This patch provides the actual implementation to detect binding loops
in property setters.
These test will help to catch all the existing binding loops that were
introduced when migrating to new bindable properties.
The logic of the new tests is taken from
tst_QObject::objectNameBinding(), but generalized to be applicable to
all bindable properties.
The original code from tst_QObject can now be removed.
The patch effectively reverts f791570b86
because a lambda returning a nullptr now means that the binding loop
test should be skipped, which is not a good default behavior.
Now when all the existing bindable properties are fixed, it's fine to
give a compilation error when adding new tests, if the class is not
default-constructible.
Task-number: QTBUG-116345
Pick-to: 6.6 6.5
Change-Id: I059d444d4bb023c050a22e5b1974565e4f581b5c
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
f5a5c59918