Acording to documentation, “You can prefix any search qualifier with a - to exclude all results that are matched by that qualifier.”
But when searching for repos, and trying to exclude certain topic is not working.
Hi 
Can you please list the specific query you used?
I tried to add something like “-topic:ruby” on the query, but that didn’t filtered the repos that had that topic
Hello, is there any news on this?
Sorry about the delayed response. I am not seeing this behavior.
I tried the query you suggested, and it returns no repositories.
It does return a ton of topics, however I did not see “ruby” in the results.
I also tried the following search:
This returns almost 80k repos, and does list Ruby as one of the languages. Is the language showing up in the language list what you were referencing in your report here?
I just ran into this same unexpected behavior. For example, see the query:
org:github topic:codeql -topic:vscode
As of this writing, that query returns 5 repositories. Despite the -topic:vscode search term, two of the repositories returned have the vscode topic.