October 2015 - ghc-tickets

[GHC] #9760: ghc -c 7.8 drops last char of file name if -osuf contains a dot
by GHC 24 Dec '15

24 Dec '15

#9760: ghc -c 7.8 drops last char of file name if -osuf contains a dot -------------------------------------+------------------------------------- Reporter: nh2 | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.8.4 Component: Build System | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Moderate (less | Type of failure: than a day) | None/Unknown Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- I discovered that if I compile with `ghc -c -osuf .something Myfile.hs` where `Myfile.hs` contains TH and thus has to dynamically link in, say, `Other.hs`, I get the error that {{{ Myfile.hs:1:1: cannot find normal object file 'Othe.dyn_o` while linking an interpreted expression }}} So `Other` was wrongly made into `Othe`, dropping the last character. If I don't pass `-osuf .something`, or have it not have a dot, everything's fine. The trouble is that `-osuf .something` worked fine in GHC <= 7.6. So I believe this is a regression, or at least a very bad error message. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9760> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9975: RecordWildCards and PatternSynonyms cause impossible bug
by GHC 24 Dec '15

24 Dec '15

#9975: RecordWildCards and PatternSynonyms cause impossible bug -------------------------------------+------------------------------------- Reporter: gamegoblin | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Keywords: | Operating System: MacOS X RecordWildCards PatternSynonyms | Type of failure: Compile-time Architecture: x86_64 | crash (amd64) | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- When using RecordWildCards with PatternSynonyms, I have found a way to cause this bug: $ /usr/local/bin/ghc-7.10.0.20141222 test.hs [1 of 1] Compiling Main ( test.hs, test.o ) ghc: panic! (the 'impossible' happened) (GHC version 7.10.0.20141222 for x86_64-apple-darwin): find_tycon Test [Test defined at test.hs:6:9, Test parent:Test defined at test.hs:4:13] Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Here is the full code that causes it: {{{#!hs {-# LANGUAGE RecordWildCards #-} {-# LANGUAGE PatternSynonyms #-} data Test = Test { x :: Int } pattern Test wat = Test { x = wat } }}} If you remove RecordWildCards, the bug does not happen. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9975> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10404: GHC panic when creating a monomorphised pattern synonym for GADT
by GHC 23 Dec '15

23 Dec '15

#10404: GHC panic when creating a monomorphised pattern synonym for GADT -------------------------------------+------------------------------------- Reporter: | Owner: Iceland_jack | Status: new Type: bug | Milestone: Priority: normal | Version: 7.10.1-rc1 Component: Compiler | Operating System: Linux Keywords: | Type of failure: GHC rejects Architecture: x86 | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- I have an expression {{{#!hs {-# LANGUAGE GADTs #-} {-# LANGUAGE PatternSynonyms #-} data Exp a where Fun :: (a -> b) - (Exp a -> Exp b) }}} and I want to create a pattern synonym for Int-expressions: {{{#!hs -- This works: -- pattern :: (a -> b) -> (Exp a -> Exp b) -- pattern IntFun f x = Fun f x pattern :: (Int -> Int) -> (Exp Int -> Exp Int) pattern IntFun f x = Fun f x }}} which results in {{{#!hs % ghci -ignore-dot-ghci Panic.hs GHCi, version 7.10.0.20150316: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( Panic.hs, interpreted ) Panic.hs:8:28: Couldn't match type ‘a’ with ‘Int’ ‘a’ is a rigid type variable bound by a pattern with constructor Fun :: forall b a. (a -> b) -> Exp a -> Exp b, in a pattern synonym declaration at Panic.hs:8:22 Expected type: Int -> Int Actual type: a -> Int Relevant bindings include b :: Exp a (bound at Panic.hs:8:28) a :: a -> Int (bound at Panic.hs:8:26) Failed, modules loaded: none. }}} So I try to be sneaky: {{{#!hs pattern :: (a ~ Int) => (a -> b) -> (Exp a -> Exp b) pattern IntFun f x = Fun f x -- % ghci -ignore-dot-ghci Panic.hs -- … -- Couldn't match type ‘a’ with ‘Int’ -- ‘a’ is a rigid type variable bound by -- the type signature for IntFun :: (a1 -> b) -> Exp a1 -> Exp b -- at Panic.hs:8:22 }}} and if I constrain both type variables it panics {{{#!hs pattern :: (a ~ Int, b ~ Int) => (a -> b) -> (Exp a -> Exp b) pattern IntFun f x = Fun f x -- Couldn't match type ‘b’ with ‘Int’ -- ‘b’ is untouchable -- inside the constraints () -- bound by the type signature for -- IntFun :: (a1 -> b) -> Exp a1 -> Exp b -- at Panic.hs:8:9-14ghc: panic! (the 'impossible' happened) -- (GHC version 7.10.0.20150316 for i386-unknown-linux): -- No skolem info: b_alF[sk] -- -- Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} The final version should look like: {{{#!hs type Name = String data Exp a where Fun :: Name -> (a -> b) -> (Exp a -> Exp b) ... pattern Suc :: Exp Int -> Exp Int pattern Suc n <- Fun _ _ n where Suc n = Fun "suc" (+ 1) n }}} Shouldn't this work? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10404> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10432: panic with kind polymorphism
by GHC 23 Dec '15

23 Dec '15

#10432: panic with kind polymorphism -------------------------------------+------------------------------------- Reporter: Ashley | Owner: Yakeley | Status: new Type: bug | Milestone: Priority: normal | Version: 7.10.1 Component: Compiler | Operating System: Unknown/Multiple (Type checker) | Type of failure: None/Unknown Keywords: | Blocked By: Architecture: | Related Tickets: Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- {{{#!hs {-# LANGUAGE ExistentialQuantification, PolyKinds, DataKinds, RankNTypes, GADTs, TypeOperators #-} module Bug where import Data.Type.Equality data WrappedType = forall a. WrapType a; matchReflK :: forall (a :: ka) (b :: kb) (r :: *). ('WrapType a :~: 'WrapType b) -> (('WrapType a ~ 'WrapType b) => r) -> r; matchReflK Refl r = r; }}} give this: {{{ Bug.hs:8:15: Couldn't match kind ‘ka’ with ‘kb’ ‘ka’ is untouchable inside the constraints ('WrapType a ~ 'WrapType b) bound by the type signature for matchReflK :: ('WrapType a ~ 'WrapType b) => r at Bug.hs:(8,15)-(9,74)ghc: panic! (the 'impossible' happened) (GHC version 7.10.1 for x86_64-unknown-linux): No skolem info: ka_aqv[sk] Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} I actually think GHC should accept this (and furthermore infer `ka ~ kb`). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10432> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11039: Panic with incorrect pattern synonym signature
by GHC 23 Dec '15

23 Dec '15

#11039: Panic with incorrect pattern synonym signature -------------------------------------+------------------------------------- Reporter: mpickering | Owner: Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 7.11 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: -------------------------------------+------------------------------------- {{{ {-# LANGUAGE PatternSynonyms #-} module Foo () where data A a = A a pattern Q :: () => (A ~ f) => a -> f a pattern Q a = A a }}} error with HEAD {{{ poly-export2.hs:7:9: error:ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.11.20151030 for x86_64-apple-darwin): No skolem info: f_amp[sk] }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11039> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10897: Incorrect ASSERT for buildPatSyn
by GHC 23 Dec '15

23 Dec '15

#10897: Incorrect ASSERT for buildPatSyn -------------------------------------+------------------------------------- Reporter: ezyang | Owner: cactus Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Consider the following two files: {{{ -- A.hs {-# LANGUAGE PatternSynonyms #-} module A where pattern Single :: a -> a pattern Single x = x -- B.hs module B where import A Single y = True }}} When I build these using one-shot compilation using a debugged GHC (i.e. with ASSERTs) I get the following error: {{{ [ezyang@hs01 ghc-quick3]$ inplace/bin/ghc-stage2 -c A.hs -fforce-recomp [ezyang@hs01 ghc-quick3]$ inplace/bin/ghc-stage2 -c B.hs -fforce-recomp ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.11.20150918 for x86_64-unknown-linux): ASSERT failed! file compiler/iface/BuildTyCl.hs, line 210 Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} I expanded the assert and discovered it was claiming the universal type variables of the matcher should be equal to the type variables of the pattern declaration. This assert cannot possibly be right: the matcher and the pattern declaration are typechecked separately and there's no reason that the local binders should actually be the same. The equality test here should be done up to alpha-renaming. The other thing I found a bit puzzling was whether or not it mattered whether or not we used the local type variables from the matcher or the freshly bound ones. I suppose if we are consistent it shouldn't matter, so I don't think the code is buggy, just a bad ASSERT. BTW: this assert problem doesn't show up with `--make` because the assert occurs during typechecking of interface files, and with `--make` we don't need to typecheck an interface file. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10897> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9739: GHC 7.8 chokes on recursive classes
by GHC 23 Dec '15

23 Dec '15

#9739: GHC 7.8 chokes on recursive classes -------------------------------------+------------------------------------- Reporter: bitonic | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.8.3 checker) | Operating System: Keywords: | Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Difficulty: Unknown | None/Unknown Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Type checking this makes GHC 7.8.3 loop: {{{#!hs {-# LANGUAGE MultiParamTypeClasses #-} module Foo where class Class3 a => Class1 a where class Class2 t a where class2 :: (Class3 t) => a -> m class (Class1 t, Class2 t t) => Class3 t where }}} Does not happen in 7.6.3. I think it's something to do with the `Class3` constraint appearing in `class2`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9739> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10426: matchGroupArity panic with PatternSynonyms
by GHC 23 Dec '15

23 Dec '15

#10426: matchGroupArity panic with PatternSynonyms ---------------------------------------+--------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Linux Architecture: x86 | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | ---------------------------------------+--------------------------------- {{{#!hs {-# LANGUAGE PatternSynonyms, ViewPatterns, EmptyCase #-} pattern Id <- (id -> _) where }}} which gives: {{{#!hs % ghc -ignore-dot-ghci tmp.FbbzjZ48OO.hs [1 of 1] Compiling Main ( tmp.FbbzjZ48OO.hs, tmp.FbbzjZ48OO.o ) ghc: panic! (the 'impossible' happened) (GHC version 7.10.0.20150316 for i386-unknown-linux): matchGroupArity Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10426> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10982: Warn about unused pattern variables in type families
by GHC 22 Dec '15

22 Dec '15

#10982: Warn about unused pattern variables in type families -------------------------------------+------------------------------------- Reporter: jstolarek | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 7.11 Keywords: newcomer | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Now that we have wildcards in type families (#3699) I want to be warned about unused pattern variables in the same way I am warned about them at the term level. For example this should cause a warning that `b` is not used: {{{#!hs type family F a b type instance F a b = a }}} Prefixing unused variable with an underscore should suppress the warning: {{{#!hs type family F a b type instance F a _b = a }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10982> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10967: Release a new stm package on Hackage
by GHC 22 Dec '15

22 Dec '15

#10967: Release a new stm package on Hackage -------------------------------------+------------------------------------- Reporter: svenpanne | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: libraries | Version: (other) | Keywords: stm | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Currently, the latest stm package on Hackage (2.4.4) doesn't compile with GHC HEAD (see e.g. https://travis-ci.org/haskell- opengl/OpenGL/jobs/85320391), which makes testing of various other packages with HEAD imposiible. Things seem to be fixed in git already, can we have a new release of stm? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10967> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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