- ghc-tickets - Haskell.org

Re: [GHC] #7500: GHC: internal error: getMBlock: mmap: Operation not permitted
by GHC 30 Mar '18

30 Mar '18

#7500: GHC: internal error: getMBlock: mmap: Operation not permitted ----------------------------------+---------------------------------------- Reporter: guest | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: 7.8.1 Component: Compiler | Version: 7.4.1 Resolution: fixed | Keywords: Operating System: Linux | Architecture: Unknown/Multiple Type of failure: Runtime crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | ----------------------------------+---------------------------------------- Comment (by mcandre): I get this low-level error message in FreeBSD / HardenedBSD. Could we update the BSD ports of GHC to improve this error message as well? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7500#comment:9> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14728: Is (GeneralizedNewtypeDeriving + associated type classes) completely bogus?
by GHC 30 Mar '18

30 Mar '18

#14728: Is (GeneralizedNewtypeDeriving + associated type classes) completely bogus? -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 (Type checker) | Keywords: deriving, | Operating System: Unknown/Multiple TypeFamilies | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- In Phab:D2636, I implemented this ability to use `GeneralizedNewtypeDeriving` to derive instances of type classes with associated type families. At the time, I thought the implementation was a no-brainer, but now I'm starting to have second thoughts. To explain what I mean, consider this program: {{{#!hs {-# LANGUAGE GeneralizedNewtypeDeriving #-} {-# LANGUAGE StandaloneDeriving #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeInType #-} module Bug where import Data.Functor.Identity import Data.Kind class C (a :: Type) where type T a (x :: a) :: Type instance C () where type T () '() = Bool deriving instance C (Identity a) }}} Quite to my surprise, this typechecks. Let's consult `-ddump-deriv` to figure out what code is being generated: {{{ $ /opt/ghc/8.2.2/bin/ghci Bug.hs -ddump-deriv GHCi, version 8.2.2: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) ==================== Derived instances ==================== Derived class instances: instance Bug.C (Data.Functor.Identity.Identity a) where Derived type family instances: type Bug.T (Data.Functor.Identity.Identity a1_a1M3) x_a1M5 = Bug.T a1_a1M3 x_a1M5 }}} Hm... OK. Since GHC was able to generate this code, surely we should be able to write it ourselves, right? {{{#!hs {-# LANGUAGE GeneralizedNewtypeDeriving #-} {-# LANGUAGE StandaloneDeriving #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeInType #-} module Bug where import Data.Functor.Identity import Data.Kind class C (a :: Type) where type T a (x :: a) :: Type instance C () where type T () '() = Bool -- deriving instance C (Identity a) instance C (Identity a) where type T (Identity a) x = T a x }}} {{{ $ /opt/ghc/8.2.2/bin/ghci Bug.hs GHCi, version 8.2.2: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Bug.hs:19:31: error: • Occurs check: cannot construct the infinite kind: a ~ Identity a • In the second argument of ‘T’, namely ‘x’ In the type ‘T a x’ In the type instance declaration for ‘T’ | 19 | type T (Identity a) x = T a x | ^ }}} Uh-oh. GHC gets quite angry when we try to type this in ourselves, which isn't a good sign. This raises the question: just what is GHC doing in the previous version of the program? I tried to answer that question by seeing if `T (Identity a) x` could ever reduce: {{{#!hs {-# LANGUAGE GeneralizedNewtypeDeriving #-} {-# LANGUAGE StandaloneDeriving #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeInType #-} module Bug where import Data.Functor.Identity import Data.Kind class C (a :: Type) where type T a (x :: a) :: Type instance C () where type T () '() = Bool deriving instance C (Identity a) f :: T (Identity ()) ('Identity '()) f = True }}} And lo and behold, you get: {{{ $ /opt/ghc/8.2.2/bin/ghci Bug.hs GHCi, version 8.2.2: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Bug.hs:19:5: error: • Couldn't match type ‘T () ('Identity '())’ with ‘Bool’ Expected type: T (Identity ()) ('Identity '()) Actual type: Bool • In the expression: True In an equation for ‘f’: f = True | 19 | f = True | ^^^^ }}} It appears that `T (Identity ()) ('Identity '())` reduced to `T () ('Identity '())`. At that point, it becomes stuck. (Perhaps it's for the best that it's the case—if `T () ('Identity '())` managed to reduce, who knows what kind of mischief GHC could get itself into.) But all of this leads me to wonder: is something broken in the implementation of this feature, or is `GeneralizedNewtypeDeriving` simply not sound with respect to associated type families? I certainly hope that it's not the latter, as it's quite a useful feature. But at the same time, it's hard to reconcile that usefulness with the strange behavior above. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14728> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12442: Pure unifier usually doesn't need to unify kinds
by GHC 30 Mar '18

30 Mar '18

#12442: Pure unifier usually doesn't need to unify kinds -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: TypeInType | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The pure unifier (in `types/Unify.hs`) is used to match up instances with actual types. Since GHC 8, it matches up the kinds with the types in a separate pass. But this is often wasteful, and sometimes downright wrong. It's wasteful because most invocations of the unifier on a list of types pass in well-kinded arguments to some type constructor. Because the kinds of type constructors are closed, if we process the list left-to-right, we will always unify the kinds of later arguments before we get to them. So we shouldn't take another pass on the kinds. It's wrong because it's conceivable for the kind to include a type family application, and using a type family application as a template in the pure unifier is very silly, indeed. I cam across this while trying to translate Idris's algebraic effects library to Haskell. My reduced test case is attached. Patch on the way. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12442> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12176: Failure of bidirectional type inference at the kind level
by GHC 30 Mar '18

30 Mar '18

#12176: Failure of bidirectional type inference at the kind level -------------------------------------+------------------------------------- Reporter: goldfire | Owner: goldfire Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: TypeInType | 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'm feeling particularly sadistic towards GHC at the moment, and so I fed it this: {{{ import Data.Kind data Proxy :: forall k. k -> Type where MkProxy :: forall k (a :: k). Proxy a data X where MkX :: forall (k :: Type) (a :: k). Proxy a -> X type Expr = (MkX :: forall (a :: Bool). Proxy a -> X) type family Foo (x :: forall (a :: k). Proxy a -> X) where Foo (MkX :: forall (a :: k). Proxy a -> X) = (MkProxy :: Proxy k) }}} Incredibly, GHC accepts it! And it even means what I wish it to, with GHCi telling me the following (with `-fprint-explicit-kinds`): {{{ λ> :i Foo type family Foo k (x :: forall (a :: k). Proxy k a -> X) :: Proxy * k where [k] Foo k ('MkX k) = 'MkProxy * k }}} That is, I wished to extract the kind parameter to `MkK`, matching against a partially-applied `MkX`, and GHC understood that intention. However, sadly, writing `Foo Expr` produces {{{ • Expected kind ‘forall (a :: k0). Proxy k0 a -> X’, but ‘Expr a0’ has kind ‘Proxy Bool a0 -> X’ • In the first argument of ‘Foo’, namely ‘Expr’ In the type ‘Foo Expr’ In the type family declaration for ‘XXX’ }}} For some reason, `Expr` is getting instantiated when it shouldn't be. Perhaps there's a simpler test case demonstrating the bug, but I feel so gleeful that this chicanery is accepted at all that I wanted to post. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12176> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14986: ghc panics when compiling stage 2
by GHC 30 Mar '18

30 Mar '18

#14986: ghc panics when compiling stage 2 -------------------------------------+------------------------------------- Reporter: terrorjack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 8.5 Keywords: | Operating System: Windows Architecture: x86_64 | Type of failure: Building GHC (amd64) | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I'm compiling a recent commit (0017a7b618353bf984d701f6d8ee2810a425e5b3), yet ghc always panics when ghc-stage1 is compiling ghc-prim. The error is as follows: {{{ "inplace/bin/ghc-stage1.exe" -hisuf hi -osuf o -hcsuf hc -static -O -H64m -Wall -this-unit-id ghc-prim-0.5.2.0 -hide-all-packages -i -ilibraries/ghc-prim/. -ilibraries/ghc-prim/dist-install/build -Ilibraries /ghc-prim/dist-install/build -ilibraries/ghc-prim/dist- install/build/./autogen -Ilibraries/ghc-prim/dist-install/build/./autogen -Ilibraries/ghc-prim/. -optP-include -optPlibraries/ghc-prim/dist- install/build/./autogen/cabal_macros.h -package-id rts -this-unit-id ghc- prim -XHaskell2010 -O2 -no-user-package-db -rtsopts -Wno-trustworthy- safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/ghc-prim/dist-install/build -hidir libraries/ghc-prim/dist- install/build -stubdir libraries/ghc-prim/dist-install/build -split-objs -c libraries/ghc-prim/./GHC/CString.hs -o libraries/ghc-prim/dist- install/build/GHC/CString.o "inplace/bin/ghc-stage1.exe" -hisuf hi -osuf o -hcsuf hc -static -O -H64m -Wall -this-unit-id ghc-prim-0.5.2.0 -hide-all-packages -i -ilibraries/ghc-prim/. -ilibraries/ghc-prim/dist-install/build -Ilibraries /ghc-prim/dist-install/build -ilibraries/ghc-prim/dist- install/build/./autogen -Ilibraries/ghc-prim/dist-install/build/./autogen -Ilibraries/ghc-prim/. -optP-include -optPlibraries/ghc-prim/dist- install/build/./autogen/cabal_macros.h -package-id rts -this-unit-id ghc- prim -XHaskell2010 -O2 -no-user-package-db -rtsopts -Wno-trustworthy- safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/ghc-prim/dist-install/build -hidir libraries/ghc-prim/dist- install/build -stubdir libraries/ghc-prim/dist-install/build -split-objs -c libraries/ghc-prim/./GHC/IntWord64.hs -o libraries/ghc-prim/dist- install/build/GHC/IntWord64.o "inplace/bin/ghc-stage1.exe" -hisuf hi -osuf o -hcsuf hc -static -O -H64m -Wall -this-unit-id base-4.11.0.0 -hide-all-packages -i -ilibraries/base/. -ilibraries/base/dist-install/build -Ilibraries/base /dist-install/build -ilibraries/base/dist-install/build/./autogen -Ilibraries/base/dist-install/build/./autogen -Ilibraries/base/include -Ilibraries/base/dist-install/build/include -optP-include -optPlibraries/base/dist-install/build/./autogen/cabal_macros.h -package- id ghc-prim-0.5.2.0 -package-id integer-simple-0.1.1.1 -package-id rts -this-unit-id base -XHaskell2010 -O2 -no-user-package-db -rtsopts -Wno- trustworthy-safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/base/dist-install/build -hidir libraries/base/dist- install/build -stubdir libraries/base/dist-install/build -split-objs -c libraries/base/./GHC/Base.hs-boot -o libraries/base/dist- install/build/GHC/Base.o-boot "inplace/bin/ghc-stage1.exe" -hisuf hi -osuf o -hcsuf hc -static -O -H64m -Wall -this-unit-id base-4.11.0.0 -hide-all-packages -i -ilibraries/base/. -ilibraries/base/dist-install/build -Ilibraries/base /dist-install/build -ilibraries/base/dist-install/build/./autogen -Ilibraries/base/dist-install/build/./autogen -Ilibraries/base/include -Ilibraries/base/dist-install/build/include -optP-include -optPlibraries/base/dist-install/build/./autogen/cabal_macros.h -package- id ghc-prim-0.5.2.0 -package-id integer-simple-0.1.1.1 -package-id rts -this-unit-id base -XHaskell2010 -O2 -no-user-package-db -rtsopts -Wno- trustworthy-safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/base/dist-install/build -hidir libraries/base/dist- install/build -stubdir libraries/base/dist-install/build -split-objs -c libraries/base/./GHC/Real.hs-boot -o libraries/base/dist- install/build/GHC/Real.o-boot "inplace/bin/ghc-stage1.exe" -hisuf hi -osuf o -hcsuf hc -static -O -H64m -Wall -this-unit-id base-4.11.0.0 -hide-all-packages -i -ilibraries/base/. -ilibraries/base/dist-install/build -Ilibraries/base /dist-install/build -ilibraries/base/dist-install/build/./autogen -Ilibraries/base/dist-install/build/./autogen -Ilibraries/base/include -Ilibraries/base/dist-install/build/include -optP-include -optPlibraries/base/dist-install/build/./autogen/cabal_macros.h -package- id ghc-prim-0.5.2.0 -package-id integer-simple-0.1.1.1 -package-id rts -this-unit-id base -XHaskell2010 -O2 -no-user-package-db -rtsopts -Wno- trustworthy-safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/base/dist-install/build -hidir libraries/base/dist- install/build -stubdir libraries/base/dist-install/build -split-objs -c libraries/base/./GHC/IO.hs-boot -o libraries/base/dist- install/build/GHC/IO.o-boot "inplace/bin/ghc-stage1.exe" -hisuf hi -osuf o -hcsuf hc -static -O -H64m -Wall -this-unit-id base-4.11.0.0 -hide-all-packages -i -ilibraries/base/. -ilibraries/base/dist-install/build -Ilibraries/base /dist-install/build -ilibraries/base/dist-install/build/./autogen -Ilibraries/base/dist-install/build/./autogen -Ilibraries/base/include -Ilibraries/base/dist-install/build/include -optP-include -optPlibraries/base/dist-install/build/./autogen/cabal_macros.h -package- id ghc-prim-0.5.2.0 -package-id integer-simple-0.1.1.1 -package-id rts -this-unit-id base -XHaskell2010 -O2 -no-user-package-db -rtsopts -Wno- trustworthy-safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/base/dist-install/build -hidir libraries/base/dist- install/build -stubdir libraries/base/dist-install/build -split-objs -c libraries/base/./Data/Semigroup/Internal.hs-boot -o libraries/base/dist- install/build/Data/Semigroup/Internal.o-boot "inplace/bin/ghc-stage1.exe" -hisuf hi -osuf o -hcsuf hc -static -O -H64m -Wall -this-unit-id ghc-prim-0.5.2.0 -hide-all-packages -i -ilibraries/ghc-prim/. -ilibraries/ghc-prim/dist-install/build -Ilibraries /ghc-prim/dist-install/build -ilibraries/ghc-prim/dist- install/build/./autogen -Ilibraries/ghc-prim/dist-install/build/./autogen -Ilibraries/ghc-prim/. -optP-include -optPlibraries/ghc-prim/dist- install/build/./autogen/cabal_macros.h -package-id rts -this-unit-id ghc- prim -XHaskell2010 -O2 -no-user-package-db -rtsopts -Wno-trustworthy- safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/ghc-prim/dist-install/build -hidir libraries/ghc-prim/dist- install/build -stubdir libraries/ghc-prim/dist-install/build -split-objs -c libraries/ghc-prim/./GHC/Tuple.hs -o libraries/ghc-prim/dist- install/build/GHC/Tuple.o "inplace/bin/ghc-stage1.exe" -hisuf hi -osuf o -hcsuf hc -static -O -H64m -Wall -this-unit-id ghc-prim-0.5.2.0 -hide-all-packages -i -ilibraries/ghc-prim/. -ilibraries/ghc-prim/dist-install/build -Ilibraries /ghc-prim/dist-install/build -ilibraries/ghc-prim/dist- install/build/./autogen -Ilibraries/ghc-prim/dist-install/build/./autogen -Ilibraries/ghc-prim/. -optP-include -optPlibraries/ghc-prim/dist- install/build/./autogen/cabal_macros.h -package-id rts -this-unit-id ghc- prim -XHaskell2010 -O2 -no-user-package-db -rtsopts -Wno-trustworthy- safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/ghc-prim/dist-install/build -hidir libraries/ghc-prim/dist- install/build -stubdir libraries/ghc-prim/dist-install/build -split-objs -c libraries/ghc-prim/./GHC/Magic.hs -o libraries/ghc-prim/dist- install/build/GHC/Magic.o "inplace/bin/ghc-stage1.exe" -hisuf p_hi -osuf p_o -hcsuf p_hc -static -prof -eventlog -O -H64m -Wall -this-unit-id ghc-prim-0.5.2.0 -hide- all-packages -i -ilibraries/ghc-prim/. -ilibraries/ghc-prim/dist- install/build -Ilibraries/ghc-prim/dist-install/build -ilibraries/ghc-prim /dist-install/build/./autogen -Ilibraries/ghc-prim/dist- install/build/./autogen -Ilibraries/ghc-prim/. -optP-include -optPlibraries/ghc-prim/dist-install/build/./autogen/cabal_macros.h -package-id rts -this-unit-id ghc-prim -XHaskell2010 -O2 -no-user- package-db -rtsopts -Wno-trustworthy-safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/ghc-prim/dist- install/build -hidir libraries/ghc-prim/dist-install/build -stubdir libraries/ghc-prim/dist-install/build -split-objs -c libraries/ghc- prim/./GHC/CString.hs -o libraries/ghc-prim/dist- install/build/GHC/CString.p_o "inplace/bin/ghc-stage1.exe" -hisuf p_hi -osuf p_o -hcsuf p_hc -static -prof -eventlog -O -H64m -Wall -this-unit-id ghc-prim-0.5.2.0 -hide- all-packages -i -ilibraries/ghc-prim/. -ilibraries/ghc-prim/dist- install/build -Ilibraries/ghc-prim/dist-install/build -ilibraries/ghc-prim /dist-install/build/./autogen -Ilibraries/ghc-prim/dist- install/build/./autogen -Ilibraries/ghc-prim/. -optP-include -optPlibraries/ghc-prim/dist-install/build/./autogen/cabal_macros.h -package-id rts -this-unit-id ghc-prim -XHaskell2010 -O2 -no-user- package-db -rtsopts -Wno-trustworthy-safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/ghc-prim/dist- install/build -hidir libraries/ghc-prim/dist-install/build -stubdir libraries/ghc-prim/dist-install/build -split-objs -c libraries/ghc- prim/./GHC/IntWord64.hs -o libraries/ghc-prim/dist- install/build/GHC/IntWord64.p_o "inplace/bin/ghc-stage1.exe" -hisuf p_hi -osuf p_o -hcsuf p_hc -static -prof -eventlog -O -H64m -Wall -this-unit-id base-4.11.0.0 -hide- all-packages -i -ilibraries/base/. -ilibraries/base/dist-install/build -Ilibraries/base/dist-install/build -ilibraries/base/dist- install/build/./autogen -Ilibraries/base/dist-install/build/./autogen -Ilibraries/base/include -Ilibraries/base/dist-install/build/include -optP-include -optPlibraries/base/dist- install/build/./autogen/cabal_macros.h -package-id ghc-prim-0.5.2.0 -package-id integer-simple-0.1.1.1 -package-id rts -this-unit-id base -XHaskell2010 -O2 -no-user-package-db -rtsopts -Wno-trustworthy-safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/base/dist-install/build -hidir libraries/base/dist-install/build -stubdir libraries/base/dist-install/build -split-objs -c libraries/base/./GHC/Base.hs-boot -o libraries/base/dist- install/build/GHC/Base.p_o-boot "inplace/bin/ghc-stage1.exe" -hisuf p_hi -osuf p_o -hcsuf p_hc -static -prof -eventlog -O -H64m -Wall -this-unit-id base-4.11.0.0 -hide- all-packages -i -ilibraries/base/. -ilibraries/base/dist-install/build -Ilibraries/base/dist-install/build -ilibraries/base/dist- install/build/./autogen -Ilibraries/base/dist-install/build/./autogen -Ilibraries/base/include -Ilibraries/base/dist-install/build/include -optP-include -optPlibraries/base/dist- install/build/./autogen/cabal_macros.h -package-id ghc-prim-0.5.2.0 -package-id integer-simple-0.1.1.1 -package-id rts -this-unit-id base -XHaskell2010 -O2 -no-user-package-db -rtsopts -Wno-trustworthy-safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/base/dist-install/build -hidir libraries/base/dist-install/build -stubdir libraries/base/dist-install/build -split-objs -c libraries/base/./GHC/Real.hs-boot -o libraries/base/dist- install/build/GHC/Real.p_o-boot "inplace/bin/ghc-stage1.exe" -hisuf p_hi -osuf p_o -hcsuf p_hc -static -prof -eventlog -O -H64m -Wall -this-unit-id base-4.11.0.0 -hide- all-packages -i -ilibraries/base/. -ilibraries/base/dist-install/build -Ilibraries/base/dist-install/build -ilibraries/base/dist- install/build/./autogen -Ilibraries/base/dist-install/build/./autogen -Ilibraries/base/include -Ilibraries/base/dist-install/build/include -optP-include -optPlibraries/base/dist- install/build/./autogen/cabal_macros.h -package-id ghc-prim-0.5.2.0 -package-id integer-simple-0.1.1.1 -package-id rts -this-unit-id base -XHaskell2010 -O2 -no-user-package-db -rtsopts -Wno-trustworthy-safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/base/dist-install/build -hidir libraries/base/dist-install/build -stubdir libraries/base/dist-install/build -split-objs -c libraries/base/./GHC/IO.hs-boot -o libraries/base/dist- install/build/GHC/IO.p_o-boot "inplace/bin/ghc-stage1.exe" -hisuf p_hi -osuf p_o -hcsuf p_hc -static -prof -eventlog -O -H64m -Wall -this-unit-id base-4.11.0.0 -hide- all-packages -i -ilibraries/base/. -ilibraries/base/dist-install/build -Ilibraries/base/dist-install/build -ilibraries/base/dist- install/build/./autogen -Ilibraries/base/dist-install/build/./autogen -Ilibraries/base/include -Ilibraries/base/dist-install/build/include -optP-include -optPlibraries/base/dist- install/build/./autogen/cabal_macros.h -package-id ghc-prim-0.5.2.0 -package-id integer-simple-0.1.1.1 -package-id rts -this-unit-id base -XHaskell2010 -O2 -no-user-package-db -rtsopts -Wno-trustworthy-safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/base/dist-install/build -hidir libraries/base/dist-install/build -stubdir libraries/base/dist-install/build -split-objs -c libraries/base/./Data/Semigroup/Internal.hs-boot -o libraries/base/dist- install/build/Data/Semigroup/Internal.p_o-boot "inplace/bin/ghc-stage1.exe" -hisuf p_hi -osuf p_o -hcsuf p_hc -static -prof -eventlog -O -H64m -Wall -this-unit-id ghc-prim-0.5.2.0 -hide- all-packages -i -ilibraries/ghc-prim/. -ilibraries/ghc-prim/dist- install/build -Ilibraries/ghc-prim/dist-install/build -ilibraries/ghc-prim /dist-install/build/./autogen -Ilibraries/ghc-prim/dist- install/build/./autogen -Ilibraries/ghc-prim/. -optP-include -optPlibraries/ghc-prim/dist-install/build/./autogen/cabal_macros.h -package-id rts -this-unit-id ghc-prim -XHaskell2010 -O2 -no-user- package-db -rtsopts -Wno-trustworthy-safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/ghc-prim/dist- install/build -hidir libraries/ghc-prim/dist-install/build -stubdir libraries/ghc-prim/dist-install/build -split-objs -c libraries/ghc- prim/./GHC/Tuple.hs -o libraries/ghc-prim/dist-install/build/GHC/Tuple.p_o "inplace/bin/ghc-stage1.exe" -hisuf p_hi -osuf p_o -hcsuf p_hc -static -prof -eventlog -O -H64m -Wall -this-unit-id ghc-prim-0.5.2.0 -hide- all-packages -i -ilibraries/ghc-prim/. -ilibraries/ghc-prim/dist- install/build -Ilibraries/ghc-prim/dist-install/build -ilibraries/ghc-prim /dist-install/build/./autogen -Ilibraries/ghc-prim/dist- install/build/./autogen -Ilibraries/ghc-prim/. -optP-include -optPlibraries/ghc-prim/dist-install/build/./autogen/cabal_macros.h -package-id rts -this-unit-id ghc-prim -XHaskell2010 -O2 -no-user- package-db -rtsopts -Wno-trustworthy-safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/ghc-prim/dist- install/build -hidir libraries/ghc-prim/dist-install/build -stubdir libraries/ghc-prim/dist-install/build -split-objs -c libraries/ghc- prim/./GHC/Magic.hs -o libraries/ghc-prim/dist-install/build/GHC/Magic.p_o "inplace/bin/ghc-stage1.exe" -hisuf hi -osuf o -hcsuf hc -static -O -H64m -Wall -this-unit-id ghc-prim-0.5.2.0 -hide-all-packages -i -ilibraries/ghc-prim/. -ilibraries/ghc-prim/dist-install/build -Ilibraries /ghc-prim/dist-install/build -ilibraries/ghc-prim/dist- install/build/./autogen -Ilibraries/ghc-prim/dist-install/build/./autogen -Ilibraries/ghc-prim/. -optP-include -optPlibraries/ghc-prim/dist- install/build/./autogen/cabal_macros.h -package-id rts -this-unit-id ghc- prim -XHaskell2010 -O2 -no-user-package-db -rtsopts -Wno-trustworthy- safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/ghc-prim/dist-install/build -hidir libraries/ghc-prim/dist- install/build -stubdir libraries/ghc-prim/dist-install/build -split-objs -c libraries/ghc-prim/./GHC/Classes.hs -o libraries/ghc-prim/dist- install/build/GHC/Classes.o "inplace/bin/ghc-stage1.exe" -hisuf hi -osuf o -hcsuf hc -static -O -H64m -Wall -this-unit-id ghc-prim-0.5.2.0 -hide-all-packages -i -ilibraries/ghc-prim/. -ilibraries/ghc-prim/dist-install/build -Ilibraries /ghc-prim/dist-install/build -ilibraries/ghc-prim/dist- install/build/./autogen -Ilibraries/ghc-prim/dist-install/build/./autogen -Ilibraries/ghc-prim/. -optP-include -optPlibraries/ghc-prim/dist- install/build/./autogen/cabal_macros.h -package-id rts -this-unit-id ghc- prim -XHaskell2010 -O2 -no-user-package-db -rtsopts -Wno-trustworthy- safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/ghc-prim/dist-install/build -hidir libraries/ghc-prim/dist- install/build -stubdir libraries/ghc-prim/dist-install/build -split-objs -c libraries/ghc-prim/./GHC/Debug.hs -o libraries/ghc-prim/dist- install/build/GHC/Debug.o "inplace/bin/ghc-stage1.exe" -hisuf hi -osuf o -hcsuf hc -static -O -H64m -Wall -this-unit-id ghc-prim-0.5.2.0 -hide-all-packages -i -ilibraries/ghc-prim/. -ilibraries/ghc-prim/dist-install/build -Ilibraries /ghc-prim/dist-install/build -ilibraries/ghc-prim/dist- install/build/./autogen -Ilibraries/ghc-prim/dist-install/build/./autogen -Ilibraries/ghc-prim/. -optP-include -optPlibraries/ghc-prim/dist- install/build/./autogen/cabal_macros.h -package-id rts -this-unit-id ghc- prim -XHaskell2010 -O2 -no-user-package-db -rtsopts -Wno-trustworthy- safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/ghc-prim/dist-install/build -hidir libraries/ghc-prim/dist- install/build -stubdir libraries/ghc-prim/dist-install/build -split-objs -c libraries/ghc-prim/dist-install/build/GHC/PrimopWrappers.hs -o libraries/ghc-prim/dist-install/build/GHC/PrimopWrappers.o "inplace/bin/ghc-stage1.exe" -hisuf p_hi -osuf p_o -hcsuf p_hc -static -prof -eventlog -O -H64m -Wall -this-unit-id ghc-prim-0.5.2.0 -hide- all-packages -i -ilibraries/ghc-prim/. -ilibraries/ghc-prim/dist- install/build -Ilibraries/ghc-prim/dist-install/build -ilibraries/ghc-prim /dist-install/build/./autogen -Ilibraries/ghc-prim/dist- install/build/./autogen -Ilibraries/ghc-prim/. -optP-include -optPlibraries/ghc-prim/dist-install/build/./autogen/cabal_macros.h -package-id rts -this-unit-id ghc-prim -XHaskell2010 -O2 -no-user- package-db -rtsopts -Wno-trustworthy-safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/ghc-prim/dist- install/build -hidir libraries/ghc-prim/dist-install/build -stubdir libraries/ghc-prim/dist-install/build -split-objs -c libraries/ghc- prim/./GHC/Classes.hs -o libraries/ghc-prim/dist- install/build/GHC/Classes.p_o "inplace/bin/ghc-stage1.exe" -hisuf p_hi -osuf p_o -hcsuf p_hc -static -prof -eventlog -O -H64m -Wall -this-unit-id ghc-prim-0.5.2.0 -hide- all-packages -i -ilibraries/ghc-prim/. -ilibraries/ghc-prim/dist- install/build -Ilibraries/ghc-prim/dist-install/build -ilibraries/ghc-prim /dist-install/build/./autogen -Ilibraries/ghc-prim/dist- install/build/./autogen -Ilibraries/ghc-prim/. -optP-include -optPlibraries/ghc-prim/dist-install/build/./autogen/cabal_macros.h -package-id rts -this-unit-id ghc-prim -XHaskell2010 -O2 -no-user- package-db -rtsopts -Wno-trustworthy-safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/ghc-prim/dist- install/build -hidir libraries/ghc-prim/dist-install/build -stubdir libraries/ghc-prim/dist-install/build -split-objs -c libraries/ghc- prim/./GHC/Debug.hs -o libraries/ghc-prim/dist-install/build/GHC/Debug.p_o "inplace/bin/ghc-stage1.exe" -hisuf p_hi -osuf p_o -hcsuf p_hc -static -prof -eventlog -O -H64m -Wall -this-unit-id ghc-prim-0.5.2.0 -hide- all-packages -i -ilibraries/ghc-prim/. -ilibraries/ghc-prim/dist- install/build -Ilibraries/ghc-prim/dist-install/build -ilibraries/ghc-prim /dist-install/build/./autogen -Ilibraries/ghc-prim/dist- install/build/./autogen -Ilibraries/ghc-prim/. -optP-include -optPlibraries/ghc-prim/dist-install/build/./autogen/cabal_macros.h -package-id rts -this-unit-id ghc-prim -XHaskell2010 -O2 -no-user- package-db -rtsopts -Wno-trustworthy-safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -odir libraries/ghc-prim/dist- install/build -hidir libraries/ghc-prim/dist-install/build -stubdir libraries/ghc-prim/dist-install/build -split-objs -c libraries/ghc-prim /dist-install/build/GHC/PrimopWrappers.hs -o libraries/ghc-prim/dist- install/build/GHC/PrimopWrappers.p_o ghc-stage1.exe: panic! (the 'impossible' happened) (GHC version 8.5.20180329 for x86_64-unknown-mingw32): Each block should be reachable from only one ProcPoint Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug make[1]: *** [libraries/ghc-prim/ghc.mk:4: libraries/ghc-prim/dist- install/build/GHC/Classes.o] Error 1 make[1]: *** Waiting for unfinished jobs.... ghc-stage1.exe: panic! (the 'impossible' happened) (GHC version 8.5.20180329 for x86_64-unknown-mingw32): Each block should be reachable from only one ProcPoint Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug make[1]: *** [libraries/ghc-prim/ghc.mk:4: libraries/ghc-prim/dist- install/build/GHC/Classes.p_o] Error 1 make: *** [Makefile:127: all] Error 2 }}} I'm using the following build.mk for those builds here: {{{ GhcEnableTablesNextToCode = NO INTEGER_LIBRARY = integer-simple SRC_HC_OPTS = -O -H64m GhcStage1HcOpts = -O GhcStage2HcOpts = -O2 GhcLibHcOpts = -O2 BUILD_PROF_LIBS = YES SplitObjs = YES SplitSections = NO BUILD_SPHINX_HTML = YES BUILD_SPHINX_PDF = NO HADDOCK_DOCS = YES EXTRA_HADDOCK_OPTS += --quickjump --hyperlinked-source }}} Still working to figure out a minimal combination of the build flags to trigger a similar error. Meanwhile, has anyone seen a similar error for a different commit/platform/build config? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14986> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14984: Rgression: 8.4.1 says "Could not deduce" when before 8.4 it could
by GHC 30 Mar '18

30 Mar '18

#14984: Rgression: 8.4.1 says "Could not deduce" when before 8.4 it could -------------------------------------+------------------------------------- Reporter: erikd | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.1 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Have some code: {{{#!hs import Test.QuickCheck import Test.QuickCheck.Monadic testPropertyIO :: Testable a => PropertyM IO a -> Property testPropertyIO = monadicIO . (=<<) stop }}} That compiles fine with ghc 7.10 through 8.2, but with 8.4.1 fails with: {{{ test/Test/Mafia/IO.hs:18:18: error: ? Could not deduce (Testable a0) arising from a use of ?monadicIO? from the context: Testable a bound by the type signature for: testPropertyIO :: forall a. Testable a => PropertyM IO a -> Property at test/Test/Mafia/IO.hs:17:1-58 The type variable ?a0? is ambiguous These potential instances exist: instance [safe] Testable prop => Testable (Gen prop) -- Defined in ?Test.QuickCheck.Property? instance [safe] Testable Discard -- Defined in ?Test.QuickCheck.Property? instance [safe] Testable Property -- Defined in ?Test.QuickCheck.Property? ...plus three others ...plus two instances involving out-of-scope types (use -fprint-potential-instances to see them all) ? In the first argument of ?(.)?, namely ?monadicIO? In the expression: monadicIO . (=<<) stop In an equation for ?testPropertyIO?: testPropertyIO = monadicIO . (=<<) stop }}} Either the compiler has been incorrectly accepting this as valid for a number of releases or this is a regression. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14984> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9406: unexpected failure for T7837(profasm)
by GHC 29 Mar '18

29 Mar '18

#9406: unexpected failure for T7837(profasm) -------------------------------------+------------------------------------- Reporter: jrp | Owner: Type: bug | Status: new Priority: low | Milestone: Component: Test Suite | Version: 7.8.3 Keywords: T7837 | Operating System: MacOS X Architecture: x86_64 (amd64) | Type of failure: Incorrect Difficulty: Unknown | result at runtime Blocked By: | Test Case: T7837 Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- This may be a test suite configuration error as the normal case works. When run with an llvm-perf build of the HEAD, I get: {{{ =====> T7837(normal) 1395 of 4068 [0, 0, 0] cd ./indexed-types/should_compile && '/Users/jrp/Projects/haskell/ghc/inplace/bin/ghc-stage2' -fforce-recomp -dcore-lint -dcmm-lint -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -c T7837.hs -O -ddump-rule-firings >T7837.comp.stderr 2>&1 =====> T7837(profasm) 1395 of 4068 [0, 0, 0] cd ./indexed-types/should_compile && '/Users/jrp/Projects/haskell/ghc/inplace/bin/ghc-stage2' -fforce-recomp -dcore-lint -dcmm-lint -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -c T7837.hs -O -prof -static -auto-all -O -ddump-rule- firings >T7837.comp.stderr 2>&1 Actual stderr output differs from expected: --- ./indexed-types/should_compile/T7837.stderr 2014-08-03 11:36:53.000000000 +0100 +++ ./indexed-types/should_compile/T7837.comp.stderr 2014-08-04 23:16:34.000000000 +0100 @@ -1,3 +1,4 @@ Rule fired: Class op abs Rule fired: Class op signum Rule fired: normalize/Double +Rule fired: Class op / *** unexpected failure for T7837(profasm) Unexpected results from: TEST="T7837" OVERALL SUMMARY for test run started at Mon Aug 4 23:16:32 2014 BST 0:00:02 spent to go through 4068 total tests, which gave rise to 19536 test cases, of which 19534 were skipped 0 had missing libraries 1 expected passes 0 expected failures 0 caused framework failures 0 unexpected passes 1 unexpected failures Unexpected failures: indexed-types/should_compile T7837 [stderr mismatch] (profasm) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9406> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14048: Data instances of kind Constraint
by GHC 29 Mar '18

29 Mar '18

#14048: Data instances of kind Constraint -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) 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: #12369 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Continuation of #12369. Allow data instances ending in `Constraint`. This may be a bug but GHC already accepts (something to do with #11715) `data family Bot :: Constraint` but I can't make instances of it. Also fails for `data family Bot :: TYPE IntRep`. I propose letting users take these disparate data types and type classes {{{#!hs data Compose :: (k' -> Type) -> (k -> k') -> (k -> Type) where Compose :: f (g a) -> Compose f g a data Compose2 :: (k' -> (kk -> Type)) -> (k -> k') -> (k -> (kk -> Type)) where Compose2 :: f (g a) b -> Compose2 f g a b -- ComposeC :: (k' -> Constraint) -> (k -> k') -> (k -> Constraint) class f (g a) => ComposeC f g a instance f (g a) => ComposeC f g a -- ComposeC2 :: (k' -> (kk -> Constraint)) -> (k -> k') -> (k -> (kk -> Constraint)) class f (g a) b => ComposeC2 f g a b instance f (g a) b => ComposeC2 f g a b }}} and unify them as instances of a 'data' family indexed by `Type`, `kk -> Type`, `Constraint`, `kk -> Constraint`. (Same can be done for `Data.Functor.Product` and `class (f a, g a) => ProductC f g a`): {{{#!hs data family (·) :: (k' -> k'') -> (k -> k') -> (k -> k'') data instance (f · g) a where Compose :: f (g a) -> (f · g) a data instance (f · g) a b where Compose2 :: f (g a) b -> (f · g) a b instance f (g a) => (f · g) a instance f (g a) b => (f · g) a b }}} ---- TODO Once we have #1311 allow data instances of unlifted types. ---- Fun note: `(·) @(kk -> Type)` is used by [https://gist.github.com/ekmett/48f1b578cadeeaeee7a309ec6933d7ec Kmett] (as `Tensor`) & to motivate [http://i.cs.hku.hk/~bruno/papers/hs2017.pdf quantified class constraints], this should automatically pick the right data instance: {{{#!hs instance (Trans t, Trans t') => Trans (t · t') where lift :: Monad m => m ~> (t · t') m lift = Compose2 . lift @t . lift @t' }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14048> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14263: typeKind is quadratic
by GHC 29 Mar '18

29 Mar '18

#14263: typeKind is quadratic -------------------------------------+------------------------------------- Reporter: goldfire | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 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: -------------------------------------+------------------------------------- While pondering Phab:D3998, I realized that any computation of a type's kind should be careful in the presence of nested `AppTy`s. And, to my horror, I realized that GHC's very own `typeKind` isn't! That is, if you have the type `a b c d e`, GHC will take a quadratic (or worse -- haven't benchmarked) amount of time computing its kind. This can be easily fixed by looking for nested `AppTy`s and using `piResultTys`, instead of repeated uses of `piResultTy` (as is currently done). NB: This was not discovered through witnessing poor performance, but it does seem like very low-hanging compiler-performance fruit. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14263> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14155: GHC mentions unlifted types out of the blue (to me anyway)
by GHC 29 Mar '18

29 Mar '18

#14155: GHC mentions unlifted types out of the blue (to me anyway) -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 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: -------------------------------------+------------------------------------- This one does me 'ead in, I accidentally type `Ran` instead of `Swap` {{{#!hs {-# Language RankNTypes, DerivingStrategies, TypeApplications, ScopedTypeVariables, GADTs, GeneralizedNewtypeDeriving, InstanceSigs, PolyKinds #-} import Data.Coerce newtype Ran g h a = Ran (forall b. (a -> g b) -> h b) newtype Swap p f g a where Swap :: p g f a -> Swap p f g a deriving newtype Show class IxPointed m where ireturn :: a -> m i i a instance IxPointed f => IxPointed (Swap f) where ireturn :: forall a i. a -> Swap f i i a ireturn a = Ran (ireturn a) }}} and get this error {{{ $ ghci -ignore-dot-ghci /tmp/bug.hs GHCi, version 8.3.20170605: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( /tmp/bug.hs, interpreted ) /tmp/bug.hs:17:15: error: • Couldn't match expected type ‘Swap f i i a’ with actual type ‘Ran g0 h0 a0’ • In the expression: Ran (ireturn a) In an equation for ‘ireturn’: ireturn a = Ran (ireturn a) In the instance declaration for ‘IxPointed (Swap f)’ • Relevant bindings include a :: a (bound at /tmp/bug.hs:17:11) ireturn :: a -> Swap f i i a (bound at /tmp/bug.hs:17:3) | 17 | ireturn a = Ran (ireturn a) | ^^^^^^^^^^^^^^^ /tmp/bug.hs:17:20: error: • Couldn't match a lifted type with an unlifted type Expected type: (a0 -> g0 b) -> h0 b Actual type: (->) (a0 -> g0 b) (a0 -> g0 b) a • In the first argument of ‘Ran’, namely ‘(ireturn a)’ In the expression: Ran (ireturn a) In an equation for ‘ireturn’: ireturn a = Ran (ireturn a) | 17 | ireturn a = Ran (ireturn a) | ^^^^^^^^^ Failed, modules loaded: none. }}} Is GHC right to bring up unlifted types? I would guess this is due to the newly added levity polymorphism of `(->) :: TYPE rep -> TYPE rep' -> Type` -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14155> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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