Because of issue #1394 and because the semantic are not properly defined
currently, we decided that future version of slint should always and only
take the binding from the right hand side, even if it has no bindings.
Since we can't change the behavior in 0.2, just add a warning instead for now.
The warning can be silenced by setting a default binding for the property on the rhs.
Ignoring the warning can still lead to panic (the one in #1394)
NOTE: This library is an internal crate of the Slint project.
This crate should not be used directly by applications using Slint.
You should use the slint crate instead.
WARNING: This crate does not follow the semver convention for versioning and can
only be used with version = "=x.y.z" in Cargo.toml.