T12531.hs:6:11: warning: [-Wtyped-holes (in -Wdefault)]
    • Found hole: _ :: Int#
    • In the first argument of ‘(+#)’, namely ‘_’
      In the first argument of ‘I#’, namely ‘(_ +# x)’
      In the expression: I# (_ +# x)
    • Relevant bindings include
        x :: Int# (bound at T12531.hs:6:3)
        f :: Int# -> Int (bound at T12531.hs:6:1)
      Valid substitutions include
        undefined :: forall (a :: TYPE r).
                     GHC.Stack.Types.HasCallStack =>
                     a
          (imported from ‘Prelude’ at T12531.hs:3:8-13
           (and originally defined in ‘GHC.Err’))