March 2015 - ghc-tickets

[GHC] #10130: Rigid/Skolum produced by unassociated values.
by GHC 02 Mar '15

02 Mar '15

#10130: Rigid/Skolum produced by unassociated values. -------------------------------------+------------------------------------- Reporter: | Owner: dukerutledge | Status: new Type: bug | Milestone: Priority: normal | Version: 7.8.4 Component: Compiler | Operating System: Linux Keywords: rigid, | Type of failure: Compile-time skolum, | crash existentialquantification, gadts, | Blocked By: nomonolocalbinds | Related Tickets: Architecture: x86_64 | (amd64) | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Here is an in depth example of a possible GHC bug. It is exacerbated by GADTs, but can be fixed with NoMonoLocalBinds. Without GADTs and just leveraging ExistentialQuantification it works fine. We've included a pretty exhaustive set of examples. {{{ {-# LANGUAGE ExistentialQuantification, GADTs #-} {- removing MonoLocalBinds fixes all of these errors {-# LANGUAGE ExistentialQuantification, GADTs, NoMonoLocalBinds #-} -} module PossibleGHCBug where data SumType = SumFoo | SumBar class SomeClass a where someType :: a -> SumType data SomeExistential = forall a. SomeClass a => SomeExistential a noError :: String -> [SomeExistential] -> String noError n st = n ++ concatMap cname st where cname (SomeExistential p) = d p d p = c $ someType p c p = case p of SumFoo -> "foo" _ -> "asdf" noError2 :: String -> [SomeExistential] -> String noError2 n st = n ++ concatMap cname st where cname (SomeExistential p) = d p d p = c $ someType p c :: SumType -> String c p = case p of SumFoo -> "foo" _ -> "asdf" ++ n noError3 :: String -> [SomeExistential] -> String noError3 n st = n ++ concatMap cname st where cname (SomeExistential p) = d p d :: SomeClass a => a -> String d p = c $ someType p c p = case p of SumFoo -> "foo" _ -> "asdf" ++ n partialTypedError :: String -> [SomeExistential] -> String partialTypedError n st = n ++ concatMap cname st where cname :: SomeExistential -> String cname (SomeExistential p) = d p d p = c $ someType p c p = case p of SumFoo -> "foo" _ -> "asdf" ++ n fullError :: String -> [SomeExistential] -> String fullError n st = n ++ concatMap cname st where cname (SomeExistential p) = d p d p = c $ someType p c p = case p of SumFoo -> "foo" _ -> "asdf" ++ n justNError :: String -> [SomeExistential] -> String justNError n st = n ++ concatMap cname st where cname (SomeExistential p) = d p d p = c $ someType p c p = case p of SumFoo -> "foo" _ -> n ignoreNError :: String -> [SomeExistential] -> String ignoreNError n st = n ++ concatMap cname st where cname (SomeExistential p) = d p d p = c $ someType p c p = case p of SumFoo -> "foo" _ -> fst ("foo", n) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10130> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9901: Error message: f is applied to two arguments, but its type has only two (sic)
by GHC 02 Mar '15

02 Mar '15

#9901: Error message: f is applied to two arguments, but its type has only two (sic) -------------------------------------+------------------------------------- Reporter: zardoz | 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: -------------------------------------+------------------------------------- I occasionally get type errors where the error message refers to a function’s arity in a contradictory way: > The function ‘X’ is applied to two arguments, […] but its type has only two. Here’s a full error message of this kind: lenstest.hs:89:12: Couldn't match type ‘Either String Int’ with ‘Maybe b0’ Expected type: [Char] -> Either String Int Actual type: [Char] -> Maybe b0 The function ‘preview’ is applied to two arguments, but its type ‘Getting (Data.Monoid.First b0) (Either b0 c0) b0 -> [Char] -> Maybe b0’ has only two In the second argument of ‘($)’, namely ‘(preview _Left "abc" :: Either String Int)’ In a stmt of a 'do' block: print $ (preview _Left "abc" :: Either String Int) Failed, modules loaded: none. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9901> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10103: Outdated comment (or bug?) in TyCon.hs
by GHC 02 Mar '15

02 Mar '15

#10103: Outdated comment (or bug?) in TyCon.hs -------------------------------------+------------------------------------- Reporter: thomie | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.8.4 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- The docstring for `coreExpandTyCon_maybe` says it should do something different than `tcExpandTyCon_maybe`, but it doesn't: {{{#!haskell -- ^ Used to create the view the /typechecker/ has on 'TyCon's. -- We expand (closed) synonyms only, cf. 'coreExpandTyCon_maybe' tcExpandTyCon_maybe = ... -- ^ Used to create the view /Core/ has on 'TyCon's. We expand -- not only closed synonyms like 'tcExpandTyCon_maybe', -- but also non-recursive @newtype@s coreExpandTyCon_maybe tycon tys = tcExpandTyCon_maybe tycon tys }}} If the code is correct, and the comment is just outdated, than Note [Newtype eta] and the docstring for `Type.coreView` should be updated as well. The last big change to `coreExpandTyCon_maybe` was made in commit fdf8656855d26105ff36bdd24d41827b05037b91. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10103> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7661: GHC build system does not detect opt-3.0 and friends
by GHC 02 Mar '15

02 Mar '15

#7661: GHC build system does not detect opt-3.0 and friends ----------------------------------------+---------------------------------- Reporter: singpolyma | Owner: dterei Type: feature request | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.7 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Building GHC failed | Unknown/Multiple Blocking: | Blocked By: | Related Tickets: ----------------------------------------+---------------------------------- Comment (by Austin Seipp <austin@…>): In [changeset:"1dfab7a8ace5f09f00f8fb695932b4324e88b822/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="1dfab7a8ace5f09f00f8fb695932b4324e88b822" Fix detection of llvm-x.x Summary: Four bug fixes and a little refactoring. * `find -perm \mode` should be `find -perm /mode` (#9697) * `find -regex '$3' should be `find -regex "$3"` (#7661) From `man sh` on my system (Ubuntu 14.04): "Enclosing characters in single quotes preserves the literal meaning of all the characters ..." * LlcCmd and OptCmd should be passed to ghc, using `-pgmlo` and `-pgmlc`, for detection of #9439. * -pgmlo and -pgmlc were undocumented because of an xml tag misplacement. Test Plan: The aclocal.m4 macro has seen about 10 iterations since its inception. Without a testsuite, I can't guarantee this version is bug free either. It's all pretty frustrating. Reviewers: bgamari, austin Reviewed By: austin Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D683 GHC Trac Issues: #9697, #7661, #9439 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7661#comment:18> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2530: deriving Show adds extra parens for constructor with record syntax
by GHC 02 Mar '15

02 Mar '15

#2530: deriving Show adds extra parens for constructor with record syntax -------------------------------------+------------------------------------- Reporter: spl | Owner: Type: bug | Status: patch Priority: lowest | Milestone: 7.12.1 Component: Compiler | Version: 6.8.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: Phab:D669 -------------------------------------+------------------------------------- Comment (by Austin Seipp <austin@…>): In [changeset:"5692643c9d17e746327588cd6157a923642b7975/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="5692643c9d17e746327588cd6157a923642b7975" Show record construction/update without parens Summary: The 2010 report mentions: "The result of `show` is a syntactically correct Haskell expression ... Parenthesis are only added where needed, //ignoring associativity//". Reviewers: austin Reviewed By: austin Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D669 GHC Trac Issues: #2530 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2530#comment:25> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9697: ./configure fails due to obselete usage of 'find -perm' in aclocal.m4
by GHC 02 Mar '15

02 Mar '15

#9697: ./configure fails due to obselete usage of 'find -perm' in aclocal.m4 -------------------------------------+------------------------------------- Reporter: nich | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 7.8.3 Keywords: aclocal.m4 find | Operating System: perm | Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Building Difficulty: Easy (less than 1 | GHC failed hour) | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- ./configure produces error message when building on current Fedora (20). According to find ver 4.5.11 the usage '-perm +XXX' has been deprecated since 2005 (use '-perm \XXX' instead). The message '/usr/bin/find: invalid mode '+111' ' is seen several times as a result. Whether this has any material impact I am not qualified to judge. I am actually trying to build HaLVM (from Galois) and first noticed the issue in their fork of GHC. However, this behaviour is also present in git HEAD (commit d7867810d5ffd08c77c30e928bb3dca21beae0b9). Making the obvious one line change in aclocal.m4 resolves the issue, and produces a clean build, for me at least. Patch attached -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9697> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10112: Desugaring of do-syntax intros unification var with -XRebindableSyntax
by GHC 02 Mar '15

02 Mar '15

#10112: Desugaring of do-syntax intros unification var with -XRebindableSyntax -------------------------------------+------------------------------------- Reporter: heisenbug | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- When compiling below snippet with GHC 7.8.x (and I believe v7.10.x) {{{ {-# LANGUAGE RankNTypes, RebindableSyntax #-} import qualified Prelude as P (>>=) :: a -> ((forall b . b) -> c) -> c a >>= f = f P.undefined return a = a fail s = P.undefined t1 = 'd' >>= (\_ -> 'k') t2 = do _ <- 'd' 'k' main = P.putStrLn [t1, t2] }}} we get this error: {{{ Ztest.hs:12:9: Cannot instantiate unification variable `t0` with a type involving foralls: forall b. b Perhaps you want ImpredicativeTypes In a stmt of a 'do' block: _ <- 'd' In the expression: do { _ <- 'd'; 'k' } In an equation for `t2`: t2 = do { _ <- 'd'; 'k' } Failed, modules loaded: none. }}} In GHC HEAD (and v7.6.x) the error does not appear. Nevertheless I'll file this bug for addition of a regression test. Discussion here: https://mail.haskell.org/pipermail/ghc- devs/2015-February/008383.html -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10112> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5850: Greater customization of GHCi prompt
by GHC 02 Mar '15

02 Mar '15

#5850: Greater customization of GHCi prompt -------------------------------------+------------------------------------- Reporter: JamesFisher | Owner: jlengyel Type: feature request | Status: patch Priority: normal | Milestone: 7.12.1 Component: GHCi | Version: 7.4.1 Resolution: | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: #9994 | Blocking: | Differential Revisions: Phab:D623 -------------------------------------+------------------------------------- Changes (by thomie): * differential: Phab:D559 => Phab:D623 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5850#comment:9> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #605: Optimisation: strict enumerations
by GHC 02 Mar '15

02 Mar '15

#605: Optimisation: strict enumerations -------------------------------------+------------------------------------- Reporter: simonmar | Owner: Type: task | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: None Resolution: None | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: N/A Blocked By: | Blocking: Related Tickets: #6135 | Differential Revisions: -------------------------------------+------------------------------------- Changes (by bgamari): * cc: bgamari (added) Old description: > Strict enumeration types should be implemented by Int#, both in the > strictness analyser and for constructor fields annotated with {-# UNPACK > #-}. New description: Strict enumeration types should be implemented by `Int#`, both in the strictness analyser and for constructor fields annotated with `{-# UNPACK #-}`. -- -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/605#comment:20> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9962: time: Show instance for UTCTime is orphan
by GHC 02 Mar '15

02 Mar '15

#9962: time: Show instance for UTCTime is orphan -------------------------------------+------------------------------------- Reporter: | Owner: SimonHengel | Status: new Type: bug | Milestone: Priority: normal | Version: 7.8.4 Component: libraries | Operating System: Unknown/Multiple (other) | Type of failure: None/Unknown Keywords: | Blocked By: Architecture: | Related Tickets: Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9962> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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