nginx – How do I see what try_files is attempting and failing?

I have some nginx conf, based off another question Nginx: serve index.html in the closest parent folder:

location /p/ {
    alias /home/seph/static/;
    index index.html;

    try_files $uri $uri.html $uri/ @step_up;
}

location @step_up {
    rewrite ^(.*)/.+ $1/ last;
}

What it is supposed to do is irrelevant for this question.

What I would like is some way to see what nginx is attempting in try_files. A log of every try_file check it does and fails, or succeeds. I want to see if it’s checking everywhere it should be.

How can I log this information?