prevent cpp from being written to all-header file

Author: pcaspers

cmake/writeAll.cmake

@@ -18,5 +18,9 @@ function(writeAll dir output autoLink headers)
   file(APPEND ${output} "\n")
   foreach(file ${headers})
     file(APPEND ${output} "#include <${dir}/${file}>\n")
+    get_filename_component(extension ${file} EXT)
+    if(NOT "${extension}" STREQUAL ".hpp" AND NOT "${extension}" STREQUAL ".h")
+      message(FATAL_ERROR "${file} does not end on hpp or h, this can not be written to ${output}")
+    endif()
   endforeach(file)
 endfunction()