This way the construction of the default value of type `T`
can be delayed until it is really needed, which is useful,
for example when `T == std::string` and the default value comes
from a string literal, as the default value string would always
be constructed otherwise, even if not needed.
Signed-off-by: Barnabás Pőcze <pobrn@protonmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>