September 2013 - ghc-tickets

Re: [GHC] #2496: Invalid Eq/Ord instances in Data.Version
by GHC 12 Sep '13

12 Sep '13

#2496: Invalid Eq/Ord instances in Data.Version -------------------------------------+------------------------------------ Reporter: guest | Owner: duncan Type: bug | Status: new Priority: normal | Milestone: _|_ Component: libraries/base | Version: 6.8.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by duncan): Note that that is a different can of worms, trailing zeros. My suggestion is to remove the unused (and useless) tag field, then the derived Eq and Ord will be fine. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2496#comment:8> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2496: Invalid Eq/Ord instances in Data.Version
by GHC 12 Sep '13

12 Sep '13

#2496: Invalid Eq/Ord instances in Data.Version -------------------------------------+------------------------------------ Reporter: guest | Owner: duncan Type: bug | Status: new Priority: normal | Milestone: _|_ Component: libraries/base | Version: 6.8.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by hvr): Related thread: - [http://permalink.gmane.org/gmane.comp.lang.haskell.libraries/7847 proposal: in base, for Data.Version, change the meaning of comparisons] -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2496#comment:7> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8273: ghc: panic! (the 'impossible' happened)
by GHC 12 Sep '13

12 Sep '13

#8273: ghc: panic! (the 'impossible' happened) -------------------------+------------------------------------------------- Reporter: | Owner: ready2go | Status: new Type: bug | Milestone: Priority: | Version: 7.4.1 normal | Operating System: Unknown/Multiple Component: | Type of failure: None/Unknown Compiler | Test Case: Prelude> data Shape = Keywords: | Circle Float Float Float | Rectangle Float Architecture: | Float Float Float deriving (show) x86_64 (amd64) | Blocking: Difficulty: | Unknown | Blocked By: | Related Tickets: | -------------------------+------------------------------------------------- Prelude> data Shape = Circle Float Float Float | Rectangle Float Float Float Float deriving (show) ghc: panic! (the 'impossible' happened) (GHC version 7.4.1 for x86_64-unknown-linux): nameModule show{tv a9J} Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug My Apologies if this is a duplicate, first time I have used trac, or this system- reproduced fault twice from fresh start of GHCi it twice on my Ubuntu 12.04 LTS system, using Haskell platform from Ubuntu repository -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8273> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8268: Local annotations ignored in ambiguity check
by GHC 11 Sep '13

11 Sep '13

#8268: Local annotations ignored in ambiguity check -------------------------------------+------------------------------------- Reporter: maxs | Owner: Type: bug | Status: new Priority: highest | Milestone: Component: Compiler (Type | Version: 7.7 checker) | Operating System: Unknown/Multiple Keywords: | Type of failure: GHC rejects Architecture: Unknown/Multiple | valid program Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- The following program type checks correctly in GHC 7.6.3 but fails in 7.7 (2013 09 04). {{{ {-# LANGUAGE FlexibleContexts, MultiParamTypeClasses, FlexibleInstances, GADTs, OverlappingInstances, ScopedTypeVariables, TypeFamilies, TypeOperators #-} module Test where newtype Exp t = Exp (Exp t) type family EltRepr a :: * type instance EltRepr () = () data TupleType a where UnitTuple :: TupleType () class (Show a) => Elt a where eltType :: {-dummy-} a -> TupleType (EltRepr a) instance Elt () where eltType _ = UnitTuple instance (Lift Exp a, Lift Exp b, Elt (Plain a), Elt (Plain b)) => Lift Exp (a, b) where type Plain (a, b) = (Plain a, Plain b) lift (x, y) = tup2 (lift x, lift y) tup2 :: (Elt a, Elt b) => (Exp a, Exp b) -> Exp (a, b) tup2 (x1, x2) = undefined -- Exp $ Tuple (NilTup `SnocTup` x1 `SnocTup` x2) class Lift c e where type Plain e lift :: e -> c (Plain e) class Lift c e => Unlift c e where unlift :: c (Plain e) -> e fst :: forall f a b. Unlift f (f a, f b) => f (Plain (f a), Plain (f b)) -> f a fst e = let (x, _:: f b) = unlift e in x }}} The error {{{ Test.hs:34:8: Could not deduce (Plain (f b0) ~ Plain (f b)) from the context (Unlift f (f a, f b)) bound by the type signature for Test.fst :: Unlift f (f a, f b) => f (Plain (f a), Plain (f b)) -> f a at Test.hs:34:8-79 NB: ‛Plain’ is a type function, and may not be injective The type variable ‛b0’ is ambiguous Expected type: f (Plain (f a), Plain (f b)) -> f a Actual type: f (Plain (f a), Plain (f b0)) -> f a In the ambiguity check for: forall (f :: * -> *) a b. Unlift f (f a, f b) => f (Plain (f a), Plain (f b)) -> f a In the type signature for ‛Test.fst’: Test.fst :: forall f a b. Unlift f (f a, f b) => f (Plain (f a), Plain (f b)) -> f a }}} GHC 7.7 reports: {{{ Actual type: f (Plain (f a), Plain (f b0)) -> f a }}} which is incorrect due to the type annotation. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8268> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #8004: Applicative/Monad proposal related warnings (AMP phase 1)
by GHC 11 Sep '13

11 Sep '13

#8004: Applicative/Monad proposal related warnings (AMP phase 1) -------------------------------------+------------------------------------ Reporter: quchen | Owner: quchen Type: feature request | Status: new Priority: high | Milestone: 7.8.1 Component: Compiler | Version: 7.6.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by Austin Seipp <austin@…>): In [changeset:75a9664af1c4e6f87794b49a215adb235b20696d/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="75a9664af1c4e6f87794b49a215adb235b20696d" Implement the AMP warning (#8004) This patch implements a warning when definitions conflict with the Applicative-Monad Proposal (AMP), described in #8004. Namely, this will cause a warning iff: * You have an instance of Monad, but not Applicative * You have an instance of MonadPlus, but not Alternative * You locally defined a function named join, <*>, or pure. In GHC 7.10, these warnings will actually be enforced with superclass constraints through changes in base, so programs will fail to compile then. This warning is enabled by default. Unfortunately, not all of our upstream libraries have accepted the appropriate patches. So we temporarily fix ./validate by ignoring the AMP warning. Dan Rosén made an initial implementation of this change, and the remaining work was finished off by David Luposchainsky. I finally made some minor refactorings. Authored-by: Dan Rosén <danr(a)chalmers.se> Authored-by: David Luposchainsky <dluposchainsky(a)gmail.com> Signed-off-by: Austin Seipp <austin(a)well-typed.com> }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8004#comment:14> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3647: unify handling and error messages for -X vs. {-#LANGUAGE ...#-} pragmas/extensions
by GHC 11 Sep '13

11 Sep '13

#3647: unify handling and error messages for -X vs. {-#LANGUAGE ...#-} pragmas/extensions -------------------------------------+------------------------------------- Reporter: eflister | Owner: Type: feature request | Status: new Priority: normal | Milestone: 7.8.1 Component: Compiler | Version: 6.10.4 (Parser) | Keywords: language pragma Resolution: | extensions error message warning Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------- Comment (by nomeata): I’m joining the “we need something copyable” section (as expressed in #8269), and I’d also throw in the argument that it is better practice to use {-# LANGUAGE ... #-} than flags. (To be honest I never understood why there are flags at all: If a source file uses a multi-way if, then it better declares that. Ok, so for GHCi you need command flags, but for anything else?..) Since error messages compactness is an issue I’m in favour of {{{ `Foo' has no constructors (EmptyDataDecls permits this) }}} since by now most GHC users will readily recognize CamelCaseWords as language extensions. This should hopefully make everyone happy. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3647#comment:19> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8269: Suggest LANGUAGE pragmas instead of -XFoo
by GHC 11 Sep '13

11 Sep '13

#8269: Suggest LANGUAGE pragmas instead of -XFoo ------------------------------------+------------------------------------- Reporter: nomeata | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Minor, but still: Currently GHC says: {{{ readFail037.hs:4:1: Too many parameters for class ‛Foo’ (Use -XMultiParamTypeClasses to allow multi-parameter classes) In the class declaration for ‛Foo’ }}} Maybe it is just me, but generally I find LANGUAGE pragmas are the way to go. So I think it should read {{{ readFail037.hs:4:1: Too many parameters for class ‛Foo’ (Use {-# LANGUAGE MultiParamTypeClasses #-} to allow multi-parameter classes) In the class declaration for ‛Foo’ }}} Note that it is easier to copying `MultiParamTypeClasses` (by double- clicking), entering "-X", and pasting, than copying `XMultiParamTypeClasses` and removing the X again. If noone complains or someone says that it is a good idea I’ll fix it myself. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8269> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8243: process.cabal source-repository field is out of date
by GHC 11 Sep '13

11 Sep '13

#8243: process.cabal source-repository field is out of date ------------------------------------+-------------------------------------- Reporter: rwbarton | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 7.7 libraries/process | Operating System: Unknown/Multiple Keywords: | Type of failure: Documentation bug Architecture: Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | ------------------------------------+-------------------------------------- From libraries/process/process.cabal: {{{ source-repository head type: git location: http://darcs.haskell.org/packages/process.git/ }}} but `git clone http://darcs.haskell.org/packages/process.git/` produces {{{ Cloning into process... error: RPC failed; result=22, HTTP code = 405 fatal: The remote end hung up unexpectedly }}} and trying to visit http://darcs.haskell.org/packages/process.git/ in a web browser redirects to http://git.haskell.org/packages/process/, which is 404. I haven't checked but I imagine there may be other libraries with the same issue. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8243> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8267: User's guide documents deprecated syntax for GADT records
by GHC 11 Sep '13

11 Sep '13

#8267: User's guide documents deprecated syntax for GADT records ------------------------------------+------------------------------------- Reporter: Feuerbach | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Documentation | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Section 7.4.7 of the user's guide distributed with GHC 7.6.3 documents the deprecated syntax for GADT records, e.g. {{{ data Term a where Lit { val :: Int } :: Term Int }}} Section 7.4.6 documents the new syntax. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8267> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8236: Assertion failure of MarkWeak
by GHC 11 Sep '13

11 Sep '13

#8236: Assertion failure of MarkWeak ------------------------------------+------------------------------------- Reporter: kazu-yamamoto | Owner: Type: bug | Status: new Priority: high | Milestone: 7.8.1 Component: Runtime System | Version: 7.7 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Runtime crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Running a web server compiled with GHC head specifying "-debug" got the following error: {{{ mighty-20130905: internal error: ASSERTION FAILED: file rts/sm/MarkWeak.c, line 371 (GHC version 7.7.20130901 for i386_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} Here is Akio's guess: I wonder if this issue could have been introduced by the commit: https://github.com/ghc/ghc/commit/6770663f764db76dbb7138ccb3aea0527d194151 It looks like after the commit, addCFinalizerToWeak# can call into the GC with the closure lock held. This means the info pointer points to stg_WHITEHOLE_info, breaking the asserted invariant. I haven't done any testing to confirm this, however. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8236> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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