QArrayDataOps: refactor appendInitialize

Instead of a manual loop, we can use std::uninitialized_value_construct.
QGenericArrayOps was using default construction, which is wrong:
appendInitalize is called from resize() and similar, so it must do value
initialization. Since the implementation between Pod and Generic ops is
now identical, centralize it in QArrayDataPointer.

Change-Id: I46c24886e1130daab79563d7f2f286ce2ba5984a
Reviewed-by: Thiago Macieira <[email protected]>
Reviewed-by: Fabian Kosmale <[email protected]>

src/corelib/tools/qarraydataops.h

@@ -38,20 +38,6 @@ struct QPodArrayOps
 
     using QArrayDataPointer<T>::QArrayDataPointer;
 
-    void appendInitialize(qsizetype newSize) noexcept
-    {
-        Q_ASSERT(this->isMutable());
-        Q_ASSERT(!this->isShared());
-        Q_ASSERT(newSize > this->size);
-        Q_ASSERT(newSize - this->size <= this->freeSpaceAtEnd());
-
-        T *where = this->end();
-        this->size = newSize;
-        const T *e = this->end();
-        while (where != e)
-            *where++ = T();
-    }
-
     void copyAppend(const T *b, const T *e) noexcept
     {
         Q_ASSERT(this->isMutable() || b == e);
@@ -293,19 +279,6 @@ struct QGenericArrayOps
 public:
     typedef typename QArrayDataPointer<T>::parameter_type parameter_type;
 
-    void appendInitialize(qsizetype newSize)
-    {
-        Q_ASSERT(this->isMutable());
-        Q_ASSERT(!this->isShared());
-        Q_ASSERT(newSize > this->size);
-        Q_ASSERT(newSize - this->size <= this->freeSpaceAtEnd());
-
-        T *const b = this->begin();
-        do {
-            new (b + this->size) T;
-        } while (++this->size != newSize);
-    }
-
     void copyAppend(const T *b, const T *e)
     {
         Q_ASSERT(this->isMutable() || b == e);

src/corelib/tools/qarraydatapointer.h

@@ -432,6 +432,19 @@ struct QArrayDataPointer
         return std::move(*this);
     }
 
+    void appendInitialize(qsizetype newSize)
+    {
+        Q_ASSERT(this->isMutable());
+        Q_ASSERT(!this->isShared());
+        Q_ASSERT(newSize > this->size);
+        Q_ASSERT(newSize - this->size <= this->freeSpaceAtEnd());
+
+        T *const b = this->begin() + this->size;
+        T *const e = this->begin() + newSize;
+        std::uninitialized_value_construct(b, e);
+        this->size = newSize;
+    }
+
     // forwards from QArrayData
     qsizetype allocatedCapacity() noexcept { return d ? d->allocatedCapacity() : 0; }
     qsizetype constAllocatedCapacity() const noexcept { return d ? d->constAllocatedCapacity() : 0; }