QCollator: enable move semantics

This necessitates adding d==0 checks in QCollator. By documenting that
moved-from instances can only be assigned to or destroyed, we can
limit the functions in which to check for d==0 to the assignment
operator and the destructor.

Doing otherwise would destroy all advantages of move semantics by
introducing a heap allocation to re-populate other.d.

Add a test for this (QCollator didn't have any before).

Change-Id: Ic6ff202072822bebfd5e48259c3d0fa345a63118
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/corelib/tools/qcollator.h b/src/corelib/tools/qcollator.h
index e5abc91967..1007aa7623 100644
--- a/src/corelib/tools/qcollator.h
+++ b/src/corelib/tools/qcollator.h
@@ -85,6 +85,12 @@ public:
     QCollator(const QCollator &);
     ~QCollator();
     QCollator &operator=(const QCollator &);
+#ifdef Q_COMPILER_RVALUE_REFS
+    QCollator(QCollator &&other)
+        : d(other.d) { other.d = 0; }
+    QCollator &operator=(QCollator &&other)
+    { swap(other); return *this; }
+#endif
 
     void swap(QCollator &other)
     { qSwap(d, other.d); }