module Bug where

import Data.Proxy

fun :: Proxy a -> ()
fun Proxy = ()

bug :: ()
bug = fun (Proxy :: Proxy Maybe)

[1 of 1] Compiling Bug              ( Bug.hs, Bug.o )

Bug.hs:9:12: error:
    • Expected kind ‘Proxy Maybe’,
        but ‘Data.Proxy.Proxy :: Proxy Maybe’ has kind ‘Proxy Maybe’
    • In the first argument of ‘fun’, namely ‘(Proxy :: Proxy Maybe)’
      In the expression: fun (Proxy :: Proxy Maybe)
      In an equation for ‘bug’: bug = fun (Proxy :: Proxy Maybe)

1. 10 gives the appropriate Couldn't match kind ‘* -> *’ with ‘*’ message.