July 2015 - ghc-tickets

Re: [GHC] #3134: encodeFloat . decodeFloat
by GHC 17 Jul '15

17 Jul '15

#3134: encodeFloat . decodeFloat -------------------------------------+------------------------------------- Reporter: roland | Owner: Type: bug | Status: new Priority: normal | Milestone: ⊥ Component: Prelude | Version: 6.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by bgamari): daniel.is.fischer, perhaps you would like to have another look now? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3134#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 17 Jul '15

17 Jul '15

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: niteria Type: bug | Status: patch Priority: high | Milestone: 7.12.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Other | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: Phab:D1073 -------------------------------------+------------------------------------- Comment (by Simon Marlow <marlowsd@…>): In [changeset:"3448f9827d2364b91bc60134aa38b74849b9d54e/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="3448f9827d2364b91bc60134aa38b74849b9d54e" Reduce non-determinism in ABI hashes with RULES and instance decls Summary: Before this change the `RULES` would be attached to one for the names from the module that appear on the left hand side. The choice depended on the `uniq` that was generated, which are known to be non-deterministic (a separate, bigger problem). Now we use `OccName`s which should be stable. Analogously for instance declarations, but they are attached to one of the types involved. Test Plan: contbuild it made `Data.Text.Internal.Fusion.Common` interface stable, previously stream fusion rule would be attached either to `streamList` or `unstreamList` depending on if the module was compiled after `cabal clean` or after `find | grep '\.o$' | xargs rm`. Reviewers: simonpj, austin, bgamari, simonmar Subscribers: puffnfresh, thomie Differential Revision: https://phabricator.haskell.org/D1073 GHC Trac Issues: #4012 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:111> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC-PGTEST] #10649: test - plz ignore
by GHC-PGTEST 17 Jul '15

17 Jul '15

#10649: test - plz ignore -------------------------------------+------------------------------------- Reporter: hvr | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10649> GHC-PGTEST <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7478: setSessionDynFlags does not always work
by GHC 16 Jul '15

16 Jul '15

#7478: setSessionDynFlags does not always work -------------------------------------+------------------------------------- Reporter: edsko | Owner: bherzog Type: bug | Status: new Priority: high | Milestone: 7.12.1 Component: Compiler | Version: 7.7 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: ghc- Related Tickets: | api/T7478 | Blocking: | Differential Revisions: Phab:D1017 -------------------------------------+------------------------------------- Comment (by Ben Gamari <ben@…>): In [changeset:"415351a938e86c4def60228552f121d91bbe7e59/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="415351a938e86c4def60228552f121d91bbe7e59" Put Opt_Static into defaultFlags if not pc_DYNAMIC_BY_DEFAULT (#7478) The test for Trac issue #7478 fails on some systems due to inconsistent default flags for dynamic vs. static linking. Test Plan: validate Reviewers: austin, thomie Reviewed By: thomie Subscribers: thomie, bgamari Differential Revision: https://phabricator.haskell.org/D1017 GHC Trac Issues: #7478 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7478#comment:21> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9618: Undocument ImpredicativeTypes
by GHC 16 Jul '15

16 Jul '15

#9618: Undocument ImpredicativeTypes -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Documentation | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Easy (less than 1 | Type of failure: hour) | None/Unknown Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- I understand that Simon Peyton Jones intends to make `ImpredicativeTypes` work some day, but it doesn't work now. I think the thing to do for now is to remove it from the user manual. It can be put back in later if it's ever fixed. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9618> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7401: Can't derive instance for Eq when datatype has no constructor, while it is trivial do do so.
by GHC 16 Jul '15

16 Jul '15

#7401: Can't derive instance for Eq when datatype has no constructor, while it is trivial do do so. -------------------------------------+------------------------------------- Reporter: jpbernardy | Owner: osa1 Type: feature request | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: deriving, Operating System: Unknown/Multiple | newcomer Type of failure: GHC rejects | Architecture: valid program | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: Phab:D978 -------------------------------------+------------------------------------- Changes (by RyanGlScott): * cc: RyanGlScott (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7401#comment:43> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10646: Adding GADTs extension makes RankNTypes code fail to compile.
by GHC 16 Jul '15

16 Jul '15

#10646: Adding GADTs extension makes RankNTypes code fail to compile. -------------------------------------+------------------------------------- Reporter: phadej | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 (Type checker) | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- The failing example: {{{#!hs {-# LANGUAGE RankNTypes #-} {-# LANGUAGE GADTs #-} data I a = I a example :: String -> I a -> String example str x = withContext x s where s i = "Foo" ++ str withContext :: I a -> (forall b. I b -> c) -> c withContext x f = f x }}} '''Without''' `GADTs`, this compiles and works fine: {{{ λ *Main > example "bar" (P 'a' "quux") "Foobar" }}} '''With''' `GADTs` the code fails to compile with an error: {{{ ex.hs:7:31: Couldn't match type ‘t0’ with ‘I b’ because type variable ‘b’ would escape its scope This (rigid, skolem) type variable is bound by a type expected by the context: I b -> String at ex.hs:7:17-31 Expected type: I b -> String Actual type: t0 -> [Char] Relevant bindings include s :: t0 -> [Char] (bound at ex.hs:9:5) In the second argument of ‘withContext’, namely ‘s’ In the expression: withContext x s Failed, modules loaded: none. }}} '''Yet''', if I add type annotation for `s`, everything seems to be fine: {{{#!hs {-# LANGUAGE RankNTypes #-} {-# LANGUAGE GADTs #-} data I a = I a example :: String -> I a -> String example str x = withContext x s where s :: I a -> String s i = "Foo" ++ str withContext :: I a -> (forall b. I b -> c) -> c withContext x f = f x }}} ---- I tried to make the failing example smaller, but seems that every bit participates. The use of `str` inside `s` especially. Is there some bug hiding inside GADTs related stuff? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10646> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10645: Fix Data.List.sortOn documentation
by GHC 16 Jul '15

16 Jul '15

#10645: Fix Data.List.sortOn documentation -------------------------------------+------------------------------------- Reporter: spl | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 7.10.2-rc2 libraries/base | Operating System: Unknown/Multiple Keywords: | Type of failure: Documentation Architecture: | bug Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- The {{{sortOn}}} documentation says: {{{ @sortOn f@ is equivalent to @sortBy . comparing f@ }}} but this is not correct (it does not type-check). It should say: {{{ @sortOn f@ is equivalent to @sortBy (comparing f)@ }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10645> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10642: Coercible regression from 7.10 to HEAD
by GHC 16 Jul '15

16 Jul '15

#10642: Coercible regression from 7.10 to HEAD -------------------------------------+------------------------------------- Reporter: darchon | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- This started out with code that compiled on 7.10, but fails on HEAD (20150711): {{{ {-# LANGUAGE TypeFamilies, StandaloneDeriving, UndecidableInstances #-} module StandaloneDeriving where type family F a newtype D a = D (F a) -- | This works on 7.10.1 and HEAD (20150711) deriving instance Eq (F a) => Eq (D a) -- | This works on 7.10.1, but fails on HEAD (20150711) deriving instance Bounded (F a) => Bounded (D a) }}} which fails on HEAD with: {{{ GHCi, version 7.11.20150711: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling StandaloneDeriving ( StandaloneDeriving.hs, interpreted ) StandaloneDeriving.hs:12:1: error: Couldn't match representation of type ‘a0’ with that of ‘F a’ arising from a use of ‘coerce’ Relevant bindings include minBound :: D a (bound at StandaloneDeriving.hs:12:1) In the expression: coerce (minBound :: F a) :: D a In an equation for ‘minBound’: minBound = coerce (minBound :: F a) :: D a When typechecking the code for ‘minBound’ in a derived instance for ‘Bounded (D a)’: To see the code I am typechecking, use -ddump-deriv In the instance declaration for ‘Bounded (D a)’ StandaloneDeriving.hs:12:1: error: Couldn't match representation of type ‘a1’ with that of ‘F a’ arising from a use of ‘coerce’ Relevant bindings include maxBound :: D a (bound at StandaloneDeriving.hs:12:1) In the expression: coerce (maxBound :: F a) :: D a In an equation for ‘maxBound’: maxBound = coerce (maxBound :: F a) :: D a When typechecking the code for ‘maxBound’ in a derived instance for ‘Bounded (D a)’: To see the code I am typechecking, use -ddump-deriv In the instance declaration for ‘Bounded (D a)’ Failed, modules loaded: none. }}} Which I managed to reduce to: {{{ {-# LANGUAGE TypeFamilies, FlexibleContexts #-} module CoerceFail where import Data.Coerce type family F a newtype D a = D (F a) -- | This works on 7.10.1, but fails on HEAD (20150711) coerceD :: Coercible (F a) (D a) => F a -> D a coerceD = coerce }}} Which also works on 7.10.1 but fails on HEAD with: {{{ GHCi, version 7.11.20150711: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling CoerceFail ( CoerceFail.hs, interpreted ) CoerceFail.hs:12:11: error: Couldn't match representation of type ‘a0’ with that of ‘F a’ arising from a use of ‘coerce’ Relevant bindings include coerceD :: F a -> D a (bound at CoerceFail.hs:12:1) In the expression: coerce In an equation for ‘coerceD’: coerceD = coerce }}} I don't know if this was never supposed to work, and the behaviour on HEAD is correct, or, if this is truly a regression from 7.10 to HEAD. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10642> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10644: Option GADTs invalidates a rank-2 function.
by GHC 15 Jul '15

15 Jul '15

#10644: Option GADTs invalidates a rank-2 function. -------------------------------------+------------------------------------- Reporter: bales | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Linux Architecture: x86_64 | Type of failure: GHC rejects (amd64) | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- This module typechecks WITHOUT the extension GADTs and doesn't typecheck WITH the extension GADTs Since it has nothing to do with GADTs, the consequence of using the option is surprising. I witnessed this behaviour on GHC versions 7.6.3, 7.8.3, 7.8.4, 7.10.1 {{{#!hs {-# LANGUAGE RankNTypes , GADTs #-} module GADTMonomorphism where problem :: (forall x . () -> x) -> (a,b) problem f = (p, p) where p = f () }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10644> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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