How to case split in monadic do block

case-split-in-do.hs

data Thing = A | B | C

getThing :: IO Thing
getThing = pure A

f :: Int -> IO ()
f i = do
    thing <- getThing
    -- TODO what can I do here to make the tactics plugin offer "case split" code action?
    case thing of
        -- This only gives code action to "Add EmptyCase" language extension..

try this:

f :: Int -> IO ()
f i = do
    thing <- getThing
    _

and then run the "Case split on thing" code action when hovering over the hole