Add qHash() overload for QSet

...using qHashRangeCommutative(). Also add a test.

[ChangeLog][QtCore][QSet] Can now be used as the key in QSet, QHash.

Change-Id: Ie7c81d257a3b324fc03d394fa7c9fcf0c6fb062a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 20 insertions, 0 deletions

diff --git a/src/corelib/tools/qset.h b/src/corelib/tools/qset.h
index 662afbf84a..baa412a550 100644
--- a/src/corelib/tools/qset.h
+++ b/src/corelib/tools/qset.h
@@ -237,6 +237,15 @@ private:
     }
 };
 
+template <typename T>
+uint qHash(const QSet<T> &key, uint seed = 0)
+Q_DECL_NOEXCEPT_EXPR(noexcept(qHashRangeCommutative(key.begin(), key.end(), seed)))
+{
+    return qHashRangeCommutative(key.begin(), key.end(), seed);
+}
+
+// inline function implementations
+
 template <class T>
 Q_INLINE_TEMPLATE void QSet<T>::reserve(int asize) { q_hash.reserve(asize); }
 
diff --git a/src/corelib/tools/qset.qdoc b/src/corelib/tools/qset.qdoc
index ab7d72611e..73599a2a72 100644
--- a/src/corelib/tools/qset.qdoc
+++ b/src/corelib/tools/qset.qdoc
@@ -968,3 +968,14 @@
 
     \sa{Serializing Qt Data Types}{Format of the QDataStream operators}
 */
+
+/*!
+    \fn uint qHash(const QSet<T> &key, uint seed = 0)
+    \relates QHash
+    \since 5.5
+
+    Returns the hash value for the \a key, using \a seed to seed the calculation.
+
+    The hash value is independent of the order of elements in \a key, that is, sets
+    that contain the same elements hash to the same value.
+*/