Fix CMake Warning FindPythonInterp and FindPythonLibs modules are removed

[rickyjames35]

When running cmake configure on this project I get:

CMP0148 is not set: The FindPythonInterp and FindPythonLibs modules
are removed. Run "cmake --help-policy CMP0148" for policy details. Use
the cmake_policy command to set the policy and suppress this warning.

This is caused by usage of deprecated functionality find_package(PythonInterp 3) in the root CMakeLists.txt.

Relevant CMake documentation: https://cmake.org/cmake/help/latest/policy/CMP0148.html

The FindPythonInterp and FindPythonLibs modules are removed.
These modules have been deprecated since CMake 3.12. CMake 3.27 and above prefer to not provide the modules.

Here's the new way of finding Python: https://cmake.org/cmake/help/latest/module/FindPython3.html#module:FindPython3

[CLAassistant]

All committers have signed the CLA.

[rickyjames35]

Seems that src/CMakeLists.txt has a couple places where the PYTHONPATH is being passed in. I was hoping this would be an easy fix but it might not be. @rpavlik do you have any thoughts?

OpenXR-SDK-Source/src/CMakeLists.txt

Line 426 in 650f751

"${CMAKE_COMMAND}" -E env "PYTHONPATH=${CODEGEN_PYTHON_PATH}"

[maksim-petukhov]

When using Python3 cmake module, Python3_EXECUTABLE should be used instead of PYTHON_EXECUTABLE in /CMakeLists.txt, /src/CMakeLists.txt and /include/openxr/CMakeLists.txt. And there is no problem with PYTHONPATH.

[rickyjames35]

Thanks @maksim-petukhov, your suggestion worked.

[rpavlik-bot]

An issue (number 2326) has been filed to correspond to this pull request in the internal Khronos GitLab (Khronos members only: KHR:openxr/openxr#2326 ), to facilitate working group processes.

This GitHub pull request will continue to be the main site of discussion.

[rpavlik]

Will this work as far back as CMake 3.16?

edit: ah, the deprecation started in 3.12, so apparently it is fine, oops. We were holding the line at 3.10 for a long time.

[rpavlik]

Thanks for this! I have squashed your commits, adjusted the commit message, added a changelog fragment, and fixed the CMake formatting (apparently the CMake format config file is not shipped in this repo?)