Default constructor value behavior change

[pemessier]

Since 5f17234 from @knatten , there is a behavior change as well, the underlying type initial value is not the same as before. For example, a POD like int or double would be initialized to 0 before this changeset which could be handy. Now it behaves like a POD by leaving the memory as-is, which is also correct. However this is a big behavior change.

Is there a way we could force the old behavior (prehaps using a new skill)?