Improved qVariantSetValue by reusing the internals if possible

This is possible if the type is the same of type < Char (simple
types)

1 files changed, 12 insertions, 1 deletions

diff --git a/src/corelib/kernel/qvariant.h b/src/corelib/kernel/qvariant.h
index d7b7e3c..284e68c 100644
--- a/src/corelib/kernel/qvariant.h
+++ b/src/corelib/kernel/qvariant.h
@@ -443,7 +443,18 @@ inline QVariant qVariantFromValue(const QVariant &t) { return t; }
 template <typename T>
 inline void qVariantSetValue(QVariant &v, const T &t)
 {
-    v = QVariant(qMetaTypeId<T>(reinterpret_cast<T *>(0)), &t);
+    //if possible we reuse the current QVariant private
+    const int type = qMetaTypeId<T>(reinterpret_cast<T *>(0));
+    QVariant::Private &d = v.data_ptr();
+    if (type <= int(QVariant::Char) || (type == d.type && v.isDetached())) {
+        d.type = type;
+        T *old = reinterpret_cast<T*>(d.is_shared ? d.data.shared->ptr : &d.data.ptr);
+        if (QTypeInfo<T>::isComplex)
+            old->~T();
+        new (old) T(t); //call the copy constructor
+    } else {
+        v = QVariant(type, &t);
+    }
 }
 
 inline QVariant::QVariant() {}