#16312: Optimization + adding an INLINE pragma triggers Core Lint error (Type of case alternatives not the same as the annotation on case) -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Here's a seemingly innocuous program, minimized from the `kan-extensions` library: {{{#!hs {-# LANGUAGE GADTs #-} {-# LANGUAGE RankNTypes #-} module Bug where newtype Curried g h a = Curried { runCurried :: forall r. g (a -> r) -> h r } instance Functor g => Functor (Curried g h) where fmap f (Curried g) = Curried (g . fmap (.f)) instance (Functor g, g ~ h) => Applicative (Curried g h) where pure a = Curried (fmap ($a)) Curried mf <*> Curried ma = Curried (ma . mf . fmap (.)) {-# INLINE (<*>) #-} -- The Core Lint error goes away if you remove this INLINE pragma }}} However, it triggers a Core Lint error on GHC 8.2.2 through HEAD if you compile it with `-O` and `-dcore-lint`: {{{ $ /opt/ghc/8.6.3/bin/ghc -fforce-recomp -dcore-lint Bug.hs -O [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) *** Core Lint errors : in result of Simplifier *** <no location info>: warning: In the expression: (case heq_sel @ (* -> *) @ (* -> *) @ h_a1eC @ h_a1eC ($d~_a1eE `cast` (((~) <* -> *>_N co_a1hx <h_a1eC>_N)_R ; N:~[0] <* -> *>_N <h_a1eC>_N <h_a1eC>_N :: (g_a1eB ~ h_a1eC) ~R# (h_a1eC ~~ h_a1eC))) of co_X1ij { __DEFAULT -> (\ (@ a_a1fg) (@ b_a1fh) (ds_d1yw :: Curried h_a1eC h_a1eC (a_a1fg -> b_a1fh)) (ds_d1yx :: Curried h_a1eC h_a1eC a_a1fg) (@ r_a1fn) -> let { g_X1zi :: h_a1eC (b_a1fh -> r_a1fn) -> h_a1eC ((a_a1fg -> b_a1fh) -> a_a1fg -> r_a1fn) [LclId, Unf=Unf{Src=<vanilla>, TopLvl=False, Value=False, ConLike=False, WorkFree=False, Expandable=False, Guidance=IF_ARGS [] 30 0}] g_X1zi = fmap @ h_a1eC ($dFunctor_a1eD `cast` ((Functor co_a1hx)_R :: Functor g_a1eB ~R# Functor h_a1eC)) @ (b_a1fh -> r_a1fn) @ ((a_a1fg -> b_a1fh) -> a_a1fg -> r_a1fn) (. @ b_a1fh @ r_a1fn @ a_a1fg) } in \ (x_X1zn :: h_a1eC (b_a1fh -> r_a1fn)) -> (ds_d1yx `cast` (N:Curried[0] <h_a1eC>_R <h_a1eC>_R <a_a1fg>_N :: Curried h_a1eC h_a1eC a_a1fg ~R# (forall r. h_a1eC (a_a1fg -> r) -> h_a1eC r))) @ r_a1fn ((ds_d1yw `cast` (N:Curried[0] <h_a1eC>_R <h_a1eC>_R <a_a1fg -> b_a1fh>_N :: Curried h_a1eC h_a1eC (a_a1fg -> b_a1fh) ~R# (forall r. h_a1eC ((a_a1fg -> b_a1fh) -> r) -> h_a1eC r))) @ (a_a1fg -> r_a1fn) (g_X1zi x_X1zn))) `cast` (forall (a :: <*>_N) (b :: <*>_N). <Curried h_a1eC h_a1eC (a -> b)>_R ->_R <Curried h_a1eC h_a1eC a>_R ->_R Sym (N:Curried[0] <h_a1eC>_R <h_a1eC>_R <b>_N) :: (forall a b. Curried h_a1eC h_a1eC (a -> b) -> Curried h_a1eC h_a1eC a -> forall r. h_a1eC (b -> r) -> h_a1eC r) ~R# (forall a b. Curried h_a1eC h_a1eC (a -> b) -> Curried h_a1eC h_a1eC a -> Curried h_a1eC h_a1eC b)) }) @ b_a1gi @ b_a1gi ((<$ @ (Curried g_a1eB h_a1eC) ($dFunctor_s1zH `cast` ((Functor (Curried (Sym co_a1hx) <h_a1eC>_N)_N)_R :: Functor (Curried h_a1eC h_a1eC) ~R# Functor (Curried g_a1eB h_a1eC))) @ (b_a1gi -> b_a1gi) @ a_a1gh (breakpoint @ b_a1gi) a1_a1z1) `cast` (Sym (Curried (Sub (Sym co_a1hx)) <h_a1eC>_R <b_a1gi -> b_a1gi>_N)_R :: Curried g_a1eB h_a1eC (b_a1gi -> b_a1gi) ~R# Curried h_a1eC h_a1eC (b_a1gi -> b_a1gi))) (a2_a1z2 `cast` (Sym (Curried (Sub (Sym co_a1hx)) <h_a1eC>_R <b_a1gi>_N)_R :: Curried g_a1eB h_a1eC b_a1gi ~R# Curried h_a1eC h_a1eC b_a1gi)) Type of case alternatives not the same as the annotation on case: Actual type: forall a b. Curried h_a1eC h_a1eC (a -> b) -> Curried h_a1eC h_a1eC a -> Curried h_a1eC h_a1eC b Annotation on case: forall a b. Curried g_a1eB h_a1eC (a -> b) -> Curried g_a1eB h_a1eC a -> Curried g_a1eB h_a1eC b }}} The size of the `-dcore-lint` output is enormous, so I'll post it separately as an attachment. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16312> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler