[pdal] Remove MSVC 2015 Support?

[Mateusz Loskot]

On Fri, 24 Jan 2020 at 16:59, Howard Butler <howard at hobu.co> wrote:
> Mateusz,
>
> We received a notice today that Azure Pipelines, which PDAL uses for CI,
> is removing its MSVC 2015 image.
> It has me wondering if the world has moved on to MSVC 2017+ and
> PDAL could move forward with requiring that (and using C++17 in the process).
>
> Since you are our resident Windows expert, what do you think?

Given that
- Visual Studio 2015 Update 3 default is C++14 [1]
- Visual Studio 2017 default is C++14 too [2]
I'd say that if a user already builds with VS2015, then she can
equally build with VS2017.
IOW, there is a common C++ version denominator provided by the two and
there is little-to-none reasons to keep using VS2015.

Given the default C++ version in VS2017 is C++14, not C++17, technically,
the switch does not mean PDAL would have to switch to C++17, just C++14.

However, some say (common among Boost'ers) if a project considers
switch to C++14 then it should just jump to C++17.
IOW, the recommended jumps are to C++11, then to C++17, then to C++20.

I hope it helps.

[1] https://devblogs.microsoft.com/cppblog/standards-version-switches-in-the-compiler/
[2] https://docs.microsoft.com/en-us/cpp/build/reference/std-specify-language-standard-version

Best regards,
--
Mateusz Loskot, http://mateusz.loskot.net