Merge pull request #599 from markshannon/python-fix-essa-nonlocal

Python ESSA: Fix definition of ESSA non-local variables.

Author: taus-semmle

python/ql/src/semmle/python/dataflow/SsaDefinitions.qll

@@ -107,11 +107,11 @@ abstract class PythonSsaSourceVariable extends SsaSourceVariable {
 
 }
 
-
 class FunctionLocalVariable extends PythonSsaSourceVariable {
 
     FunctionLocalVariable() {
-        this.(LocalVariable).getScope() instanceof Function and not this.(LocalVariable).escapes()
+        this.(LocalVariable).getScope() instanceof Function and
+        not this instanceof NonLocalVariable
     }
 
     override ControlFlowNode getAnImplicitUse() {
@@ -120,8 +120,14 @@ class FunctionLocalVariable extends PythonSsaSourceVariable {
 
     override ControlFlowNode getScopeEntryDefinition() {
         not this.(LocalVariable).getId() = "*" and
-        not this.(LocalVariable).isParameter() and
-        this.(LocalVariable).getScope().getEntryNode() = result
+        exists(Scope s |
+            s.getEntryNode() = result |
+            s = this.(LocalVariable).getScope() and
+            not this.(LocalVariable).isParameter()
+            or
+            s != this.(LocalVariable).getScope() and
+            s = this.(LocalVariable).getALoad().getScope()
+        )
     }
 
     override CallNode redefinedAtCallSite() { none() }
@@ -131,7 +137,10 @@ class FunctionLocalVariable extends PythonSsaSourceVariable {
 class NonLocalVariable extends PythonSsaSourceVariable {
 
     NonLocalVariable() {
-        this.(LocalVariable).getScope() instanceof Function and this.(LocalVariable).escapes()
+        exists(Function f |
+            this.(LocalVariable).getScope() = f and
+            this.(LocalVariable).getAStore().getScope() != f
+        )
     }
 
     override ControlFlowNode getAnImplicitUse() {

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

@@ -698,18 +698,15 @@
 | r_regressions.py:61 | obj_0 = ParameterDefinition |
 | r_regressions.py:61 | obj_3 = phi(obj_1, obj_2) |
 | r_regressions.py:62 | is_class_0 = isinstance() |
-| r_regressions.py:62 | name_2 = CallsiteRefinement(name_1) |
 | r_regressions.py:62 | obj_1 = ArgumentRefinement(obj_0) |
 | r_regressions.py:64 | is_class_1 = Pi(is_class_0) [true] |
-| r_regressions.py:64 | name_3 = CallsiteRefinement(name_2) |
 | r_regressions.py:66 | func_1 = obj |
 | r_regressions.py:66 | is_class_2 = Pi(is_class_0) [false] |
 | r_regressions.py:68 | _wrapper_0 = FunctionExpr |
 | r_regressions.py:68 | args_0 = ParameterDefinition |
 | r_regressions.py:68 | func_2 = phi(func_0, func_1) |
 | r_regressions.py:68 | is_class_3 = phi(is_class_1, is_class_2) |
 | r_regressions.py:68 | kwargs_0 = ParameterDefinition |
-| r_regressions.py:68 | name_4 = phi(name_2, name_3) |
 | r_regressions.py:68 | self_0 = ParameterDefinition |
 | r_regressions.py:73 | is_class_4 = Pi(is_class_3) [true] |
 | r_regressions.py:73 | obj_2 = ArgumentRefinement(obj_1) |

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

@@ -103,7 +103,6 @@
 | b_condition.py:82 | Local Variable foo | ControlFlowNode for callable() | refinement |
 | b_condition.py:83 | Local Variable bar | ControlFlowNode for bar | definition |
 | b_condition.py:83 | Local Variable foo | Entry node for Function bar | definition |
-| b_condition.py:84 | Local Variable foo | ControlFlowNode for foo() | refinement |
 | b_condition.py:87 | Global Variable split_bool1 | ControlFlowNode for split_bool1 | definition |
 | b_condition.py:87 | Local Variable x | ControlFlowNode for x | definition |
 | b_condition.py:87 | Local Variable y | ControlFlowNode for y | definition |

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

@@ -148,10 +148,8 @@
 | b_condition.py:79 | t_3 | ControlFlowNode for t |
 | b_condition.py:81 | bar_2 | Exit node for Function odasa6261 |
 | b_condition.py:81 | foo_5 | Exit node for Function odasa6261 |
-| b_condition.py:82 | foo_0 | ControlFlowNode for callable() |
 | b_condition.py:82 | foo_0 | ControlFlowNode for foo |
 | b_condition.py:84 | foo_3 | ControlFlowNode for foo |
-| b_condition.py:84 | foo_3 | ControlFlowNode for foo() |
 | b_condition.py:87 | x_3 | Exit node for Function split_bool1 |
 | b_condition.py:87 | x_8 | Exit node for Function split_bool1 |
 | b_condition.py:87 | y_3 | Exit node for Function split_bool1 |

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

@@ -175,10 +175,8 @@
 | b_condition.py:81 | bar | Exit node for Function odasa6261 |
 | b_condition.py:81 | foo | Exit node for Function odasa6261 |
 | b_condition.py:82 | callable | ControlFlowNode for callable |
-| b_condition.py:82 | foo | ControlFlowNode for callable() |
 | b_condition.py:82 | foo | ControlFlowNode for foo |
 | b_condition.py:84 | foo | ControlFlowNode for foo |
-| b_condition.py:84 | foo | ControlFlowNode for foo() |
 | b_condition.py:87 | x | Exit node for Function split_bool1 |
 | b_condition.py:87 | y | Exit node for Function split_bool1 |
 | b_condition.py:88 | x | ControlFlowNode for x |