How to exclude files based on mkid --lang-map=$HOME/.id-lang.map for gnu id creation?

Question

I am using mkid to create a gnu id database. In my source code directory some .c files get generated on compilation. Now I need to ignore the paths of these unwanted generated files, while creating gnu id database. So, I added following in ~/.id-lang.map file:

# Default language
**              IGNORE

# Exclude generated .c files
*/gen/*         IGNORE          # --> my attempt to exclude some files, but not working??

# list header files before code files
*.h             C
*.h.in          C
*.H             C++
*.hh            C++
*.hpp           C++
*.hxx           C++

# list C code files after header files
*.c             C
*.C             C++
*.cc            C++
*.cpp           C++
*.cxx           C++

Now, I create gnu id database using following command:

mkid --lang-map=$HOME/.id-lang.map

But with this mkid command and ~/.id-lang.map file, I am unable to exclude files based on pattern match. It's a repeating search while using gid.

So I want to know is there any issue with my id-lang.map file or mkid command or it's a bug?

If you are a gnu id database user, please let me know your comments or suggestion I can try to resolve this issue.

References:

https://www.gnu.org/software/idutils/manual/html_node/Language-map.html https://www.gnu.org/software/idutils/manual/html_node/Extraction-options.html#Extraction-options https://www.vim.org/scripts/script.php?script_id=251