Merge pull request #1149 from jbj/resource-not-released-in-destructor-Qt

C++: Fix special-casing of Qt library in resource-not-released-in-destructor

Author: geoffw0

cpp/ql/src/jsf/4.10 Classes/AV Rule 79.ql

@@ -267,7 +267,7 @@ predicate automaticallyReleased(Assignment acquire)
 {
   // sub-types of the Qt type QObject are released by their parent (if they have one)
   exists(NewExpr alloc |
-    alloc.getType() = qtObject() and
+    alloc.getAllocatedType() = qtObject() and
     acquire.getRValue() = alloc and
     alloc.getInitializer() = qtParentConstructor().getACallToThisFunction()
   )

cpp/ql/test/query-tests/jsf/4.10 Classes/AV Rule 79/QObject.cpp

@@ -0,0 +1,25 @@
+struct QObject {
+  QObject(QObject *parent);
+  void setParent(QObject *parent);
+};
+
+struct DerivedFromQObject : public QObject {
+  DerivedFromQObject(QObject *parent);
+};
+
+class MyQtUser {
+  DerivedFromQObject *noParent, *constructorParent, *laterParent;
+
+  MyQtUser(QObject *parent) {
+    // This object sets its parent pointer to null and thus must be deleted
+    // manually.
+    noParent = new DerivedFromQObject(nullptr); // BAD [NOT DETECTED]
+
+    // This object does not need to be deleted because it will be deleted by
+    // its parent object when the time is right.
+    constructorParent = new DerivedFromQObject(parent); // GOOD
+
+    laterParent = new DerivedFromQObject(nullptr); // GOOD
+    laterParent->setParent(parent);
+  }
+};