Python: Give most non-self instance attributes the 'unknown' value; improves reachability analysis.

Author: markshannon

python/ql/src/semmle/python/pointsto/PointsTo.qll

@@ -610,7 +610,6 @@ module PointsTo {
                 points_to(obj_node, context, x, icls, _) and
                 (not x instanceof ModuleObject and not x instanceof ClassObject) and
                 not icls.isBuiltin() and
-                Types::class_has_attribute_bool(icls, name) = false and
                 value = unknownValue() and cls = theUnknownType() and origin = f
             )
         )

python/ql/test/library-tests/PointsTo/guarded/PointsTo.expected

@@ -61,6 +61,7 @@
 | test.py | 408 | ControlFlowNode for x | int 1 | 404 |
 | test.py | 420 | ControlFlowNode for Attribute | NoneType None | 418 |
 | test.py | 427 | ControlFlowNode for Attribute | NoneType None | 418 |
+| test.py | 435 | ControlFlowNode for y | int 1 | 433 |
 | type_test.py | 5 | ControlFlowNode for d | Dict | 2 |
 | type_test.py | 14 | ControlFlowNode for x | int 0 | 11 |
 | type_test.py | 16 | ControlFlowNode for x | float 1.0 | 11 |

python/ql/test/library-tests/PointsTo/guarded/PointsToWithType.expected

@@ -61,6 +61,7 @@
 | test.py | 408 | ControlFlowNode for x | int 1 | builtin-class int | 404 |
 | test.py | 420 | ControlFlowNode for Attribute | NoneType None | builtin-class NoneType | 418 |
 | test.py | 427 | ControlFlowNode for Attribute | NoneType None | builtin-class NoneType | 418 |
+| test.py | 435 | ControlFlowNode for y | int 1 | builtin-class int | 433 |
 | type_test.py | 5 | ControlFlowNode for d | Dict | builtin-class dict | 2 |
 | type_test.py | 14 | ControlFlowNode for x | int 0 | builtin-class int | 11 |
 | type_test.py | 16 | ControlFlowNode for x | float 1.0 | builtin-class float | 11 |

python/ql/test/library-tests/PointsTo/guarded/test.py

@@ -426,3 +426,10 @@ def meth(self):
         else:
             use(self.x)
             return lambda : use(self.x)
+
+
+def test_on_unknown_attr():
+    e = E()
+    y = 1
+    if e.attr:
+        use(y)

python/ql/test/library-tests/PointsTo/new/PointsToUnknown.expected

@@ -225,3 +225,5 @@
 | r_regressions.py:52 | ControlFlowNode for msg | 51 |
 | r_regressions.py:64 | ControlFlowNode for do_validation | 64 |
 | r_regressions.py:64 | ControlFlowNode for do_validation() | 64 |
+| r_regressions.py:90 | ControlFlowNode for Attribute | 90 |
+| r_regressions.py:90 | ControlFlowNode for Attribute() | 90 |