September 2015 - ghc-tickets

[GHC] #10404: GHC panic when creating a monomorphised pattern synonym for GADT
by GHC 23 Dec '15

23 Dec '15

#10404: GHC panic when creating a monomorphised pattern synonym for GADT -------------------------------------+------------------------------------- Reporter: | Owner: Iceland_jack | Status: new Type: bug | Milestone: Priority: normal | Version: 7.10.1-rc1 Component: Compiler | Operating System: Linux Keywords: | Type of failure: GHC rejects Architecture: x86 | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- I have an expression {{{#!hs {-# LANGUAGE GADTs #-} {-# LANGUAGE PatternSynonyms #-} data Exp a where Fun :: (a -> b) - (Exp a -> Exp b) }}} and I want to create a pattern synonym for Int-expressions: {{{#!hs -- This works: -- pattern :: (a -> b) -> (Exp a -> Exp b) -- pattern IntFun f x = Fun f x pattern :: (Int -> Int) -> (Exp Int -> Exp Int) pattern IntFun f x = Fun f x }}} which results in {{{#!hs % ghci -ignore-dot-ghci Panic.hs GHCi, version 7.10.0.20150316: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( Panic.hs, interpreted ) Panic.hs:8:28: Couldn't match type ‘a’ with ‘Int’ ‘a’ is a rigid type variable bound by a pattern with constructor Fun :: forall b a. (a -> b) -> Exp a -> Exp b, in a pattern synonym declaration at Panic.hs:8:22 Expected type: Int -> Int Actual type: a -> Int Relevant bindings include b :: Exp a (bound at Panic.hs:8:28) a :: a -> Int (bound at Panic.hs:8:26) Failed, modules loaded: none. }}} So I try to be sneaky: {{{#!hs pattern :: (a ~ Int) => (a -> b) -> (Exp a -> Exp b) pattern IntFun f x = Fun f x -- % ghci -ignore-dot-ghci Panic.hs -- … -- Couldn't match type ‘a’ with ‘Int’ -- ‘a’ is a rigid type variable bound by -- the type signature for IntFun :: (a1 -> b) -> Exp a1 -> Exp b -- at Panic.hs:8:22 }}} and if I constrain both type variables it panics {{{#!hs pattern :: (a ~ Int, b ~ Int) => (a -> b) -> (Exp a -> Exp b) pattern IntFun f x = Fun f x -- Couldn't match type ‘b’ with ‘Int’ -- ‘b’ is untouchable -- inside the constraints () -- bound by the type signature for -- IntFun :: (a1 -> b) -> Exp a1 -> Exp b -- at Panic.hs:8:9-14ghc: panic! (the 'impossible' happened) -- (GHC version 7.10.0.20150316 for i386-unknown-linux): -- No skolem info: b_alF[sk] -- -- Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} The final version should look like: {{{#!hs type Name = String data Exp a where Fun :: Name -> (a -> b) -> (Exp a -> Exp b) ... pattern Suc :: Exp Int -> Exp Int pattern Suc n <- Fun _ _ n where Suc n = Fun "suc" (+ 1) n }}} Shouldn't this work? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10404> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10432: panic with kind polymorphism
by GHC 23 Dec '15

23 Dec '15

#10432: panic with kind polymorphism -------------------------------------+------------------------------------- Reporter: Ashley | Owner: Yakeley | Status: new Type: bug | Milestone: Priority: normal | Version: 7.10.1 Component: Compiler | Operating System: Unknown/Multiple (Type checker) | Type of failure: None/Unknown Keywords: | Blocked By: Architecture: | Related Tickets: Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- {{{#!hs {-# LANGUAGE ExistentialQuantification, PolyKinds, DataKinds, RankNTypes, GADTs, TypeOperators #-} module Bug where import Data.Type.Equality data WrappedType = forall a. WrapType a; matchReflK :: forall (a :: ka) (b :: kb) (r :: *). ('WrapType a :~: 'WrapType b) -> (('WrapType a ~ 'WrapType b) => r) -> r; matchReflK Refl r = r; }}} give this: {{{ Bug.hs:8:15: Couldn't match kind ‘ka’ with ‘kb’ ‘ka’ is untouchable inside the constraints ('WrapType a ~ 'WrapType b) bound by the type signature for matchReflK :: ('WrapType a ~ 'WrapType b) => r at Bug.hs:(8,15)-(9,74)ghc: panic! (the 'impossible' happened) (GHC version 7.10.1 for x86_64-unknown-linux): No skolem info: ka_aqv[sk] Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} I actually think GHC should accept this (and furthermore infer `ka ~ kb`). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10432> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10897: Incorrect ASSERT for buildPatSyn
by GHC 23 Dec '15

23 Dec '15

#10897: Incorrect ASSERT for buildPatSyn -------------------------------------+------------------------------------- Reporter: ezyang | Owner: cactus Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Consider the following two files: {{{ -- A.hs {-# LANGUAGE PatternSynonyms #-} module A where pattern Single :: a -> a pattern Single x = x -- B.hs module B where import A Single y = True }}} When I build these using one-shot compilation using a debugged GHC (i.e. with ASSERTs) I get the following error: {{{ [ezyang@hs01 ghc-quick3]$ inplace/bin/ghc-stage2 -c A.hs -fforce-recomp [ezyang@hs01 ghc-quick3]$ inplace/bin/ghc-stage2 -c B.hs -fforce-recomp ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.11.20150918 for x86_64-unknown-linux): ASSERT failed! file compiler/iface/BuildTyCl.hs, line 210 Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} I expanded the assert and discovered it was claiming the universal type variables of the matcher should be equal to the type variables of the pattern declaration. This assert cannot possibly be right: the matcher and the pattern declaration are typechecked separately and there's no reason that the local binders should actually be the same. The equality test here should be done up to alpha-renaming. The other thing I found a bit puzzling was whether or not it mattered whether or not we used the local type variables from the matcher or the freshly bound ones. I suppose if we are consistent it shouldn't matter, so I don't think the code is buggy, just a bad ASSERT. BTW: this assert problem doesn't show up with `--make` because the assert occurs during typechecking of interface files, and with `--make` we don't need to typecheck an interface file. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10897> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9739: GHC 7.8 chokes on recursive classes
by GHC 23 Dec '15

23 Dec '15

#9739: GHC 7.8 chokes on recursive classes -------------------------------------+------------------------------------- Reporter: bitonic | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.8.3 checker) | Operating System: Keywords: | Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Difficulty: Unknown | None/Unknown Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Type checking this makes GHC 7.8.3 loop: {{{#!hs {-# LANGUAGE MultiParamTypeClasses #-} module Foo where class Class3 a => Class1 a where class Class2 t a where class2 :: (Class3 t) => a -> m class (Class1 t, Class2 t t) => Class3 t where }}} Does not happen in 7.6.3. I think it's something to do with the `Class3` constraint appearing in `class2`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9739> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10426: matchGroupArity panic with PatternSynonyms
by GHC 23 Dec '15

23 Dec '15

#10426: matchGroupArity panic with PatternSynonyms ---------------------------------------+--------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Linux Architecture: x86 | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | ---------------------------------------+--------------------------------- {{{#!hs {-# LANGUAGE PatternSynonyms, ViewPatterns, EmptyCase #-} pattern Id <- (id -> _) where }}} which gives: {{{#!hs % ghc -ignore-dot-ghci tmp.FbbzjZ48OO.hs [1 of 1] Compiling Main ( tmp.FbbzjZ48OO.hs, tmp.FbbzjZ48OO.o ) ghc: panic! (the 'impossible' happened) (GHC version 7.10.0.20150316 for i386-unknown-linux): matchGroupArity Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10426> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10828: TH can't represent all GADTs in its AST
by GHC 21 Dec '15

21 Dec '15

#10828: TH can't represent all GADTs in its AST -------------------------------------+------------------------------------- Reporter: spinda | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Template | Version: 7.10.2 Haskell | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- For example, it's impossible to add a kind signature on a data type with `DataD`. In {{{Con}}} I believe it's possible to encode GADT constructor signatures using {{{NormalC}}} (haven't tried this yet), but ideally there would be another constructor specific to GADTs to go along with {{{RecC}}}, {{{InfixC}}}, and {{{ForallC}}}. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10828> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10901: failing build of ghc in openSUSE with ncurses-6.0
by GHC 21 Dec '15

21 Dec '15

#10901: failing build of ghc in openSUSE with ncurses-6.0 -------------------------------------+------------------------------------- Reporter: mimi.vx | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build | Version: 7.10.2 System | Keywords: | Operating System: Linux Architecture: | Type of failure: Building GHC Unknown/Multiple | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- build of GHC-7.10.2 in openSUSE:Factory always fails with: {{{ [ 530s] "/usr/bin/ghc" -o utils/ghc-pkg/dist/build/tmp/ghc-pkg -hisuf hi -osuf o -hcsuf hc -static -H32m -O -package-db libraries/bootstrapping.conf -hide-all-packages -i -iutils/ghc-pkg/. -iutils/ghc-pkg/dist/build -iutils/ghc-pkg/dist/build/autogen -Iutils/ghc- pkg/dist/build -Iutils/ghc-pkg/dist/build/autogen -optP-include -optPutils/ghc-pkg/dist/build/autogen/cabal_macros.h -package Cabal-1.22.4.0 -package base-4.7.0.1 -package bin-package-db-0.0.0.0 -package binary-0.7.5.0 -package bytestring-0.10.4.0 -package containers-0.5.5.1 -package directory-1.2.1.0 -package filepath-1.3.0.2 -package process-1.2.0.0 -package terminfo-0.4.0.1 -package unix-2.7.0.1 -XHaskell2010 -no-user-package-db -rtsopts -odir utils/ghc- pkg/dist/build -hidir utils/ghc-pkg/dist/build -stubdir utils/ghc- pkg/dist/build -optl-L'/home/abuild/rpmbuild/BUILD/ghc-7.10.2/libraries/terminfo/dist- boot/build' -optl-L'/home/abuild/rpmbuild/BUILD/ghc-7.10.2/libraries/bin- package-db/dist-boot/build' -optl-L'/home/abuild/rpmbuild/BUILD/ghc-7.10.2/libraries/Cabal/Cabal/dist- boot/build' -optl-L'/usr/lib/ghc-7.8.3/process-1.2.0.0' -optl-L'/usr/lib/ghc-7.8.3/pretty-1.1.1.1' -optl-L'/usr/lib/ghc-7.8.3/directory-1.2.1.0' -optl-L'/usr/lib/ghc-7.8.3/unix-2.7.0.1' -optl-L'/usr/lib/ghc-7.8.3/time-1.4.2' -optl-L'/usr/lib/ghc-7.8.3/old- locale-1.0.0.6' -optl-L'/usr/lib/ghc-7.8.3/filepath-1.3.0.2' -optl-L'/home/abuild/rpmbuild/BUILD/ghc-7.10.2/libraries/binary/dist- boot/build' -optl-L'/usr/lib/ghc-7.8.3/containers-0.5.5.1' -optl-L'/usr/lib/ghc-7.8.3/bytestring-0.10.4.0' -optl-L'/usr/lib/ghc-7.8.3/deepseq-1.3.0.2' -optl-L'/usr/lib/ghc-7.8.3/array-0.5.0.0' -optl-L'/usr/lib/ghc-7.8.3/base-4.7.0.1' -optl-L'/usr/lib/ghc-7.8.3 /integer-simple-0.1.1.0' -optl-L'/usr/lib/ghc-7.8.3/ghc-prim-0.3.1.0' -optl-L'/usr/lib/ghc-7.8.3/rts-1.0' -optl-ltinfo -optl-lrt -optl-lutil -optl-ldl -optl-lpthread -optl-lm -optl-lrt -optl-ldl -static -H32m -O -package-db libraries/bootstrapping.conf -hide-all-packages -i -iutils /ghc-pkg/. -iutils/ghc-pkg/dist/build -iutils/ghc-pkg/dist/build/autogen -Iutils/ghc-pkg/dist/build -Iutils/ghc-pkg/dist/build/autogen -optP- include -optPutils/ghc-pkg/dist/build/autogen/cabal_macros.h -package Cabal-1.22.4.0 -package base-4.7.0.1 -package bin-package-db-0.0.0.0 -package binary-0.7.5.0 -package bytestring-0.10.4.0 -package containers-0.5.5.1 -package directory-1.2.1.0 -package filepath-1.3.0.2 -package process-1.2.0.0 -package terminfo-0.4.0.1 -package unix-2.7.0.1 -XHaskell2010 -no-user-package-db -rtsopts utils/ghc- pkg/dist/build/Main.o utils/ghc-pkg/dist/build/Version.o [ 531s] /home/abuild/rpmbuild/BUILD/ghc-7.10.2/libraries/terminfo/dist- boot/build/libHSterminfo-0.4.0.1.a(Base.o): In function `c8bd_info': [ 531s] /tmp/ghc13028_0/ghc13028_6.o:(.text+0x1a1a): undefined reference to `cur_term' [ 531s] /tmp/ghc13028_0/ghc13028_6.o:(.text+0x1a1e): undefined reference to `cur_term' [ 531s] /home/abuild/rpmbuild/BUILD/ghc-7.10.2/libraries/terminfo/dist- boot/build/libHSterminfo-0.4.0.1.a(Base.o): In function `c8bw_info': [ 531s] /tmp/ghc13028_0/ghc13028_6.o:(.text+0x1b2a): undefined reference to `cur_term' [ 531s] /tmp/ghc13028_0/ghc13028_6.o:(.text+0x1b2e): undefined reference to `cur_term' [ 531s] /home/abuild/rpmbuild/BUILD/ghc-7.10.2/libraries/terminfo/dist- boot/build/libHSterminfo-0.4.0.1.a(Base.o): In function `s7EW_info': [ 531s] /tmp/ghc13028_0/ghc13028_6.o:(.text+0x1d02): undefined reference to `cur_term' [ 531s] /home/abuild/rpmbuild/BUILD/ghc-7.10.2/libraries/terminfo/dist- boot/build/libHSterminfo-0.4.0.1.a(Base.o):/tmp/ghc13028_0/ghc13028_6.o:(.text+0x1d06): more undefined references to `cur_term' follow [ 531s] collect2: error: ld returned 1 exit status [ 531s] utils/ghc-pkg/ghc.mk:46: recipe for target 'utils/ghc- pkg/dist/build/tmp/ghc-pkg' failed [ 531s] make[1]: *** [utils/ghc-pkg/dist/build/tmp/ghc-pkg] Error 1 [ 531s] make[1]: *** Waiting for unfinished jobs.... [ 536s] <<ghc: 16682217032 bytes, 1311 GCs, 64109709/196614400 avg/max bytes residency (23 samples), 431M in use, 0.00 INIT (0.00 elapsed), 72.41 MUT (72.86 elapsed), 32.57 GC (32.60 elapsed) :ghc>> [ 540s] Makefile:71: recipe for target 'all' failed [ 540s] make: *** [all] Error 2 [ 540s] error: Bad exit status from /var/tmp/rpm-tmp.1kHoMD (%build) }}} in openSUSE was today updated ncurses to version 6.0 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10901> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10039: Make Const (Control.Applicative) kind polymorphic in its second argument
by GHC 21 Dec '15

21 Dec '15

#10039: Make Const (Control.Applicative) kind polymorphic in its second argument -------------------------------------+------------------------------------- Reporter: | Owner: Iceland_jack | Status: new Type: feature | Milestone: request | Version: 7.8.4 Priority: normal | Operating System: Unknown/Multiple Component: | Type of failure: None/Unknown libraries/base | Blocked By: Keywords: | Related Tickets: Architecture: | Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Is there any reason why `Const` isn't kind polymorphic? {{{#!hs newtype Const a (b :: k) = Const { getConst :: a } deriving (Generic, Generic1) }}} An example where I need it is for [[http://wiki.ocharles.org.uk/Name%20Binding%20in%20EDSLs|interpreting typed PHOAS]], the following fails to compile complaining that `The first argument of ‘PTerm’ should have kind ‘Ty -> *’, but ‘Const Char’ has kind ‘* -> *’`: {{{#!hs {-# LANGUAGE DataKinds, KindSignatures, GADTs, RankNTypes, PolyKinds #-} import Control.Applicative data Ty = TyBool | TyArr Ty Ty data PTerm :: (Ty -> *) -> Ty -> * where Var :: v t -> PTerm v t Tru :: PTerm v 'TyBool Fals :: PTerm v 'TyBool App :: PTerm v ('TyArr t1 t2) -> PTerm v t1 -> PTerm v t2 Abs :: (v t1 -> PTerm v t2) -> PTerm v ('TyArr t1 t2) newtype Term t = Term (forall v. PTerm v t) showT :: Term t -> String showT (Term pterm) = show' 'a' pterm where show' :: Char -> PTerm (Const Char) t -> String show' _ (Var (Const c)) = [c] show' _ Tru = "True" show' _ Fals = "False" show' s (App x y) = "(" ++ show' s x ++ ") " ++ show' s y show' s (Abs f) = [s] ++ ". " ++ show' (succ s) (f (Const s)) }}} but it compiles if one defines a bespoke form of `Const` with kind `* -> Ty -> *` (or the more general suggestion at the beginning of the ticket), I implemented all the related instances from `Control.Applicative` and the compiled without a hitch. Relevant discussion: a [[http://stackoverflow.com/questions/2023052/haskell-specifying-kind-in- data-declaration|question on StackOverflow]] that predates the `PolyKinds` extension effectively wants to define `type Const' (a :: * -> *) = Const Integer a` which would be possible if it were kind polymorphic. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10039> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10865: Poly-kinded Const
by GHC 21 Dec '15

21 Dec '15

#10865: Poly-kinded Const -------------------------------------+------------------------------------- Reporter: int-index | Owner: ekmett Type: feature | Status: new request | Priority: normal | Milestone: Component: Core | Version: 7.10.2 Libraries | Keywords: poly- | Operating System: Unknown/Multiple kinded, Const | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Currently `Const` is defined as {{{ newtype Const a b = Const { getConst :: a } }}} I propose to define it poly-kinded in the second argument like so: {{{ newtype Const a (b :: k) = Const { getConst :: a } }}} This should be completely backwards-compatible. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10865> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10372: panic! compiling Y combinator with optimizations
by GHC 21 Dec '15

21 Dec '15

#10372: panic! compiling Y combinator with optimizations -------------------------------------+------------------------------------- Reporter: cdk | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: panic, | Operating System: Unknown/Multiple simplifier | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- The following causes GHC 7.6.3, 7.8.3 and 7.10.1 (at least) to panic when compiling with optimizations: {{{#!hs module Y (y) where newtype Rec a = Rec { out :: Rec a -> a} k x = out x x y f = (f . k) (Rec (f . k)) }}} {{{ /tmp ««« ghc -O y.hs -fforce-recomp [1 of 1] Compiling Y ( y.hs, y.o ) ghc: panic! (the 'impossible' happened) (GHC version 7.10.1 for x86_64-unknown-linux): Simplifier ticks exhausted When trying UnfoldingDone a_sof To increase the limit, use -fsimpl-tick-factor=N (default 100) If you need to do this, let GHC HQ know, and what factor you needed To see detailed counts use -ddump-simpl-stats Total ticks: 5282 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10372> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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