#14175: Panic repSplitTyConApp_maybe -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.2.2 Component: Compiler (Type | Version: 8.2.1 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: #13910 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * related: => #13910 Comment: On HEAD, this gives a slightly different panic: {{{ $ ghc5/inplace/bin/ghc-stage2 --interactive Bug.hs GHCi, version 8.3.20170818: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Whoops ( Bug.hs, interpreted ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.3.20170818 for x86_64-unknown-linux): getRuntimeRep j_a1tG[sk:1] :: k_a1tJ[tau:1] Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1142:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:1982:18 in ghc:Type }}} This is a characteristic that it shares with the program in #13910. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14175#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14175: Panic repSplitTyConApp_maybe -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.2.2 Component: Compiler (Type | Version: 8.2.1 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: #13910 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): Thanks. I have a fix for this on my laptop. Not quite daring to push during ICFP lest I break something (alghoug it validates). With the fix I get {{{ T14175a.hs:11:15: error: Not in scope: type variable k | 11 | data CD :: (k -> *) -> (k -> *) -> * | ^ T14175a.hs:11:27: error: Not in scope: type variable k | 11 | data CD :: (k -> *) -> (k -> *) -> * | ^ }}} for comment:1 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14175#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14175: Panic repSplitTyConApp_maybe -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.2.2 Component: Compiler (Type | Version: 8.2.1 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: #13910 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): After my fix I get this for comment:4 {{{ c:/code/HEAD/inplace/bin/ghc-stage1 -c T14175b.hs T14175b.hs:13:3: error: Expected kind (k1 -> *) -> * , but CD k (a :: k -> *) :: (k -> *) -> * has kind k1 -> * In the data instance declaration for CD In the instance declaration for C (Maybe a) | 13 | data CD k (a :: k -> *) :: (k -> *) -> * | ^^^^^^^^^^^^^^^^^^^^^^^ }}} That looks pretty weird too. But at least neither crashes, which is the first thing. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14175#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14175: Panic repSplitTyConApp_maybe -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.2.2 Component: Compiler (Type | Version: 8.2.1 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: #13910 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Simon Peyton Jones ): In [changeset:"8bf865d3db69c6f4a09f3e5e3880c087c0a7c7f0/ghc" 8bf865d3/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="8bf865d3db69c6f4a09f3e5e3880c087c0a7c7f0" Tidying could cause ill-kinded types I found (Trac #14175) that the tidying we do when reporting type error messages could cause a well-kinded type to become ill-kinded. Reason: we initialised the tidy-env with a completely un-zonked TidyEnv accumulated in the TcLclEnv as we come across lexical type-varialbe bindings. Solution: zonk them. But I ended up refactoring a bit: * Get rid of tcl_tidy :: TidyEnv altogether * Instead use tcl_bndrs :: TcBinderStack This used to contain only Ids, but now I've added those lexically scoped TyVars too. * Change names: TcIdBinderStack -> TcBinderStack TcIdBinder -> TcBinder extendTcIdBndrs -> extendTcBinderStack * Now tcInitTidyEnv can grab those TyVars from the tcl_bndrs, zonk, and tidy them. The only annoyance is that I had to add TcEnv.hs-boot, to break the recursion between the zonking code and the TrRnMonad functions like addErrTc that call tcInitTidyEnv. Tiresome, but in fact that file existed already. }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14175#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14175: Panic repSplitTyConApp_maybe -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: 8.2.2 Component: Compiler (Type | Version: 8.2.1 checker) | Resolution: fixed | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Compile-time | Test Case: indexed- crash or panic | types/should_fail/T14175 Blocked By: | Blocking: Related Tickets: #13910 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): After this patch, GHC HEAD gives this error for the program in comment:2: {{{ Bug.hs:11:3: error: • Expected kind ‘(k -> *) -> (k -> *) -> *’, but ‘CD :: (k -> *) -> (k -> *) -> *’ has kind ‘Maybe a -> Maybe a -> *’ • In the data instance declaration for ‘CD’ In the instance declaration for ‘C (Maybe a)’ | 11 | data CD :: (k -> *) -> (k -> *) -> * | ^^^^^^^ }}} And this error for the program in comment:4: {{{ Bug.hs:13:3: error: • Expected kind ‘(k -> *) -> *’, but ‘CD k (a :: k -> *) :: (k -> *) -> *’ has kind ‘k -> *’ • In the data instance declaration for ‘CD’ In the instance declaration for ‘C (Maybe a)’ | 13 | data CD k (a :: k -> *) :: (k -> *) -> * | ^^^^^^^^^^^^^^^^^^^^^^^ }}} As you observed, these error messages aren't great and could likely be improved. Should I open a separate ticket for this? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14175#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14175: Panic repSplitTyConApp_maybe -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: 8.2.2 Component: Compiler (Type | Version: 8.2.1 checker) | Resolution: fixed | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Compile-time | Test Case: indexed- crash or panic | types/should_fail/T14175 Blocked By: | Blocking: Related Tickets: #13910, #14230 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * related: #13910 => #13910, #14230 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14175#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler