Darwin: Remove QMacAutoReleasePool heap allocation detection

This is handled by the Objective-C runtime nowadays, where it will
abort if the situation is detected, with the option to break on
objc_autoreleasePoolInvalid to debug the situation.

Pick-to: 6.5
Change-Id: Idf2c4aacc77e41a3deebf270303f4f13cfb0819b
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

src/corelib/kernel/qcore_mac.mm

@@ -217,38 +217,7 @@ QT_USE_NAMESPACE
 @interface QT_MANGLE_NAMESPACE(QMacAutoReleasePoolTracker) : NSObject
 @end
 
-@implementation QT_MANGLE_NAMESPACE(QMacAutoReleasePoolTracker) {
-    NSAutoreleasePool **m_pool;
-}
-
-- (instancetype)initWithPool:(NSAutoreleasePool **)pool
-{
-    if ((self = [self init]))
-        m_pool = pool;
-    return self;
-}
-
-- (void)dealloc
-{
-    if (*m_pool) {
-        // The pool is still valid, which means we're not being drained from
-        // the corresponding QMacAutoReleasePool (see below).
-
-        // QMacAutoReleasePool has only a single member, the NSAutoreleasePool*
-        // so the address of that member is also the QMacAutoReleasePool itself.
-        QMacAutoReleasePool *pool = reinterpret_cast<QMacAutoReleasePool *>(m_pool);
-        qWarning() << "Premature drain of" << pool << "This can happen if you've allocated"
-            << "the pool on the heap, or as a member of a heap-allocated object. This is not a"
-            << "supported use of QMacAutoReleasePool, and might result in crashes when objects"
-            << "in the pool are deallocated and then used later on under the assumption they"
-            << "will be valid until" << pool << "has been drained.";
-
-        // Reset the pool so that it's not drained again later on
-        *m_pool = nullptr;
-    }
-
-    [super dealloc];
-}
+@implementation QT_MANGLE_NAMESPACE(QMacAutoReleasePoolTracker)
 @end
 QT_NAMESPACE_ALIAS_OBJC_CLASS(QMacAutoReleasePoolTracker);
 
@@ -291,28 +260,15 @@ QMacAutoReleasePool::QMacAutoReleasePool()
     }
 #endif
 
-    [[[trackerClass alloc] initWithPool:
-        reinterpret_cast<NSAutoreleasePool **>(&pool)] autorelease];
+    [[trackerClass new] autorelease];
 }
 
 QMacAutoReleasePool::~QMacAutoReleasePool()
 {
-    if (!pool) {
-        qWarning() << "Prematurely drained pool" << this << "finally drained. Any objects belonging"
-            << "to this pool have already been released, and have potentially been invalid since the"
-            << "premature drain earlier on.";
-        return;
-    }
-
-    // Save and reset pool before draining, so that the pool tracker can know
-    // that it's being drained by its owning pool.
-    NSAutoreleasePool *savedPool = static_cast<NSAutoreleasePool*>(pool);
-    pool = nullptr;
-
     // Drain behaves the same as release, with the advantage that
     // if we're ever used in a garbage-collected environment, the
     // drain acts as a hint to the garbage collector to collect.
-    [savedPool drain];
+    [static_cast<NSAutoreleasePool*>(pool) drain];
 }
 
 #ifndef QT_NO_DEBUG_STREAM

tests/auto/corelib/tools/qmacautoreleasepool/tst_qmacautoreleasepool.mm

@@ -14,7 +14,6 @@ private slots:
     void noPool();
     void rootLevelPool();
     void stackAllocatedPool();
-    void heapAllocatedPool();
 };
 
 static id lastDeallocedObject = nil;
@@ -63,26 +62,6 @@ void tst_QMacAutoreleasePool::stackAllocatedPool()
     [pool drain];
 }
 
-void tst_QMacAutoreleasePool::heapAllocatedPool()
-{
-    // The special case, a pool allocated on the heap, or as a member of a
-    // heap allocated object. This is not a supported use of QMacAutoReleasePool,
-    // and will result in warnings if the pool is prematurely drained.
-
-    NSObject *allocedObject = nil;
-    {
-        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
-        QMacAutoReleasePool *qtPool = nullptr;
-        {
-            qtPool = new QMacAutoReleasePool;
-            allocedObject = [[[DeallocTracker alloc] init] autorelease];
-        }
-        [pool drain];
-        delete qtPool;
-    }
-    QCOMPARE(lastDeallocedObject, allocedObject);
-}
-
 QTEST_APPLESS_MAIN(tst_QMacAutoreleasePool)
 
 #include "tst_qmacautoreleasepool.moc"