May 2014 - ghc-tickets

[GHC] #9093: Type synonym accepted with out-of-scope kind variable
by GHC 14 May '14

14 May '14

#9093: Type synonym accepted with out-of-scope kind variable --------------------------+------------------------------------------------ Reporter: | Owner: goldfire | Status: new Type: bug | Milestone: Priority: normal | Version: 7.8.2 Component: | Operating System: Unknown/Multiple Compiler | Type of failure: GHC accepts invalid program Keywords: | Test Case: Architecture: | Blocking: Unknown/Multiple | Difficulty: | Unknown | Blocked By: | Related Tickets: | --------------------------+------------------------------------------------ When I say {{{ {-# LANGUAGE PolyKinds #-} import Data.Proxy import GHC.Exts type X = Proxy (Any :: k) }}} I get no error. If I then ask GHCi about `X` (with `-fprint-explicit- kinds`), I see this: {{{ *Main> :i X type X = Proxy AnyK (Any AnyK) }}} I think my original code should be rejected. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9093> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9107: An alternative to witness values
by GHC 14 May '14

14 May '14

#9107: An alternative to witness values ----------------------------------------------+---------------------------- Reporter: spacekitteh | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.9 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: ----------------------------------------------+---------------------------- So, I might have come up with a nicer notation to providing type witnesses. Say I have a class thusly: {{{ class Metric a where measure :: Vector f -> Vector f -> f }}} and an example instance: {{{ instance Metric "Euclidean" where measure = sum . (zipWith (*)) }}} In order to actually use a specific metric, one would have to modify the type signature to include a witness, and use it such as {{{measure undefined::"Euclidean" a b}}}. Personally, I find such expressions to be ugly clutter. Instead, here are three alternate proposals which don't require including a witness: 1. {{{(Metric "Euclidean") => <term involving measure>}}} for example {{{dot a b = (Metric "Euclidean") => measure a b}}} 2. New keyword similar to "where" {{{ dot a b = measure a b assuming (Metric "Euclidean") }}} 3. New keyword similar to "let..in" {{{dot a b = assume (Metric "Euclidean") in measure a b}}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9107> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8991: HLint: Illegal instruction (core dumped)
by GHC 14 May '14

14 May '14

#8991: HLint: Illegal instruction (core dumped) ----------------------------------+------------------------------------- Reporter: tensor5 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.1 Keywords: | Operating System: Unknown/Multiple Architecture: x86_64 (amd64) | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------------+------------------------------------- After upgrading to 7.8.1 output of {{{hlint}}} is {{{Illegal instruction (core dumped)}}} on any file that I tested. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8991> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9055: unregisterised build fails with: globalRegMaybe not defined for this platform
by GHC 13 May '14

13 May '14

#9055: unregisterised build fails with: globalRegMaybe not defined for this platform -----------------------------------+--------------------------------------- Reporter: trommler | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.9 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time crash Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | -----------------------------------+--------------------------------------- Building HEAD fails with: {{{ make[1]: *** [rts/dist/build/Updates.o] Error 1 ghc-stage1: panic! (the 'impossible' happened) (GHC version 7.9.20140429 for powerpc64-unknown-linux): globalRegMaybe not defined for this platform }}} on Linux powerpc64 and x86_64 (unregisterised). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9055> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7104: Add tryWriteTBQueue to Control.Concurrent.STM.TBQueue
by GHC 13 May '14

13 May '14

#7104: Add tryWriteTBQueue to Control.Concurrent.STM.TBQueue --------------------------------------+------------------------------------ Reporter: joeyadams | Owner: simonmar Type: feature request | Status: new Priority: normal | Milestone: 7.10.1 Component: libraries (other) | Version: 7.4.2 Resolution: | Keywords: stm Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: --------------------------------------+------------------------------------ Changes (by ihameed): * cc: idhameed@… (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7104#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9088: Per-thread Haskell thread list/numbering (remove global lock from thread allocation)
by GHC 13 May '14

13 May '14

#9088: Per-thread Haskell thread list/numbering (remove global lock from thread allocation) ------------------------------+-------------------------------------------- Reporter: ezyang | Owner: simonmar Type: bug | Status: new Priority: low | Milestone: Component: Runtime | Version: 7.9 System | Operating System: Unknown/Multiple Keywords: | Type of failure: Runtime performance bug Architecture: | Test Case: Unknown/Multiple | Blocking: Difficulty: Unknown | Blocked By: | Related Tickets: | ------------------------------+-------------------------------------------- Currently, we take out the scheduler lock when a thread is allocated, in order to make sure we allocate a fresh thread ID and can attach it to the global thread list in the nursery. If we partition the thread ID space per originating capability and maintain thread lists per OS thread, we can remove this lock. Marking low priority because no one seems to be running into this as their particular scaling problem (and there may be other reasons why high thread churn doesn't scale across cores). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9088> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9098: Don't use unsafe coerce when desugaring lazy pattersn
by GHC 12 May '14

12 May '14

#9098: Don't use unsafe coerce when desugaring lazy pattersn ------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | 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: | ------------------------------------+------------------------------------- Christiaan Baaij asks (on ghc-devs): when I ask for the desugaring of: {{{ module PatError where paterror :: Maybe Int -> Int paterror (Just i) = i }}} I get the following: {{{ PatError.paterror = \ (ds_dIS :: Data.Maybe.Maybe GHC.Types.Int) -> break<1>() case ds_dIS of _ [Occ=Dead] { __DEFAULT -> (\ _ [Occ=Dead, OS=OneShot] -> Control.Exception.Base.patError @ GHC.Types.Int "PatError.hs:4:1-21|function paterror"#) GHC.Prim.void#; Data.Maybe.Just i_aqG -> break<0>(i_aqG) i_aqG } }}} Where `Control.Exception.Base.patError` is applied to `Int`. However, when I compile the almost identical code with an irrefutable pattern: {{{ module PatError2 where patError :: Maybe Int -> Int patError ~(Just i) = i }}} I get the following core: {{{ PatError2.paterror = \ (ds_dIT :: Data.Maybe.Maybe GHC.Types.Int) -> break<1>() let { i_aqG :: GHC.Types.Int [LclId, Str=DmdType] i_aqG = case ds_dIT of _ [Occ=Dead] { __DEFAULT -> (\ _ [Occ=Dead, OS=OneShot] -> (Control.Exception.Base.irrefutPatError @ () "PatError2.hs:4:1-22|(Data.Maybe.Just i)"#) `cast` (UnivCo representational () GHC.Types.Int :: () ~# GHC.Types.Int)) GHC.Prim.void#; Data.Maybe.Just i_aqG -> i_aqG } } in break<0>(i_aqG) i_aqG }}} Where `Control.Exception.Base.patError` is first applied to `()` after which it is casted to `GHC.Types.Int`. Out of the `[Note]` for the `UnivCo` coercion: {{{ The UnivCo ("universal coercion") serves two rather separate functions: - the implementation for unsafeCoerce# - placeholder for phantom parameters in a TyConAppCo }}} It seems to be used in the `unsafeCoerce#` role here. My question is: why can't the irrefutable pattern be translated to `Control.Exception.Base.irrefutPatError' applied to 'Int'? Instead of using this 'cast'? I find the cast-less version much more readable. Greetings, Christiaan -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9098> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7602: Threaded RTS performing badly on recent OS X (10.8?)
by GHC 12 May '14

12 May '14

#7602: Threaded RTS performing badly on recent OS X (10.8?) -------------------------------------+------------------------------------- Reporter: simonmar | Owner: thoughtpolice Type: bug | Status: new Priority: high | Milestone: 7.8.3 Component: Runtime System | Version: Resolution: | Keywords: thread-local Operating System: MacOS X | state, TLS clang Type of failure: Runtime | Architecture: x86_64 (amd64) performance bug | Difficulty: Unknown Test Case: | Blocked By: 7678 Blocking: | Related Tickets: -------------------------------------+------------------------------------- Changes (by thoughtpolice): * priority: highest => high Comment: I have a patch incoming Real Soon for this. Yay! -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7602#comment:45> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7478: setSessionDynFlags does not always work
by GHC 12 May '14

12 May '14

#7478: setSessionDynFlags does not always work -------------------------------------+------------------------------------ Reporter: edsko | Owner: Type: bug | Status: new Priority: high | Milestone: 7.8.3 Component: Compiler | Version: 7.7 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: ghc-api/T7478 | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Changes (by thoughtpolice): * priority: highest => high Comment: Lowering priority to be a bit more realistic on the milestone page. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7478#comment:13> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5987: Too many symbols in ghc package DLL
by GHC 12 May '14

12 May '14

#5987: Too many symbols in ghc package DLL -------------------------------------+------------------------------------ Reporter: igloo | Owner: thoughtpolice Type: bug | Status: new Priority: high | Milestone: 7.8.3 Component: Compiler | Version: 7.5 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: 3658 | Related Tickets: -------------------------------------+------------------------------------ Changes (by thoughtpolice): * priority: highest => high -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5987#comment:34> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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