January 2018 - ghc-tickets

[GHC] #14744: Non-exhaustive patterns in case in GHCi with quantified class contexts
by GHC 31 Jan '18

31 Jan '18

#14744: Non-exhaustive patterns in case in GHCi with quantified class contexts -------------------------------------+------------------------------------- Reporter: kosmikus | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.5 Keywords: wipT2893, | Operating System: Unknown/Multiple QuantifiedConstraints | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This appears in the wip/T2893 branch. To reproduce, create the following module {{{ {-# LANGUAGE ConstraintKinds, GADTs, KindSignatures, QuantifiedConstraints #-} module Bug where import GHC.Exts data Foo :: (* -> Constraint) -> * where MkFoo :: (forall a . c a => c (f a), c a) => (f a) -> Foo c }}} and load it into GHCi: {{{ Bug> foo = MkFoo "foo" :: Foo Show *** Exception: compiler/typecheck/TcType.hs:(1965,9)-(1985,76): Non- exhaustive patterns in case }}} Putting the same declaration into the module itself does not seem to trigger the bug. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14744> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2893: Implement "Quantified constraints" proposal (was: Implement "Quantified contexts" proposal)
by GHC 31 Jan '18

31 Jan '18

#2893: Implement "Quantified constraints" proposal -------------------------------------+------------------------------------- Reporter: porges | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: 6.10.1 Resolution: | Keywords: | QuantifiedConstraints Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4353 Wiki Page: | -------------------------------------+------------------------------------- Description changed by simonpj: Old description: > See: [wiki:QuantifiedContexts] New description: See: [wiki:QuantifiedContexts Quantified constraints wiki page] -- -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2893#comment:31> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5927: A type-level "implies" constraint on Constraints
by GHC 31 Jan '18

31 Jan '18

#5927: A type-level "implies" constraint on Constraints -------------------------------------+------------------------------------- Reporter: illissius | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.4.1 checker) | Keywords: Resolution: | QuantifiedConstraints 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 simonpj): * keywords: QuantifiedContexts => QuantifiedConstraints -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5927#comment:28> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2893: Implement "Quantified contexts" proposal
by GHC 31 Jan '18

31 Jan '18

#2893: Implement "Quantified contexts" proposal -------------------------------------+------------------------------------- Reporter: porges | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: 6.10.1 Resolution: | Keywords: | QuantifiedConstraints Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4353 Wiki Page: | -------------------------------------+------------------------------------- Changes (by simonpj): * keywords: QuantifiedContexts => QuantifiedConstraints -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2893#comment:30> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3134: encodeFloat . decodeFloat
by GHC 30 Jan '18

30 Jan '18

#3134: encodeFloat . decodeFloat -------------------------------------+------------------------------------- Reporter: roland | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: ⊥ Component: Prelude | Version: 6.10.1 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 lelf): * cc: lelf (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3134#comment:6> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7414: plugins always trigger recompilation
by GHC 30 Jan '18

30 Jan '18

#7414: plugins always trigger recompilation -------------------------------------+------------------------------------- Reporter: jwlato | Owner: (none) Type: feature request | Status: new Priority: high | Milestone: 8.6.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: plugin, | RecompilationCheck Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #12567 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by bgamari): mpickering has written a [[ttps://github.com/ghc-proposals/ghc- proposals/pull/108|proposal]] describing one way to fix this for core-to- core plugins. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7414#comment:14> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2893: Implement "Quantified contexts" proposal
by GHC 29 Jan '18

29 Jan '18

#2893: Implement "Quantified contexts" proposal -------------------------------------+------------------------------------- Reporter: porges | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: 6.10.1 Resolution: | Keywords: | QuantifiedContexts Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4353 Wiki Page: | -------------------------------------+------------------------------------- Changes (by simonpj): * differential: => Phab:D4353 Comment: You can review the code at Phab:D4353 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2893#comment:29> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7398: RULES don't apply to a newtype constructor
by GHC 29 Jan '18

29 Jan '18

#7398: RULES don't apply to a newtype constructor -------------------------------------+------------------------------------- Reporter: shachaf | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #6082, #10418, | Differential Rev(s): #13290 | Wiki Page: | -------------------------------------+------------------------------------- Comment (by nomeata): > The alternative is to try to make the rule work after inlining MkT, by being clever about casts. That might be possible. We somewhat do this already: We have {{{ {-# RULES "map/coerce" [1] map coerce = coerce #-} }}} which fires in all these cases: {{{ foo :: [Int] -> [Int] foo = map id fooAge :: [Int] -> [Age] fooAge = map Age fooCoerce :: [Int] -> [Age] fooCoerce = map coerce fooUnsafeCoerce :: [Int] -> [Age] fooUnsafeCoerce = map unsafeCoerce }}} (this is `testsuite/tests/simplCore/should_run/T2110.hs`). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7398#comment:16> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7398: RULES don't apply to a newtype constructor
by GHC 29 Jan '18

29 Jan '18

#7398: RULES don't apply to a newtype constructor -------------------------------------+------------------------------------- Reporter: shachaf | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #6082, #10418, | Differential Rev(s): #13290 | Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): Currently, wen you have {{{ {-# RULES "foo" forall x. f (g x) = h x #-} }}} we have to delay inlining `g` until the rule has had a decent chance to fire. We currently do this manually, usually thus {{{ {-# NOINLINE[1] f,g #-} }}} The obvious thing for newtypes (and indeed other data constructors, if they have wrappers that unpack their arguments) is to delay inlining them. Something like {{{ newtype T a = MkT (Maybe a) {-# NOINLINE[1] MkT #-} }}} We don't support that right now, but we could. The alternative is to try to make the rule work ''after'' inlining `MkT`, by being clever about casts. That might be possible. But it doesn't work for data constructors like {{{ data S = MkS {-# UNPACK #-} !Int }}} where the wrapper evaluates and unboxes the argument. After inlining, the original `(f (MkS x))` turns into `f (case x ov I# y -> MkS y)`, which is a lot harder to match. So I think my suggestion, for now, is that we might want to allow users to put a NOINLINE pragma on data constructors. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7398#comment:15> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14594: 2 modules / 2500LOC takes nearly 3 minutes to build
by GHC 29 Jan '18

29 Jan '18

#14594: 2 modules / 2500LOC takes nearly 3 minutes to build -------------------------------------+------------------------------------- Reporter: schyler | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I tested this from a brand new MacBook 15" with 8 threads x 2.8 GHz Intel Core i7 / 16 GB RAM on OS X: {{{ $ time stack build WARNING: /Users/kvanb/git/github-webhooks/github-webhooks.cabal was generated with a newer version of hpack, please upgrade and try again. github-webhooks-1.0.0: unregistering (local file changes: github- webhooks.cabal package.yaml spec/DecodeEventsSpec.hs spec/Spec.hs src/GitHub/Data/Webhooks...) github-webhooks-1.0.0: configure (lib) Configuring github-webhooks-1.0.0... github-webhooks-1.0.0: build (lib) Preprocessing library github-webhooks-1.0.0... [1 of 3] Compiling Paths_github_webhooks ( .stack- work/dist/x86_64-osx/Cabal-1.24.2.0/build/autogen/Paths_github_webhooks.hs, .stack-work/dist/x86_64-osx/Cabal-1.24.2.0/build/Paths_github_webhooks.o ) [2 of 3] Compiling GitHub.Data.Webhooks.Payload ( src/GitHub/Data/Webhooks/Payload.hs, .stack- work/dist/x86_64-osx/Cabal-1.24.2.0/build/GitHub/Data/Webhooks/Payload.o ) [3 of 3] Compiling GitHub.Data.Webhooks.Events ( src/GitHub/Data/Webhooks/Events.hs, .stack- work/dist/x86_64-osx/Cabal-1.24.2.0/build/GitHub/Data/Webhooks/Events.o ) github-webhooks-1.0.0: copy/register Installing library in /Users/kvanb/git/github-webhooks/.stack- work/install/x86_64-osx/lts-9.18/8.0.2/lib/x86_64-osx-ghc-8.0.2/github- webhooks-1.0.0-LDmeffpkXvwH6ZXCPE95ke Registering github-webhooks-1.0.0... real 2m49.342s user 2m42.441s sys 0m5.805s }}} Source code has about 30 derivations of the form: {{{#!hs type IssueState = Text data HookIssue = HookIssue { whIssueUrl :: !URL , whIssueLabelsUrl :: !URL , whIssueCommentsUrl :: !URL , whIssueEventsUrl :: !URL , whIssueHtmlUrl :: !URL , whIssueId :: !Int , whIssueNumber :: !Int , whIssueTitle :: !Text , whIssueUser :: !HookUser , whIssueLabels :: !(Vector HookIssueLabels) , whIssueState :: IssueState , whIssueIsLocked :: !Bool , whIssueAssignee :: !(Maybe HookUser) , whIssueMilestone :: !(Maybe HookMilestone) , whIssueCommentCount :: !Int , whIssueCreatedAt :: !UTCTime , whIssueUpdatedAt :: !UTCTime , whIssueClosedAt :: !(Maybe UTCTime) , whIssueBody :: !Text } deriving (Eq, Show, Typeable, Data, Generic) instance NFData HookIssue where rnf = genericRnf }}} Steps to reproduce 1. clone https://github.com/onrock-eng/github-webhooks 2. checkout sha 40a7ecc3a5845717055ee372b89e645a498cf1e2 3. time stack build This is really ''really'' ''**really**'' slow. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14594> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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