There are two options currently disabled which make the analysis weaker:
- scalar_implicit_cast: as the name would suggest, it considers scalar types to be equivalent. While MW is pretty lax, this could hide bugs, and there are cases where scalars are not equivalent (e.g. T232651)
- null_casts_as_any_type: does what it says on the tin. Setting this to true will produce some false positives, so it should probably be done as the last step.
The idea is to strengthen the default config, and re-relax it on a per-repo basis if needed. For instance, enabling scalar_implicit_cast would create roughly 1200 new issues for core, which is not something that can be fixed in one go. At the same time, having it enabled as default will allow us to fix repos with fewer errors, and start enforcing higher standards there.