After updating to the latest master commit of pybind11, my AppVeyor build on Windows is hitting an error:

-- pybind11 v2.6.0 dev
-- Found PythonInterp: C:\Python36-x64\python.exe (found version "3.6.8") 
-- Found PythonLibs: C:/Python36-x64/libs/python36.lib
-- Configuring done
CMake Error at 3rdparty/pybind11/tools/pybind11Tools.cmake:152 (target_link_libraries):
  Error evaluating generator expression:
    $<COMPILE_LANGUAGE:CXX>
  $<COMPILE_LANGUAGE:...> may not be used with Visual Studio generators.
Call Stack (most recent call first):
  python/CMakeLists.txt:1 (pybind11_add_module)

(and a few repetitions of that error). Full build log is here, if you can access it: https://ci.appveyor.com/project/patrikhuber/eos/builds/34429669

This is with cmake-3.10.1 from https://cmake.org/files/v3.10/cmake-3.10.1-win64-x64.zip. According to the pybind11 CMake requirements, the minimum is 3.7 so this should work?

Environment: AppVeyor os: Visual Studio 2017, and CMake Generator "Visual Studio 15 Win64".

If I change my AppVeyor build script to cmake-3.18.1 (https://github.com/Kitware/CMake/releases/download/v3.18.1/cmake-3.18.1-win64-x64.zip), then it works, no error.

I could try a few cmake versions in-between, if that helps. The repo/branch for this is https://github.com/patrikhuber/eos/blob/fix-appveyor-pybind11-cmake/appveyor.yml.

I have no issues upgrading my CMake version, no need to fix this for ancient CMake versions. People should be on latest CMake versions anyway :-) But I thought it would be good to report this, so that if appropriate, you might want to update the minimum required version for pybind11. Or perhaps I'm making some mistake!