#14393: Levity-polymorphic join point crashes 8.2 -------------------------------------+------------------------------------- Reporter: simonpj | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.2.2 Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by simonpj: Old description:

This program crashes both GHC 8.0 and 8.2 {{{ {-# LANGUAGE ViewPatterns, PatternSynonyms #-}

module Foo where

data PrimOp = AddOp | Add2Op | OtherOp | BotherOp

data Expr = Var PrimOp | App Expr Expr | BApp [Expr] | BOp Expr Expr | L Integer

pattern BinOpApp :: Expr -> PrimOp -> Expr -> Expr pattern BinOpApp x op y = Var op `App` x `App` y

pattern (:+:) :: Expr -> Expr -> Expr pattern x :+: y <- BinOpApp x (isAddOp -> True) y

isAddOp :: PrimOp -> Bool isAddOp AddOp = True isAddOp Add2Op = True isAddOp _ = False

pattern (:++:) :: Integer -> Expr -> Expr pattern l :++: x <- (isAdd -> Just (l,x))

isAdd :: Expr -> Maybe (Integer,Expr) {-# INLINE isAdd #-} isAdd e = case e of L l :+: x -> Just (l,x) x :+: L l -> Just (l,x) _ -> Nothing }}} Reason: the matching function, generated by the pattern synonym `:++:`, has a levity-polymorphic join point.

8.0 has a Lint Error. 8.2 crashes with {{{ (GHC version 8.2.1.20171024 for x86_64-unknown-linux): runtimeRepPrimRep typePrimRep (r_a1kX :: TYPE rep_a1kW) rep_a1kW Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1133:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1137:37 in ghc:Outputable pprPanic, called at compiler/simplStg/RepType.hs:360:5 in ghc:RepType runtimeRepPrimRep, called at compiler/simplStg/RepType.hs:342:5 in ghc:RepType kindPrimRep, called at compiler/simplStg/RepType.hs:305:18 in ghc:RepType typePrimRep, called at compiler/simplStg/RepType.hs:128:19 in ghc:RepType }}} I think this is just #13394, comment:4 again. It was fixed in comment:5 of that ticket, but the fix has not yet been transferred to 8.2.

New description: This program (derived from Phab:D2858) crashes both GHC 8.0 and 8.2 {{{ {-# LANGUAGE ViewPatterns, PatternSynonyms #-} module Foo where data PrimOp = AddOp | Add2Op | OtherOp | BotherOp data Expr = Var PrimOp | App Expr Expr | BApp [Expr] | BOp Expr Expr | L Integer pattern BinOpApp :: Expr -> PrimOp -> Expr -> Expr pattern BinOpApp x op y = Var op `App` x `App` y pattern (:+:) :: Expr -> Expr -> Expr pattern x :+: y <- BinOpApp x (isAddOp -> True) y isAddOp :: PrimOp -> Bool isAddOp AddOp = True isAddOp Add2Op = True isAddOp _ = False pattern (:++:) :: Integer -> Expr -> Expr pattern l :++: x <- (isAdd -> Just (l,x)) isAdd :: Expr -> Maybe (Integer,Expr) {-# INLINE isAdd #-} isAdd e = case e of L l :+: x -> Just (l,x) x :+: L l -> Just (l,x) _ -> Nothing }}} Reason: the matching function, generated by the pattern synonym `:++:`, has a levity-polymorphic join point. 8.0 has a Lint Error. 8.2 crashes with {{{ (GHC version 8.2.1.20171024 for x86_64-unknown-linux): runtimeRepPrimRep typePrimRep (r_a1kX :: TYPE rep_a1kW) rep_a1kW Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1133:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1137:37 in ghc:Outputable pprPanic, called at compiler/simplStg/RepType.hs:360:5 in ghc:RepType runtimeRepPrimRep, called at compiler/simplStg/RepType.hs:342:5 in ghc:RepType kindPrimRep, called at compiler/simplStg/RepType.hs:305:18 in ghc:RepType typePrimRep, called at compiler/simplStg/RepType.hs:128:19 in ghc:RepType }}} I think this is just #13394, comment:4 again. It was fixed in comment:5 of that ticket, but the fix has not yet been transferred to 8.2. -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14393#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler