Since lambdas are represented by callable objects, we need to adjust addr space of implicit obj parameter.
This patch suggests to use __generic for OpenCL mode. Then any lambda variable declared in __constant addr space (which is not convertible to __generic) would fail to compile with a diagnostic.
Towards generic C++ mode it might be better to just use add space from the lambda variable to qualify internal class member functions of lambda? However, I am not clear how to propagate the addr space since we are handling the initializers before the variable declaration. Alternatively it might make sense to just disallow qualifying lambdas with an addr space since they have internal compiler representation defined by the implementation.