Do I understand correctly, that to create new database with codeql for cpp project, it is enough to provide a list of files and build flags?

If so, can you please add an option to create a database from compile_commands.json file (https://clang.llvm.org/docs/JSONCompilationDatabase.html)?

If project uses cmake, to generate it, it is enough to define a single var:

set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

If project uses autotools, like bitcoin or linux, it is enough to execute compiledb

./autotools.sh
./configure
compiledb -n make

I am sure, there are ways to generate one for other build systems.

This feature can save a lot of time during database creation for cpp projects, because generation of this file is fast, as opposed to providing -c flag to codeql binary to actually build the project.