demo: specify `HasCallStack` separately for different instance of same typeclass

test-typeclass-callstack.hs

{-# language InstanceSigs #-}

import GHC.Stack

class Next v where
    next :: HasCallStack => v -> v

instance Next Bool where
    next :: Bool -> Bool
    next x = if x < maxBound then not x else undefined

instance Next Int where
    next :: HasCallStack => Int -> Int
    next x = if x < maxBound then x + 1 else undefined

main :: IO ()
main = do
    --print (next maxBound :: Bool)
    print (next maxBound :: Int)