Linux autocompletions work with complete.

 ]➬complete -p  cmake
 complete -F _cmake cmake

So _cmake is in charge.

]➬type _cmake > cmake.sh

And now just see/debug it. You modify in for example _cmake_mine and call to test it:

. cmake.sh
complete -F _cmake_mine cmake

To get help for any builtin bash command (no man bullshit):

 help complete
 help [[
 help for

Have fun! ;)

Linux autocompletions work with complete.

 ]➬complete -p  cmake
 complete -F _cmake cmake

So _cmake is in charge.

]➬type _cmake > cmake.sh

And now just see/debug it. You modify in for example _cmake_mine and call to test it:

. cmake.sh
complete -F _cmake_mine cmake

To get help for any builtin bash command:

 help complete
 help [[
 help for