Predicate TypeTrackingInput::storeStep

Holds if nodeFrom is being written to the contents of the object in nodeTo.

Note that the choice of nodeTo does not have to make sense “chronologically”. All we care about is whether the contents of nodeTo can have a specific type, and the assumption is that if a specific type appears here, then any access of that particular content can yield something of that particular type.

Thus, in an example such as

def foo(y)
   x = Foo.new
   bar(x)
   x.content = y
   baz(x)
end

def bar(x)
   z = x.content
end

for the content write x.content = y, we will have contents being the literal string "content", nodeFrom will be y, and nodeTo will be the Foo object created on the first line of the function. This means we will track the fact that x.content can have the type of y into the assignment to z inside bar, even though this content write happens after bar is called.