Trying to quote and splice a polymorphic function doesn't work unless you have a type signature.

{-# LANGUAGE TemplateHaskell #-}
module A where

foo1 x = x

test_foo = [|| foo1 ||]

{-# LANGUAGE TemplateHaskell #-}
module B where

import A

qux = $$(test_foo)

The type of qux is Any -> Any! Which is clearly wrong.

Adding a type signature to qux fixes the problem.

qux :: a -> a
qux = $$(test_foo)

Either there should be a better error or this should just work.

It seems that this has always been broken. Ryan tested on GHC 7.8.4 for me.