C++: Fix ThisParameterNode after IR changes

Author: rdmarsh2

cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll

@@ -162,11 +162,7 @@ class ExprNode extends InstructionNode {
  * as `x` in `f(x)` and implicit parameters such as `this` in `x.f()`
  */
 class ParameterNode extends InstructionNode {
-  ParameterNode() {
-    instr instanceof InitializeParameterInstruction
-    or
-    instr instanceof InitializeThisInstruction
-  }
+  override InitializeParameterInstruction instr;
 
   /**
    * Holds if this node is the parameter of `c` at the specified (zero-based)
@@ -180,7 +176,9 @@ class ParameterNode extends InstructionNode {
  * flow graph.
  */
 private class ExplicitParameterNode extends ParameterNode {
-  override InitializeParameterInstruction instr;
+  ExplicitParameterNode() {
+    exists(instr.getParameter())
+  }
 
   override predicate isParameterOf(Function f, int i) { f.getParameter(i) = instr.getParameter() }
 
@@ -191,7 +189,9 @@ private class ExplicitParameterNode extends ParameterNode {
 }
 
 private class ThisParameterNode extends ParameterNode {
-  override InitializeThisInstruction instr;
+  ThisParameterNode() {
+    instr.getIRVariable() instanceof IRThisVariable
+  }
 
   override predicate isParameterOf(Function f, int i) {
     i = -1 and instr.getEnclosingFunction() = f

cpp/ql/test/library-tests/dataflow/dataflow-tests/dataflow-ir-consistency.expected

@@ -19,9 +19,7 @@ uniqueNodeLocation
 missingLocation
 | Nodes without location: 4 |
 uniqueNodeToString
-| lambdas.cpp:2:6:2:9 | (no string representation) | Node should have one toString but has 0. |
 missingToString
-| Nodes without toString: 1 |
 parameterCallable
 localFlowIsLocal
 compatibleTypesReflexive

cpp/ql/test/library-tests/dataflow/dataflow-tests/test_diff.expected

@@ -40,7 +40,6 @@
 | test.cpp:347:17:347:22 | test.cpp:349:10:349:18 | AST only |
 | test.cpp:359:13:359:18 | test.cpp:365:10:365:14 | AST only |
 | test.cpp:373:13:373:18 | test.cpp:369:10:369:14 | AST only |
-| test.cpp:373:13:373:18 | test.cpp:375:10:375:14 | AST only |
 | test.cpp:399:7:399:9 | test.cpp:401:8:401:10 | AST only |
 | test.cpp:405:7:405:9 | test.cpp:408:8:408:10 | AST only |
 | test.cpp:416:7:416:11 | test.cpp:418:8:418:12 | AST only |

cpp/ql/test/library-tests/dataflow/dataflow-tests/test_ir.expected

@@ -65,6 +65,7 @@
 | test.cpp:266:12:266:12 | x | test.cpp:265:22:265:27 | call to source |
 | test.cpp:289:14:289:14 | x | test.cpp:305:17:305:22 | call to source |
 | test.cpp:318:7:318:7 | x | test.cpp:314:4:314:9 | call to source |
+| test.cpp:375:10:375:14 | field | test.cpp:373:13:373:18 | call to source |
 | test.cpp:385:8:385:10 | tmp | test.cpp:382:48:382:54 | source1 |
 | test.cpp:392:8:392:10 | tmp | test.cpp:388:53:388:59 | source1 |
 | test.cpp:394:10:394:12 | tmp | test.cpp:388:53:388:59 | source1 |

cpp/ql/test/library-tests/dataflow/fields/dataflow-ir-consistency.expected

@@ -2,6 +2,7 @@ uniqueEnclosingCallable
 uniqueTypeBound
 | by_reference.cpp:106:21:106:41 | Chi | Node should have one type bound but has 2. |
 | by_reference.cpp:126:21:126:40 | Chi | Node should have one type bound but has 2. |
+| file://:0:0:0:0 | Chi | Node should have one type bound but has 2. |
 uniqueTypeRepr
 uniqueNodeLocation
 | D.cpp:1:17:1:17 | o | Node should have one location but has 3. |