Issue with the doc Generation

Basically I don't know how to solve this. I need some help

https://gitlab.idiap.ch/bob/bob.ip.gabor/builds/16503

Warning, treated as error:
/local/gitlab-runner/builds/6b02994f/0/bob/bob.ip.gabor/doc/c_cpp_api.rst:54: WARNING: cpp:type reference target not found: blitz

Just a note for the sphinx build, now warnings are errors. Be careful, our documentations are full of warnings. I fixed almost 50 WARNINGS so far