Revert "Kotlin: Adjust ExtensionReceiverAccess.toString to not return hard coded this value"

This reverts commit 9649a8f.

Author: tamasvajk

java/ql/lib/semmle/code/java/Expr.qll

@@ -1894,18 +1894,16 @@ class VarAccess extends Expr, @varaccess {
  * An access to an extension receiver parameter. This is a parameter access that takes the form of `this` in Kotlin.
  */
 class ExtensionReceiverAccess extends VarAccess {
-  Parameter p;
-
   ExtensionReceiverAccess() {
-    this.getVariable() = p and
-    p.isExtensionParameter()
+    exists(Parameter p |
+      this.getVariable() = p and
+      p.isExtensionParameter()
+    )
   }
 
   override string getAPrimaryQlClass() { result = "ExtensionReceiverAccess" }
 
-  override string toString() {
-    if p.getName() = "<this>" then result = "this" else result = p.getName()
-  }
+  override string toString() { result = "this" }
 }
 
 /**

java/ql/test/kotlin/library-tests/methods/exprs.expected

@@ -306,10 +306,10 @@
 | methods3.kt:3:1:3:49 | fooBarTopLevelMethodExt(...) | MethodAccess |
 | methods3.kt:3:1:3:49 | int | TypeAccess |
 | methods3.kt:3:1:3:49 | int | TypeAccess |
-| methods3.kt:3:1:3:49 | p0 | ExtensionReceiverAccess |
 | methods3.kt:3:1:3:49 | p1 | VarAccess |
 | methods3.kt:3:1:3:49 | p1 | VarAccess |
 | methods3.kt:3:1:3:49 | p2 | VarAccess |
+| methods3.kt:3:1:3:49 | this | ExtensionReceiverAccess |
 | methods3.kt:3:5:3:10 | String | TypeAccess |
 | methods3.kt:3:36:3:45 | int | TypeAccess |
 | methods3.kt:3:45:3:45 | 1 | IntegerLiteral |
@@ -327,10 +327,10 @@
 | methods3.kt:6:5:6:45 | int | TypeAccess |
 | methods3.kt:6:5:6:45 | int | TypeAccess |
 | methods3.kt:6:5:6:45 | p0 | VarAccess |
-| methods3.kt:6:5:6:45 | p1 | ExtensionReceiverAccess |
 | methods3.kt:6:5:6:45 | p2 | VarAccess |
 | methods3.kt:6:5:6:45 | p2 | VarAccess |
 | methods3.kt:6:5:6:45 | p3 | VarAccess |
+| methods3.kt:6:5:6:45 | this | ExtensionReceiverAccess |
 | methods3.kt:6:9:6:14 | String | TypeAccess |
 | methods3.kt:6:32:6:41 | int | TypeAccess |
 | methods3.kt:6:41:6:41 | 1 | IntegerLiteral |

java/ql/test/kotlin/library-tests/parameter-defaults/PrintAst.expected

@@ -566,7 +566,7 @@ test.kt:
 #   19|         2: [ReturnStmt] return ...
 #   19|           0: [MethodAccess] f(...)
 #   19|             -1: [VarAccess] p0
-#   19|             0: [ExtensionReceiverAccess] p1
+#   19|             0: [ExtensionReceiverAccess] this
 #   19|             1: [VarAccess] p2
 #   19|             2: [VarAccess] p3
 #   19|             3: [VarAccess] p4
@@ -774,7 +774,7 @@ test.kt:
 #   56|         2: [ReturnStmt] return ...
 #   56|           0: [MethodAccess] test(...)
 #   56|             -1: [VarAccess] p0
-#   56|             0: [ExtensionReceiverAccess] p1
+#   56|             0: [ExtensionReceiverAccess] this
 #   56|             1: [VarAccess] p2
 #   56|             2: [VarAccess] p3
 #   56|             3: [VarAccess] p4