CodeQL scans flagged lines like this in file `lib/fuser_mqubit.h`:

```c++
IO::messagef(" gates are fused into %lu gates\n", stat.num_fused_gates);
```

The CodeQL warning is:

> Each call to the printf function or a related function should include the type and sequence of arguments defined by the format. If the function is passed arguments of a different type or in a different sequence then the arguments are reinterpreted to fit the type and sequence expected, resulting in unpredictable behavior.