function (disallow_intree_builds)  # Adapted from LLVM's toplevel CMakeLists.txt file  if( CMAKE_SOURCE_DIR STREQUAL CMAKE_BINARY_DIR AND NOT MSVC_IDE )    message(FATAL_ERROR "      In-source builds are not allowed. CMake would overwrite the      makefiles distributed with utf8proc. Please create a directory      and run cmake from there. Building in a subdirectory is      fine, e.g.:              mkdir build        cd build        cmake ..            This process created the file `CMakeCache.txt' and the      directory `CMakeFiles'. Please delete them.            ")  endif()endfunction()