Cannot use cmakefiles with FetchContent (external) mechanism.

[bsergean]

https://cmakebyexample.dev/use-library-fetchcontent/

I'm trying to consume this library like this, but I'm getting some cmake errors. I think most of them should be simple to fix, like using CMAKE_CURRENT_DIR or something like that in some path.

If I set the config to auto I get

-- The Fortran compiler identification is GNU 11.4.0
-- Detecting Fortran compiler ABI info
-- Detecting Fortran compiler ABI info - done
-- Check for working Fortran compiler: /usr/bin/gfortran - skipped
-- automatic configuration requested
CMake Error at /home/benjamin.sergeant/projects/xxx/build/temp/CMakeFiles/CMakeTmp/CMakeLists.txt:22 (target_sources):
  Cannot find source file:

    /home/benjamin.sergeant/projects/xxx/build/detect/config/config_detect.c


CMake Error at /home/benjamin.sergeant/projects/xxx/build/temp/CMakeFiles/CMakeTmp/CMakeLists.txt:21 (add_executable):
  No SOURCES given to target: cmTC_8e5d3


CMake Error at build/_deps/blis-src/CMakeLists.txt:68 (try_run):
  Failed to generate test project build system.


-- Configuring incomplete, errors occurred!

If I set the config to zen, I get a new error

-- CPM: adding package tinyxml2@10.0.0 (10.0.0)
-- CPM: adding package blis@4.2 (4.2)
/usr/bin/python3.10: can't open file '/home/benjamin.sergeant/projects/xxx/build/cmake/read_registry.py': [Errno 2] No such file or directory
-- configuration 'zen' is registered.
CMake Error at build/_deps/blis-src/CMakeLists.txt:102 (list):
  list GET given empty list


CMake Error at build/_deps/blis-src/CMakeLists.txt:103 (list):
  list GET given empty list


CMake Error at build/_deps/blis-src/CMakeLists.txt:104 (list):
  list GET given empty list

I'm actually using something called 'CPM' which is a wrapper around FetchContnt.