October 2018 - ghc-tickets

[GHC] #15789: GHC panic using visible kind applications and a higher-rank kind
by GHC 29 Nov '18

29 Nov '18

#15789: GHC panic using visible kind applications and a higher-rank kind -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 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: -------------------------------------+------------------------------------- Using visible kind applications (#12045): {{{#!hs {-# Language LiberalTypeSynonyms #-} {-# Language PolyKinds #-} {-# Language RankNTypes #-} {-# Language DataKinds #-} import Data.Kind type Cat ob = ob -> ob -> Type data Zero :: forall (cat :: forall xx. xx -> Type) a. forall b. Cat (forall b. cat b u) }}} {{{ $ ghci -ignore-dot-ghci 546_bug.hs GHCi, version 8.7.20181017: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( 546_bug.hs, interpreted ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.7.20181017 for x86_64-unknown-linux): ASSERT failed! Type-correct unfilled coercion hole {co_a1yl} Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1160:37 in ghc:Outputable pprPanic, called at compiler/utils/Outputable.hs:1219:5 in ghc:Outputable assertPprPanic, called at compiler/typecheck/TcHsSyn.hs:1805:99 in ghc:TcHsSyn Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug > }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15789> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15764: GHC panic from PolyKinds + DataKinds
by GHC 29 Nov '18

29 Nov '18

#15764: GHC panic from PolyKinds + DataKinds -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 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: -------------------------------------+------------------------------------- Playing around with GhcKinds/KindInference/Examples gives me a GHC panic {{{#!hs -- https://ghc.haskell.org/trac/ghc/wiki/GhcKinds/KindInference/Examples?versi… {-# Language PolyKinds #-} {-# Language KindSignatures #-} {-# Language DataKinds #-} import Data.Kind import Data.Proxy import GHC.TypeLits class C6 (k :: Type) (a :: k) (b :: Proxy (a :: k)) where type T6 (proxy :: Proxy '(k, b)) }}} on an out of date version of HEAD I get {{{ $ ghci -ignore-dot-ghci 519.hs GHCi, version 8.7.20180828: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( 519.hs, interpreted ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.7.20180828 for x86_64-unknown-linux): ASSERT failed! 1 0 k_a1FD[tau:0] Proxy a_a1EN[sk:1] Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1160:37 in ghc:Outputable pprPanic, called at compiler/utils/Outputable.hs:1219:5 in ghc:Outputable assertPprPanic, called at compiler/typecheck/TcMType.hs:768:54 in ghc:TcMType Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug > }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15764> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15804: GHC panic (Visible kind application diff): data T :: (a :: k) -> *
by GHC 29 Nov '18

29 Nov '18

#15804: GHC panic (Visible kind application diff): data T :: (a :: k) -> * -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 Keywords: | Operating System: Unknown/Multiple TypeApplications | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- (using [https://phabricator.haskell.org/D5229 Visual Kind Application (D5229)]) This might be the root cause of some of my previous {{{#!hs {-# Language PolyKinds #-} data T :: (a :: k) -> * }}} {{{ $ ghci -ignore-dot-ghci 580.hs GHCi, version 8.7.20181017: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( 580.hs, interpreted ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.7.20181017 for x86_64-unknown-linux): ASSERT failed! Type-correct unfilled coercion hole {co_a1xI} Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1160:37 in ghc:Outputable pprPanic, called at compiler/utils/Outputable.hs:1219:5 in ghc:Outputable assertPprPanic, called at compiler/typecheck/TcHsSyn.hs:1805:99 in ghc:TcHsSyn Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug > }}} on 8.6.1 this gives {{{ $ ~/.stack/programs/x86_64-linux/ghc-8.6.1/bin/ghci -ignore-dot-ghci 580.hs GHCi, version 8.6.1: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( /home/baldur/hs/580.hs, interpreted ) /home/baldur/hs/580.hs:3:11: error: • Expected a type, but ‘(a :: k)’ has kind ‘k’ • In the kind ‘(a :: k) -> *’ | 3 | data T :: (a :: k) -> * | ^^^^^^^^ Failed, no modules loaded. Prelude> }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15804> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14880: GHC panic: updateRole
by GHC 29 Nov '18

29 Nov '18

#14880: GHC panic: updateRole -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 (Type checker) | Keywords: Roles | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The following program panics on GHC 8.0.2, 8.2.2, 8.4.1, and HEAD: {{{#!hs {-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeInType #-} {-# LANGUAGE TypeOperators #-} module Bug where import Data.Kind import Data.Type.Equality ((:~:)(..)) type SameKind (a :: k) (b :: k) = (() :: Constraint) data TyFun :: Type -> Type -> Type type a ~> b = TyFun a b -> Type infixr 0 ~> type family Apply (f :: k1 ~> k2) (x :: k1) :: k2 type f @@ x = f `Apply` x infixl 9 @@ type family WhyCong (x :: Type) (y :: Type) (f :: x ~> y) (a :: x) (z :: x) (e :: a :~: z) :: Type where WhyCong _ _ f a z _ = f @@ a :~: f @@ z data WhyCongSym1 (x :: Type) :: forall (a :: x) (y :: Type) (z :: x). Type ~> (x ~> y) ~> x ~> x ~> a :~: z ~> Type data WhyCongSym0 :: forall (x :: Type) (a :: x) (y :: Type) (z :: x). Type ~> Type ~> (x ~> y) ~> x ~> x ~> a :~: z ~> Type where WhyCongSym0KindInference :: forall x arg. SameKind (Apply WhyCongSym0 arg) (WhyCongSym1 arg) => WhyCongSym0 x }}} {{{ $ /opt/ghc/8.2.2/bin/ghc Bug.hs [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.2.2 for x86_64-unknown-linux): updateRole WhyCongSym0 arg_aYV[sk:1] [aYU :-> 4, a22o :-> 0, a22p :-> 1, a22q :-> 2, a22r :-> 3] Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1133:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1137:37 in ghc:Outputable pprPanic, called at compiler/typecheck/TcTyDecls.hs:656:23 in ghc:TcTyDecls }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14880> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15809: Use level numbers for generalisation
by GHC 29 Nov '18

29 Nov '18

#15809: Use level numbers for generalisation -------------------------------------+------------------------------------- Reporter: simonpj | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 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's type inference engine goes to quite a bit of effort to pin a ''level number'' on every type variable (both skolems and unification variables). '''Idea''': when generalising a type or kind, use those level numbers to decide which variables to generalise. This could completely replace the "global tyvars" field of the `TcLclEnv` (the `tcl_tyvars` field), which is very tiresome to maintain. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15809> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15414: Why both gen and gen_no in bdescr?
by GHC 29 Nov '18

29 Nov '18

#15414: Why both gen and gen_no in bdescr? -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.6.1 Component: Runtime | Version: 8.4.3 System | 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: -------------------------------------+------------------------------------- Block descriptors currently contain both `gen` (a `generation *`) and `gen_no` (a `uint16_t, which is `gen->no` cached). I wonder whether it would be worthwhile to drop the former and always use `generations[bd->gen_no]`. Afterall, this would save an entire word per descriptor which may improve our caches' coverage of the bdescr region appreciably. Presumably the `generations` array would be hot enough to stay in cache in such a scheme, so I would guess that the cost would be small-ish. Simon, have you measured this in the past? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15414> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8177: Roles for type families
by GHC 29 Nov '18

29 Nov '18

#8177: Roles for type families ------------------------------------+------------------------------------- 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: | ------------------------------------+------------------------------------- Now that we have [wiki:Roles roles], it might be helpful to be able to give a role signature for a data/type family. At the moment, data/type family constructors have all parameters conservatively assigned to be role `N`. Thus {{{ data family D a -- Parameter conservatively assumed to be N class C a where op :: D a -> a instance C Int where .... newtype N a = MkN a deriving( C ) -- Rejected }}} The generalised-newtype-deriving clause `deriving( C )` is rejected because `D` might use its parameter at role `N` thus: {{{ data instance D [b] = MkD (F b) -- F is a type function }}} It would be strictly more expressive if we could * '''Declare''' the roles of D's arguments (as we can declare their kinds). E.g. {{{ data family D a@R }}} * '''Check''' that each family instance obeys that role signature. E.g. given the preceding role signature, reject this instance: {{{ data instance D [b] = MkD (F b) -- F is a type function }}} I think there is no technical difficulty here. Just a question of doing it. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8177> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14506: Configure Harbormaster to trigger CircleCI commits
by GHC 28 Nov '18

28 Nov '18

#14506: Configure Harbormaster to trigger CircleCI commits -------------------------------------+------------------------------------- Reporter: bgamari | Owner: bgamari Type: bug | Status: new Priority: normal | Milestone: Component: Continuous | Version: 8.2.1 Integration | 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: -------------------------------------+------------------------------------- -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14506> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15293: Set up staging branch
by GHC 28 Nov '18

28 Nov '18

#15293: Set up staging branch -------------------------------------+------------------------------------- Reporter: bgamari | Owner: bgamari Type: task | Status: new Priority: highest | Milestone: 8.6.1 Component: Continuous | Version: 8.4.3 Integration | 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: -------------------------------------+------------------------------------- Goal: Keep commits that would break CI out of `master`. Approach: Introduce a staging branch where commits will first land to go through the full CI workup. When a commit passes on `staging`, merge it into `master`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15293> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14950: GHC 8.2.2: GHCi duplicates breakpoint range prompt
by GHC 28 Nov '18

28 Nov '18

#14950: GHC 8.2.2: GHCi duplicates breakpoint range prompt -------------------------------------+------------------------------------- Reporter: lierdakil | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.2.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Other Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I think breakpoint range is being printed twice, once as part of prompt, and the second time by itself. To reproduce, create `test.hs` file like this: {{{#!hs module Test where test :: IO () test = putStrLn "Hello, World!" }}} Then run the following GHCi session: {{{ $ ghci test.hs GHCi, version 8.2.2: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Test ( test.hs, interpreted ) Ok, one module loaded. *Test> :break test Breakpoint 0 activated at test.hs:4:8-31 *Test> :trace test Stopped in Test.test, test.hs:4:8-31 _result :: IO () = _ [test.hs:4:8-31] [test.hs:4:8-31] *Test> :set prompt "" [test.hs:4:8-31] }}} Notice `[test.hs:4:8-31]` is printed twice, and is even printed when prompt is set to `""`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14950> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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