October 2018 - ghc-tickets

[GHC] #15752: Renaming `Pat` in `HsSyn` to `HsPat` for Consistency
by GHC 16 Oct '18

16 Oct '18

#15752: Renaming `Pat` in `HsSyn` to `HsPat` for Consistency -------------------------------------+------------------------------------- Reporter: Shayan-Najd | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15752> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15278: Add -Werror=compat, enable it in the testsuite
by GHC 16 Oct '18

16 Oct '18

#15278: Add -Werror=compat, enable it in the testsuite -------------------------------------+------------------------------------- Reporter: int-index | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.8.1 Component: Compiler | Version: Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- = Proposed change Add a flag `-Werror=compat` to GHC which would have the effect of `-Werror=x -Werror=y ...` where `x, y, ...` are warnings from `minusWcompatOpts`. Enable `-Wcompat -Werror=compat` in the testsuite. = Motivation 1. `-Werror=compat` would be a convenient shorthand to ensure forwards- compatibility of code. I can imagine Haskell libs enabling it on their CI. 2. Enabling `-Wcompat -Werror=compat` in the testsuite would allow us to easily see the impact that a new warning has on code. It also means that in the period between adding the warning and making the actual breaking change, all new test cases that are being added to the testsuite will be forwards-compatible. This is good because it will make the actual breaking change contain less irrelevant testsuite updates. The idea came up during my work on Phab:D4834 which defines a new warning and adds it to `-Wcompat`. Ryan Scott raised the following concern: > There are likely many tests in the testsuite that will now fail due to this change—I'm unclear if you're intending to fix them by explicitly quantifying their kind variables, or leaving the new error message as-is. My intention was to update the test cases, but it turned out that I couldn't even locate these test cases without `make EXTRA_HC_OPTS="-fwarn- implicit-kind-vars -Werror=implicit-kind-vars"`. And even if I updated the testsuite, nothing would prevent new test cases that are not forwards- compatible, because the warning isn't enabled by default (and without `-Werror=compat`, enabling `-Wcompat` would not cause test failures in all circumstances). = Implementation plan 1. Add new flags: `-Werror=compat`, `-Wno-error=compat`, `-Wwarn=compat`. 2. Document these flags in the User's Guide. 3. Enable `-Wcompat -Werror=compat` in the testsuite by default and fix all tests that break. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15278> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1: Implicit parameters cause strange behavi
by GHC 16 Oct '18

16 Oct '18

#1: Implicit parameters cause strange behavi --------------------------------+-------------------- Reporter: nobody | Owner: nobody Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 5.0 Resolution: Fixed | Keywords: Type of failure: None/Unknown | --------------------------------+-------------------- Comment (by Ben Gamari <ben@…>): In [changeset:"104599f3f157613589e78627c915e4dc20ee54b4/ghc" 104599f/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="104599f3f157613589e78627c915e4dc20ee54b4" Add a RTS option -xp to load PIC object anywhere in address space Add a RTS option -xp to load PIC object anywhere in address space. We do this by relaxing the requirement of <0x80000000 result of `mmapForLinker` and implying USE_CONTIGUOUS_MMAP. We also need to change calls to `ocInit` and `ocGetNames` to avoid dangling pointers when the address of `oc->image` is changed by `ocAllocateSymbolExtra`. Test Plan: ``` $ uname -a Linux localhost 4.18.8-arch1-1-ARCH #1 SMP PREEMPT Sat Sep 15 20:34:48 UTC 2018 x86_64 GNU/Linux $ cat mk/build.mk DYNAMIC_GHC_PROGRAMS = NO DYNAMIC_BY_DEFAULT = NO GhcRTSWays += thr_debug EXTRA_HC_OPTS += -debug WAY_p_HC_OPTS += -fPIC -fexternal-dynamic-refs $ inplace/bin/ghc-stage2 --interactive -prof +RTS -xp GHCi, version 8.7.20180928: http://www.haskell.org/ghc/ :? for help ghc-stage2: R_X86_64_32 relocation out of range: ghczmprim_GHCziTypes_ZMZN_closure = 7f690bffab59 Recompile /data/users/watashi/ghc/libraries/ghc-prim/dist-install/build/HSghc-prim -0.5.3.o with -fPIC -fexternal-dynamic-refs. ghc-stage2: unable to load package `ghc-prim-0.5.3' $ strace -f -e open,mmap inplace/bin/ghc-stage2 --interactive -prof -fexternal-interpreter -opti+RTS -opti-xp ... [pid 1355283] open("/data/users/watashi/ghc/libraries/base/dist-install/build/libHSbas e-4.12.0.0_p.a", O_RDONLY) = 14 [pid 1355283] mmap(NULL, 8192, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f6a84842000 [pid 1355283] open("/data/users/watashi/ghc/libraries/base/dist-install/build/libHSbas e-4.12.0.0_p.a", O_RDONLY) = 14 [pid 1355283] mmap(NULL, 8192, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f6a84676000 ... Prelude> System.Posix.Process.getProcessID ... [pid 1355283] open("/data/users/watashi/ghc/libraries/unix/dist-install/build/libHSuni x-2.7.2.2_p.a", O_RDONLY) = 14 [pid 1355283] mmap(NULL, 45056, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f6a67d60000 [pid 1355283] open("/data/users/watashi/ghc/libraries/unix/dist-install/build/libHSuni x-2.7.2.2_p.a", O_RDONLY) = 14 [pid 1355283] mmap(NULL, 57344, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f6a67d52000 ... ``` ``` $ uname -a Darwin watashis-iMac.local 18.0.0 Darwin Kernel Version 18.0.0: Wed Aug 22 20:13:40 PDT 2018; root:xnu-4903.201.2~1/RELEASE_X86_64 x86_64 $ mv /Users/watashi/gao/ghc/libraries/integer-gmp/dist-install/build/HSintege r-gmp-1.0.2.0.o{,._DISABLE_GHC_ISSUE_15105} $ inplace/bin/ghc-stage2 --interactive +RTS -xp GHCi, version 8.7.20181003: http://www.haskell.org/ghc/ :? for help Prelude> System.Posix.Process.getProcessID 42791 Prelude> Data.Set.fromList [1 .. 10] fromList [1,2,3,4,5,6,7,8,9,10] Prelude> Leaving GHCi. $ inplace/bin/ghc-stage2 --interactive -prof -fexternal-interpreter GHCi, version 8.7.20181003: http://www.haskell.org/ghc/ :? for help Prelude> System.Posix.Process.getProcessID 42806 Prelude> Data.Set.fromList [1 .. 10] fromList [1,2,3,4,5,6,7,8,9,10] Prelude> Leaving GHCi. ``` Also test with something that used to hit the 2Gb limit and it loads and runs without problem. Reviewers: simonmar, bgamari, angerman, Phyx, hvr, erikd Reviewed By: simonmar Subscribers: rwbarton, carter Differential Revision: https://phabricator.haskell.org/D5195 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1#comment:7> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13600: surprising error message with bang pattern
by GHC 15 Oct '18

15 Oct '18

#13600: surprising error message with bang pattern -------------------------------------+------------------------------------- Reporter: andrewufrank | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Keywords: | Operating System: Linux Architecture: x86_64 | Type of failure: Poor/confusing (amd64) | error message Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- the following code {{{ f3 :: [Int] -> IO Int f3 x = return (sum x) f4 :: [Int] -> IO Int f4 !x = return (sum x) }}} gives `The type signature for ‘f4’ lacks an accompanying binding` for the second function (the two functions are exactly the same except for the added bang). I do not understand bang patterns well, but would expect a more instructive error message. without the type definition, the second function f4 compiles with the bang). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13600> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15738: -ddump-splices omits required parentheses around quantified constraints
by GHC 15 Oct '18

15 Oct '18

#15738: -ddump-splices omits required parentheses around quantified constraints -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.8.1 Component: Template | Version: 8.6.1 Haskell | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- If you compile this program with `-ddump-splices`: {{{#!hs {-# LANGUAGE QuantifiedConstraints #-} {-# LANGUAGE TemplateHaskell #-} {-# OPTIONS_GHC -ddump-splices #-} module Bug where import Language.Haskell.TH data Foo x = MkFoo x $([d| f :: (forall a. Eq (Foo a)) => Foo x -> Foo x -> Bool f = (==) |]) }}} You'll notice something fishy: {{{ $ /opt/ghc/8.6.1/bin/ghci Bug.hs GHCi, version 8.6.1: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Bug.hs:(10,3)-(12,6): Splicing declarations [d| f_a1Ia :: (forall a_a1Ic. Eq (Foo a_a1Ic)) => Foo x_a1Ib -> Foo x_a1Ib -> Bool f_a1Ia = (==) |] ======> f_a5tj :: forall a_a5tk. Eq (Foo a_a5tk) => Foo x_a5ti -> Foo x_a5ti -> Bool f_a5tj = (==) Ok, one module loaded. }}} The signature for `f` gets pretty-printed as: {{{#!hs f_a5tj :: forall a_a5tk. Eq (Foo a_a5tk) => Foo x_a5ti -> Foo x_a5ti -> Bool }}} Which is just plain wrong—there is a missing set of parentheses around the quantified constraint `forall a_a5tk. Eq (Foo a_a5tk)`. Patch incoming. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15738> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12430: TypeFamilyDependencies accepts invalid injectivity annotation
by GHC 15 Oct '18

15 Oct '18

#12430: TypeFamilyDependencies accepts invalid injectivity annotation -------------------------------------+------------------------------------- Reporter: vagarenko | Owner: Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 8.0.1 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC accepts Unknown/Multiple | invalid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Consider this code (depends on singletons-2.2): {{{#!hs {-# LANGUAGE TypeFamilies, DataKinds, PolyKinds, TypeOperators, KindSignatures, TypeInType, TypeFamilyDependencies, UndecidableInstances #-} module Bug where import Data.Kind (Type) import Data.Singletons.Prelude (Map, SndSym0) import GHC.TypeLits (Nat) data Payload = A | B newtype NewType a = NewType Int type NatList = [(Nat, Payload)] type StripNatList (natList :: NatList) = Map SndSym0 natList type family Family (natList :: NatList) = (r :: Type) | r -> natList where Family '[] = () Family xs = NewType (StripNatList xs) }}} Why GHC is okay with injectivity annotation for `Family`: `r -> natList`? These two types: {{{#!hs type Foo = Family '[ '(0, 'A), '(1, 'B)] type Bar = Family '[ '(0, 'A), '(0, 'B)] }}} are obviously map to the same type: {{{#!hs *Bug Data.Singletons.Prelude> :kind! Foo Foo :: * = NewType ('A :$$$ '['B]) *Bug Data.Singletons.Prelude> :kind! Bar Bar :: * = NewType ('A :$$$ '['B]) }}} ---- If inline `StripNatList` inside `Family` definition: {{{#!hs type family Family (natList :: NatList) = (r :: Type) | r -> natList where Family '[] = () Family xs = NewType (Map SndSym0 xs) }}} or change `StripNatList` definition to type family: {{{#!hs type family StripNatList (natList :: NatList) where StripNatList '[] = '[] StripNatList ('(n, x) ': xs) = x ': StripNatList xs }}} compilation expectedly fails with `Type family equation violates injectivity annotation.` ---- Moreover, if I remove `NewType` from `Family` and change result kind: {{{#!hs type family Family (natList :: NatList) = (r :: [Payload]) | r -> natList where Family xs = StripNatList xs }}} it fails with correct error regardless of `StripNatList` definition. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12430> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14341: Show instance for TypeReps is a bit broken
by GHC 15 Oct '18

15 Oct '18

#14341: Show instance for TypeReps is a bit broken -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Core | Version: 8.2.1 Libraries | Keywords: Typeable | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): Phab:D4084 | Wiki Page: -------------------------------------+------------------------------------- There are two problems. 1. Showing typereps of tuples can produce unnecessary parentheses: {{{ Prelude K T> typeRep @(Int, Maybe Bool) (Int,(Maybe Bool)) }}} The fix is trivial. 2. Showing typereps of ticked (i.e., lifted) tuples and lists gives hard- to-read results, because it does not use the usual special syntax: {{{ Prelude K T> typeRep @'(Int, Maybe Bool) '(,) * * Int (Maybe Bool) Prelude K T> typeRep @'[1,2,3] ': Nat 1 (': Nat 2 (': Nat 3 ('[] Nat))) }}} Fixing the lifted tuple case is trivial. Fixing the lifted list case is slightly less trivial, but not hard. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14341> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15748: panic
by GHC 15 Oct '18

15 Oct '18

#15748: panic -------------------------------------+------------------------------------- Reporter: awf | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ GHCi, version 8.4.3: http://www.haskell.org/ghc/ :? for help Prelude> :print getChar >>= return ghc.exe: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-unknown-mingw32): isUnliftedType t1_a1tM[rt] :: TYPE t_a1tL[rt] Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler\utils\Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler\\types\\Type.hs:1939:10 in ghc:Type Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15748> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15750: Investigate haddock.base perf test
by GHC 15 Oct '18

15 Oct '18

#15750: Investigate haddock.base perf test -------------------------------------+------------------------------------- Reporter: goldfire | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Component: Test Suite | Version: 8.6.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I've seen failures in the `haddock.base` perf test when making changes that really should have no effect on performance. My guess is that this perf test is sitting right on the line of the acceptable range. We should confirm this hunch and then update the values to recenter the range. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15750> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15725: Core Lint error: Trans coercion mis-match
by GHC 15 Oct '18

15 Oct '18

#15725: Core Lint error: Trans coercion mis-match -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.8.1 Component: Compiler | Version: 8.6.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: #15703 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I discovered this when debugging #15703. The following code fails to compile with `-dcore-lint`: {{{#!hs {-# LANGUAGE DefaultSignatures #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeApplications #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeInType #-} {-# LANGUAGE TypeOperators #-} {-# LANGUAGE UndecidableInstances #-} module Bug where import Data.Functor.Identity (Identity(..)) import Data.Kind (Type) import GHC.Exts (Any) ----- -- The important bits ----- type instance Meth (x :: Identity a) = GenericMeth x instance SC Identity ------------------------------------------------------------------------------- data family Sing :: forall k. k -> Type data instance Sing :: forall a. Identity a -> Type where SIdentity :: Sing x -> Sing ('Identity x) newtype Par1 p = Par1 p data instance Sing :: forall p. Par1 p -> Type where SPar1 :: Sing x -> Sing ('Par1 x) type family Rep1 (f :: Type -> Type) :: Type -> Type class PGeneric1 (f :: Type -> Type) where type From1 (z :: f a) :: Rep1 f a type To1 (z :: Rep1 f a) :: f a class SGeneric1 (f :: Type -> Type) where sFrom1 :: forall (a :: Type) (z :: f a). Sing z -> Sing (From1 z) sTo1 :: forall (a :: Type) (r :: Rep1 f a). Sing r -> Sing (To1 r :: f a) type instance Rep1 Identity = Par1 instance PGeneric1 Identity where type From1 ('Identity x) = 'Par1 x type To1 ('Par1 x) = 'Identity x instance SGeneric1 Identity where sFrom1 (SIdentity x) = SPar1 x sTo1 (SPar1 x) = SIdentity x type family GenericMeth (x :: f a) :: f a where GenericMeth x = To1 (Meth (From1 x)) type family Meth (x :: f a) :: f a class SC f where sMeth :: forall a (x :: f a). Sing x -> Sing (Meth x) default sMeth :: forall a (x :: f a). ( SGeneric1 f, SC (Rep1 f) , Meth x ~ GenericMeth x ) => Sing x -> Sing (Meth x) sMeth sx = sTo1 (sMeth (sFrom1 sx)) dummy :: f a -> () dummy _ = () type instance Meth (x :: Par1 p) = x instance SC Par1 where sMeth x = x }}} {{{ $ /opt/ghc/8.6.1/bin/ghc -fforce-recomp Bug.hs -dcore-lint [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) *** Core Lint errors : in result of Simplifier *** <no location info>: warning: [in body of letrec with binders x_s1Nw :: Sing (From1 x_a1Jc)] Trans coercion mis-match: D:R:Rep1Identity[0] <a_a1Jb>_N ; Sym (Sym (D:R:Rep1Identity[0]) <a_a1Jb>_N) Rep1 Identity a_a1Jb Par1 a_a1Jb Rep1 Identity a_a1Jb Par1 a_a1Jb *** Offending Program *** <elided> $csMeth_a1J9 [Occ=LoopBreaker] :: forall a (x :: Identity a). Sing x -> Sing (Meth x) [LclId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=False, ConLike=False, WorkFree=False, Expandable=False, Guidance=IF_ARGS [] 100 60}] $csMeth_a1J9 = \ (@ a_a1Jb) (@ (x_a1Jc :: Identity a_a1Jb)) -> case heq_sel @ (Identity a_a1Jb) @ (Identity a_a1Jb) @ (Meth x_a1Jc) @ (GenericMeth x_a1Jc) (($d~_s1Nz @ a_a1Jb @ x_a1Jc) `cast` (((~) <Identity a_a1Jb>_N ((To1 <Identity>_N <a_a1Jb>_N (Coh (Sym (D:R:MethTYPEPar1px[0] <a_a1Jb>_N (Coh (Sym (Coh <From1 x_a1Jc>_N (D:R:Rep1Identity[0] <a_a1Jb>_N))) (D:R:Rep1Identity[0] <a_a1Jb>_N)))) (Sym (D:R:Rep1Identity[0]) <a_a1Jb>_N) ; (Meth <*>_N (Sym (D:R:Rep1Identity[0])) <a_a1Jb>_N (Coh <From1 x_a1Jc>_N (D:R:Rep1Identity[0] <a_a1Jb>_N)))_N))_N ; (Sym (D:R:GenericMeth[0] <Identity>_N <a_a1Jb>_N <x_a1Jc>_N) ; Sym (D:R:MethTYPEIdentityax[0] <a_a1Jb>_N <x_a1Jc>_N))) ((To1 <Identity>_N <a_a1Jb>_N (Coh (Sym (Coh (Sym (Coh <From1 x_a1Jc>_N (D:R:Rep1Identity[0] <a_a1Jb>_N))) (D:R:Rep1Identity[0] <a_a1Jb>_N))) (Sym (D:R:Rep1Identity[0]) <a_a1Jb>_N) ; (Sym (D:R:MethTYPEPar1px[0] <a_a1Jb>_N (Coh (Sym (Coh <From1 x_a1Jc>_N (D:R:Rep1Identity[0] <a_a1Jb>_N))) (D:R:Rep1Identity[0] <a_a1Jb>_N))) ; (Meth <*>_N (Sym (D:R:Rep1Identity[0])) <a_a1Jb>_N (Coh <From1 x_a1Jc>_N (D:R:Rep1Identity[0] <a_a1Jb>_N)))_N)))_N ; Sym (D:R:GenericMeth[0] <Identity>_N <a_a1Jb>_N <x_a1Jc>_N)))_R ; N:~[0] <Identity a_a1Jb>_N <Meth x_a1Jc>_N <GenericMeth x_a1Jc>_N :: (To1 (From1 x_a1Jc) ~ To1 (From1 x_a1Jc)) ~R# (Meth x_a1Jc ~~ GenericMeth x_a1Jc))) of co_a1Kd { __DEFAULT -> (\ (sx_aEZ :: Sing x_a1Jc) -> let { x_s1Nw :: Sing (From1 x_a1Jc) [LclId] x_s1Nw = $csFrom1_a1Jz @ a_a1Jb @ x_a1Jc sx_aEZ } in case x_s1Nw `cast` ((Sing (D:R:Rep1Identity[0] <a_a1Jb>_N) (Coh (Sym (Coh <From1 x_a1Jc>_N (D:R:Rep1Identity[0] <a_a1Jb>_N ; Sym (Sym (D:R:Rep1Identity[0]) <a_a1Jb>_N)))) (Sym (D:R:Rep1Identity[0]) <a_a1Jb>_N)))_R ; (Nth:3 (Inst (forall (x :: Sym (D:R:Rep1Identity[0]) <a_a1Jb>_N). (Sing (Sym (D:R:Rep1Identity[0]) <a_a1Jb>_N) (Sym (Coh <x>_N (Sym (D:R:Rep1Identity[0]) <a_a1Jb>_N))))_R ->_R (Sing (Sym (D:R:Rep1Identity[0]) <a_a1Jb>_N) (Sym (D:R:MethTYPEPar1px[0] <a_a1Jb>_N <x>_N) ; (Meth <*>_N (Sym (D:R:Rep1Identity[0])) <a_a1Jb>_N (Sym (Coh <x>_N (Sym (D:R:Rep1Identity[0]) <a_a1Jb>_N))))_N))_R) (Coh <From1 x_a1Jc>_N (Sym (Sym (D:R:Rep1Identity[0]) <a_a1Jb>_N)))) ; ((Sing (D:R:Rep1Identity[0] <a_a1Jb>_N))_R ; D:R:SingPar10[0] <a_a1Jb>_N) (Sym (Coh <Meth (From1 x_a1Jc)>_N (D:R:Rep1Identity[0] <a_a1Jb>_N)))) :: Sing (From1 x_a1Jc |> Sym (D:R:Rep1Identity[0]) <a_a1Jb>_N) ~R# R:SingPar1 a_a1Jb (Meth (From1 x_a1Jc) |> D:R:Rep1Identity[0] <a_a1Jb>_N)) of { SPar1 @ x_a1JZ co_a1K0 x_a195 -> ($WSIdentity @ a_a1Jb @ x_a1JZ x_a195) `cast` ((Sing <Identity a_a1Jb>_N (Sym (D:R:To1IdentityaPar1[0] <a_a1Jb>_N <x_a1JZ>_N) ; (To1 <Identity>_N <a_a1Jb>_N (Sym (Coh (Sym (Coh <'Par1 x_a1JZ>_N (Sym (D:R:Rep1Identity[0]) <a_a1Jb>_N))) (Sym (D:R:Rep1Identity[0]) <a_a1Jb>_N)) ; (Coh <'Par1 x_a1JZ>_N (Sym (D:R:Rep1Identity[0]) <a_a1Jb>_N) ; (Sym co_a1K0 ; Coh <Meth (From1 x_a1Jc)>_N (D:R:Rep1Identity[0] <a_a1Jb>_N)))))_N))_R :: Sing ('Identity x_a1JZ) ~R# Sing (To1 (Meth (From1 x_a1Jc)))) }) `cast` (<Sing x_a1Jc>_R ->_R (Sing <Identity a_a1Jb>_N (Sym (D:R:GenericMeth[0] <Identity>_N <a_a1Jb>_N <x_a1Jc>_N) ; Sym co_a1Kd))_R :: (Sing x_a1Jc -> Sing (To1 (Meth (From1 x_a1Jc)))) ~R# (Sing x_a1Jc -> Sing (Meth x_a1Jc))) } end Rec } }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15725> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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