cope with xtensor include files move

[KrisThielemans]

Fixes #216

[KrisThielemans]

@johnstairs @naegelejd could you please check this? There are now MacOS compilation problems with older xtensor 0.25, and using yardl is becoming awkward.

[KrisThielemans]

This doesn't work yet as the version macros aren't defined yet, so we cannot test on them.

[KrisThielemans]

It does works now, but it's a bit ugly as xtensor.hpp actually includes pretty much all of xtensor. So , the easiest might be to just include that file, which presumably would be more future proof anyway.

[naegelejd]

I don't think including xtensor/xtensor.hpp up front is the best solution. The version macros are actually defined in xtensor_config.hpp.

It looks like other xtensor users have chosen to use __has_include to check for existence of xtensor_config.hpp, then pull in the correct header locations based on version.

Example: https://github.com/fastscape-lem/fastscapelib/pull/174/files

[KrisThielemans]

So we require c++17? If so, fine for me! It'd be great if you could do this. We had to rely on a hand-compiled version.

[KrisThielemans]

So we require c++17?

I cannot see this is the generated CMakeLists.txt.

It's fine for PETSIRD to require this, but not sure in general.

Whatever choice you make, this issue is causing loads of trouble I'm afraid.

[naegelejd]

Yes, Yardl only supports C++17 or newer (docs).

I opened #254 to fix this and update documentation.

[KrisThielemans]

Yes, Yardl only supports C++17 or newer (docs).

Is it in the exported CMakeLists.txt? (I don't think so)

I opened #254 to fix this and update documentation.

excellent. thanks!

[naegelejd]

Thanks Kris. No, the yardl-generated CMakeLists.txt does not specify any C++ version requirements. That's because it's not a standalone CMake file (it must be included by another CMakeLists.txt), thus it should not prescribe the C++ version for the "parent" codebase.

What we should do is specify a "minimum supported C++ version" in the generated CMakeLists.txt, but I'm not aware of any such mechanisms in CMake.