August 2017 - ghc-tickets

[GHC] #13471: segmentation fault by compiling GHC
by GHC 06 Jun '18

06 Jun '18

#13471: segmentation fault by compiling GHC -------------------------------------+------------------------------------- Reporter: vanto | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 8.0.2 Keywords: | Operating System: Linux Architecture: x86_64 | Type of failure: Building GHC (amd64) | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Hi,\\ I tried to compile GHC on my computer.\\ by compiling GHC under Linux I got this error message.\\ {{{ compiler/ghc.mk:588: recipe for target 'compiler/stage2/build/DynFlags.o' failed make[1]: *** [compiler/stage2/build/DynFlags.o] segmentation fault Makefile:122: recipe for target 'install' failed make: *** [install] Error 2 }}} on my computer Linux runs on VirtualBox.\\ the problem is probably with my hardware but as I know nothing I tell you this issue.\\ {{{ ~/ghc/inplace/bin$ /ghc-stage1 --version The Glorious Glasgow Haskell Compilation System, version 8.3.20170322 }}} Hope this help\\ -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13471> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12075: Fails to build on powerpcspe because of inline assembly
by GHC 05 Jun '18

05 Jun '18

#12075: Fails to build on powerpcspe because of inline assembly --------------------------------+---------------------------------------- Reporter: glaubitz | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Linux Architecture: powerpc | Type of failure: Building GHC failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: --------------------------------+---------------------------------------- Hello! I'm currently bootstrapping GHC on powerpcspe (e500v2) which is a PowerPC architecture without an FPU but with signal processing extensions (hence SPE). When building GHC on this architecture, it detects the host architecture as powerpc-linux-gnuspe or short "powerpc" which works most of the time. However, GHC contains some inline assembly in rts/StgCRunAsm.s which uses FPU instructions not available on e500v2 CPUs resulting in assembler error, here with GHC 7.10.3: {{{ "inplace/bin/ghc-stage1" -optc-fno-stack-protector -optc-Wall -optc-Wextra -optc-Wstrict-prototypes -optc-Wmissing-prototypes -optc-Wmissing- declarations -optc-Winline -optc-Waggregate-return -optc-Wpointer-arith -optc-Wmissing-noreturn -optc-Wnested-externs -optc-Wredundant-decls -optc-Iincludes -optc-Iincludes/dist -optc-Iincludes/dist- derivedconstants/header -optc-Iincludes/dist-ghcconstants/header -optc- Irts -optc-Irts/dist/build -optc-DCOMPILING_RTS -optc- DUSE_LIBFFI_FOR_ADJUSTORS -optc-fno-strict-aliasing -optc-fno-common -optc-Irts/dist/build/autogen -optc-O2 -optc-fomit-frame-pointer -optc-g -optc-DRtsWay=\"rts_v\" -optc-w -static -H32m -O -lffi -optl-pthread -lffi -optl-pthread -Iincludes -Iincludes/dist -Iincludes/dist- derivedconstants/header -Iincludes/dist-ghcconstants/header -Irts -Irts/dist/build -DCOMPILING_RTS -this-package-key rts -dcmm-lint -i -irts -irts/dist/build -irts/dist/build/autogen -Irts/dist/build -Irts/dist/build/autogen -O2 -c rts/StgCRun.c -o rts/dist/build/StgCRun.o /bin/bash: warning: setlocale: LC_ALL: cannot change locale (en_US.UTF-8) /bin/bash: warning: setlocale: LC_ALL: cannot change locale (en_US.UTF-8) /tmp/ghcf20d_0/ghc_1.s: Assembler messages: /tmp/ghcf20d_0/ghc_1.s:24:0: Error: unrecognized opcode: `stfd' (...) /tmp/ghcf20d_0/ghc_1.s:67:0: Error: unrecognized opcode: `lfd' /tmp/ghcf20d_0/ghc_1.s:68:0: Error: unrecognized opcode: `lfd' /tmp/ghcf20d_0/ghc_1.s:69:0: Error: unrecognized opcode: `lfd' rts/ghc.mk:236: recipe for target 'rts/dist/build/StgCRun.o' failed make[3]: *** [rts/dist/build/StgCRun.o] Error 1 Makefile:71: recipe for target 'all' failed make[2]: *** [all] Error 2 make[2]: Leaving directory '/usr/src/ghc-7.10.3' dh_auto_build: make -j1 returned exit code 2 debian/rules:109: recipe for target 'override_dh_auto_build' failed make[1]: *** [override_dh_auto_build] Error 2 make[1]: Leaving directory '/usr/src/ghc-7.10.3' debian/rules:47: recipe for target 'binary-arch' failed make: *** [binary-arch] Error 2 (sid2-powerpcspe-sbuild)root@atlantis:/usr/src/ghc-7.10.3# }}} This can be verified by commenting out the assembly which will make the above compile command execute without any problems. Trying to continue compiling GHC will still fail with: {{{ "inplace/bin/ghc-stage1" -static -H32m -O -lffi -optl-pthread -lffi -optl-pthread -Iincludes -Iincludes/dist -Iincludes/dist- derivedconstants/header -Iincludes/dist-ghcconstants/header -Irts -Irts/dist/build -DCOMPILING_RTS -this-package-key rts -dcmm-lint -i -irts -irts/dist/build -irts/dist/build/autogen -Irts/dist/build -Irts/dist/build/autogen -O2 -c rts/HeapStackCheck.cmm -o rts/dist/build/HeapStackCheck.o /bin/bash: warning: setlocale: LC_ALL: cannot change locale (en_US.UTF-8) /bin/bash: warning: setlocale: LC_ALL: cannot change locale (en_US.UTF-8) /tmp/ghcca51_0/ghc_3.s: Assembler messages: /tmp/ghcca51_0/ghc_3.s:525:0: Error: unrecognized opcode: `lfs' /tmp/ghcca51_0/ghc_3.s:538:0: Error: unrecognized opcode: `lfd' /tmp/ghcca51_0/ghc_3.s:592:0: Error: unrecognized opcode: `stfs' /tmp/ghcca51_0/ghc_3.s:604:0: Error: unrecognized opcode: `stfd' rts/ghc.mk:236: recipe for target 'rts/dist/build/HeapStackCheck.o' failed make[3]: *** [rts/dist/build/HeapStackCheck.o] Error 1 Makefile:71: recipe for target 'all' failed make[2]: *** [all] Error 2 make[2]: Leaving directory '/usr/src/ghc-7.10.3' dh_auto_build: make -j1 returned exit code 2 debian/rules:109: recipe for target 'override_dh_auto_build' failed make[1]: *** [override_dh_auto_build] Error 2 make[1]: Leaving directory '/usr/src/ghc-7.10.3' debian/rules:47: recipe for target 'binary-arch' failed make: *** [binary-arch] Error 2 (sid2-powerpcspe-sbuild)root@atlantis:/usr/src/ghc-7.10.3# }}} So, there is obviously more assembly code that needs to be disabled on powerpcspe. For that, I suggest testing whether the compiler sets __NO_FPRS__which is only set on powerpc hosts without FP registers: {{{ root@atlantis:~# echo | gcc -E -dM -|grep -i FP #define __NO_FPRS__ 1 root@atlantis:~# dpkg --print-architecture powerpcspe root@atlantis:~# uname -m ppc root@atlantis:~# }}} For reference, on a real powerpc host, the output is as follows: {{{ (sid_powerpc-dchroot)glaubitz@partch:~$ echo | gcc -E -dM -|grep -i FP #define __FP_FAST_FMAF 1 #define __FP_FAST_FMA 1 (sid_powerpc-dchroot)glaubitz@partch:~$ dpkg --print-architecture powerpc (sid_powerpc-dchroot)glaubitz@partch:~$ uname -m ppc (sid_powerpc-dchroot)glaubitz@partch:~$ }}} If you need any more input, please let me know. Adrian -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12075> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8516: Add (->) representation and the Invariant class to GHC.Generics
by GHC 04 Jun '18

04 Jun '18

#8516: Add (->) representation and the Invariant class to GHC.Generics ----------------------------------------------+---------------------------- Reporter: nfrisby | Owner: Type: feature request | Status: new Priority: low | Milestone: Component: Compiler (Type checker) | Version: 7.7 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Moderate (less than a day) | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: ----------------------------------------------+---------------------------- We currently disallow any use of the parameter in the domain of (->). {{{ newtype F a = F ((a -> Int) -> Int) deriving Generic1 <interactive>:4:38: Can't make a derived instance of `Generic1 (F g)': Constructor `F' must use the last type parameter only as the last argument of a data type, newtype, or (->) In the data declaration for `F' }}} !DeriveFunctor succeeds for this F. I'd like to add this representation type to GHC.Generics and !DeriveGeneric. {{{ newtype (f :->: g) a = FArrow1 (f a -> g a) }}} We could then represent the first example above. We could also derive the more interesting Generic1 (F g). {{{ newtype F g a = F (g a -> Int) deriving Generic1 type instance Rep1 (F g) = Rec1 g :->: Rec0 Int instance Generic1 (F g) where to x = F $ unRec0 . unArrow1 x . Rec1 from (F x) = FArrow1 $ Rec0 . x . unRec1 }}} Admittedly, there's not many generic definitions impeded by not having (:->:). Contra- and in-variant types are uncommon. I'm suggesting this feature without strong motivating examples because I think this would streamline the implementation of -XDeriveGenerics in some ways while also making it more general — assuming that we added the Invariant class to base or ghc-prim. {{{ class Invariant t where invmap :: (a -> b) -> (b -> a) -> t a -> t b invmap_covariant :: Functor t => (a -> b) -> (b -> a) -> t a -> t b invmap_covariant f _ = fmap f instance (Invariant f,Invariant g) => Invariant (FArrow f g) where invmap co contra (FArrow h) = FArrow $ invmap co contra . h . invmap contra co }}} (Of course, Invariant should be a super class of Functor. :/ ) Now we can handle quite involved examples: {{{ newtype F g h a = F (g (h a)) deriving Generic1 instance Invariant g => Generic1 (F g h) where to x = invmap unRec1 Rec1 $ unComp1 x from (F x) = Comp1 $ invmap Rec1 unRec1 }}} All of that said, I'm mostly opening this ticket so I can get feedback on difficulties I might not be anticipating and have a place to reference from the compiler source code comments. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8516> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14070: Allow ‘unsafe’ deriving strategy, deriving code with ‘unsafeCoerce’
by GHC 04 Jun '18

04 Jun '18

#14070: Allow ‘unsafe’ deriving strategy, deriving code with ‘unsafeCoerce’ -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 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: -------------------------------------+------------------------------------- This {{{#!hs newtype M m a = M (m a) deriving newtype Functor }}} produces something similar to {{{#!hs instance Functor m => Functor (M m) where fmap :: forall a a'. (a -> a') -> (M m a -> M m a') fmap = coerce (fmap @m @a @a') }}} but as wiki:Roles2 points out, this fails for methods such as `join_`: {{{#!hs class MonadJoin m where join_ :: m (m a) -> m a newtype M m a = M (m a) deriving newtype MonadJoin -- Couldn't match representation of type ‘m (M m a)’ with that of ‘m (m a)’ }}} I think the user should be given the option to respect the roles or not by supplying `unsafe` wiki:Commentary/Compiler/DerivingStrategies {{{#!hs newtype M m a = M (m a) deriving unsafe newtype MonadJoin -- -( Produces `unsafeCoerce' instead of `coerce' )- -- instance MonadJoin m => MonadJoin (M m) where -- join_ :: forall a. M m (M m a) -> M m a -- join_ = unsafeCoerce (join_ @m @a) }}} This lets us (`newtype`-) derive a host of instances that we currently can not: `Traversable`, `Distributive` (currently forbidden due to [https://hackage.haskell.org/package/distributive-0.5.2/docs/Data- Distributive.html#v:distribute distribute]), [https://hackage.haskell.org/package/linear-1.20.7/docs/Linear- Matrix.html#v:trace Trace], [http://hackage.haskell.org/package/profunctors-5/docs/Data-Profunctor- Monad.html ProfunctorMonad / ProfunctorComonad], ... It does not seem like lenses (`FunctorWithIndex`, `FoldableWithIndex`, `TraversableWithIndex`) work with this though -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14070> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12152: panic: Loading temp shared object failed
by GHC 03 Jun '18

03 Jun '18

#12152: panic: Loading temp shared object failed -------------------------------------+------------------------------------- Reporter: crockeea | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 (Linking) | Keywords: | Operating System: Linux Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I've attached a no-Haskell-code project that fails when I run `cabal repl` with the following: {{{ ghc: panic! (the 'impossible' happened) (GHC version 7.10.3 for x86_64-unknown-linux): Loading temp shared object failed: /tmp/ghc60744_0/libghc_1.so: undefined symbol: _ZN2Zq1qE }}} Building the project works fine, so the problem seems to be (only) with dynamic linking. The issue can be resolved by swapping the order of the .cpp files in the cabal file. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12152> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9247: Document -XDatatypeContexts in flag reference
by GHC 03 Jun '18

03 Jun '18

#9247: Document -XDatatypeContexts in flag reference ------------------------------------+------------------------------------- Reporter: goldfire | Owner: goldfire Type: bug | Status: new Priority: low | Milestone: Component: Documentation | Version: 7.8.2 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- It may be a deprecated feature, but it still exists and should be listed. I can do this. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9247> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11066: Inacessible branch should be warning - otherwise breaks type soundness?
by GHC 03 Jun '18

03 Jun '18

#11066: Inacessible branch should be warning - otherwise breaks type soundness? -------------------------------------+------------------------------------- Reporter: rrnewton | Owner: Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 7.10.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- GHC 7.10.2 reports inaccessible branches as a type error, and I think this is really a bug. First, the implicit thinking seems to be "why would a user want to write inaccessible cases, they'd be crazy!". But that only applies to human-written code. Program generators can have a great deal of trouble avoiding this error, unless they replicate the GHC type checker to predict the problem and prune branches. (That's why we are hitting this error and are stuck.) Second, it seems like this is a problem for type soundness. See the attached program where "step1" typechecks but "step2" does not. And yet, the operational semantics should allow step1 to reduce to step2. Indeed, in the "GADTs meet their match" paper it seems like the intent was to warn for these inaccessible cases, not error. For example, the paper contains the language: "If we warn that a right-hand side of a non-redundant clause is inaccessible," -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11066> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14059: COMPLETE sets don't work at all with data family instances
by GHC 03 Jun '18

03 Jun '18

#14059: COMPLETE sets don't work at all with data family instances -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Keywords: | Operating System: Unknown/Multiple PatternSynonyms, | PatternMatchWarnings | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Here's some code that uses a pattern synonym for a data family GADT constructor, along with a corresponding `COMPLETE` set: {{{#!hs {-# LANGUAGE GADTs #-} {-# LANGUAGE PatternSynonyms #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeInType #-} {-# LANGUAGE TypeOperators #-} {-# OPTIONS_GHC -Wincomplete-patterns #-} module Bug where data family Sing (a :: k) data instance Sing (z :: Bool) where SFalse :: Sing False STrue :: Sing True pattern STooGoodToBeTrue :: forall (z :: Bool). () => z ~ True => Sing z pattern STooGoodToBeTrue = STrue {-# COMPLETE SFalse, STooGoodToBeTrue #-} wibble :: Sing (z :: Bool) -> Bool wibble STrue = True wobble :: Sing (z :: Bool) -> Bool wobble STooGoodToBeTrue = True }}} However, if you compile this, you might be surprised to find out that GHC only warns about `wibble` being non-exhaustive: {{{ $ ghci Bug.hs GHCi, version 8.2.1: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Bug.hs:23:1: warning: [-Wincomplete-patterns] Pattern match(es) are non-exhaustive In an equation for ‘wibble’: Patterns not matched: SFalse | 23 | wibble STrue = True | ^^^^^^^^^^^^^^^^^^^ }}} I believe the use of data families is the culprit here, since a variant of this program which doesn't use data families correctly warns for both `wibble` and `wobble`: {{{#!hs {-# LANGUAGE GADTs #-} {-# LANGUAGE PatternSynonyms #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeInType #-} {-# LANGUAGE TypeOperators #-} {-# OPTIONS_GHC -Wincomplete-patterns #-} module Foo where data SBool (z :: Bool) where SFalse :: SBool False STrue :: SBool True pattern STooGoodToBeTrue :: forall (z :: Bool). () => z ~ True => SBool z pattern STooGoodToBeTrue = STrue {-# COMPLETE SFalse, STooGoodToBeTrue #-} wibble :: SBool z -> Bool wibble STrue = True wobble :: SBool z -> Bool wobble STooGoodToBeTrue = True }}} {{{ $ ghci Foo.hs GHCi, version 8.2.1: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Foo ( Foo.hs, interpreted ) Foo.hs:20:1: warning: [-Wincomplete-patterns] Pattern match(es) are non-exhaustive In an equation for ‘wibble’: Patterns not matched: SFalse | 20 | wibble STrue = True | ^^^^^^^^^^^^^^^^^^^ Foo.hs:23:1: warning: [-Wincomplete-patterns] Pattern match(es) are non-exhaustive In an equation for ‘wobble’: Patterns not matched: SFalse | 23 | wobble STooGoodToBeTrue = True | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14059> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13777: Poor error message around CUSKs
by GHC 03 Jun '18

03 Jun '18

#13777: Poor error message around CUSKs -------------------------------------+------------------------------------- Reporter: goldfire | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1-rc2 Keywords: TypeInType, | Operating System: Unknown/Multiple CUSKs | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- While typing up comment:7:ticket:13761, I came across a poor error message around CUSKs. {{{ data Proxy (a :: k) = P data S :: forall k. Proxy k -> Type where MkS :: S (P :: Proxy Maybe) }}} produces {{{ You have written a *complete user-suppled kind signature*, but the following variable is undetermined: k0 :: * Perhaps add a kind signature. Inferred kinds of user-written variables: }}} That promised list of the kinds of user-written variables is empty. Either GHC should find something to print (like `k :: k0`, perhaps) or omit the header. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13777> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12939: ghc-8.0.1.20161117 did not install ghc.1 manpage
by GHC 02 Jun '18

02 Jun '18

#12939: ghc-8.0.1.20161117 did not install ghc.1 manpage ----------------------------------------+--------------------------------- Reporter: juhpetersen | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.2 Component: Build System | Version: 8.0.2-rc1 Keywords: | Operating System: Linux Architecture: Unknown/Multiple | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ----------------------------------------+--------------------------------- This seems to be a build regression from ghc-8.0.1. The ghc.1 manpage was not installed for the 8.0.2 RC1 build. I reported this in mail earlier and unfortunately in the meantime lost the buildlogs on Fedora Copr, but since the upstream binary tarballs for Linux also don't seem to contain ghc.1 either it should not be too hard to reproduce. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12939> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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