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[GHC] #15816: Visible kind applications + data family: `U :: Type' said to be of kind `k0 -> k1` in error message
by GHC 16 Jan '19

16 Jan '19

#15816: Visible kind applications + data family: `U :: Type' said to be of kind `k0 -> k1` in error message -------------------------------------+------------------------------------- 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 the [https://phabricator.haskell.org/D5229 visible kind applications (D5229)] (#12045) patch. GHC erroneously calls `U :: Type` a "function" of kind `k0 -> k1` if I understand this right, {{{ $ ghci GHCi, version 8.7.20181017: http://www.haskell.org/ghc/ :? for help Prelude> :set prompt "> " > import Data.Kind (Type) > > :set -XTypeFamilies > :set -XTypeApplications > > data family U :: Type > data instance U @Int <interactive>:7:1: error: • Cannot apply function of kind ‘k0 -> k1’ to visible kind argument ‘Int’ • In the data instance declaration for ‘U’ > }}} I expect something like "Cannot apply type `U` to visible kind argument `Int`" or {{{ > data instance U Int = MkU <interactive>:7:1: error: • Expected kind ‘* -> *’, but ‘U’ has kind ‘*’ • In the data instance declaration for ‘U’ > }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15816> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15362: Template Haskell ignores bad type family definitions
by GHC 16 Jan '19

16 Jan '19

#15362: Template Haskell ignores bad type family definitions -------------------------------------+------------------------------------- Reporter: goldfire | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Template | Version: 8.4.3 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: -------------------------------------+------------------------------------- This garbage is accepted: {{{#!hs data Nat = Zero | Succ Nat $( [d| type family a + b where Maybe Zero b = b Succ a + b = Succ (a + b) |] ) }}} Note the `Maybe` photo-bombing in the first equation. The problem is that TH uses the symbol declared in the family head for all the equations, ignoring what's actually there. This is sad. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15362> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15788: Core Lint error, from visible kind applications
by GHC 16 Jan '19

16 Jan '19

#15788: Core Lint error, from visible kind applications -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 Keywords: #12045 | 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 {-# Language RankNTypes #-} {-# Language GADTs #-} {-# Language TypeApplications #-} {-# Language PolyKinds #-} {-# Options_GHC -dcore-lint #-} import Data.Kind data A :: forall k. Type where MkA :: A @k }}} this cute bug crashes under the [https://phabricator.haskell.org/D5229 visible kind application] diff, produces: {{{ $ ghci -ignore-dot-ghci 545_bug.hs GHCi, version 8.7.20181017: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( 545_bug.hs, interpreted ) *** Core Lint errors : in result of Tidy Core *** <no location info>: warning: In the type ‘forall (k :: k_a1xN[sk:1]) k. A’ @ k_a1xN[sk:1] is out of scope *** Offending Program *** $WMkA [InlPrag=INLINE[2]] :: forall (k :: k_a1xN[sk:1]) k. A [GblId[DataConWrapper], Caf=NoCafRefs, Unf=Unf{Src=InlineStable, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=ALWAYS_IF(arity=0,unsat_ok=True,boring_ok=True) Tmpl= \ (@ (k_a1y5 :: k_a1xN[sk:1])) (@ k_X1xP) -> MkA @ k_X1xP @ k_a1y5}] $WMkA = \ (@ (k_a1y5 :: k_a1xN[sk:1])) (@ k_X1xP) -> MkA @ k_X1xP @ k_a1y5 $trModule1_r1zb :: Addr# [GblId, Caf=NoCafRefs, Unf=OtherCon []] $trModule1_r1zb = "main"# $trModule2_r1zu :: TrName [GblId, Caf=NoCafRefs, Unf=OtherCon []] $trModule2_r1zu = TrNameS $trModule1_r1zb $trModule3_r1zv :: Addr# [GblId, Caf=NoCafRefs, Unf=OtherCon []] $trModule3_r1zv = "Main"# $trModule4_r1zw :: TrName [GblId, Caf=NoCafRefs, Unf=OtherCon []] $trModule4_r1zw = TrNameS $trModule3_r1zv $trModule :: Module [GblId, Caf=NoCafRefs, Unf=OtherCon []] $trModule = Module $trModule2_r1zu $trModule4_r1zw $krep_r1zx :: KindRep [GblId, Caf=NoCafRefs, Unf=OtherCon []] $krep_r1zx = KindRepVar 1# $krep1_r1zy :: KindRep [GblId, Caf=NoCafRefs, Unf=OtherCon []] $krep1_r1zy = KindRepVar 0# $tcA1_r1zz :: Addr# [GblId, Caf=NoCafRefs, Unf=OtherCon []] $tcA1_r1zz = "A"# $tcA2_r1zA :: TrName [GblId, Caf=NoCafRefs, Unf=OtherCon []] $tcA2_r1zA = TrNameS $tcA1_r1zz $tcA :: TyCon [GblId, Unf=OtherCon []] $tcA = TyCon 16201120719427956884## 13080046616073797921## $trModule $tcA2_r1zA 2# krep$* $krep2_r1zB :: [KindRep] [GblId, Caf=NoCafRefs, Unf=OtherCon []] $krep2_r1zB = : @ KindRep $krep1_r1zy ([] @ KindRep) $krep3_r1zC :: [KindRep] [GblId, Caf=NoCafRefs, Unf=OtherCon []] $krep3_r1zC = : @ KindRep $krep_r1zx $krep2_r1zB $krep4_r1zD :: KindRep [GblId, Unf=OtherCon []] $krep4_r1zD = KindRepTyConApp $tcA $krep3_r1zC $tc'MkA1_r1zE :: Addr# [GblId, Caf=NoCafRefs, Unf=OtherCon []] $tc'MkA1_r1zE = "'MkA"# $tc'MkA2_r1zF :: TrName [GblId, Caf=NoCafRefs, Unf=OtherCon []] $tc'MkA2_r1zF = TrNameS $tc'MkA1_r1zE $tc'MkA :: TyCon [GblId, Unf=OtherCon []] $tc'MkA = TyCon 1695572187443655535## 16213897990811765752## $trModule $tc'MkA2_r1zF 2# $krep4_r1zD *** End of Offense *** <no location info>: error: Compilation had errors *** Exception: ExitFailure 1 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15788> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15793: Type family doesn't reduce with visible kind application
by GHC 16 Jan '19

16 Jan '19

#15793: Type family doesn't reduce with visible kind application -------------------------------------+------------------------------------- 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: -------------------------------------+------------------------------------- If we un-comment `f2` {{{#!hs {-# Language RankNTypes #-} {-# Language TypeFamilies #-} {-# Language TypeApplications #-} {-# Language PolyKinds #-} import Data.Kind type family F1 (a :: Type) :: Type where F1 a = Maybe a f1 :: F1 a f1 = Nothing type family F2 :: forall (a :: Type). Type where F2 @a = Maybe a -- f2 :: F2 @a -- f2 = Nothing }}} this program fails with {{{ • Couldn't match kind ‘forall a1. *’ with ‘* -> *’ When matching types F2 :: forall a. * Maybe :: * -> * Expected type: F2 Actual type: Maybe a • In the expression: Nothing In an equation for ‘f2’: f2 = Nothing | 20 | f2 = Nothing | ^^^^^^^ Failed, no modules loaded. }}} It also succeeds replacing `Nothing` with `undefined` {{{#!hs f2 :: F2 @a f2 = undefined }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15793> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15807: GHC panic with visible kind applications
by GHC 16 Jan '19

16 Jan '19

#15807: GHC panic with visible kind applications ----------------------------------------+--------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 Keywords: TypeApplications | Operating System: Linux Architecture: Unknown/Multiple | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ----------------------------------------+--------------------------------- Using the https://phabricator.haskell.org/D5229 diff This is '''fine''' {{{#!hs {-# Language RankNTypes #-} {-# Language TypeApplications #-} {-# Language PolyKinds #-} {-# Language GADTs #-} import Data.Kind data App :: forall (f :: Type -> Type). Type -> Type where MkApp :: f a -> App @f a }}} Kind polymorphic is '''fine''' {{{#!hs {-# Language RankNTypes #-} {-# Language TypeApplications #-} {-# Language PolyKinds #-} {-# Language GADTs #-} import Data.Kind data App :: forall k (f :: k -> Type). k -> Type where MkApp :: f a -> App @k @(f :: k -> Type) (a :: k) }}} But offing the visibility of `k` '''fails''' {{{#!hs {-# Language RankNTypes #-} {-# Language TypeApplications #-} {-# Language PolyKinds #-} {-# Language GADTs #-} import Data.Kind data App :: forall (f :: k -> Type). k -> Type where MkApp :: f a -> App @(f :: k -> Type) (a :: k) }}} {{{#!hs {-# Language RankNTypes #-} {-# Language TypeApplications #-} {-# Language PolyKinds #-} {-# Language GADTs #-} import Data.Kind data App :: forall (f :: k -> Type). k -> Type where MkApp :: f a -> App @f a }}} {{{ $ ghci -ignore-dot-ghci 581_bug.hs GHCi, version 8.7.20181017: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( 581_bug.hs, interpreted ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.7.20181017 for x86_64-unknown-linux): ASSERT failed! 2 1 f_a1yB[tau:1] f_a1yx[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:778:54 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/15807> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16125: Broken Links in docs/users_guide/using-optimisation.rst
by GHC 16 Jan '19

16 Jan '19

#16125: Broken Links in docs/users_guide/using-optimisation.rst -------------------------------------+------------------------------------- Reporter: supersven | Owner: (none) Type: bug | Status: new Priority: low | Milestone: Component: Documentation | Version: 8.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #1574 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ Chapter 7 of `Andre Santos's PhD thesis <http://research.microsoft.com/en-us/um/people/simonpj/papers /santos-thesis.ps.gz>`__ }}} Following this link leads to a 404 not found. I think the correct one should be: https://www.microsoft.com/en-us/research/publication /compilation-transformation-non-strict-functional-languages/ ----- {{{ implementation is described in the paper `Theory and Practice of Demand Analysis in Haskell`<https://www.microsoft.com/en-us/research/wp- content/uploads/2017/03/demand-jfp-draft.pdf>`__. }}} This one contains one ` too much. The rendered link points to the document (using-optimisation.html) itself. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16125> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15797: GHC panic using visible kind application
by GHC 16 Jan '19

16 Jan '19

#15797: GHC panic using visible kind application -------------------------------------+------------------------------------- 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: -------------------------------------+------------------------------------- {{{#!hs {-# Language RankNTypes #-} {-# Language TypeFamilies #-} {-# Language ScopedTypeVariables #-} {-# Language TypeApplications #-} {-# Language DataKinds #-} {-# Language PolyKinds #-} {-# Language TypeOperators #-} {-# Language GADTs #-} {-# Options_GHC -dcore-lint #-} import Data.Kind class Ríki (obj :: Type) where type Obj :: obj -> Constraint type Obj = Bæ @obj class Bæ (a :: k) instance Bæ @k (a :: k) data EQ :: forall ob. ob -> ob -> Type where EQ :: EQ a a instance Ríki (EQ @ob) }}} {{{ $ ghci -dcore-lint 568_bug.hs GHCi, version 8.7.20181017: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( 568_bug.hs, interpreted ) WARNING: file compiler/types/TyCoRep.hs, line 2567 in_scope InScope {ob_a1zs co_a1zt} tenv [] cenv [a1zt :-> co_a1zt] tys [Bæ] cos [] needInScope [a1zn :-> co_a1zn, a1zs :-> ob_a1zs] ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.7.20181017 for x86_64-unknown-linux): Core Lint error <no location info>: warning: In the type ‘Bæ’ Unfilled coercion hole: {co_a1zn} <no location info>: warning: In the type ‘Bæ’ co_a1zn :: (ob_a1zs -> ob_a1zs -> *) ~# * [LclId[CoVarId]] is out of scope Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1160:37 in ghc:Outputable pprPanic, called at compiler/typecheck/FamInst.hs:171:31 in ghc:FamInst Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug > }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15797> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15798: Flag to warn when deriving strategy is not explicitly specified
by GHC 16 Jan '19

16 Jan '19

#15798: Flag to warn when deriving strategy is not explicitly specified -------------------------------------+------------------------------------- Reporter: andrewthad | Owner: (none) Type: feature | Status: new request | 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: -------------------------------------+------------------------------------- In my code, I aim to always specify deriving strategies. I would like to add a flag `-fwarn-unspecified-deriving` that would cause a warning to be emitted when someone wrote this: {{{ newtype Foo = Foo Int deriving (Show) }}} The user would be required to instead write: {{{ newtype Foo = Foo Int deriving newtype (Show) }}} Or they could use `stock` if that was the behavior they wanted. This flag would be off by default. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15798> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16131: -ddump-cmm doesn't work when compiling cmm files
by GHC 16 Jan '19

16 Jan '19

#16131: -ddump-cmm doesn't work when compiling cmm files -------------------------------------+------------------------------------- Reporter: osa1 | 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 want to see Cmm generated for `StgMiscClosures.cmm` so I tried adding `-ddump-cmm` to the command the build system runs to build it, which doesn't work: {{{ $ "inplace/bin/ghc-stage1" -static -O0 -H64m -Wall -Iincludes -Iincludes/dist -Iincludes/dist-derivedconstants/header -Iincludes/dist- ghcconstants/header -Irts -Irts/dist/build -DCOMPILING_RTS -DFS_NAMESPACE=rts -this-unit-id rts -dcmm-lint -i -irts -irts/dist/build -Irts/dist/build -irts/dist/build/./autogen -Irts/dist/build/./autogen -O2 -Wcpp-undef -Wnoncanonical-monad-instances -c rts/StgMiscClosures.cmm -o rts/dist/build/StgMiscClosures.o -fforce-recomp -ddump-cmm }}} Why do I need cmm dumps of cmm files? - When building Cmm even the parser does code generation, so the Cmm after parsing is quite different than the input and contains useful information. - I want all macros to be expanded, running CPP manually is painful. - I currently can't see output of Cmm optimisations when building Cmm files. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16131> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #16031: Show instance for Data.Fixed does not show parentheses for negatives
by GHC 16 Jan '19

16 Jan '19

#16031: Show instance for Data.Fixed does not show parentheses for negatives -------------------------------------+------------------------------------- Reporter: skeuchel | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 8.7 libraries/base | Keywords: Data.Fixed, | Operating System: Unknown/Multiple Show | Architecture: | Type of failure: Incorrect result Unknown/Multiple | at runtime Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- When showing negative numbers most types emit parentheses in precedence level 11 because the result is not atomic: {{{#!hs GHCi, version 8.7.20181015: http://www.haskell.org/ghc/ :? for help Prelude> show (Just (-1 :: Int)) "Just (-1)" Prelude> show (Just (-1 :: Float)) "Just (-1.0)" }}} However, the Show instance for Fixed does not {{{#!hs Prelude> :m Data.Fixed Prelude Data.Fixed> show (Just (-1 :: Fixed E2)) "Just -1.00" Prelude Data.Fixed> }}} I would expect it to, because of consistency and because the result "Just -1.00" is ill-typed when seen as an expression. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16031> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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