July 2014 - ghc-tickets

[GHC] #9331: Release Cabal 1.22 before GHC 7.10 release
by GHC 31 Jul '15

31 Jul '15

#9331: Release Cabal 1.22 before GHC 7.10 release -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: task | Status: new Priority: normal | Milestone: 7.10.1 Component: Package system | Version: 7.9 Keywords: | Differential Revisions: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: -------------------------------------+------------------------------------- Just a tracking bug so we don't forget. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9331> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8488: Annotations should not distinguish type and value
by GHC 31 Jul '15

31 Jul '15

#8488: Annotations should not distinguish type and value ------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | 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: | ------------------------------------+------------------------------------- In `HsDecls` we have {{{ data AnnDecl name = HsAnnotation (AnnProvenance name) (Located (HsExpr name)) data AnnProvenance name = ValueAnnProvenance name | TypeAnnProvenance name | ModuleAnnProvenance }}} And there's now a similar 3-way distinction in Template Haskell `Syntax`: {{{ data AnnTarget = ModuleAnnotation | TypeAnnotation Name | ValueAnnotation Name }}} But there's really no need to distinguish between `TypeAnnProvenance` and `ValueAnnProvenance` (and similarly in the TH vesrion) because the namespace on the `Name` makes that distinction. So the current story is redundant, and hence has silly case where you have a `ValueAnnProvenance` on a type constructor. Better to collapse the two. I'm making this a ticket so that people can comment. I hope that Gergely may be able to do it as part of his TH/annotation work. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8488> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8387: View patterns + pattern bindings: finnicky about scoping
by GHC 31 Jul '15

31 Jul '15

#8387: View patterns + pattern bindings: finnicky about scoping ----------------------------+---------------------------------------------- Reporter: | Owner: tinctorius | Status: new Type: bug | Milestone: Priority: normal | Version: 7.6.3 Component: Compiler | Operating System: Unknown/Multiple Keywords: | Type of failure: GHC rejects valid program Architecture: | Test Case: Unknown/Multiple | Blocking: Difficulty: Unknown | Blocked By: | Related Tickets: | ----------------------------+---------------------------------------------- Assume `{-# LANGUAGE ViewPatterns #-}`. This works: {{{ (id -> ()) = () }}} This also works: {{{ di :: a -> a di = \x -> x where (di -> ()) = () }}} But none of the following work: {{{ (di -> ()) = () -- Not in scope: di di :: a -> a di = \x -> x }}} {{{ di :: a -> a di = \x -> x (di -> ()) = () -- Not in scope: di }}} {{{ (di -> ()) = () -- Not in scope: di where di :: a -> a di = \x -> x }}} This looks like a bug to me. Is it? And is this in any way related to #4061? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8387> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9230: Make -fwarn-tabs the default
by GHC 31 Jul '15

31 Jul '15

#9230: Make -fwarn-tabs the default -------------------------------------------+------------------------------- Reporter: dfeuer | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Easy (less than 1 hour) | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: -------------------------------------------+------------------------------- Tabs trip up an awful lot of Haskell beginners. Turning the warning on by default will likely save them a lot of grief. Any insane^h^h^h^h^h^hexperienced Haskellers who like tabs will have no trouble disabling the warning in their pragmas. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9230> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9070: "Simplifier ticks exhausted"
by GHC 31 Jul '15

31 Jul '15

#9070: "Simplifier ticks exhausted" ----------------------------------+------------------------------------- Reporter: dermesser | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: x86_64 (amd64) | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------------+------------------------------------- I know nothing more than what GHC said (I'm on debian, installed from the repositories). {{{ (GHC version 7.6.3 for x86_64-unknown-linux): Simplifier ticks exhausted When trying UnfoldingDone base:GHC.Base.$fMonadIO_$c>>={v rJ2} [gid] 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: 31764 }}} The code triggering the error is the code commented out in lines 52-54: {{{ 42 redis_family_raw <- getEnv redisFamilyVar 43 redis_addr <- getEnv redisAddressVar 44 redis_port <- getEnv redisPortVar 45 46 (family,redis_family) <- case (parseFamily family_raw,parseFamily redis_family_raw) of 47 (Just fam, Just rfam) -> return (fam,rfam) 48 x -> fail $ "Unknown address family: " ++ show x 49 50 sockaddr <- getSockAddr family broker_address broker_port_raw 51 52 --redis_conn <- case redis_family of 53 -- WAFamilyInet -> R.connect $ defaultConnectInfo { connectHost = redis_addr, connectPort = Service redis_port } 54 -- WAFamilyUnix -> R.connect $ defaultConnectInfo { connectPort = UnixSocket redis_addr } }}} However, this bug occurs only when compiling with cabal. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9070> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9227: Coverage Condition cannot be turned off
by GHC 31 Jul '15

31 Jul '15

#9227: Coverage Condition cannot be turned off ------------------------------------+------------------------------------- Reporter: augustss | 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: | ------------------------------------+------------------------------------- Compile this program {{{ {-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies #-} module Bug1 where class C a b | a -> b data A a = A data B a = B instance C (A a) (B b) }}} and observe the error message {{{ Bug1.hs:9:10: Illegal instance declaration for `C (A a) (B b)' The coverage condition fails in class `C' for functional dependency: `a -> b' Reason: lhs type `A a' does not determine rhs type `B b' In the instance declaration for `C (A a) (B b)' }}} Then read manual, sec 7.6.3.3: {{{ Both the Paterson Conditions and the Coverage Condition are lifted if you give the -XUndecidableInstances flag }}} Compile again with -XUndecidableInstances. Observe the exact same error message. Either the compiler or the documentation is wrong. I certainly hope it is the compiler, because it worked in 7.6 and was quite useful. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9227> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8253: example "Core syntax" is ancient
by GHC 31 Jul '15

31 Jul '15

#8253: example "Core syntax" is ancient -------------------------------------+------------------------------------- Reporter: rwbarton | 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: Documentation Difficulty: Easy (less than 1 | bug hour) | Test Case: Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- [http://www.haskell.org/ghc/docs/7.6.3/html/users_guide/options- debugging.html#idp39365504 User's guide section 4.19.5] has some funky "Core syntax" that (according to git blame) dates back to at least 2000, and probably longer ago than that. It could use an update. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8253> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8151: ghc-7.4.2 on OpenIndiana (Solaris) createSubprocess fails
by GHC 31 Jul '15

31 Jul '15

#8151: ghc-7.4.2 on OpenIndiana (Solaris) createSubprocess fails ----------------------------+-------------------------------------------- Reporter: troydm | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.4.2 Keywords: | Operating System: Solaris Architecture: x86 | Type of failure: Runtime performance bug Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------+-------------------------------------------- when i'm compiling this test.hs with ghc -thread ./test.hs and then execute it i get Starting Subprocess Exit code: ExitFailure 127 This error code indicates that command isn't found (i have ghc in /usr/local/bin) and it's specified in PATH variable, however it acts as if it's not even there however if i remove -threaded flag and recompile code again, it works Starting Subprocess ghc: no input files Usage: For basic information, try the `--help' option. Exit code: ExitFailure 1 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8151> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9114: Invalid UTF8 not round-tripped correctly
by GHC 31 Jul '15

31 Jul '15

#9114: Invalid UTF8 not round-tripped correctly ------------------------------------+------------------------------------- Reporter: nomeata | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: libraries/base | 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: | ------------------------------------+------------------------------------- As reported by Robert Bihlmeyer at http://bugs.debian.org/748125, the promised round-tripping of invalid UTF8 sequences in filenames through String does not work: ``` $ mkdir foo $ touch foo/$(echo -e '\xC0\xB7.txt') $ ghc -e 'System.Directory.getDirectoryContents "foo" >>= print . last' "7.txt" ``` The sequence 0xC8B7 is an (invalid) encoding of 37, i.e. `'7'`, so if it is mapped to `'7'`, no round-tripping is possible. (Other invalid byte sequences are round-tripped.) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9114> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9385: Additions to Control.Monad
by GHC 31 Jul '15

31 Jul '15

#9385: Additions to Control.Monad -------------------------------------+------------------------------------- Reporter: olf | Owner: Type: feature request | Status: new Priority: low | Milestone: Component: libraries/base | Version: 7.8.2 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- I'd like to propose the following additions/changes to Control.Monad: `mfilter` can be generalised: {{{#!hs gen_mfilter :: Monad m => (a -> m ()) -> m a -> m a gen_mfilter f ma = (\a -> liftM (const a) (f a)) =<< ma }}} Now we obtain the old `mfilter` as {{{#!hs gen_mfilter.(guard.) }}} Further, `m ()` is a monoid for every monad, which would cause conflicts for `[()]`, to name one example. (The usual monoid instance of `[()]` is addition of natural numbers, while the monadic monoid instance is multiplication.) More generally, the monoid `m ()` acts on every type `m a` in the following way: {{{#!hs mtimes :: Monad m => m () -> m a -> m a mtimes = gen_mfilter.const = liftM2 (flip const) when = mtimes.guard }}} For example, each element of a list can be duplicated like this: {{{#!hs mtimes [(),()] }}} To see why these functions are useful, consider the `DDist` monad of the ProbabilityMonads package: Since `DDist ()` is essentially the monoid of real numbers with multiplication, `gen_mfilter f` updates a distribution by multiplying the weight of `x` by `f x`. Another example is the state monad `ST s`, where type `(a -> ST s ())` is essentially `a -> s -> s`, so these functions encode changes that, when used with `gen_mfilter` alter state, not the value. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9385> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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