[GHC] #15598: RebindableSyntax with RankNTypes and type class method call yields panic.
#15598: RebindableSyntax with RankNTypes and type class method call yields panic. -------------------------------------+------------------------------------- Reporter: romanb | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.3 Keywords: | Operating System: Linux RebindableSyntax, RankNTypes | Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The following program in a file `ghc-panic.hs` {{{ {-# LANGUAGE GADTSyntax , RankNTypes , RebindableSyntax #-} import Prelude hiding ((>>=)) data InfDo where InfDo :: String -> (forall a. a -> InfDo) -> InfDo prog :: InfDo prog = do _ <- show (42 :: Int) prog where (>>=) = InfDo main :: IO () main = let x = prog in x `seq` return () }}} when loaded into GHCi yields {{{ λ> main ghc: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-unknown-linux): nameModule system $dShow_abfY Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/basicTypes/Name.hs:241:3 in ghc:Name }}} and separate compilation yields {{{ $ ghc ghc-panic.hs [1 of 1] Compiling Main ( ghc-panic.hs, ghc-panic.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-unknown-linux): StgCmmEnv: variable not found $dShow_a1qI local binds for: $tcInfDo $trModule $tcInfDo1_r1th $tcInfDo2_r1tH $trModule1_r1tI $trModule2_r1tJ $trModule3_r1tK $trModule4_r1tL sat_s1E4 Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/codeGen/StgCmmEnv.hs:149:9 in ghc:StgCmmEnv }}} The problem disappears when either the rank-2 type is removed from `InfDo` or when the call to `show` is replaced by a static string. Besides 8.4.3, also reproduced with 8.6.0.20180714 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15598 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#15598: RebindableSyntax with RankNTypes and type class method call yields panic. -------------------------------------+------------------------------------- Reporter: romanb | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.3 Resolution: | Keywords: | RebindableSyntax, RankNTypes Operating System: Linux | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by romanb: Old description:
The following program in a file `ghc-panic.hs`
{{{
{-# LANGUAGE GADTSyntax , RankNTypes , RebindableSyntax #-}
import Prelude hiding ((>>=))
data InfDo where InfDo :: String -> (forall a. a -> InfDo) -> InfDo
prog :: InfDo prog = do _ <- show (42 :: Int) prog where (>>=) = InfDo
main :: IO () main = let x = prog in x `seq` return () }}}
when loaded into GHCi yields
{{{ λ> main ghc: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-unknown-linux): nameModule system $dShow_abfY Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/basicTypes/Name.hs:241:3 in ghc:Name }}}
and separate compilation yields
{{{ $ ghc ghc-panic.hs [1 of 1] Compiling Main ( ghc-panic.hs, ghc-panic.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-unknown-linux): StgCmmEnv: variable not found $dShow_a1qI local binds for: $tcInfDo $trModule $tcInfDo1_r1th $tcInfDo2_r1tH $trModule1_r1tI $trModule2_r1tJ $trModule3_r1tK $trModule4_r1tL sat_s1E4 Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/codeGen/StgCmmEnv.hs:149:9 in ghc:StgCmmEnv }}}
The problem disappears when either the rank-2 type is removed from `InfDo` or when the call to `show` is replaced by a static string.
Besides 8.4.3, also reproduced with 8.6.0.20180714
New description: The following program in a file `ghc-panic.hs` {{{#!hs {-# LANGUAGE GADTSyntax , RankNTypes , RebindableSyntax #-} import Prelude hiding ((>>=)) data InfDo where InfDo :: String -> (forall a. a -> InfDo) -> InfDo prog :: InfDo prog = do _ <- show (42 :: Int) prog where (>>=) = InfDo main :: IO () main = let x = prog in x `seq` return () }}} when loaded into GHCi yields {{{ λ> main ghc: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-unknown-linux): nameModule system $dShow_abfY Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/basicTypes/Name.hs:241:3 in ghc:Name }}} and separate compilation yields {{{ $ ghc ghc-panic.hs [1 of 1] Compiling Main ( ghc-panic.hs, ghc-panic.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-unknown-linux): StgCmmEnv: variable not found $dShow_a1qI local binds for: $tcInfDo $trModule $tcInfDo1_r1th $tcInfDo2_r1tH $trModule1_r1tI $trModule2_r1tJ $trModule3_r1tK $trModule4_r1tL sat_s1E4 Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/codeGen/StgCmmEnv.hs:149:9 in ghc:StgCmmEnv }}} The problem disappears when either the rank-2 type is removed from `InfDo` or when the call to `show` is replaced by a static string. Besides 8.4.3, also reproduced with 8.6.0.20180714 -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15598#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#15598: RebindableSyntax with RankNTypes and type class method call yields panic. -------------------------------------+------------------------------------- Reporter: romanb | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.3 Resolution: | Keywords: | RebindableSyntax, RankNTypes Operating System: Linux | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: 14963 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by romanb): * related: => 14963 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15598#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#15598: RebindableSyntax with RankNTypes and type class method call yields panic. -------------------------------------+------------------------------------- Reporter: romanb | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.3 Resolution: | Keywords: | RebindableSyntax, RankNTypes Operating System: Linux | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: 14963 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by romanb: Old description:
The following program in a file `ghc-panic.hs`
{{{#!hs
{-# LANGUAGE GADTSyntax , RankNTypes , RebindableSyntax #-}
import Prelude hiding ((>>=))
data InfDo where InfDo :: String -> (forall a. a -> InfDo) -> InfDo
prog :: InfDo prog = do _ <- show (42 :: Int) prog where (>>=) = InfDo
main :: IO () main = let x = prog in x `seq` return () }}}
when loaded into GHCi yields
{{{ λ> main ghc: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-unknown-linux): nameModule system $dShow_abfY Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/basicTypes/Name.hs:241:3 in ghc:Name }}}
and separate compilation yields
{{{ $ ghc ghc-panic.hs [1 of 1] Compiling Main ( ghc-panic.hs, ghc-panic.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-unknown-linux): StgCmmEnv: variable not found $dShow_a1qI local binds for: $tcInfDo $trModule $tcInfDo1_r1th $tcInfDo2_r1tH $trModule1_r1tI $trModule2_r1tJ $trModule3_r1tK $trModule4_r1tL sat_s1E4 Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/codeGen/StgCmmEnv.hs:149:9 in ghc:StgCmmEnv }}}
The problem disappears when either the rank-2 type is removed from `InfDo` or when the call to `show` is replaced by a static string.
Besides 8.4.3, also reproduced with 8.6.0.20180714
New description: The following program in a file `ghc-panic.hs` {{{#!hs {-# LANGUAGE GADTSyntax , RankNTypes , RebindableSyntax #-} import Prelude hiding ((>>=)) data InfDo where InfDo :: String -> (forall a. a -> InfDo) -> InfDo prog :: InfDo prog = do _ <- show (42 :: Int) prog where (>>=) = InfDo main :: IO () main = let x = prog in x `seq` return () }}} when loaded into GHCi yields {{{ λ> main ghc: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-unknown-linux): nameModule system $dShow_abfY Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/basicTypes/Name.hs:241:3 in ghc:Name }}} and separate compilation yields {{{ $ ghc ghc-panic.hs [1 of 1] Compiling Main ( ghc-panic.hs, ghc-panic.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-unknown-linux): StgCmmEnv: variable not found $dShow_a1qI local binds for: $tcInfDo $trModule $tcInfDo1_r1th $tcInfDo2_r1tH $trModule1_r1tI $trModule2_r1tJ $trModule3_r1tK $trModule4_r1tL sat_s1E4 Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/codeGen/StgCmmEnv.hs:149:9 in ghc:StgCmmEnv }}} The problem disappears when either the rank-2 type is removed from `InfDo` or when the call to `show` is replaced by a static string. Besides 8.4.3, also reproduced with 8.6.0.20180714. I believe it is somewhat related to [https://ghc.haskell.org/trac/ghc/ticket/14963] -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15598#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#15598: RebindableSyntax with RankNTypes and type class method call yields panic. -------------------------------------+------------------------------------- Reporter: romanb | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.3 Resolution: | Keywords: | RebindableSyntax, RankNTypes Operating System: Linux | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: 14963 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): I think you are right in connecting it with #14963. But your example here is nothing to do with GHCi, nor with `-fdefer-type-errors`, so it's helpful. Lint complains immediately {{{ *** Core Lint errors : in result of Desugar (before optimization) *** <no location info>: warning: In the expression: show @ Int $dShow_a1rx (I# 42#) $dShow_a1rx :: Show Int [LclId] is out of scope *** Offending Program *** Rec { $dMonad_a1rX :: Monad IO [LclId] $dMonad_a1rX = $fMonadIO $tcInfDo :: TyCon [LclIdX] $tcInfDo = TyCon 14827517540190131426## 17869035366104385648## $trModule (TrNameS "InfDo"#) 0# krep$* $trModule :: Module [LclIdX] $trModule = Module (TrNameS "main"#) (TrNameS "T15598"#) prog :: InfDo [LclIdX] prog = letrec { >>=_aW0 :: String -> (forall a. a -> InfDo) -> InfDo [LclId] >>=_aW0 = letrec { >>=_a1ri :: String -> (forall a. a -> InfDo) -> InfDo [LclId] >>=_a1ri = InfDo; } in >>=_a1ri; } in >>=_aW0 (show @ Int $dShow_a1rx (I# 42#)) (\ (@ a_a1rp) -> let { $dShow_a1rx :: Show Int [LclId] $dShow_a1rx = $fShowInt } in \ (ds_d1De :: a_a1rp) -> prog) main :: IO () [LclIdX] main = letrec { x_a1ca :: InfDo [LclId] x_a1ca = letrec { x_a1rI :: InfDo [LclId] x_a1rI = prog; } in x_a1rI; } in case x_a1ca of x_a1ca { __DEFAULT -> return @ IO $dMonad_a1rX @ () () } end Rec } *** End of Offense *** }}} This is pretty bad. It's all in `tcSyntaxOp`, I believe. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15598#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
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