Writing CodeQL Queries for SerenityOS

I previously added CodeQL static analysis support to the SerenityOS build workflow. https://github.com/SerenityOS/serenity/pull/4175

Unfortunately you there doesn’t seem to be a way to consume the CodeQL database that as part of that build pipline on GitHub. This seems like a bit of an oversight, and I have raised an issue here: https://github.com/github/codeql-action/issues/355

To work around that we will need to create our own database so we can write some custom CodeQL queries.

Here are the steps I put together:

1. Setup a clone of the VSCode Starter Workspace (docs)

   $ git clone https://github.com/github/vscode-codeql-starter.git
   $ cd vscode-codeql-starter
   $ git submodule update --init --remote
   

2. Build a codeql database for serenity OS (docs):

   $ codeql database create -l cpp -s /home/bgianf/src/serenity -c "make -j -C /home/bgianf/src/serenity/BuildMake" ~/serenity-codeql
   

3. Install the VS Code CodeQL extension (docs)

4. Configure the VS Code CodeQL extension to point to your new database (~/serenityy-codeql)

5. Open the vscode-codeql-starter workspace in VS Code.

6. Open the cpp/example.ql query and start writing queries and executing them against the database.

   This simple example finds all classes in the AK standard library in SerenityOS:

   import cpp
   
   from Class c
   where c.getQualifiedName().matches("AK::%")
   select base.getQualifiedName()