CPP: Use newer dataflow for the fix.

Author: geoffw0

cpp/ql/src/Critical/NewDelete.qll

@@ -3,6 +3,7 @@
  */
 import cpp
 import semmle.code.cpp.controlflow.SSA
+import semmle.code.cpp.dataflow.DataFlow
 
 /**
  * Holds if `alloc` is a use of `malloc` or `new`.  `kind` is
@@ -46,10 +47,9 @@ predicate allocExprOrIndirect(Expr alloc, string kind) {
     alloc.(FunctionCall).getTarget() = rtn.getEnclosingFunction() and
     (
       allocExprOrIndirect(rtn.getExpr(), kind) or
-      exists(SsaDefinition def, LocalScopeVariable v |
-        // alloc via SSA
-        allocExprOrIndirect(def.getAnUltimateDefiningValue(v), kind) and
-        rtn.getExpr() = def.getAUse(v)
+      exists(Expr e |
+        allocExprOrIndirect(e, kind) and
+        DataFlow::localFlow(DataFlow::exprNode(e), DataFlow::exprNode(rtn.getExpr()))
       )
     )
   )

cpp/ql/test/query-tests/Critical/NewFree/NewFreeMismatch.expected

@@ -6,6 +6,7 @@
 | test.cpp:91:3:91:11 | delete | There is a malloc/delete mismatch between this delete and the corresponding $@. | test.cpp:88:28:88:36 | call to my_malloc | malloc |
 | test.cpp:99:3:99:11 | call to my_delete | There is a malloc/delete mismatch between this delete and the corresponding $@. | test.cpp:96:28:96:33 | call to malloc | malloc |
 | test.cpp:138:2:138:9 | delete | There is a malloc/delete mismatch between this delete and the corresponding $@. | test.cpp:135:12:135:22 | call to my_malloc_2 | malloc |
+| test.cpp:155:2:155:9 | delete | There is a malloc/delete mismatch between this delete and the corresponding $@. | test.cpp:152:12:152:22 | call to my_malloc_3 | malloc |
 | test.cpp:232:2:232:9 | delete | There is a malloc/delete mismatch between this delete and the corresponding $@. | test.cpp:226:7:226:12 | call to malloc | malloc |
 | test.cpp:233:2:233:12 | delete[] | There is a malloc/delete mismatch between this delete[] and the corresponding $@. | test.cpp:226:7:226:12 | call to malloc | malloc |
 | test.cpp:235:2:235:5 | call to free | There is a new/free mismatch between this free and the corresponding $@. | test.cpp:227:7:227:13 | new | new |

cpp/ql/test/query-tests/Critical/NewFree/test.cpp

@@ -152,7 +152,7 @@ void test3()
 	void *b = my_malloc_3(10);
 
 	free(a); // GOOD
-	delete b; // BAD: malloc -> delete [NOT DETECTED]
+	delete b; // BAD: malloc -> delete
 }
 
 void test4(bool do_array_delete)