Logging not disabled

nolog.hs

{-# LANGUAGE GeneralizedNewtypeDeriving, FlexibleInstances, OverloadedStrings, UndecidableInstances #-}

import Control.Monad.Logger
import Control.Monad.Trans
import Control.Monad.Trans.Identity
import Data.Coerce

class Monad m => MonadFoo m where
  foo :: m ()

newtype FooT m a = FooT (IdentityT m a)
  deriving (Functor, Applicative, Monad, MonadTrans, MonadLogger)

runFooT :: FooT m a -> m a
runFooT = coerce

instance MonadLogger m => MonadFoo (FooT m) where
  foo = lift (logErrorN "Logging active")

instance {-# OVERLAPPABLE #-} (MonadFoo m, MonadTrans t, Monad (t m)) => MonadFoo (t m) where
  foo = lift foo

main = runStdoutLoggingT $ runFooT $ do
  logInfoN "Stdout logging, message displayed"
  foo
  runNoLoggingT $ do
    logInfoN "No logging, this message not displayed"
    foo

ghci> :main
[Info] Stdout logging, message displayed
[Error] Logging active
[Error] Logging active