Swift: Get rid of the unnecessary parameter/argument position for the closure. Instead, we can just reuse the 'this' parameter and argument.

Author: MathiasVP

swift/ql/lib/codeql/swift/dataflow/internal/DataFlowDispatch.qll

@@ -293,14 +293,12 @@ private module Cached {
   newtype TArgumentPosition =
     TThisArgument() or
     // we rely on default exprs generated in the caller for ordering
-    TPositionalArgument(int n) { n = any(Argument arg).getIndex() } or
-    TClosureSelfArgument()
+    TPositionalArgument(int n) { n = any(Argument arg).getIndex() }
 
   cached
   newtype TParameterPosition =
     TThisParameter() or
-    TPositionalParameter(int n) { n = any(Argument arg).getIndex() } or
-    TClosureSelfParameter()
+    TPositionalParameter(int n) { n = any(Argument arg).getIndex() }
 }
 
 import Cached
@@ -333,10 +331,6 @@ class ThisParameterPosition extends ParameterPosition, TThisParameter {
   override string toString() { result = "this" }
 }
 
-class ClosureSelfParameter extends ParameterPosition, TClosureSelfParameter {
-  override string toString() { result = "{ ... }" }
-}
-
 /** An argument position. */
 class ArgumentPosition extends TArgumentPosition {
   /** Gets a textual representation of this position. */
@@ -353,18 +347,11 @@ class ThisArgumentPosition extends ArgumentPosition, TThisArgument {
   override string toString() { result = "this" }
 }
 
-class ClosureSelfArgument extends ArgumentPosition, TClosureSelfArgument {
-  override string toString() { result = "{ ... }" }
-}
-
 /** Holds if arguments at position `apos` match parameters at position `ppos`. */
 pragma[inline]
 predicate parameterMatch(ParameterPosition ppos, ArgumentPosition apos) {
   ppos instanceof TThisParameter and
   apos instanceof TThisArgument
   or
   ppos.(PositionalParameterPosition).getIndex() = apos.(PositionalArgumentPosition).getIndex()
-  or
-  ppos instanceof TClosureSelfParameter and
-  apos instanceof TClosureSelfArgument
 }

swift/ql/lib/codeql/swift/dataflow/internal/DataFlowPrivate.qll

@@ -422,7 +422,7 @@ private module ParameterNodes {
   class ClosureSelfParameterNode extends ParameterNodeImpl, ClosureSelfReferenceNode {
     override predicate isParameterOf(DataFlowCallable c, ParameterPosition pos) {
       c.asSourceCallable() = this.getClosure() and
-      pos instanceof ClosureSelfParameter
+      pos instanceof TThisParameter
     }
   }
 
@@ -649,7 +649,7 @@ private module ArgumentNodes {
     override predicate argumentOf(DataFlowCall call, ArgumentPosition pos) {
       apply = call.asCall() and
       not exists(apply.getStaticTarget()) and
-      pos instanceof ClosureSelfArgument
+      pos instanceof ThisArgumentPosition
     }
   }
 }