Python: move restriction into branch predicate

Otherwise we get loads of nodes with missing locations
from the brnach nodes that are not matched.

Author: yoff

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

@@ -1534,11 +1534,7 @@ class SynthCapturingClosureParameterNode extends ParameterNodeImpl,
 {
   private Function callable;
 
-  SynthCapturingClosureParameterNode() {
-    this = TSynthCapturingClosureParameterNode(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))
-  }
+  SynthCapturingClosureParameterNode() { this = TSynthCapturingClosureParameterNode(callable) }
 
   final Function getCallable() { result = callable }
 
@@ -1661,15 +1657,14 @@ class CapturingClosureArgumentNode extends CfgNode, ArgumentNode {
   CallNode callNode;
 
   CapturingClosureArgumentNode() {
-    this.getNode() = callNode.getFunction() and
+    node = callNode.getFunction() and
     exists(Function target | resolveCall(callNode, target, _) |
       target = any(VariableCapture::CapturedVariable v).getACapturingScope()
     )
   }
 
   override string toString() { result = "Capturing closure argument" }
 
-  // final override Location getLocation() { result = callNode.getLocation() }
   override predicate argumentOf(DataFlowCall call, ArgumentPosition pos) {
     callNode = call.getNode() and
     pos.isLambdaSelf()

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

@@ -119,7 +119,9 @@ newtype TNode =
   TSynthCaptureNode(VariableCapture::Flow::SynthesizedCaptureNode cn) or
   /** A synthetic node representing the heap of a function. Used for variable capture. */
   TSynthCapturingClosureParameterNode(Function f) {
-    f = any(VariableCapture::CapturedVariable v).getACapturingScope()
+    f = any(VariableCapture::CapturedVariable v).getACapturingScope() and
+    // TODO: Remove this restriction when adding proper support for captured variables in the body of the function we generate for comprehensions
+    exists(TFunction(f))
   }
 
 private import semmle.python.internal.CachedStages