5 files changed, 19 insertions, 10 deletions
diff --git a/src/corelib/kernel/qeventdispatcher_unix.cpp b/src/corelib/kernel/qeventdispatcher_unix.cpp
index 64b813bb13..9afbb84abf 100644
--- a/src/corelib/kernel/qeventdispatcher_unix.cpp
+++ b/src/corelib/kernel/qeventdispatcher_unix.cpp
@@ -286,7 +286,7 @@ void QEventDispatcherUNIXPrivate::markPendingSocketNotifiers()
         }
     }
 
-    pollfds.resize(0);
+    pollfds.clear();
 }
 
 int QEventDispatcherUNIXPrivate::activateSocketNotifiers()
@@ -480,8 +480,8 @@ bool QEventDispatcherUNIX::processEvents(QEventLoop::ProcessEventsFlags flags)
     if (!canWait || (include_timers && d->timerList.timerWait(wait_tm)))
         tm = &wait_tm;
 
+    d->pollfds.clear();
     d->pollfds.reserve(1 + (include_notifiers ? d->socketNotifiers.size() : 0));
-    d->pollfds.resize(0);
 
     if (include_notifiers)
         for (auto it = d->socketNotifiers.cbegin(); it != d->socketNotifiers.cend(); ++it)
diff --git a/src/corelib/tools/qregexp.cpp b/src/corelib/tools/qregexp.cpp
index fd67193302..f8f3347786 100644
--- a/src/corelib/tools/qregexp.cpp
+++ b/src/corelib/tools/qregexp.cpp
@@ -2335,7 +2335,7 @@ QRegExpCharClass::QRegExpCharClass()
 void QRegExpCharClass::clear()
 {
     c = 0;
-    r.resize(0);
+    r.clear();
     n = false;
 }
 
diff --git a/src/corelib/tools/qvector.cpp b/src/corelib/tools/qvector.cpp
index b3247b8af5..ef1c9c17b0 100644
--- a/src/corelib/tools/qvector.cpp
+++ b/src/corelib/tools/qvector.cpp
@@ -502,8 +502,19 @@
 
 /*! \fn void QVector::clear()
 
-    Removes all the elements from the vector and releases the memory used by
-    the vector.
+    Removes all the elements from the vector.
+
+    \note Until Qt 5.6, this also released the memory used by
+    the vector. From Qt 5.7, the capacity is preserved. To shed
+    all capacity, swap with a default-constructed vector:
+    \code
+    QVector<T> v ...;
+    QVector<T>().swap(v);
+    Q_ASSERT(v.capacity() == 0);
+    \endcode
+    or call squeeze().
+
+    \sa squeeze()
 */
 
 /*! \fn const T &QVector::at(int i) const
diff --git a/src/corelib/tools/qvector.h b/src/corelib/tools/qvector.h
index d60be78ade..13ae121450 100644
--- a/src/corelib/tools/qvector.h
+++ b/src/corelib/tools/qvector.h
@@ -419,7 +419,7 @@ void QVector<T>::resize(int asize)
 }
 template <typename T>
 inline void QVector<T>::clear()
-{ *this = QVector<T>(); }
+{ resize(0); }
 template <typename T>
 inline const T &QVector<T>::at(int i) const
 { Q_ASSERT_X(i >= 0 && i < d->size, "QVector<T>::at", "index out of range");
diff --git a/src/corelib/xml/qxmlstream_p.h b/src/corelib/xml/qxmlstream_p.h
index 4c6c206bf3..ab0bbba413 100644
--- a/src/corelib/xml/qxmlstream_p.h
+++ b/src/corelib/xml/qxmlstream_p.h
@@ -1020,10 +1020,8 @@ bool QXmlStreamReaderPrivate::parse()
         prefix.clear();
         qualifiedName.clear();
         namespaceUri.clear();
-        if (publicNamespaceDeclarations.size())
-            publicNamespaceDeclarations.clear();
-        if (attributes.size())
-            attributes.resize(0);
+        publicNamespaceDeclarations.clear();
+        attributes.clear();
         if (isEmptyElement) {
             setType(QXmlStreamReader::EndElement);
             Tag &tag = tagStack_pop();