Python: make compile again

also improve comment

Author: yoff

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

@@ -1531,7 +1531,7 @@ abstract class ParameterNodeImpl extends Node {
 class LambdaSelfReferenceNode extends ParameterNodeImpl, TLambdaSelfReferenceNode {
   private Function callable;
 
-  LambdaSelfReferenceNode() { 
+  LambdaSelfReferenceNode() {
     this = TLambdaSelfReferenceNode(callable) and
     // TODO: Remove this restriction when adding proper support for captured variables in the body of the function we generate for comprehensions
     exists(TFunction(callable))
@@ -1624,10 +1624,10 @@ private class SummaryPostUpdateNode extends FlowSummaryNode, PostUpdateNodeImpl
   override Node getPreUpdateNode() { result = pre }
 }
 
-private class CapturePostUpdateNode extends PostUpdateNodeImpl, CaptureNode {
-  private CaptureNode pre;
+private class SynthCapturePostUpdateNode extends PostUpdateNodeImpl, SynthCaptureNode {
+  private SynthCaptureNode pre;
 
-  CapturePostUpdateNode() {
+  SynthCapturePostUpdateNode() {
     VariableCapture::Flow::capturePostUpdateNode(this.getSynthesizedCaptureNode(),
       pre.getSynthesizedCaptureNode())
   }

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

@@ -392,12 +392,13 @@ module VariableCapture {
     ExprCfgNode() { isExpressionNode(this) }
   }
 
-  private predicate closureFlowStep(ExprCfgNode fromNode, ExprCfgNode toNode) {
-    // simpleAstFlowStep(e1, e2)
-    // or
+  private predicate closureFlowStep(ExprCfgNode nodeFrom, ExprCfgNode nodeTo) {
+    // TODO: Other languages have an extra case here looking like
+    //   simpleAstFlowStep(nodeFrom, nodeTo)
+    // we should investigate the potential benefit of adding that.
     exists(SsaVariable def |
-      def.getAUse() = e2 and
-      def.getAnUltimateDefinition().getDefinition().(DefinitionNode).getValue() = e1
+      def.getAUse() = nodeTo and
+      def.getAnUltimateDefinition().getDefinition().(DefinitionNode).getValue() = nodeFrom
     )
   }
 
@@ -492,7 +493,7 @@ module VariableCapture {
   module Flow = Shared::Flow<Location, CaptureInput>;
 
   private Flow::ClosureNode asClosureNode(Node n) {
-    result = n.(CaptureNode).getSynthesizedCaptureNode()
+    result = n.(SynthCaptureNode).getSynthesizedCaptureNode()
     or
     result.(Flow::ExprNode).getExpr() = n.(CfgNode).getNode()
     or
@@ -665,7 +666,7 @@ predicate simpleLocalFlowStep(Node nodeFrom, Node nodeTo) {
   or
   summaryFlowSteps(nodeFrom, nodeTo)
   or
-  variableCaptureFlowStep(nodeFrom, nodeTo)
+  variableCaptureLocalFlowStep(nodeFrom, nodeTo)
 }
 
 /**

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

@@ -481,17 +481,15 @@ class StarPatternElementNode extends Node, TStarPatternElementNode {
  * A synthesized data flow node representing a closure object that tracks
  * captured variables.
  */
-class CaptureNode extends Node, TCaptureNode {
+class SynthCaptureNode extends Node, TSynthCaptureNode {
   private VariableCapture::Flow::SynthesizedCaptureNode cn;
 
-  CaptureNode() { this = TCaptureNode(cn) }
+  SynthCaptureNode() { this = TSynthCaptureNode(cn) }
 
   /** Gets the `SynthesizedCaptureNode` that this node represents. */
   VariableCapture::Flow::SynthesizedCaptureNode getSynthesizedCaptureNode() { result = cn }
 
-  override Scope getScope() {
-    result = cn.getEnclosingCallable()
-  }
+  override Scope getScope() { result = cn.getEnclosingCallable() }
 
   override Location getLocation() { result = cn.getLocation() }