The `instanceFieldStep` disjunct of `TypeTrackingInput::levelStepCall`
that was added in 7.2.0 uses `classInstanceTracker(cls)` -- which is
itself a type-tracker -- inside `levelStepCall`. That creates a
structural mutual recursion between the main type-tracker fixpoint and
`classInstanceTracker`, causing the type-tracker delta to blow up to
~100M tuples per iteration on some OOP-heavy Python codebases.
Verified on the python/mypy database: SSRF query wall time goes from
~12s before the offending commit to >40 minutes after it.
This hotfix temporarily drops the `instanceFieldStep` disjunct and
keeps only `inheritedFieldStep`, which does not pull on the call
graph and is well-behaved (verified at ~12s on mypy). The
`instanceFieldStep` helper predicate itself is kept in place, and
the `levelStepCall` body has a commented-out call to it so the
change is trivial to re-enable once the recursion issue is properly
addressed.
As discussed in a meeting today, this will end up presenting an query
suite that's easier to use for customers.
Since https://github.com/github/codeql/pull/6589 has JUST been merged,
if we get this change in fast enough, no end-user will ever have run
`py/sqlalchemy-textclause-injection` as part of LGTM.com or Code
Scanning.
We were mixing between things, so this is just to keep things
consistent. Even though it's not strictly needed for all queries,
it does look nice I think
