Pybind11 build failed on MSVC + std:c++latest on windows

[QuellaZhang]

Pybind11 failed when build with std:c++latest by msvc on Windows, I use latest version 978d439 on master branch. Could you please help take a look at this?

You can repro this issue as the steps below:

1. git clone https://github.com/pybind/pybind11 D:\Pybind11\src
2. open a VS 2017 amd64 command prompt as admin and browse to D:\Pybind11
3. set CL=/std:c++latest
4. cmake -G "Visual Studio 15 2017 Win64" -DCMAKE_SYSTEM_VERSION=10.0.17134.0 ..\src\

Failures:
================================== FAILURES ===================================
______________________________ test_string_view _______________________________

     capture = <conftest.Capture object at 0x00000000051CE470>
     
         @pytest.mark.skipif(not hasattr(m, "has_string_view"), reason="no <string_view>")
         def test_string_view(capture):
             """Tests support for C++17 string_view arguments and return values"""
             assert m.string_view_chars("Hi") == [72, 105]
             assert m.string_view_chars("Hi 🎂") == [72, 105, 32, 0xf0, 0x9f, 0x8e, 0x82]
     >       assert m.string_view16_chars("Hi 🎂") == [72, 105, 32, 0xd83c, 0xdf82]
     E       TypeError: string_view16_chars(): incompatible function arguments. The following argument types are supported:
     E           1. (arg0: unicode) -> list
     E       
     E       Invoked with: 'Hi \xf0\x9f\x8e\x82'
     
     test_builtin_casters.py:117: TypeError

[wjakob]

The CI builds test c++latest on MSVC2017, and they seem to work fine.

[QuellaZhang]

Sorry for the confusion, we (the Microsoft C++ team) use the Pybind11 project as part of our "Real world code" tests, that next release of MSVC will have this behavior.

[QuellaZhang]

Hi, @wjakob , recently VS2019 preview 1 was released, could you try this version? You can download it here: https://visualstudio.microsoft.com/vs/preview/ .

[QuellaZhang]

Any update?

[QuellaZhang]

@wjakob Any update about this issue?

[YannickJadoul]

pybind11 was somehow never tested with the C++17 standard against Python 2.7. Fixed in #2314.