November 2016 - ghc-tickets

Re: [GHC] #2893: Implement "Quantified contexts" proposal
by GHC 21 Nov '16

21 Nov '16

#2893: Implement "Quantified contexts" proposal -------------------------------------+------------------------------------- Reporter: porges | Owner: Type: feature request | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: 6.10.1 Resolution: | Keywords: proposal 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): Replying to [comment:20 RyanGlScott]: > 2. What does it mean to automatically generate instances for `(:=>)`? That is the question isn't it, I imagined it as `Typeable` or `Coercible` where the compiler creates instances on the fly but which instances I do not know. > While those classes are neat tricks that can get you some of the functionality of `QuantifiedConstraints`/`ImplicationConstraints`, they don't go all the way. `QuantifiedConstraints` and `ImplicationConstraints` would certainly be preferable! Are there any plans to research / implement such features? They would enable a lot of awesome code that is currently beyond reach. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2893#comment:21> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12697: Improve output of pattern synonym info
by GHC 21 Nov '16

21 Nov '16

#12697: Improve output of pattern synonym info -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple PatternSynonyms | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{#!hs import GHC.Prim import Data.Kind data TypeRep :: forall k. k -> Type where TI :: TypeRep Int TB :: TypeRep Bool TL :: TypeRep [] TA :: TypeRep f -> TypeRep x -> TypeRep (f x) data (a::k1) :~~: (b::k2) where HRefl :: a :~~: a deriving instance Show (a :~~: b) eqTT :: TypeRep (a::k1) -> TypeRep (b::k2) -> Maybe (a :~~: b) eqTT TI TI = Just HRefl eqTT TB TB = Just HRefl eqTT TL TL = Just HRefl pattern IsList <- (eqTT TL -> Just HRefl) where IsList = TL }}} What is the type of `IsList`? The result of `:type` is only accurate when used as an expression (`IsList :: TypeRep []`) and the result of `:info` is uses `~#` {{{ >>> :info IsList pattern IsList :: forall k2 (b :: k2). () => ((* -> *) ~# k2, [] ~# b) => TypeRep b }}} which won't parse (`parse error on input ‘~#’`). {{{#!hs -- t9R4.hs:20:67: error: … -- • Expected kind ‘* -> *’, but ‘b’ has kind ‘k2’ -- • In the second argument of ‘~’, namely ‘b’ -- Compilation failed. pattern IsList :: forall k2 (b :: k2). () => ((* -> *) ~ k2, [] ~ b) => TypeRep b pattern IsList <- (eqTT TL -> Just HRefl) where IsList = TL }}} The user may try to use `~` but we need [https://hackage.haskell.org/package/ghc-prim-0.5.0.0/docs/GHC- Types.html#t:-126--126- heterogeneous equality from GHC.Types] (`~~`) {{{#!hs pattern IsList :: forall k2 (b :: k2). () => ((* -> *) ~ k2, [] ~~ b) => TypeRep b }}} and in the end, we only need {{{#!hs pattern List :: () => [] ~~ b => T b }}} `:info` should show something closer to that! Copy-pasting should work -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12697> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12024: GHC leaks GHC.Prim.~# into type
by GHC 21 Nov '16

21 Nov '16

#12024: GHC leaks GHC.Prim.~# into type -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 (Type checker) | 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: -------------------------------------+------------------------------------- {{{#!hs data A a where X :: A [xxx] pattern X' = X }}} the inferred type of which is {{{ >>> :info X' pattern X' :: () => t GHC.Prim.~# [xxx] => A t }}} Casts use unlifted equality as I understand it, but lifted would present a nicer UI: {{{#!hs pattern X' :: () => t ~> [xxx] => A t pattern X' = X }}} In my own code this means I get the following monster {{{#!hs pattern MkArr :: () => (GetTy a, GetTy b, GetTy t, a GHC.Prim.~# 'Sca ('Number 'I32), b GHC.Prim.~# 'Sca a1, t GHC.Prim.~# 'Arr a1, GetSca a1) => Exp a -> Id -> Exp b -> Exp t }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12024> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12855: ghc-8.0.2_rc1 inlines string literals too aggressively, breaks tests of http-client-0.4.30
by GHC 21 Nov '16

21 Nov '16

#12855: ghc-8.0.2_rc1 inlines string literals too aggressively, breaks tests of http-client-0.4.30 -------------------------------------+------------------------------------- Reporter: slyfox | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.2 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: -------------------------------------+------------------------------------- GHC version 8.0.1.20161117 {{{#!hs -- $ cat BodySpec.hs -- $ ghc --make -O1 -package={base,bytestring} BodySpec.hs -o a && ./a {- # OPTIONS_GHC -Wall -Werror #-} module Main (main) where import qualified Data.ByteString as S import qualified Data.ByteString.Char8 as S8 main :: IO () main = (S8.concat (map S.singleton (S.unpack (S8.pack "<foo>"))) == S8.empty) `seq` return () }}} {{{ $ ghc --make -O1 -package={base,bytestring} BodySpec.hs -o a && ./a Segmentation fault (core dumped) }}} The cause is similar to #12757: low-level optimisations inline string literal (or it's wrapping value? i don't know) in multiple places. That breaks pinter-chasing in bytestring package. {{{ $ strings a | fgrep '<foo>' <foo> <foo> <foo> <foo> }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12855> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #8440: Get rid of the remaining static flags
by GHC 21 Nov '16

21 Nov '16

#8440: Get rid of the remaining static flags -------------------------------------+------------------------------------- Reporter: thoughtpolice | Owner: Type: task | Status: new Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: Resolution: | 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: | -------------------------------------+------------------------------------- Changes (by mpickering): * owner: siddhanathan => -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8440#comment:6> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3384: Add HsSyn prettyprinter tests
by GHC 21 Nov '16

21 Nov '16

#3384: Add HsSyn prettyprinter tests -------------------------------------+------------------------------------- Reporter: igloo | Owner: Type: task | Status: new Priority: normal | Milestone: 8.2.1 Component: Test Suite | Version: Resolution: | 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: | -------------------------------------+------------------------------------- Changes (by alanz): * milestone: ⊥ => 8.2.1 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3384#comment:13> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12862: Operator (!) causes weird pretty printing and parsing
by GHC 21 Nov '16

21 Nov '16

#12862: Operator (!) causes weird pretty printing and parsing -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 (Parser) | 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: -------------------------------------+------------------------------------- {{{#!hs class Key key where data TotalMap key :: Type -> Type (!) :: TotalMap key val -> (key -> val) instance Key Bool where data TotalMap Bool val = BoolMap val val (!) :: TotalMap Bool val -> (Bool -> val) (BoolMap f _) ! False = f }}} puts unnecessary parentheses around the wildcard pattern: {{{ tf6t.hs:14:3-23: error: … Parse error in pattern: (BoolMap f (_)) Compilation failed. }}} and with no parentheses {{{#!hs BoolMap f _ ! False = f }}} it talks about missing method, pattern bindings and doesn't list a space between `!` and `False`: {{{ tf6t.hs:13:3-5: error: … The class method signature for ‘!’ lacks an accompanying binding (The class method signature must be given where ‘!’ is declared) tf6t.hs:14:3-25: error: … Pattern bindings (except simple variables) not allowed in instance declaration: BoolMap f _ !False = f Compilation failed. }}} All of these issues go away if the operator is called something other than `!`, it works if written prefix {{{#!hs (!) (BoolMap f _) False = f }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12862> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7353: Make system IO interruptible on Windows
by GHC 21 Nov '16

21 Nov '16

#7353: Make system IO interruptible on Windows -------------------------------------+------------------------------------- Reporter: joeyadams | Owner: refold Type: bug | Status: new Priority: normal | Milestone: Component: Core Libraries | Version: 7.6.1 Resolution: | Keywords: Operating System: Windows | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by winter): * cc: drkoster@… (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7353#comment:31> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12861: "ghc-pkgh-6.9"
by GHC 21 Nov '16

21 Nov '16

#12861: "ghc-pkgh-6.9" -------------------------------------+------------------------------------- Reporter: juhpetersen | Owner: Type: bug | Status: new 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: -------------------------------------+------------------------------------- ghc-pkg.cabal has version 6.9, which may be okay, but `ghc-pkg --version` outputs the same version as ghc which seems slightly confusing. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12861> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12858: clock_gettime support on OS X is a nightmare
by GHC 20 Nov '16

20 Nov '16

#12858: clock_gettime support on OS X is a nightmare ----------------------------------------+--------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: high | Milestone: 8.0.2 Component: Compiler | Version: 8.0.1 Keywords: | Operating System: MacOS X Architecture: Unknown/Multiple | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ----------------------------------------+--------------------------------- Darwin did not support `clock_gettime` until Sierra, which added it. Unfortunately, the existing `MACOSX_DEPLOYMENT_TARGET` environment variable has no effect on its availability, so binary distributions compiled on Sierra will be incompatible with older releases. We have three options for dealing with this, 1. Disable `clock_gettime` support in our OS X binary distributions (e.g. `./configure ac_cv_func_clock_gettime=no`) 2. Produce one binary distribution for Sierra and another for previous releases 3. Making it possible to change timer backends at runtime. At the moment I'm leaning towards (1). (2) is another possibility. (3) seems like a road to madness. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12858> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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