Remove "delete value" from QSharedPointer

This allows a QSharedPointer to be used in contexts where the class in
question is still forward-declared. This produced a warning in Qt 4 due
to the expansion of the template, even if there was no chance of the
pointer being deleted there (because the reference count could not drop
to zero).

Now, not only is the warning removed, but you can actually have the
reference count drop to zero in a forward-declared class and it will
do the right thing. That's because the deleter function is always
recorded from the point of construction and we're sure that it wasn't
forward-declared.

The unit test for forward-declarations had to be rewritten. The
previous version was passing only because the QSharedPointer object
was created under the "tracking pointers" mode, which causes a custom
deleter to be used in all cases.

Task-number: QTBUG-25819
Change-Id: Ife37a4cea4551d94084b49ee03504dd39b8802c1
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
Reviewed-by: Bradley T. Hughes <bradley.hughes@nokia.com>

1 files changed, 16 insertions, 50 deletions

diff --git a/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp b/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
index 7c3f0e5415..b8cf0a7b78 100644
--- a/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
+++ b/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
@@ -1,6 +1,7 @@
 /****************************************************************************
 **
 ** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Copyright (C) 2012 Intel Corporation.
 ** Contact: http://www.qt-project.org/
 **
 ** This file is part of the test suite of the Qt Toolkit.
@@ -48,6 +49,7 @@
 #include <QtCore/QVector>
 
 #include "externaltests.h"
+#include "forwarddeclared.h"
 #include "wrapper.h"
 
 #include <stdlib.h>
@@ -68,9 +70,9 @@ private slots:
     void basics();
     void operators();
     void swap();
-    void forwardDeclaration1();
-    void forwardDeclaration2();
+    void useOfForwardDeclared();
     void memoryManagement();
+    void dropLastReferenceOfForwardDeclared();
     void downCast();
     void functionCallDownCast();
     void upCast();
@@ -341,43 +343,12 @@ void tst_QSharedPointer::swap()
     QVERIFY(*p1 == 42);
 }
 
-class ForwardDeclared;
-ForwardDeclared *forwardPointer();
-void externalForwardDeclaration();
-extern int forwardDeclaredDestructorRunCount;
-
-void tst_QSharedPointer::forwardDeclaration1()
+void tst_QSharedPointer::useOfForwardDeclared()
 {
-#if defined(Q_CC_SUN) || defined(Q_CC_WINSCW) || defined(Q_CC_RVCT)
-    QSKIP("This type of forward declaration is not valid with this compiler");
-#else
-    externalForwardDeclaration();
-
-    struct Wrapper { QSharedPointer<ForwardDeclared> pointer; };
-
-    forwardDeclaredDestructorRunCount = 0;
-    {
-        Wrapper w;
-        w.pointer = QSharedPointer<ForwardDeclared>(forwardPointer());
-        QVERIFY(!w.pointer.isNull());
-    }
-    QCOMPARE(forwardDeclaredDestructorRunCount, 1);
-#endif
+    // this just a compile test: use the forward-declared class
+    QSharedPointer<ForwardDeclared> sp;
 }
 
-#include "forwarddeclared.h"
-
-void tst_QSharedPointer::forwardDeclaration2()
-{
-    forwardDeclaredDestructorRunCount = 0;
-    {
-        struct Wrapper { QSharedPointer<ForwardDeclared> pointer; };
-        Wrapper w1, w2;
-        w1.pointer = QSharedPointer<ForwardDeclared>(forwardPointer());
-        QVERIFY(!w1.pointer.isNull());
-    }
-    QCOMPARE(forwardDeclaredDestructorRunCount, 1);
-}
 
 void tst_QSharedPointer::memoryManagement()
 {
@@ -444,6 +415,15 @@ void tst_QSharedPointer::memoryManagement()
     QCOMPARE(ptr.data(), (Data*)0);
 }
 
+void tst_QSharedPointer::dropLastReferenceOfForwardDeclared()
+{
+    // pointer to shared-pointer is weird, but we need to do it so that
+    // we can drop the last reference in a different .cpp than where it was created
+    forwardDeclaredDestructorRunCount = 0;
+    delete forwardPointer();
+    QCOMPARE(forwardDeclaredDestructorRunCount, 1);
+}
+
 class DerivedData: public Data
 {
 public:
@@ -1715,17 +1695,6 @@ void tst_QSharedPointer::invalidConstructs_data()
            "ptr = new Data;";
 
     // use of forward-declared class
-    QTest::newRow("forward-declaration")
-#ifdef Q_CC_CLANG
-        // Deleting a forward declaration is undefined, which results in a linker error with clang
-        << &QTest::QExternalTest::tryLinkFail
-#else
-        // Other compilers accept the code, but do not call the destructor at run-time
-        << &QTest::QExternalTest::tryRun
-#endif
-        << "forwardDeclaredDestructorRunCount = 0;\n"
-           "{ QSharedPointer<ForwardDeclared> ptr = QSharedPointer<ForwardDeclared>(forwardPointer()); }\n"
-           "exit(forwardDeclaredDestructorRunCount);";
     QTest::newRow("creating-forward-declaration")
         << &QTest::QExternalTest::tryCompileFail
         << "QSharedPointer<ForwardDeclared>::create();";
@@ -1839,7 +1808,6 @@ void tst_QSharedPointer::invalidConstructs()
 
     QTest::QExternalTest test;
     test.setQtModules(QTest::QExternalTest::QtCore);
-    test.setExtraProgramSources(QStringList() << QFINDTESTDATA("forwarddeclared.cpp"));
     test.setProgramHeader(
         "#define QT_SHAREDPOINTER_TRACK_POINTERS\n"
         "#define QT_DEBUG\n"
@@ -1849,9 +1817,7 @@ void tst_QSharedPointer::invalidConstructs()
         "struct Data { int i; };\n"
         "struct DerivedData: public Data { int j; };\n"
         "\n"
-        "extern int forwardDeclaredDestructorRunCount;\n"
         "class ForwardDeclared;\n"
-        "ForwardDeclared *forwardPointer();\n"
         );
 
     QFETCH(QString, code);