d026fad3d962eed0119351cd37f34490e09153fd added converting constructors for QPointer. This however made converting _assignments_ ambiguous, introducing a regression for users coming from Qt < 6.6. This code: QPointer<Base> base; QPointer<Derived> derived; base = derived; used to convert `derived` to `Derived *` (using the implicit conversion operator from `QPointer<Derived>` to `Derived *`), and then the assignment operator for `QPointer<Base>` that took a `Base *`. The introduction of the conversion constructor in 6.6 makes it possible to convert `QPointer<Derived>` to `QPointer<Base>`, and then fall back to the compiler-generated assignment operator for `QPointer<Base>`. The result is that the code above is now ambiguous and stops compiling. Fix this by adding a converting assignment operator for QPointer. I'm only adding the const-lvalue overload because the implementation requires going through the private QWeakPointer::assign helper. We cannot copy-assign or move-assign the inner QWeakPointer, as those assignments require lock()ing the QWeakPointer and that's not possible on a QObject-tracking QWeakPointer (but cf. QTBUG-117483). Assigning from a rvalue QPointer would mean calling assign() on the internal QWeakPointer _and_ clear the incoming QPointer, and that's strictly worse than the lvalue overload (where we just call assign()). Change-Id: I33fb2a22b3d5110284d78e3d7c6cc79a5b73b67b Pick-to: 6.6 6.6.0 Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>