Combining callcatcher and cmake

Question

My aim is to find procedures in our large and old codebase that are never called. Our code, called neci, is mostly Fortran and some C/C++ code. From the top answer to this question I stumbled over the wonderful tool callcatcher but I have difficulties in combining it with cmake.

When I use callcatcher by compiling manually a bunch of Fortran files, everything works correctly and finds unused procedures.

Now I wanted to embed this tool into our cmake compilation process and used.

cmake \
    -DCMAKE_BUILD_TYPE=Debug \
    -DCMAKE_Fortran_COMPILER=mpifort -DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx \
    -DCMAKE_Fortran_COMPILER_LAUNCHER=callcatcher -DCMAKE_C_COMPILER_LAUNCHER=callcatcher -DCMAKE_CXX_COMPILER_LAUNCHER=callcatcher \
    -DCMAKE_Fortran_LINKER_LAUNCHER=callcatcher -DCMAKE_C_LINKER_LAUNCHER=callcatcher -DCMAKE_CXX_LINKER_LAUNCHER=callcatcher \
     ~/code/neci

The computer then warns about:

CMake Warning:
  Manually-specified variables were not used by the project:

    CMAKE_Fortran_LINKER_LAUNCHER

And indeed when I compile with VERBOSE=3 make -j neci I see that files are correctly compiled with callcatcher but the linking step does not prepend the call with callcatcher.

My questions are:

1. How can I force cmake to prepend the linker command with callcatcher?
2. If the first question hides an XY problem, how can I solve my original aim of finding uncalled procedures without callcatcher.

My cmake version is 3.21.3.