POC: Use SimultaneousTypeTraverser in RuleLevelHelper::transformAcceptedType

[VincentLanglet]

Static analysis is failing because TypeTraverserInstanceofVisitor doesn't support SimultaneousTypeTraverser (not sure it should).

The only current test failing is

16: Function ReturnListNullables\doFoo() should return array<string>|null but returns list<string|null>.

but I feel like we could reproduce more errors because...

UnionType/Intersection types doesn't work well with the SimultaneousTypeTraverser because

• when it's called with A&B&C and A we're not traversing because second type is not an Intersection
• when it's called with A&B&C and A&C we're not traversing because types count are different

The main issue would be, when traversing A&B&C and A&C, to match types in order to

• traverse (A, A)
• traverse (B, Never)
• traverse (C, C)