CMake error at installation

[RealPolitiX]

I got an error trying to compile with cmake on Ubuntu 18.04 (Python==3.7.3)

CMake Error at CMakeLists.txt:80 (FIND_PACKAGE):
  By not providing "FindPython3.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "Python3", but
  CMake did not find one.

  Could not find a package configuration file provided by "Python3" with any
  of the following names:

    Python3Config.cmake
    python3-config.cmake

  Add the installation prefix of "Python3" to CMAKE_PREFIX_PATH or set
  "Python3_DIR" to a directory containing one of the above files.  If
  "Python3" provides a separate development package or SDK, be sure it has
  been installed.


-- Configuring incomplete, errors occurred!
See also "/mnt/pcshare/users/rpx/gitpod/fastpli/build/CMakeFiles/CMakeOutput.log".
Makefile:36: recipe for target 'build/Makefile' failed
make: *** [build/Makefile] Error 1

[fmatuschke]

Hi, I noticed this error as well. CMake depricated the FindPythonInterp and FindPythonLibs files to the newer method FindPython3 in the version 3.12.
The CMake version in Ubuntu 18.04 LTS is 3.10.2 to old.
However since I want at least to support Ubuntu 18.04 LTS and Python 3.6 I switched to the old methods in 8969658.
Interestingly this error was not catched by the CI.

[fmatuschke]

I will leave this Issue open until I found a nice solution which supports both CMake versions. Additionally I noticed in the past, there can be some Issues with multiple installed Python versions. That was also the reason, why I switched to the new method.