Remove python script for calculating PACKAGE_RELATIVE_PATH for cmake config files

[ret2libc]

With #2057 we introduced CMake files generated from meson, so that systems without pkg-config (e.g. windows) can still easily discover Rizin libs. They are also useful for cmake projects such as rz-ghidra or cutter, which nowadays provide their own "FindRizin.cmake" files.

However, due to mesonbuild/meson#9702 we had to introduce a workaround in 393ed4e . See files librz/RzModulesConfig.cmake.in and PACKAGE_RELATIVE_PATH in the librz/<lib>/meson.build files.

This issue is to remind ourselves to remove this workaround once meson will make a release with a fix for the above issue.

[ret2libc]

@PACKAGE_INIT@ should be used in the cmake.in files and meson should replace that with the right get_filename_component(PACKAGE_PREFIX_DIR_WORKAROUND and set_and_check definitions.

[ret2libc]

This is probably going to be long term, as even if meson makes a release now we don't want to bump the required version of meson too soon to have some kind of compatibility with distros.

[thestr4ng3r]

With #2948, we are deliberately not using meson's cmake module anymore, so calculating the relative path and generating the @PACKAGE_INIT@-like code ourselves is done on purpose.
This means this issue is reduced to just replacing the python script used at

rizin/meson.build

Line 184 in d7699a9

cmake_package_relative_path = run_command(py3_exe, cmake_package_prefix_dir_py, rizin_prefix, rizin_cmakedir / 'xxx', check: true).stdout().strip()

by something that does not require python.
A similar case is here too:

rizin/meson.build

Lines 160 to 164 in d7699a9

	# Calcualte BINDIR's depth to be able to find the root directory during runtime
	# in portable builds
	py_cmd = 'import os; print((1 if r"@0@" == os.sep else len(os.path.normpath(r"@0@").split(os.sep))) - (1 if r"@1@" == os.sep else len(os.path.normpath(r"@1@").split(os.sep))))'.format(rizin_prefix / rizin_bindir, rizin_prefix)
	py_cmd = run_command(py3_exe, '-c', py_cmd, check: true)
	bindir_depth = py_cmd.stdout().strip()

I currently see two ways to do this:

• Use pure meson functionality (see also https://mesonbuild.com/Fs-module.html) - This is rather cumbersome because of meson's extremely limited support for path operations. Closest I could get to a solution is this, but it seems fragile:

  cmakedir = prefix / rizin_cmakedir
  cmakedir_rel = ''
  foreach i : [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] # hack to get a while loop with an upper bound on the interations
    if cmakedir == rizin_prefix
      break
    endif
    cmakedir = fs.parent(cmakedir)
    cmakedir_rel = cmakedir_rel / '..'
  endforeach
  

• Do the calculation dynamically in cmake in the final rz_<...>Config.cmake file - One could simply emit the prefix and cmake path to the config file and do the calculation then in the cmake code. See https://github.com/Kitware/CMake/blob/b634b8a83bd82ea9c2fdc339f5b57e9c0634539f/Modules/CMakePackageConfigHelpers.cmake#L273 for reference, which is the code in cmake that implements this statically. This will result in slightly more complex config files and there might be some differences between the env that rizin was built on and the one it is installed in, but it seems feasible.

[XVilka]

@thestr4ng3r we could also simply request extending their FS module.

[thestr4ng3r]

Sure, but that too will take a long time until the update is widespread enough for us to use.

[XVilka]

In fact we could do it in parallel and use the hack you mentioned meanwhile, while sometime in the future switch to the right solution.

[ret2libc]

Do the calculation dynamically in cmake in the final rz_<...>Config.cmake file -

I'm ok with this option.

[eli-schwartz]

• This is rather cumbersome because of meson's extremely limited support for path operations.

mesonbuild/meson#7908

[thestr4ng3r]

• This is rather cumbersome because of meson's extremely limited support for path operations.

mesonbuild/meson#7908

This should indeed solve it cleanly.