[GHC] #13932: GHCi dumps "panic!" ("initTc: unsolved constraints")

GHC ghc-devs at haskell.org
Fri Jul 7 01:55:01 UTC 2017


#13932: GHCi dumps "panic!" ("initTc: unsolved constraints")
--------------------------------------+-------------------------------
           Reporter:  aiya000         |             Owner:  (none)
               Type:  bug             |            Status:  new
           Priority:  normal          |         Milestone:
          Component:  Compiler        |           Version:  8.0.1
           Keywords:  ghci            |  Operating System:  Linux
       Architecture:  x86_64 (amd64)  |   Type of failure:  GHCi crash
          Test Case:                  |        Blocked By:
           Blocking:                  |   Related Tickets:
Differential Rev(s):                  |         Wiki Page:
--------------------------------------+-------------------------------
 Hi, I'm Japanese.


 I'm developping https://github.com/aiya000/hs-zuramaru now :)

 A problem is happend in https://github.com/aiya000/hs-
 zuramaru/commit/79b850167537afe9efa4f812ef6ce02ec129630c !

 ghci says

 {{{
 [7 of 9] Compiling Maru.Main        ( /home/aiya000/Repository/hs-
 zuramaru/src/Maru/Main.hs, inte
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.2 for x86_64-unknown-linux):
         initTc: unsolved constraints
   WC {wc_insol =
         [W] makeLensesWith_amym :: t_amyl[tau:1] (CHoleCan:
 makeLensesWith)
         [W] .~_amyv :: t_amyu[tau:1] (CHoleCan: .~)
         [W] &_amyE :: t_amyD[tau:1] (CHoleCan: &)
         [W] lensRules_amyL :: t_amyK[tau:1] (CHoleCan: lensRules)}

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
 }}}

 (This is shorten message, I'll write full message to last line)


 It maybe happened after I introduced extensible-effects and microlens
 (microlens-th, microlens-mtl),
 and used it.

 I cannot understand details of the problem x(


 My linux distribution is

 {{{
 $ uname -a
 Linux BlueAloha 4.6.0-1-surfacepro3 #1 SMP PREEMPT Wed Apr 5 14:12:33 JST
 2017 x86_64 GNU/Linux
 }}}



 Below line is the full message of ghci

 {{{
 No extra-dep setting found for package at URL:

 https://github.com/aiya000/hs-throwable-exceptions.git

 This is usually a mistake, external packages should typically
 be treated as extra-deps to avoid spurious test case failures.
 No extra-dep setting found for package at URL:

 https://github.com/aiya000/hs-throwable-exceptions.git

 This is usually a mistake, external packages should typically
 be treated as extra-deps to avoid spurious test case failures.
 No extra-dep setting found for package at URL:

 https://github.com/aiya000/hs-throwable-exceptions.git

 This is usually a mistake, external packages should typically
 be treated as extra-deps to avoid spurious test case failures.
 No extra-dep setting found for package at URL:

 https://github.com/aiya000/hs-throwable-exceptions.git

 This is usually a mistake, external packages should typically
 be treated as extra-deps to avoid spurious test case failures.
 zuramaru-0.1.0.0: initial-build-steps (lib + exe)
 Log files have been written to: /home/aiya000/Repository/hs-zuramaru
 /.stack-work/logs/
 The following GHC options are incompatible with GHCi and have not been
 passed to it: -threaded
 Configuring GHCi with the following packages: zuramaru, throwable-
 exceptions
 Using main module: 1. Package `zuramaru' component exe:maru with main-is
 file: /home/aiya000/Repository/hs-zuramaru/app/Main.hs
 GHCi, version 8.0.2: http://www.haskell.org/ghc/  :? for help
 Loaded GHCi configuration from /home/aiya000/.dotfiles/.ghci
 [1 of 7] Compiling Maru.Type.SExpr  ( /home/aiya000/Repository/hs-
 zuramaru/src/Maru/Type/SExpr.hs, interpreted )
 [2 of 7] Compiling Maru.Type.Parser ( /home/aiya000/Repository/hs-
 zuramaru/src/Maru/Type/Parser.hs, interpreted )
 /home/aiya000/Repository/hs-zuramaru/src/Maru/Type/Parser.hs:46:1-22:
 Splicing declarations
     makeLenses ''MaruState
   ======>
     parseLogs :: Lens.Micro.Type.Lens' MaruState [ParseLog]
     parseLogs f_ahmF (MaruState x_ahmG x_ahmH)
       = fmap (\ y_ahmI -> MaruState y_ahmI x_ahmH) (f_ahmF x_ahmG)
     {-# INLINE parseLogs #-}
     parseNestLevel :: Lens.Micro.Type.Lens' MaruState Int
     parseNestLevel f_ahmJ (MaruState x_ahmK x_ahmL)
       = fmap (\ y_ahmM -> MaruState x_ahmK y_ahmM) (f_ahmJ x_ahmL)
     {-# INLINE parseNestLevel #-}
 [3 of 7] Compiling Maru.Type        ( /home/aiya000/Repository/hs-
 zuramaru/src/Maru/Type.hs, interpreted )
 [4 of 7] Compiling Maru.Parser      ( /home/aiya000/Repository/hs-
 zuramaru/src/Maru/Parser.hs, interpreted )
 [5 of 7] Compiling Control.Exception.Throwable.TH (
 /home/aiya000/Repository/hs-zuramaru/.stack-
 work/downloaded/iT3mDZWO7QnR/src/Control/Exception/Throwable/TH.hs,
 interpreted )
 [6 of 7] Compiling Maru.Eval        ( /home/aiya000/Repository/hs-
 zuramaru/src/Maru/Eval.hs, interpreted )
 /home/aiya000/Repository/hs-zuramaru/src/Maru/Eval.hs:29:1-66: Splicing
 declarations
     declareException "NoSuchSymbolException" ["NoSuchSymbolException"]
   ======>
     data NoSuchSymbolException a_akj2
       = NoSuchSymbolException {noSuchSymbolExceptionCause :: String,
                                noSuchSymbolExceptionClue :: a_akj2}
     instance Show a_akj3 => Show (NoSuchSymbolException a_akj3) where
       show (NoSuchSymbolException cause_akj4 _)
         = ("NoSuchSymbolException: " ++ (show cause_akj4))
     instance (Typeable a_akj5, Show a_akj5) =>
              Exception (NoSuchSymbolException a_akj5)
     noSuchSymbolException :: String -> NoSuchSymbolException ()
     noSuchSymbolException x_akj6 = NoSuchSymbolException x_akj6 ()

 /home/aiya000/Repository/hs-zuramaru/src/Maru/Eval.hs:41:1: warning:
 [-Worphans]
     Orphan instance:
       instance (Monoid a, Monad m) => MonadFail (EitherT a m)
     To avoid this
         move the instance declaration to the module of the class or of the
 type, or
         wrap the type with a newtype and declare the instance on the new
 type.

 /home/aiya000/Repository/hs-zuramaru/src/Maru/Eval.hs:106:24: warning:
 [-Wunused-matches]
     Defined but not used: ‘x’

 /home/aiya000/Repository/hs-zuramaru/src/Maru/Eval.hs:109:13: warning:
 [-Wunused-local-binds]
     Defined but not used: ‘val’
 [7 of 7] Compiling Maru.Main        ( /home/aiya000/Repository/hs-
 zuramaru/src/Maru/Main.hs, interpreted )
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.2 for x86_64-unknown-linux):
         initTc: unsolved constraints
   WC {wc_insol =
         [W] makeLensesWith_amlb :: t_amla[tau:1] (CHoleCan:
 makeLensesWith)
         [W] .~_amlk :: t_amlj[tau:1] (CHoleCan: .~)
         [W] &_amlt :: t_amls[tau:1] (CHoleCan: &)
         [W] lensRules_amlA :: t_amlz[tau:1] (CHoleCan: lensRules)}

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

 [7 of 8] Compiling Maru.Main        ( /home/aiya000/Repository/hs-
 zuramaru/src/Maru/Main.hs, inte
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.2 for x86_64-unknown-linux):
         initTc: unsolved constraints
   WC {wc_insol =
         [W] makeLensesWith_amsk :: t_amsj[tau:1] (CHoleCan:
 makeLensesWith)
         [W] .~_amst :: t_amss[tau:1] (CHoleCan: .~)
         [W] &_amsC :: t_amsB[tau:1] (CHoleCan: &)
         [W] lensRules_amsJ :: t_amsI[tau:1] (CHoleCan: lensRules)}

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

 [7 of 9] Compiling Maru.Main        ( /home/aiya000/Repository/hs-
 zuramaru/src/Maru/Main.hs, inte
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.2 for x86_64-unknown-linux):
         initTc: unsolved constraints
   WC {wc_insol =
         [W] makeLensesWith_amym :: t_amyl[tau:1] (CHoleCan:
 makeLensesWith)
         [W] .~_amyv :: t_amyu[tau:1] (CHoleCan: .~)
         [W] &_amyE :: t_amyD[tau:1] (CHoleCan: &)
         [W] lensRules_amyL :: t_amyK[tau:1] (CHoleCan: lensRules)}

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug


 <no location info>: error:
     Could not find module ‘Control.Exception.Throwable’
     It is a member of the hidden package ‘throwable-exceptions-0.1.0.8
 @throwable-exceptions-0.1.0
 Loaded GHCi configuration from /tmp/ghci30810/ghci-script
 Prelude Data.Text Data.Char Language.Haskell.TH T TIO>
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13932>
GHC <http://www.haskell.org/ghc/>
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