QVarLengthArray: fix appending an already-contained item

Like the lvalue QVector::append() overload, when we reallocate,
we need to take a copy of the function's argument because the
reference will get stale upon reallocation.

Add a test.

[ChangeLog][QtCore][QVarLengthArray] Fixed a bug involving
appending an item already in the container to the container
again.

Change-Id: I06eeed6cb383dd5924e47a302bb3d1666d04c8e8
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 0e3d6fe4f69955bf98e23a382caf5251e2b47ea0)

1 files changed, 15 insertions, 2 deletions

diff --git a/tests/auto/corelib/tools/qvarlengtharray/tst_qvarlengtharray.cpp b/tests/auto/corelib/tools/qvarlengtharray/tst_qvarlengtharray.cpp
index 82f78b2b0b..466b7a3ac4 100644
--- a/tests/auto/corelib/tools/qvarlengtharray/tst_qvarlengtharray.cpp
+++ b/tests/auto/corelib/tools/qvarlengtharray/tst_qvarlengtharray.cpp
@@ -82,8 +82,21 @@ struct Foo
 
 void tst_QVarLengthArray::append()
 {
-    QVarLengthArray<QString> v;
-    v.append(QString("hello"));
+    QVarLengthArray<QString, 2> v;
+    v.append(QString("1"));
+    v.append(v.front());
+    QCOMPARE(v.capacity(), 2);
+    // transition from prealloc to heap:
+    v.append(v.front());
+    QVERIFY(v.capacity() > 2);
+    QCOMPARE(v.front(), v.back());
+    while (v.size() < v.capacity())
+        v.push_back(v[0]);
+    QCOMPARE(v.back(), v.front());
+    QCOMPARE(v.size(), v.capacity());
+    // transition from heap to larger heap:
+    v.push_back(v.front());
+    QCOMPARE(v.back(), v.front());
 
     QVarLengthArray<int> v2; // rocket!
     v2.append(5);