March 2017 - ghc-tickets

Re: [GHC] #1600: Optimisation: CPR the results of IO
by GHC 10 Mar '17

10 Mar '17

#1600: Optimisation: CPR the results of IO -------------------------------------+------------------------------------- Reporter: simonmar | Owner: (none) Type: task | Status: new Priority: lowest | Milestone: Component: Compiler | Version: 6.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #8598 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Simon Peyton Jones <simonpj@…>): In [changeset:"900cfdc2700ad9e8c7a12dd25bb0396e5e7651df/ghc" 900cfdc2/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="900cfdc2700ad9e8c7a12dd25bb0396e5e7651df" Do not generate a data-con wrapper for !Int# See Note [Data con wrappers and unlifted types] in MkId. We were being totally stupid! See Trac #1600 comment:66 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1600#comment:67> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13409: Data types with higher-rank kinds are pretty-printed strangely
by GHC 10 Mar '17

10 Mar '17

#13409: Data types with higher-rank kinds are pretty-printed strangely -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 (Type checker) | Keywords: TypeInType | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #13399 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- First observed in https://ghc.haskell.org/trac/ghc/ticket/13399#comment:5. If you define this: {{{#!hs data Foo :: (* -> *) -> (forall k. k -> *) }}} and type `:i Foo` into GHCi, you get this back: {{{ type role Foo phantom nominal phantom data Foo (a :: * -> *) k (c :: k) }}} This seems to imply that Foo has three visible type parameters, which isn't true at all! -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13409> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13384: Windows build thinks sqrt (-1) == -1
by GHC 10 Mar '17

10 Mar '17

#13384: Windows build thinks sqrt (-1) == -1 -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.2.1 Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect result Unknown/Multiple | at runtime Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- As of 749740f9c3cb25ee95e04a21c1ef73e1bf96afb1, {{{ $ inplace/bin/ghc-stage2 --interactive GHCi, version 8.1.20170306: http://www.haskell.org/ghc/ :? for help Prelude> sqrt (-1) :: Double -1.0 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13384> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11555: catch under unsafePerformIO breaks on -O1
by GHC 10 Mar '17

10 Mar '17

#11555: catch under unsafePerformIO breaks on -O1 -------------------------------------+------------------------------------- Reporter: slyfox | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1-rc2 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: -------------------------------------+------------------------------------- Discovered on xmonad-0.12 test failure. Happens on today's -HEAD and ghc-8.0.1-rc1,-rc2 Short example is (needs only base): {{{#!hs -- cat F.hs module F where import qualified Control.Exception as C import System.IO.Unsafe import qualified Data.List as L abort :: String -> a abort x = error $ "xmonad: StackSet: " ++ x prop_abort x = unsafePerformIO $ C.catch (abort "fail") (\(C.SomeException e) -> return $ "xmonad: StackSet: fail" `L.isPrefixOf` show e ) where _ = x :: Int }}} Session 1 [ok]: {{{ $ ghci F.hs GHCi, version 8.0.0.20160204: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling F ( F.hs, interpreted ) Ok, modules loaded: F. *F> prop_abort 1 True }}} Session 2 [fails]: {{{ $ ghci -O1 -fobject-code F.hs GHCi, version 8.0.0.20160204: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling F ( F.hs, F.o ) Ok, modules loaded: F. Prelude F> prop_abort 1 *** Exception: xmonad: StackSet: fail CallStack (from HasCallStack): error, called at F.hs:9:11 in main:F }}} I would expect exception to be caught on both cases. Is it unreasonable expectation in light of unsafePerformIO? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11555> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13348: Consider making throw and throwIO strict
by GHC 10 Mar '17

10 Mar '17

#13348: Consider making throw and throwIO strict -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: 8.4.1 Component: Core | Version: 8.1 Libraries | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Other Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- It's possible for code to throw an exception that itself throws an imprecise exception. Such an exception is tricky to catch. For example: {{{#!hs import Control.Exception strange = throwIO (undefined :: SomeException) `catch` \ex -> case () of _ | Just _ <- (fromException ex :: Maybe IOError) -> print "IOError" | otherwise -> print "Something else" }}} You might think that this would catch the exception and print "Something else", but in fact it does not. If others think this is as surprising as I do, perhaps we should make `throwIO` and `throw` strict, so an exception will never itself be bottom. Using {{{#!hs throwIO' !e = throwIO e }}} in the code above instead of `throwIO` allows the exception to be caught. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13348> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1409: Allow recursively dependent modules transparently (without .hs-boot or anything)
by GHC 10 Mar '17

10 Mar '17

#1409: Allow recursively dependent modules transparently (without .hs-boot or anything) -------------------------------------+------------------------------------- Reporter: Isaac Dupree | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: 6.10.2 Resolution: | Keywords: backpack Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #9256 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by mentheta): * cc: mentheta (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1409#comment:70> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13406: IO hack in demand analyzer can miss I/O
by GHC 10 Mar '17

10 Mar '17

#13406: IO hack in demand analyzer can miss I/O -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Other Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- If someone digs into the `IO` type, they could (with good reason, even!) decide that they want to produce something other than an unboxed pair. Here's an example, imitating `StateT st IO a` in a way that's sure to be unboxed well: {{{#!hs newtype IOState st a = IOState { unIOState :: State# RealWorld -> st -> (# State# RealWorld, st, a #) } }}} This won't trip `io_hack_reqd`, so demand analysis won't see it as I/O, and everything will be wrong. Urk. Furthermore, in the future, we may allow newtypes around unlifted types, in which case this stuff gets even messier. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13406> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4083: Generalized newtype deriving fails for newtypes that are type family instances
by GHC 09 Mar '17

09 Mar '17

#4083: Generalized newtype deriving fails for newtypes that are type family instances -------------------------------------+------------------------------------- Reporter: RANDY Ruler of | Owner: (none) Zexernet | Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 6.12.1 Resolution: invalid | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Iceland_jack): For type families see #13404 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4083#comment:2> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13402: GHC .prof tabular output glues columns together
by GHC 09 Mar '17

09 Mar '17

#13402: GHC .prof tabular output glues columns together -------------------------------------+------------------------------------- Reporter: dredozubov | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Keywords: | Operating System: MacOS X Architecture: | Type of failure: Debugging Unknown/Multiple | information is incorrect Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- After profiling an application i can see output like this: {{{ mkFareSegment Amadeus.Semantic.MasterPricer.Conversion.Offer.FareSegments204150 88315 0.1 0.0 0.2 0.1 }}} Columns are glued together in this particular part: `Amadeus.Semantic.MasterPricer.Conversion.Offer.FareSegments204150` It's a work project, so i won't attach the whole .prof file, but it seems that the issue occurs when the fully qualified name is too long. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13402> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1106: During install, network's Typeable.h clobbers base's copy
by GHC 09 Mar '17

09 Mar '17

#1106: During install, network's Typeable.h clobbers base's copy -------------------------------------+--------------------------------- Reporter: bos | Owner: igloo Type: merge | Status: closed Priority: normal | Milestone: 6.6.1 Component: Compiler | Version: 6.6 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Test Case: -------------------------------------+--------------------------------- Changes (by Joachim Breitner <mail@…>): * failure: => None/Unknown Comment: In [changeset:"712c45d035797a392e33bba3f8ec4293af61ecab/ghc" 712c45d/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="712c45d035797a392e33bba3f8ec4293af61ecab" integerConstantFolding: no longer broken with -DDEBUG (#1106) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1106#comment:8> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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