QVarLengthArray: optimize pop_back()

Don't call realloc() with all its machinery when we know exactly what
to do: destroy the last element and decrease the size by one.

Extend the test, removing the unused Foo class for a new Tracker one.

Change-Id: I568eef4f6335669689fb16fd23af92cb4d6464bd
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/src/corelib/tools/qvarlengtharray.h b/src/corelib/tools/qvarlengtharray.h
index ba65ae7ef2..2f62526076 100644
--- a/src/corelib/tools/qvarlengtharray.h
+++ b/src/corelib/tools/qvarlengtharray.h
@@ -112,7 +112,9 @@ public:
 
     inline void removeLast() {
         Q_ASSERT(s > 0);
-        realloc(s - 1, a);
+        if (QTypeInfo<T>::isComplex)
+            ptr[s - 1].~T();
+        --s;
     }
     inline int size() const { return s; }
     inline int count() const { return s; }