec2, _Objty=vec2, _Types=<>]"
C:/dvs/p4/build/sw/tools/win32/msvc/16.0.0/VC//include\xmemory0(939): here was declared deprecated ("warning STL4010: Various members of std::allocator are deprecated in C++17. Use std::allocator_traits instead of accessing these members directly. You can define _SILENCE_CXX17_OLD_ALLOCATOR_MEMBERS_DEPRECATION_WARNING or _SILENCE_ALL_CXX17_DEPRECATION_WARNINGS to acknowledge that you have received this warning.")
...

NVBug 200619442

[alliepiper]

Reopening -- the typedefs on std::allocator were deprecated, too, and are still blocking this for QA.

[alliepiper]

The root cause of the MSVC/C++17 std::allocator bugs is that CMake will apparently ignore any requested CUDA_STANDARD that it doesn't know how to handle. I've filed a bug about it here: https://gitlab.kitware.com/cmake/cmake/-/issues/20953.

We'll need to bump the CMake version to 3.18 (which is still in RC...) to get support for any C++17 targets.

Fortunately CMake is easy to install on most platforms and the release cycles are short, so we should see a full 3.18 soon. If anyone has issue upgrading in the meantime, let me know.

CMake downloads: https://cmake.org/download/
CMake apt repo instructions: https://apt.kitware.com/

[gevtushenko]

The problem seems to appear on fresh VS install (16.10.2):

C:/Users/evtus/Documents/GitHub/nvidia/thrust\thrust/detail/allocator/allocator_traits.h(143): error C2220: the following warning is treated as an error
C:/Users/evtus/Documents/GitHub/nvidia/thrust\thrust/detail/allocator/allocator_traits.h(143): warning C4996: 'std::allocator<int>::is_always_equal': warning STL4010: Various members of std::allocator are deprecated in C++17. Use std::allocator_traits instead of accessing these members directly. You can define _SILENCE_CXX17_OLD_ALLOCATOR_MEMBERS_DEPRECATION_WARNING or _SILENCE_ALL_CXX17_DEPRECATION_WARNINGS to acknowledge that you have received this warning.
C:/Users/evtus/Documents/GitHub/nvidia/thrust\thrust/detail/type_traits.h(455): note: see reference to class template instantiation 'thrust::detail::allocator_traits_detail::nested_is_always_equal<std::allocator<int>>' being compiled
C:/Users/evtus/Documents/GitHub/nvidia/thrust\thrust/detail/allocator/allocator_traits.inl(67): note: see reference to class template instantiation 'thrust::detail::eval_if<true,thrust::detail::allocator_traits_detail::nested_is_always_equal<std::allocator<int>>,thrust::detail::is_empty<std::allocator<int>>>' being compiled
C:/Users/evtus/Documents/GitHub/nvidia/thrust\thrust/detail/contiguous_storage.h(42): note: see reference to class template instantiation 'thrust::detail::allocator_traits<Alloc>' being compiled
        with
        [
            Alloc=std::allocator<int>
        ]
C:/Users/evtus/Documents/GitHub/nvidia/thrust\thrust/detail/vector_base.h(47): note: see reference to class template instantiation 'thrust::detail::contiguous_storage<T,Alloc>' being compiled
        with
        [
            T=int,
            Alloc=std::allocator<int>
        ]
C:/Users/evtus/Documents/GitHub/nvidia/thrust\thrust/host_vector.h(52): note: see reference to class template instantiation 'thrust::detail::vector_base<T,Alloc>' being compiled
        with
        [
            T=int,
            Alloc=std::allocator<int>
        ]
C:\Users\evtus\Documents\GitHub\nvidia\thrust\testing\copy_n.cu(23): note: see reference to class template instantiation 'thrust::host_vector<int,std::allocator<int>>' being compiled

Using the following modification leads to successful compilation:

#if THRUST_CPP_DIALECT >= 2017
  using is_always_equal = typename is_empty<allocator_type>;
#else
  using is_always_equal = typename allocator_traits_detail::nested_is_always_equal<allocator_type>;
#endif

But I can't verify the fix for older standards due to the following issue.

[alliepiper]

NVBug 200723050 is related.