January 2019 - ghc-tickets

[GHC] #16173: Move `Data.Profunctor` from `profunctors` package to `base`
by GHC 21 Jan '19

21 Jan '19

#16173: Move `Data.Profunctor` from `profunctors` package to `base` -------------------------------------+------------------------------------- Reporter: chshersh | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Core | Version: 8.6.3 Libraries | Keywords: base, | Operating System: Unknown/Multiple profunctor, QuantifiedConstraints | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #14767 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- `Contravariant` was added in GHC 8.6. * https://hackage.haskell.org/package/base-4.12.0.0/docs/Data-Functor- Contravariant.html `Profunctor` also looks like fundamental abstraction to be worth considering adding to `base`. Having both `Profunctor` and `Choice` typeclasses in the `base` library will also allow to write `microprism` package similar to `microlens`. Prisms often turns to be very useful since they allow to work nicely with sum types. {{{#!hs type Prism s t a b = forall p f. (Choice p, Applicative f) => p a (f b) -> p s (f t) }}} Additional context for this ticket from Reddit: * https://www.reddit.com/r/haskell/comments/8v53cb/announce_ghc_861alpha1_ava… It was proposed on Reddit to use `QuantifiedConstraints` for `Profunctor`. I'm not quite fluent with `QuantifiedConstraints`, but I think this may looks like this (mostly copy-pasting code from `profunctors` package): {{{#!hs {-# LANGUAGE QuantifiedConstraints #-} class (forall a . Functor (p a)) => Profunctor p where {-# MINIMAL dimap | (lmap, rmap) #-} dimap :: (a -> b) -> (c -> d) -> p b c -> p a d dimap f g = lmap f . rmap g lmap :: (a -> b) -> p b c -> p a c lmap f = dimap f id rmap :: (b -> c) -> p a b -> p a c rmap = dimap id instance Profunctor (->) where dimap ab cd bc = cd . bc . ab lmap = flip (.) rmap = (.) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16173> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16207: GHC 8.6.3 hangs building wreq-0.5.3.1 on Windows
by GHC 21 Jan '19

21 Jan '19

#16207: GHC 8.6.3 hangs building wreq-0.5.3.1 on Windows -------------------------------------+------------------------------------- Reporter: cromachina | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 Keywords: | Operating System: Windows Architecture: x86_64 | Type of failure: Compile-time (amd64) | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- `cabal new-install wreq-0.5.3.1 -j1` Observe ghc.exe seemingly stuck in an infinite loop after the following line with no allocating or IO occurring: `[ 5 of 15] Compiling Network.Wreq.Internal.Lens ( Network\Wreq\Internal\Lens.hs, dist\build\Network\Wreq\Internal\Lens.o )` -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16207> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16180: Make addForeignFilePath support asm
by GHC 21 Jan '19

21 Jan '19

#16180: Make addForeignFilePath support asm -------------------------------------+------------------------------------- Reporter: hsyl20 | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Template | Version: 8.6.3 Haskell | 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: -------------------------------------+------------------------------------- Currently Language.Haskell.TH.Syntax.addForeignFilePath only supports C, ObjC, C++, ObjC++ and objects (.o). I would like it to support assembly files (.s) too. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16180> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16179: Mention DerivingStrategies in the warning when DeriveAnyClass and GeneralizedNewtypeDeriving are both enabled
by GHC 21 Jan '19

21 Jan '19

#16179: Mention DerivingStrategies in the warning when DeriveAnyClass and GeneralizedNewtypeDeriving are both enabled -------------------------------------+------------------------------------- Reporter: ckoparkar | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: 8.10.1 Component: Compiler | Version: Keywords: deriving | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- When {{{DeriveAnyClass}}} and {{{GeneralizedNewtypeDeriving}}} are both enabled, GHC prints out the following warning for every {{{deriving C}}}: {{{ #!haskell warning: • Both DeriveAnyClass and GeneralizedNewtypeDeriving are enabled Defaulting to the DeriveAnyClass strategy for instantiating C }}} Would it be useful to point the users to {{{DerivingStrategies}}} ? {{{Use DerivingStrategies to pick a different strategy}}}, or something similar? I'm not sure if this was already discussed before, I couldn't find any related tickets. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16179> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15613: GHCi command, tracing steps of instance resolution for Constraint or expression
by GHC 21 Jan '19

21 Jan '19

#15613: GHCi command, tracing steps of instance resolution for Constraint or expression -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: feature | Status: new request | Priority: lowest | Milestone: Component: GHCi | Version: Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #15610 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Another GHCi command (#15610) to trace the process of instance resolution for a constraint. This is already something people do by hand (ticket:10318#comment:6) and would be a great tool for explorers of Haskell This constraint ultimately boils down to lists being monoids and `Int` being a number {{{ >> :elab Monoid (a -> b -> ([c], Sum Int)) Monoid (a -> b -> ([c], Sum Int)) ==> Monoid (b -> ([c], Sum Int)) ==> Monoid ([c], Sum Int) ==> Monoid [c] ==> Monoid (Sum Int) ==> Num Int }}} If resolving the type class fails, it can pinpoint what caused it to fail {{{ >> data A >> :elab Show (A, Int -> Int) Show (A, Int -> Int) <~bRZsz NO instance~> ==> Show A <NO instance> ==> Show (Int -> Int) <NO instance> }}} A verbose version can explain each step {{{ >> :elab +v Monoid (a -> b -> ([c], Sum Int) Monoid (a -> b -> ([c], Sum Int)) -- Monoid b => Monoid (a -> b) (‘GHC.Base’) ==> Monoid (b -> ([c], Sum Int)) -- Monoid b => Monoid (a -> b) (‘GHC.Base’) ==> Monoid ([c], Sum Int) -- Monoid b => Monoid (a -> b) (‘GHC.Base’) ==> Monoid [c] -- Monoid [a] (‘GHC.Base’) ==> Monoid (Sum Int) -- Num a => Monoid (Sum a) (‘Data.Monoid’) ==> Num Int -- Num Int (‘GHC.Num’) }}} {{{ >> :elab +v Num (Int, Float, Rational) Num (Int, Float, Rational) -- (Num a, Num b, Num c) => Num (a, b, c) (‘Data.NumInstances.Tuple’) ==> Num Int -- Num Int (‘GHC.Num’) ==> Num Float -- Num Float (‘GHC.Float’) ==> Num Rational -- type Rational = Ratio Integer (‘GHC.Real’) = Num (Ration Integer) -- Integral a => Num (Ratio a) (‘GHC.Real’) ==> Integral Integer -- Integral Integer (‘GHC.Real’) }}} ---- Not the same idea but similar. Listing instance resolution that takes place in an expression {{{ >> :elab (+) @Int from: (+) @Int Num Int }}} {{{ >> :elab2 comparing (length @[]) <> compare from: length @[] Foldable [] from: comparing (length @[]) Ord Int from: comparing (length @[]) <> compare Monoid ([a] -> [a] -> Ordering) ==> Monoid ([a] -> Ordering) ==> Monoid Ordering }}} {{{ >> :elab2 ask 'a' from: ask 'a' MonadReader Char ((->) m) ==> MonadReader Char ((->) Char) }}} not sure about that last one, or how to visualize them but I think it gives the right idea. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15613> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14193: Add RTS flag to disable 1TB address space allocaiton
by GHC 20 Jan '19

20 Jan '19

#14193: Add RTS flag to disable 1TB address space allocaiton -------------------------------------+------------------------------------- Reporter: nh2 | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #9706, #14192 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- GHC 8.0 changed the default behaviour on Linux to allocate 1 TB virtual memory for Haskell programs (#9706). While shown to be good for performance (a small percentage gain), it has created me a couple problems, especially when: * trying to disable overcommit in Linux to get more reliable memory behaviour and avoid swapping / the OOM-killer (all Haskell programs crash at startup) * and in debugging (e.g. #14192) Currently you can turn that feature off only via a compile-time switch, e.g. `./configure --disable-large-address-space`. I'd like to request to make it possible to turn this behaviour off at run- time with an RTS flag, so that when the flag is given, it uses the old block-allocator. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14193> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16156: Broken tests on Windows
by GHC 20 Jan '19

20 Jan '19

#16156: Broken tests on Windows -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 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: -------------------------------------+------------------------------------- I'll be marking these as broken: {{{ Unexpected results from: TEST="T10598_TH T11072gcc T12530 T13618 T15324 T15858 T15904 T2276_ghci T7477 T8759 T9086 TH_NestedSplices dynbrk004 plugin-recomp-change plugin- recomp-flags plugin-recomp-impure plugins09 plugins10 plugins11 print009 print012 print023 result001" SUMMARY for test run started at Mon Jan 7 01:57:14 2019 GST 1:57:17 spent to go through 6747 total tests, which gave rise to 19416 test cases, of which 12221 were skipped 47 had missing libraries 6945 expected passes 180 expected failures 0 caused framework failures 0 caused framework warnings 0 unexpected passes 23 unexpected failures 0 unexpected stat failures Unexpected failures: ffi/should_run/T2276_ghci.run T2276_ghci [bad exit code] (ghci) ghci/linking/dyn/T11072gcc.run T11072gcc [bad exit code] (normal) ghc-e/should_run/T9086.run T9086 [bad exit code] (normal) ghci.debugger/scripts/print009.run print009 [bad exit code] (ghci- ext) ghci.debugger/scripts/print012.run print012 [bad exit code] (ghci- ext) ghci.debugger/scripts/print023.run print023 [bad exit code] (ghci- ext) hp2ps/T15904.run T15904 [bad exit code] (normal) ghci.debugger/scripts/dynbrk004.run dynbrk004 [bad exit code] (ghci- ext) ghci.debugger/scripts/result001.run result001 [bad exit code] (ghci- ext) plugins/plugin-recomp-change.run plugin-recomp-change [bad exit code] (normal) plugins/T15858.run T15858 [bad exit code] (ghci) th/TH_NestedSplices.run TH_NestedSplices [exit code non-0] (normal) th/T7477.run T7477 [exit code non-0] (ext- interp) th/T8759.run T8759 [exit code non-0] (ext- interp) th/T10598_TH.run T10598_TH [exit code non-0] (normal) th/T12530.run T12530 [exit code non-0] (normal) th/T13618.run T13618 [exit code non-0] (normal) th/T15324.run T15324 [exit code non-0] (ext- interp) plugins/plugins09.run plugins09 [bad stdout] (normal) plugins/plugins10.run plugins10 [bad stdout] (normal) plugins/plugins11.run plugins11 [bad stdout] (normal) plugins/plugin-recomp-impure.run plugin-recomp-impure [bad exit code] (normal) plugins/plugin-recomp-flags.run plugin-recomp-flags [bad exit code] (normal) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16156> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3701: allow existential wrapper newtypes
by GHC 19 Jan '19

19 Jan '19

#3701: allow existential wrapper newtypes -------------------------------------+------------------------------------- Reporter: duncan | Owner: (none) Type: feature request | Status: new Priority: low | Milestone: Component: Compiler (Type | Version: 6.10.4 checker) | 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 glaebhoerl): * cc: glaebhoerl (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3701#comment:16> 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 19 Jan '19

19 Jan '19

#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 glaebhoerl): * cc: glaebhoerl (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1409#comment:76> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7259: Eta expansion of products in System FC
by GHC 19 Jan '19

19 Jan '19

#7259: Eta expansion of products in System FC -------------------------------------+------------------------------------- Reporter: simonpj | Owner: simonpj Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.1 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 glaebhoerl): * cc: glaebhoerl (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7259#comment:26> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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