Python: Model data-flow for x or y and x and y

Author: RasmusWL

python/change-notes/2021-10-08-add-dataflow-for-boolean-expressions.md

@@ -0,0 +1,3 @@
+lgtm,codescanning
+* Added data-flow from `x` in both `x or y` and `x and y`, as described in the
+  [Python Language Reference](https://docs.python.org/3/reference/expressions.html#boolean-operations).

python/ql/lib/semmle/python/dataflow/new/internal/DataFlowPrivate.qll

@@ -200,6 +200,9 @@ module EssaFlow {
     // If expressions
     nodeFrom.asCfgNode() = nodeTo.asCfgNode().(IfExprNode).getAnOperand()
     or
+    // boolean inline expressions such as `x or y` or `x and y`
+    nodeFrom.asCfgNode() = nodeTo.asCfgNode().(BoolExprNode).getAnOperand()
+    or
     // Flow inside an unpacking assignment
     iterableUnpackingFlowStep(nodeFrom, nodeTo)
     or

python/ql/test/experimental/dataflow/coverage/test.py

@@ -426,12 +426,12 @@ def test_call_extra_keyword_flow():
 
 def test_or(x = False):
     # if we don't know the value of the lhs, we should always add flow
-    SINK(x or SOURCE) #$ MISSING: flow="SOURCE -> BoolExp"
+    SINK(x or SOURCE) #$ flow="SOURCE -> BoolExpr"
 
 
 def test_and(x = True):
     # if we don't know the value of the lhs, we should always add flow
-    SINK(x and SOURCE) #$ MISSING: flow="SOURCE -> BoolExp"
+    SINK(x and SOURCE) #$ flow="SOURCE -> BoolExpr"
 
 
 # 6.12. Assignment expressions