GHC and GHCi dumps "panic!" ("initTc: unsolved constraints")

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>

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	GhciCrash
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
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