code: def patch_f90_compiler(f90_compiler):
      
      if not is_macos_gfortran(f90_compiler):
          return
  
      library_dirs = f90_compiler.library_dirs
      # ``library_dirs`` is a list (i.e. mutable), so we can update in place.
      library_dirs[:] = setup_helpers.gfortran_search_path(library_dirs)
docs: Patch up ``f90_compiler.library_dirs``.
  
      On macOS, a Homebrew installed ``gfortran`` needs some help. The
      ``numpy.distutils`` "default" constructor for ``Gnu95FCompiler`` only has
      a single library search path, but there are many library paths included in
      the full ``gcc`` install.
  
      Args:
          f90_compiler (numpy.distutils.fcompiler.FCompiler): A Fortran compiler
              instance.