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Merge pull request #14417 from github/tausbn/python-add-flow-for-assignment-expressions
2 parents be16cb4 + 8e1bb4b commit f1266a3

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Lines changed: 46 additions & 9 deletions

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‎python/ql/lib/semmle/python/Flow.qll‎

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Original file line numberDiff line numberDiff line change
@@ -547,6 +547,31 @@ class IfExprNode extends ControlFlowNode {
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override IfExp getNode() { result = super.getNode() }
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}
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/** A control flow node corresponding to an assignment expression such as `lhs := rhs`. */
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class AssignmentExprNode extends ControlFlowNode {
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AssignmentExprNode() { toAst(this) instanceof AssignExpr }
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/** Gets the flow node corresponding to the left-hand side of the assignment expression */
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ControlFlowNode getTarget() {
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exists(AssignExpr a |
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this.getNode() = a and
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a.getTarget() = result.getNode() and
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result.getBasicBlock().dominates(this.getBasicBlock())
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)
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}
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/** Gets the flow node corresponding to the right-hand side of the assignment expression */
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ControlFlowNode getValue() {
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exists(AssignExpr a |
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this.getNode() = a and
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a.getValue() = result.getNode() and
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result.getBasicBlock().dominates(this.getBasicBlock())
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)
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}
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override AssignExpr getNode() { result = super.getNode() }
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}
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/** A control flow node corresponding to a binary expression, such as `x + y` */
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class BinaryExprNode extends ControlFlowNode {
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BinaryExprNode() { toAst(this) instanceof BinaryExpr }
@@ -630,6 +655,8 @@ class DefinitionNode extends ControlFlowNode {
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Stages::AST::ref() and
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exists(Assign a | a.getATarget().getAFlowNode() = this)
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or
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exists(AssignExpr a | a.getTarget().getAFlowNode() = this)
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or
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exists(AnnAssign a | a.getTarget().getAFlowNode() = this and exists(a.getValue()))
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or
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exists(Alias a | a.getAsname().getAFlowNode() = this)
@@ -787,6 +814,9 @@ private AstNode assigned_value(Expr lhs) {
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/* lhs = result */
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exists(Assign a | a.getATarget() = lhs and result = a.getValue())
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or
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/* lhs := result */
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exists(AssignExpr a | a.getTarget() = lhs and result = a.getValue())
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or
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/* lhs : annotation = result */
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exists(AnnAssign a | a.getTarget() = lhs and result = a.getValue())
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or

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

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@@ -357,6 +357,9 @@ module EssaFlow {
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// If expressions
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nodeFrom.asCfgNode() = nodeTo.asCfgNode().(IfExprNode).getAnOperand()
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or
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// Assignment expressions
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nodeFrom.asCfgNode() = nodeTo.asCfgNode().(AssignmentExprNode).getValue()
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or
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// boolean inline expressions such as `x or y` or `x and y`
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nodeFrom.asCfgNode() = nodeTo.asCfgNode().(BoolExprNode).getAnOperand()
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or

‎python/ql/test/experimental/dataflow/coverage/dataflow-consistency.expected‎

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Original file line numberDiff line numberDiff line change
@@ -33,10 +33,10 @@ identityLocalStep
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| test.py:167:13:167:18 | ControlFlowNode for SOURCE | Node steps to itself |
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| test.py:216:10:216:15 | ControlFlowNode for SOURCE | Node steps to itself |
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| test.py:242:9:242:12 | ControlFlowNode for SINK | Node steps to itself |
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| test.py:669:9:669:12 | ControlFlowNode for SINK | Node steps to itself |
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| test.py:670:9:670:14 | ControlFlowNode for SINK_F | Node steps to itself |
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| test.py:678:9:678:12 | ControlFlowNode for SINK | Node steps to itself |
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| test.py:686:9:686:12 | ControlFlowNode for SINK | Node steps to itself |
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| test.py:692:5:692:8 | ControlFlowNode for SINK | Node steps to itself |
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| test.py:673:9:673:12 | ControlFlowNode for SINK | Node steps to itself |
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| test.py:674:9:674:14 | ControlFlowNode for SINK_F | Node steps to itself |
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| test.py:682:9:682:12 | ControlFlowNode for SINK | Node steps to itself |
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| test.py:690:9:690:12 | ControlFlowNode for SINK | Node steps to itself |
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| test.py:696:5:696:8 | ControlFlowNode for SINK | Node steps to itself |
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missingArgumentCall
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multipleArgumentCall

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

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Original file line numberDiff line numberDiff line change
@@ -435,10 +435,14 @@ def test_and(x = True):
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# 6.12. Assignment expressions
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def test_assignment_expression():
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def test_assignment_expression_flow_lhs():
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x = NONSOURCE
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SINK(x := SOURCE) #$ MISSING:flow="SOURCE -> x"
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if x := SOURCE:
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SINK(x) #$ flow="SOURCE, l:-1 -> x"
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def test_assignment_expression_flow_out():
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x = NONSOURCE
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SINK(x := SOURCE) #$ flow="SOURCE -> AssignExpr"
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# 6.13. Conditional expressions
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def test_conditional_true():
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# Condition is evaluated first, so x is SOURCE once chosen
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def test_conditional_evaluation_true():
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x = NONSOURCE
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SINK(x if (SOURCE == (x := SOURCE)) else NONSOURCE) #$ MISSING:flow="SOURCE -> IfExp"
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SINK(x if (SOURCE == (x := SOURCE)) else NONSOURCE) #$ flow="SOURCE -> IfExp"
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# Condition is evaluated first, so x is SOURCE once chosen
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def test_conditional_evaluation_false():
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x = NONSOURCE
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SINK(NONSOURCE if (NONSOURCE == (x := SOURCE)) else x) #$ MISSING:flow="SOURCE -> IfExp"
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SINK(NONSOURCE if (NONSOURCE == (x := SOURCE)) else x) #$ flow="SOURCE -> IfExp"
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# 6.14. Lambdas

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