In hindsight, having a `.getMetrics()` method that just returns `this`
is somewhat weird. It's possible that it predates the existence of the
inline cast, however.
Gets rid of the `getMetrics` methods on the `Function`, `Class`, and
`Module` classes. To access the metrics, one must first import the
`LegacyPointsTo` module, and then either change the type to
`{Function,Class,Module}Metrics` or cast to the appropriate type.
The `Builtins` module is deeply entwined with points-to, so it would be
nice to not have this dependence. Happily, the only thing we used
`Builtin` for was to get the names of known builtins, and for this we
already maintain such a set of names in
`dataflow.new.internal.Builtins`.
For whatever reason, the CFG node for exceptions and exception groups
was placed with the points-to code. (Probably because a lot of the
predicates depended on points-to.)
However, as it turned out, two of the SSA modules only depended on
non-points-to properties of these nodes, and so it was fairly
straightforward to remove the imports of `LegacyPointsTo` for those
modules.
In the process, I moved the aforementioned CFG node types into
`Flow.qll`, and changed the classes in the `Exceptions` module to the
`...WithPointsTo` form that we introduced elsewhere.
Turns out the `ImportTime` module (despite living in
`semmle.python.types` does not actually depend on points-to, so some of
the `LegacyPointsTo` imports could be replaced or removed.
Gets rid of a bunch of predicates relating to reachability (which
depended on the modelling of exceptions, which uses points-to), moving
them to `LegacyPointsTo`. In the process, we gained a new class
`BasicBlockWithPointsTo`.
This frees `Class.qll`, `Exprs.qll`, and `Function.qll` from the
clutches of points-to. For the somewhat complicated setup with
`getLiteralObject` (an abstract method), I opted for a slightly ugly but
workable solution of just defining a predicate on `ImmutableLiteral`
that inlines each predicate body, special-cased to the specific instance
to which it applies.
For now, these have just been made into `private` imports. After doing
this, I went through all of the (now not compiling) files and added in
private imports to the modules that they actually depended on.
I also added an explicit import of `LegacyPointsTo` (even though it may
be unnecessary) in cases where the points-to dependency was somewhat
surprising (and one we want to get rid of). This was primarily inside
the various SSA layers.
For modules inside `semmle.python.{types, objects, pointsto}` I did not
bother, as these are fairly clearly related to points-to.
