March 2018 - ghc-tickets

[GHC] #14478: Abstract pattern synonyms (for hsig and hs-boot)
by GHC 27 Mar '18

27 Mar '18

#14478: Abstract pattern synonyms (for hsig and hs-boot) -------------------------------------+------------------------------------- Reporter: ezyang | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 (Type checker) | Keywords: backpack | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Most declaration forms (data types, values, type families, etc) support forward declaration in hs-boot/hsig files. However, pattern synonyms do not. This seems like a major omission! Some problems to solve: * The obvious syntax `pattern Foo :: pat_ty` is insufficient to specify whether or not a pattern is bidirectional or unidirectional. How should this be represented syntactically? * What is the interaction with bundling? Should it be possible to export a bundle of abstract pattern synonyms, with the intent that this means an implementation must also have bundled them together * See also #12717; abstract pattern synonym should be implementable with a plain old constructor -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14478> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12915: cmmImplementSwitchPlans creates duplicate blocks
by GHC 27 Mar '18

27 Mar '18

#12915: cmmImplementSwitchPlans creates duplicate blocks -------------------------------------+------------------------------------- Reporter: alexbiehl | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 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: -------------------------------------+------------------------------------- Given this c-- code *after* common block elimination and *before* cmmImplementSwitchPlans: {{{#!hs ... cfzc: _sfh3::P64 = R1; _cfB7::I64 = %MO_UU_Conv_W32_W64(I32[I64[_sfh3::P64 - 1] - 4]); switch [0 .. 20] _cfB7::I64 { case 2 : goto cfAR; case 4 : goto cfAV; case 6 : goto cfAZ; default: goto cfAC; } cfAZ: _sfh6::I64 = I64[_sfh3::P64 + 7]; _sfgp::I64 = 1; goto sfgo; cfAV: _sfh5::I64 = I64[_sfh3::P64 + 7]; _sfgp::I64 = 1; goto sfgo; cfAR: _sfh4::I64 = I64[_sfh3::P64 + 7]; _sfgp::I64 = 1; goto sfgo; sfgo: ... }}} Everything is fine, the blocks cfAZ, cfAV and cfAR are all a little different. But after cmmImplementSwitchPlans the code becomes: {{{#!hs ... cfzc: _sfgl::I64 = I64[Sp + 24]; _sfgn::P64 = P64[Sp + 16]; _cfB7::I64 = %MO_UU_Conv_W32_W64(I32[I64[R1 - 1] - 4]); if (_cfB7::I64 < 5) goto ufBe; else goto ufBg; ufBe: if (_cfB7::I64 < 4) goto ufBf; else goto cfAV; ufBf: if (_cfB7::I64 != 2) goto cfAC; else goto cfAR; cfAR: _sfgp::I64 = 1; goto sfgo; cfAV: _sfgp::I64 = 1; goto sfgo; ufBg: if (_cfB7::I64 != 6) goto cfAC; else goto cfAZ; cfAZ: _sfgp::I64 = 1; goto sfgo; sfgo: ... }}} We can now see that cfAZ, cfAV and cfAR are code duplicates! Now, https://github.com/ghc/ghc/blob/master/compiler/cmm/CmmPipeline.hs#L72 states {{{ ... ----------- Eliminate common blocks ------------------------------------- g <- {-# SCC "elimCommonBlocks" #-} condPass Opt_CmmElimCommonBlocks elimCommonBlocks g Opt_D_dump_cmm_cbe "Post common block elimination" -- Any work storing block Labels must be performed _after_ -- elimCommonBlocks g <- {-# SCC "createSwitchPlans" #-} runUniqSM $ cmmImplementSwitchPlans dflags g dump Opt_D_dump_cmm_switch "Post switch plan" g ... }}} For some reason I don't understand cmmImplementSwitchPlans is run *after* elimCommonBlocks. Although it seems elimCommonBlocks can deal with the constructs introduced in cmmImplementSwitchPlans. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12915> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14496: Invoking GHC 8.2.1 executable anywhere results in access violation on Windows 10
by GHC 27 Mar '18

27 Mar '18

#14496: Invoking GHC 8.2.1 executable anywhere results in access violation on Windows 10 -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Keywords: | Operating System: Windows Architecture: | Type of failure: GHC doesn't work Unknown/Multiple | at all Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This apparently started to happen somewhat recently, as I've been able to run GHC 8.2.1 on Windows before. (Perhaps it was a recent update that changed things?) In any case, any attempt to run GHC or GHCi 8.2.1 immediately results in an access violation, and always at the same memory location: {{{ $ ghc --version The Glorious Glasgow Haskell Compilation System, version 8.2.1 $ ghc Access violation in generated code when reading 000000001170399e $ ghci WARNING: GHCi invoked via 'ghci.exe' in MinTTY consoles (e.g., Cygwin or MSYS) doesn't handle Ctrl-C well; use the 'ghcii.sh' shell wrapper instead GHCi, version 8.2.1: http://www.haskell.org/ghc/ :? for help Access violation in generated code when reading 000000001170399e }}} Strangely enough, GHC 8.0.2 and older do not suffer from this issue, just 8.2.1. In case it's useful, here's the `strace` output: {{{ $ strace ghc Access violation in generated code when reading 000000001170399e create_child: ghc --- Process 10324 created --- Process 10324 loaded C:\Windows\System32\ntdll.dll at 00007ffa31280000 --- Process 10324 loaded C:\Windows\System32\kernel32.dll at 00007ffa31170000 --- Process 10324 loaded C:\Windows\System32\KernelBase.dll at 00007ffa2dd40000 --- Process 10324 loaded C:\Windows\System32\apphelp.dll at 00007ffa2b500000 --- Process 10324 loaded C:\Windows\System32\AcLayers.dll at 00007ffa03630000 --- Process 10324 loaded C:\Windows\System32\msvcrt.dll at 00007ffa30ab0000 --- Process 10324 loaded C:\Windows\System32\user32.dll at 00007ffa2e850000 --- Process 10324 loaded C:\Windows\System32\win32u.dll at 00007ffa2dba0000 --- Process 10324 loaded C:\Windows\System32\gdi32.dll at 00007ffa2ec30000 --- Process 10324 loaded C:\Windows\System32\gdi32full.dll at 00007ffa2da00000 --- Process 10324 loaded C:\Windows\System32\msvcp_win.dll at 00007ffa2d960000 --- Process 10324 loaded C:\Windows\System32\ucrtbase.dll at 00007ffa2dbc0000 --- Process 10324 loaded C:\Windows\System32\shlwapi.dll at 00007ffa2e7f0000 --- Process 10324 loaded C:\Windows\System32\combase.dll at 00007ffa30e50000 --- Process 10324 loaded C:\Windows\System32\rpcrt4.dll at 00007ffa2e9e0000 --- Process 10324 loaded C:\Windows\System32\bcryptprimitives.dll at 00007ffa2dcc0000 --- Process 10324 loaded C:\Windows\System32\sfc.dll at 0000000180000000 --- Process 10324 loaded C:\Windows\System32\winspool.drv at 00007ffa1db00000 --- Process 10324 loaded C:\Windows\System32\IPHLPAPI.DLL at 00007ffa2cb90000 --- Process 10324 loaded C:\Windows\System32\bcrypt.dll at 00007ffa2d0d0000 --- Process 10324 loaded C:\Windows\System32\sfc_os.dll at 00007ffa1c2e0000 --- Process 10324 loaded C:\Windows\System32\imm32.dll at 00007ffa31220000 --- Process 10324 loaded C:\Windows\System32\shell32.dll at 00007ffa2ef80000 --- Process 10324 loaded C:\Windows\System32\cfgmgr32.dll at 00007ffa2e700000 --- Process 10324 thread 3948 created --- Process 10324 loaded C:\Windows\System32\SHCore.dll at 00007ffa30cf0000 --- Process 10324 loaded C:\Windows\System32\windows.storage.dll at 00007ffa2dfb0000 --- Process 10324 loaded C:\Windows\System32\advapi32.dll at 00007ffa30da0000 --- Process 10324 loaded C:\Windows\System32\sechost.dll at 00007ffa2eb00000 --- Process 10324 thread 4764 created --- Process 10324 loaded C:\Windows\System32\kernel.appcore.dll at 00007ffa2d660000 --- Process 10324 loaded C:\Windows\System32\powrprof.dll at 00007ffa2d5f0000 --- Process 10324 loaded C:\Windows\System32\profapi.dll at 00007ffa2d5d0000 --- Process 10324 thread 3852 created --- Process 10324 loaded C:\Windows\System32\wsock32.dll at 00007ffa1c2b0000 --- Process 10324 loaded C:\Windows\System32\ws2_32.dll at 00007ffa2ef10000 --- Process 10324 loaded C:\Windows\System32\ws2_32.dll at 0000000000150000 --- Process 10324 unloaded DLL at 0000000000150000 --- Process 10324 thread 4872 created --- Process 10324 thread 5780 created --- Process 10324 thread 8360 created --- Process 10324, exception c0000005 at 00007ffa3129c12e --- Process 10324 thread 8360 exited with status 0x1 --- Process 10324 thread 5780 exited with status 0x1 --- Process 10324 thread 4872 exited with status 0x1 --- Process 10324 thread 3852 exited with status 0x1 --- Process 10324 thread 4764 exited with status 0x1 --- Process 10324 thread 3948 exited with status 0x1 --- Process 10324 exited with status 0x1 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14496> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13938: Iface type variable out of scope: k1
by GHC 27 Mar '18

27 Mar '18

#13938: Iface type variable out of scope: k1 -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 (Type checker) | Keywords: TypeInType, | Operating System: Unknown/Multiple TypeApplications | Architecture: | Type of failure: Incorrect Unknown/Multiple | error/warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I managed to make GHC spit out an unusual warning when doing some dependent Haskell recently. This issue is reproducible on GHC 8.0.1, 8.0.2, 8.2.1, and HEAD. You'll need these two files: {{{#!hs {-# LANGUAGE AllowAmbiguousTypes #-} {-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE ExistentialQuantification #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TemplateHaskell #-} {-# LANGUAGE TypeApplications #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeInType #-} {-# LANGUAGE TypeOperators #-} module Eliminator where import Data.Kind (Type) data family Sing (a :: k) data instance Sing (z :: [a]) where SNil :: Sing '[] SCons :: Sing x -> Sing xs -> Sing (x:xs) data TyFun :: Type -> Type -> Type type a ~> b = TyFun a b -> Type infixr 0 ~> type family Apply (f :: k1 ~> k2) (x :: k1) :: k2 type a @@ b = Apply a b infixl 9 @@ data FunArrow = (:->) -- ^ '(->)' | (:~>) -- ^ '(~>)' class FunType (arr :: FunArrow) where type Fun (k1 :: Type) arr (k2 :: Type) :: Type class FunType arr => AppType (arr :: FunArrow) where type App k1 arr k2 (f :: Fun k1 arr k2) (x :: k1) :: k2 type FunApp arr = (FunType arr, AppType arr) instance FunType (:->) where type Fun k1 (:->) k2 = k1 -> k2 $(return []) -- This is only necessary for GHC 8.0 -- GHC 8.2 is smarter instance AppType (:->) where type App k1 (:->) k2 (f :: k1 -> k2) x = f x instance FunType (:~>) where type Fun k1 (:~>) k2 = k1 ~> k2 $(return []) instance AppType (:~>) where type App k1 (:~>) k2 (f :: k1 ~> k2) x = f @@ x infixr 0 -?> type (-?>) (k1 :: Type) (k2 :: Type) (arr :: FunArrow) = Fun k1 arr k2 elimList :: forall (a :: Type) (p :: [a] -> Type) (l :: [a]). Sing l -> p '[] -> (forall (x :: a) (xs :: [a]). Sing x -> Sing xs -> p xs -> p (x:xs)) -> p l elimList = elimListPoly @(:->) elimListTyFun :: forall (a :: Type) (p :: [a] ~> Type) (l :: [a]). Sing l -> p @@ '[] -> (forall (x :: a) (xs :: [a]). Sing x -> Sing xs -> p @@ xs -> p @@ (x:xs)) -> p @@ l elimListTyFun = elimListPoly @(:~>) @_ @p elimListPoly :: forall (arr :: FunArrow) (a :: Type) (p :: ([a] -?> Type) arr) (l :: [a]). FunApp arr => Sing l -> App [a] arr Type p '[] -> (forall (x :: a) (xs :: [a]). Sing x -> Sing xs -> App [a] arr Type p xs -> App [a] arr Type p (x:xs)) -> App [a] arr Type p l elimListPoly SNil pNil _ = pNil elimListPoly (SCons x (xs :: Sing xs)) pNil pCons = pCons x xs (elimListPoly @arr @a @p @xs xs pNil pCons) }}} {{{#!hs {-# LANGUAGE AllowAmbiguousTypes #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeApplications #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeInType #-} {-# LANGUAGE TypeOperators #-} {-# LANGUAGE UndecidableInstances #-} module ListSpec where import Eliminator import Data.Kind import Data.Type.Equality import GHC.TypeLits type family Length (l :: [a]) :: Nat where {} type family Map (f :: a ~> b) (l :: [a]) :: [b] where {} type WhyMapPreservesLength (f :: x ~> y) (l :: [x]) = Length l :~: Length (Map f l) data WhyMapPreservesLengthSym1 (f :: x ~> y) :: [x] ~> Type type instance Apply (WhyMapPreservesLengthSym1 f) l = WhyMapPreservesLength f l mapPreservesLength :: forall (x :: Type) (y :: Type) (f :: x ~> y) (l :: [x]). Length l :~: Length (Map f l) mapPreservesLength = elimListTyFun @x @(WhyMapPreservesLengthSym1 f) @l undefined undefined undefined }}} You'll need to compile the files like this: {{{ $ /opt/ghc/8.0.2/bin/ghc -fforce-recomp -O2 -c Eliminator.hs $ /opt/ghc/8.0.2/bin/ghc -fforce-recomp -O2 -c ListSpec.hs ./Eliminator.hi Declaration for elimListTyFun Unfolding of elimListTyFun: Iface type variable out of scope: k2 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13938> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14038: TypeApplications regression in GHC HEAD: ‘p0’ is untouchable inside the constraints: ()
by GHC 27 Mar '18

27 Mar '18

#14038: TypeApplications regression in GHC HEAD: ‘p0’ is untouchable inside the constraints: () -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.4.1 Component: Compiler | Version: 8.3 (Type checker) | 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: -------------------------------------+------------------------------------- This file: {{{#!hs {-# LANGUAGE AllowAmbiguousTypes #-} {-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE ExistentialQuantification #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeApplications #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeInType #-} {-# LANGUAGE TypeOperators #-} module Eliminator where import Data.Kind (Type) data family Sing (a :: k) data instance Sing (z :: [a]) where SNil :: Sing '[] SCons :: Sing x -> Sing xs -> Sing (x:xs) data TyFun :: Type -> Type -> Type type a ~> b = TyFun a b -> Type infixr 0 ~> type family Apply (f :: k1 ~> k2) (x :: k1) :: k2 type a @@ b = Apply a b infixl 9 @@ data FunArrow = (:->) -- ^ '(->)' | (:~>) -- ^ '(~>)' class FunType (arr :: FunArrow) where type Fun (k1 :: Type) arr (k2 :: Type) :: Type class FunType arr => AppType (arr :: FunArrow) where type App k1 arr k2 (f :: Fun k1 arr k2) (x :: k1) :: k2 type FunApp arr = (FunType arr, AppType arr) instance FunType (:->) where type Fun k1 (:->) k2 = k1 -> k2 instance AppType (:->) where type App k1 (:->) k2 (f :: k1 -> k2) x = f x instance FunType (:~>) where type Fun k1 (:~>) k2 = k1 ~> k2 instance AppType (:~>) where type App k1 (:~>) k2 (f :: k1 ~> k2) x = f @@ x infixr 0 -?> type (-?>) (k1 :: Type) (k2 :: Type) (arr :: FunArrow) = Fun k1 arr k2 elimList :: forall (a :: Type) (p :: [a] -> Type) (l :: [a]). Sing l -> p '[] -> (forall (x :: a) (xs :: [a]). Sing x -> Sing xs -> p xs -> p (x:xs)) -> p l elimList = elimListPoly @(:->) elimListTyFun :: forall (a :: Type) (p :: [a] ~> Type) (l :: [a]). Sing l -> p @@ '[] -> (forall (x :: a) (xs :: [a]). Sing x -> Sing xs -> p @@ xs -> p @@ (x:xs)) -> p @@ l elimListTyFun = elimListPoly @(:~>) @_ @p elimListPoly :: forall (arr :: FunArrow) (a :: Type) (p :: ([a] -?> Type) arr) (l :: [a]). FunApp arr => Sing l -> App [a] arr Type p '[] -> (forall (x :: a) (xs :: [a]). Sing x -> Sing xs -> App [a] arr Type p xs -> App [a] arr Type p (x:xs)) -> App [a] arr Type p l elimListPoly SNil pNil _ = pNil elimListPoly (SCons x (xs :: Sing xs)) pNil pCons = pCons x xs (elimListPoly @arr @a @p @xs xs pNil pCons) }}} Typechecks in GHC 8.2.1 without issue, but fails in GHC HEAD: {{{ $ ghc5/inplace/bin/ghc-stage2 --interactive Bug.hs GHCi, version 8.3.20170725: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Eliminator ( Bug.hs, interpreted ) Bug.hs:59:12: error: • Couldn't match type ‘p0’ with ‘p’ because type variables ‘a1’, ‘p’ would escape their scope These (rigid, skolem) type variables are bound by the type signature for: elimList :: forall a1 (p :: [a1] -> *) (l :: [a1]). Sing l -> p '[] -> (forall (x :: a1) (xs :: [a1]). Sing x -> Sing xs -> p xs -> p (x : xs)) -> p l at Bug.hs:(54,1)-(58,15) Expected type: Sing l -> p '[] -> (forall (x :: a1) (xs :: [a1]). Sing x -> Sing xs -> p xs -> p (x : xs)) -> p l Actual type: Sing l -> App [a1] (':->) * p0 '[] -> (forall (x :: a1) (xs :: [a1]). Sing x -> Sing xs -> App [a1] (':->) * p0 xs -> App [a1] (':->) * p0 (x : xs)) -> App [a1] (':->) * p0 l • In the expression: elimListPoly @(:->) In an equation for ‘elimList’: elimList = elimListPoly @(:->) • Relevant bindings include elimList :: Sing l -> p '[] -> (forall (x :: a1) (xs :: [a1]). Sing x -> Sing xs -> p xs -> p (x : xs)) -> p l (bound at Bug.hs:59:1) | 59 | elimList = elimListPoly @(:->) | ^^^^^^^^^^^^^^^^^^^ Bug.hs:59:12: error: • Couldn't match type ‘p0’ with ‘p’ ‘p0’ is untouchable inside the constraints: () bound by a type expected by the context: forall (x :: a1) (xs :: [a1]). Sing x -> Sing xs -> App [a1] (':->) * p0 xs -> App [a1] (':->) * p0 (x : xs) at Bug.hs:59:12-30 ‘p’ is a rigid type variable bound by the type signature for: elimList :: forall a1 (p :: [a1] -> *) (l :: [a1]). Sing l -> p '[] -> (forall (x :: a1) (xs :: [a1]). Sing x -> Sing xs -> p xs -> p (x : xs)) -> p l at Bug.hs:(54,1)-(58,15) Expected type: Sing x -> Sing xs -> App [a1] (':->) * p0 xs -> App [a1] (':->) * p0 (x : xs) Actual type: Sing x -> Sing xs -> p xs -> p (x : xs) • In the expression: elimListPoly @(:->) In an equation for ‘elimList’: elimList = elimListPoly @(:->) • Relevant bindings include elimList :: Sing l -> p '[] -> (forall (x :: a1) (xs :: [a1]). Sing x -> Sing xs -> p xs -> p (x : xs)) -> p l (bound at Bug.hs:59:1) | 59 | elimList = elimListPoly @(:->) | ^^^^^^^^^^^^^^^^^^^ }}} A workaround is to explicitly apply `p` with `TypeApplications` in line 59: {{{#!hs elimList = elimListPoly @(:->) @_ @p }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14038> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13910: Inlining a definition causes GHC to panic (repSplitTyConApp_maybe)
by GHC 27 Mar '18

27 Mar '18

#13910: Inlining a definition causes GHC to panic (repSplitTyConApp_maybe) -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1-rc2 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: #13877 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Here is a program which I believe //should// typecheck: {{{#!hs {-# LANGUAGE AllowAmbiguousTypes #-} {-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TemplateHaskell #-} {-# LANGUAGE Trustworthy #-} {-# LANGUAGE TypeApplications #-} {-# LANGUAGE TypeFamilyDependencies #-} {-# LANGUAGE TypeInType #-} {-# LANGUAGE TypeOperators #-} module Bug where import Data.Kind import Data.Type.Equality data family Sing (a :: k) class SingKind k where type Demote k = (r :: *) | r -> k fromSing :: Sing (a :: k) -> Demote k toSing :: Demote k -> SomeSing k data SomeSing k where SomeSing :: Sing (a :: k) -> SomeSing k withSomeSing :: forall k r . SingKind k => Demote k -> (forall (a :: k). Sing a -> r) -> r withSomeSing x f = case toSing x of SomeSing x' -> f x' data TyFun :: * -> * -> * type a ~> b = TyFun a b -> * infixr 0 ~> type family Apply (f :: k1 ~> k2) (x :: k1) :: k2 type a @@ b = Apply a b infixl 9 @@ data FunArrow = (:->) | (:~>) class FunType (arr :: FunArrow) where type Fun (k1 :: Type) arr (k2 :: Type) :: Type class FunType arr => AppType (arr :: FunArrow) where type App k1 arr k2 (f :: Fun k1 arr k2) (x :: k1) :: k2 type FunApp arr = (FunType arr, AppType arr) instance FunType (:->) where type Fun k1 (:->) k2 = k1 -> k2 $(return []) -- This is only necessary for GHC 8.0 -- GHC 8.2 is smarter instance AppType (:->) where type App k1 (:->) k2 (f :: k1 -> k2) x = f x instance FunType (:~>) where type Fun k1 (:~>) k2 = k1 ~> k2 $(return []) instance AppType (:~>) where type App k1 (:~>) k2 (f :: k1 ~> k2) x = f @@ x infixr 0 -?> type (-?>) (k1 :: Type) (k2 :: Type) (arr :: FunArrow) = Fun k1 arr k2 data instance Sing (z :: a :~: b) where SRefl :: Sing Refl instance SingKind (a :~: b) where type Demote (a :~: b) = a :~: b fromSing SRefl = Refl toSing Refl = SomeSing SRefl (~>:~:) :: forall (k :: Type) (a :: k) (b :: k) (r :: a :~: b) (p :: forall (y :: k). a :~: y ~> Type). Sing r -> p @@ Refl -> p @@ r (~>:~:) SRefl pRefl = pRefl type WhyReplacePoly (arr :: FunArrow) (from :: t) (p :: (t -?> Type) arr) (y :: t) (e :: from :~: y) = App t arr Type p y data WhyReplacePolySym (arr :: FunArrow) (from :: t) (p :: (t -?> Type) arr) :: forall (y :: t). from :~: y ~> Type type instance Apply (WhyReplacePolySym arr from p :: from :~: y ~> Type) x = WhyReplacePoly arr from p y x replace :: forall (t :: Type) (from :: t) (to :: t) (p :: t -> Type). p from -> from :~: to -> p to replace = replacePoly @(:->) replaceTyFun :: forall (t :: Type) (from :: t) (to :: t) (p :: t ~> Type). p @@ from -> from :~: to -> p @@ to replaceTyFun = replacePoly @(:~>) @_ @_ @_ @p replacePoly :: forall (arr :: FunArrow) (t :: Type) (from :: t) (to :: t) (p :: (t -?> Type) arr). FunApp arr => App t arr Type p from -> from :~: to -> App t arr Type p to replacePoly from eq = withSomeSing eq $ \(singEq :: Sing r) -> (~>:~:) @t @from @to @r @(WhyReplacePolySym arr from p) singEq from type WhyLeibnizPoly (arr :: FunArrow) (f :: (t -?> Type) arr) (a :: t) (z :: t) = App t arr Type f a -> App t arr Type f z data WhyLeibnizPolySym (arr :: FunArrow) (f :: (t -?> Type) arr) (a :: t) :: t ~> Type type instance Apply (WhyLeibnizPolySym arr f a) z = WhyLeibnizPoly arr f a z leibnizPoly :: forall (arr :: FunArrow) (t :: Type) (f :: (t -?> Type) arr) (a :: t) (b :: t). FunApp arr => a :~: b -> App t arr Type f a -> App t arr Type f b leibnizPoly = replaceTyFun @t @a @b @(WhyLeibnizPolySym arr f a) id leibniz :: forall (t :: Type) (f :: t -> Type) (a :: t) (b :: t). a :~: b -> f a -> f b leibniz = replaceTyFun @t @a @b @(WhyLeibnizPolySym (:->) f a) id -- The line above is what you get if you inline the definition of leibnizPoly. -- It causes a panic, however. -- -- An equivalent implementation is commented out below, which does *not* -- cause GHC to panic. -- -- leibniz = leibnizPoly @(:->) leibnizTyFun :: forall (t :: Type) (f :: t ~> Type) (a :: t) (b :: t). a :~: b -> f @@ a -> f @@ b leibnizTyFun = leibnizPoly @(:~>) @_ @f }}} GHC 8.2.1 and HEAD panic on the definition of `leibniz`, however: {{{ $ /opt/ghc/8.2.1/bin/ghci Bug.hs GHCi, version 8.2.0.20170623: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) ghc: panic! (the 'impossible' happened) (GHC version 8.2.0.20170623 for x86_64-unknown-linux): repSplitTyConApp_maybe (f_a5vT[sk:2] |> Sym (Trans (Sym (D:R:Funk1:->k2[0] <k1>_N <k2>_N)) (D:R:Funk1:->k2[0] <t>_N <*>_N))) a_a5vU[sk:2] (f_a5vT[sk:2] |> Sym (Trans (Sym (D:R:Funk1:->k2[0] <k1>_N <k2>_N)) (D:R:Funk1:->k2[0] <t>_N <*>_N))) a_a5vU[sk:2] k2_a5l0 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/types/Type.hs:1122:5 in ghc:Type Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} Interestingly, GHC 8.0.1 and 8.0.2 do not give the same panic—they give the panic from #13877: {{{ $ /opt/ghc/8.0.2/bin/ghci Bug.hs GHCi, version 8.0.2: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Bug.hs:134:64: error:ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-linux): No skolem info: k2_a4KV Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13910> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14889: ghc-HEAD broke cross-compilation on multiple tagets due to --via-asm switch
by GHC 27 Mar '18

27 Mar '18

#14889: ghc-HEAD broke cross-compilation on multiple tagets due to --via-asm switch -------------------------------------+------------------------------------- Reporter: slyfox | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.5 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: -------------------------------------+------------------------------------- Commit http://git.haskell.org/ghc.git/commitdiff/5f6fcf7808b16d066ad0fb2068225b3f2… enables '''--via-asm''' for all targets: {{{ ifeq "$(CrossCompiling)" "YES" -SRC_HSC2HS_OPTS_STAGE1 += --cross-compile -SRC_HSC2HS_OPTS_STAGE2 += --cross-compile +# We'll assume we compile with gcc or clang, and both support `-S` and can as such use the +# --via-asm pass, which should be faster and is required for cross compiling to windows, as +# the c compiler complains about non-constant expressions even though they are constant and +# end up as constants in the assembly. +SRC_HSC2HS_OPTS_STAGE1 += --cross-compile --via-asm +SRC_HSC2HS_OPTS_STAGE2 += --cross-compile --via-asm endif }}} But the discussion in original submission https://github.com/haskell/hsc2hs/pull/5 talks about opt-in and mostly x86 assembly support. Before this change targets like sparc were cross-compiling just fine. Now '''sparc-unknown-linux-gnu''' fails as: {{{ hsc2hs: Failed to extract integer CallStack (from HasCallStack): error, called at utils/hsc2hs/CrossCodegen.hs:606:27 in main:CrossCodegen make[1]: *** [libraries/unix/ghc.mk:4: libraries/unix/dist- install/build/System/Posix/Files.hs] Error 1 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14889> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3559: split ghci modules off into their own package
by GHC 26 Mar '18

26 Mar '18

#3559: split ghci modules off into their own package -------------------------------------+------------------------------------- Reporter: igloo | Owner: (none) Type: task | Status: closed Priority: low | Milestone: Component: GHCi | Version: 6.10.4 Resolution: wontfix | 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 bgamari): * status: new => closed * resolution: => wontfix Comment: We now have `libraries/ghci`. I'm not sure what this ticket intended but I'm going to close this as not immediately actionable. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3559#comment:12> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3215: Valgrind support
by GHC 26 Mar '18

26 Mar '18

#3215: Valgrind support ------------------------------------+-------------------------------- Reporter: cmcq | Owner: (none) Type: feature request | Status: closed Priority: normal | Milestone: ⊥ Component: Runtime System | Version: 6.10.3 Resolution: | Keywords: valgrind Operating System: Linux | Architecture: x86 Type of failure: None/Unknown | Test Case: yes Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | ------------------------------------+-------------------------------- Changes (by bgamari): * status: new => closed Comment: Valgrind has worked reasonably well the few times I have used it to track down RTS issues. I'm going to close this. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3215#comment:10> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3122: Enhance --info
by GHC 26 Mar '18

26 Mar '18

#3122: Enhance --info -------------------------------------+------------------------------------- Reporter: igloo | Owner: duncan Type: feature request | Status: closed Priority: lowest | Milestone: Component: Compiler | Version: 6.10.1 Resolution: fixed | 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 bgamari): * status: new => closed * resolution: => fixed Comment: I'm going to close this as it's not clearly actionable. If you can think of something that you would like to see `--info` report do open a ticket. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3122#comment:16> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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