Summary:
Creating a persistent reference to an Activity leads to a nasty form of memory leaks (see http://android-developers.blogspot.com/2009/01/avoiding-memory-leaks.html, https://corner.squareup.com/2015/05/leak-canary.html). There are many ways to create a bad persistent reference to an Activity, but the most obvious one is via a static field.
This diff implements a very simple form of Activity leak checking by inspecting postconditions to see if a subtype of Activity is reachable from a static field (and it reports an error if so). This is a very simple and limited form of leak checking that does not understand the Android lifecycle at all. In particular, if one creates a persistent reference to an Activity and then nulls it out in `onDestroy` (a reasonably common pattern), this approach will wrongly report a bug.
Summary:
@public
Using InferBuiltins.assume previously caused an assertion failure in the analyzer. Fixed this, and fixed the implementation of the assume builtin to block when the assumed condition cannot hold.
Test Plan: Added several new tests.
Summary:
@public
The models for Java no longer require to keep the original fields since we now make the union of the fields from the models and the fields from the code to analyze.
Test Plan: Infer CI. No functional change intended.