March 2015 - ghc-tickets

[GHC] #10107: Add Functor etc. to Data.Monoid wrappers
by GHC 18 Mar '15

18 Mar '15

#10107: Add Functor etc. to Data.Monoid wrappers -------------------------------------+------------------------------------- Reporter: phadej | Owner: Type: feature | Status: new request | Milestone: 7.12.1 Priority: normal | Version: 7.8.4 Component: | Operating System: Unknown/Multiple libraries/base | Type of failure: None/Unknown Keywords: | Blocked By: Architecture: | Related Tickets: Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Add Functor, Foldable, Traversable, Monad, Applicative, MonadFix and Data to wrappers in Data.Monoid Discussion on libraries list: https://mail.haskell.org/pipermail/libraries/2015-February/024989.html -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10107> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10099: cabal install broken with ghc 7.10.1-rc2
by GHC 17 Mar '15

17 Mar '15

#10099: cabal install broken with ghc 7.10.1-rc2 -------------------------------------+------------------------------------- Reporter: trommler | Owner: Type: bug | Status: new Priority: highest | Milestone: 7.10.1 Component: Package | Version: 7.10.1-rc2 system | Operating System: Unknown/Multiple Keywords: | Type of failure: Runtime crash Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Trying to install a package with cabal-install and Cabal from ghc 7.10-rc2 consistently gives this error message (`primitive` is just an example): {{{ peter@montebre:~> cabal install primitive Resolving dependencies... Configuring primitive-0.5.4.0... cabal: Distribution/Client/Config.hs:(246,37)-(299,9): Missing field in record construction configProf }}} This is my package database: {{{ peter@montebre:~> ghc-pkg list /usr/lib64/ghc-7.10.0.20150123/package.conf.d Cabal-1.22.1.0 HTTP-4000.2.19 array-0.5.0.1 base-4.8.0.0 bin-package-db-0.0.0.0 binary-0.7.3.0 bytestring-0.10.6.0 containers-0.5.6.2 deepseq-1.4.0.0 directory-1.2.2.0 filepath-1.3.1.0 ghc-7.10.0.20150123 ghc-prim-0.3.1.0 haskeline-0.7.2.0 hoopl-3.10.0.2 hpc-0.6.0.2 integer-gmp-1.0.0.0 mtl-2.2.1 network-2.4.2.3 old-locale-1.0.0.7 old-time-1.1.0.3 parsec-3.1.8 pretty-1.1.2.0 process-1.2.2.0 random-1.0.1.1 rts-1.0 stm-2.4.2 syb-0.4.4 template-haskell-2.10.0.0 terminfo-0.4.0.1 text-1.2.0.4 th-desugar-1.5 th-lift-0.7 time-1.5.0.1 transformers-0.4.2.0 unix-2.7.1.0 xhtml-3000.2.1 zlib-0.5.4.2 }}} I updated only those packages (from their versions in Haskell Platform) that would not compile with 7.101-rc2. I am setting this to highest as this issue would be very annoying for everyone. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10099> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7543: Constraint synonym instances
by GHC 17 Mar '15

17 Mar '15

#7543: Constraint synonym instances -------------------------------------+------------------------------------- Reporter: monoidal | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by bheklilr): I don't have a particular attachment to being able to do this, my biggest concern is that it's somewhat inconsistent behavior. If a constraint isn't a class, then it shouldn't be possible to make an instance of it. Or we should allow all constraints to be instantiated as classes. This could lead to some interesting problems to have to solve, such as when two constraints are used that could have overlapping names {{{ module C1 where class C1 a where c :: a -> a }}} ---- {{{ module C2 where class C2 a where c :: a -> a }}} ---- {{{ module C where import C1 import C2 type Cs a = (C1 a, C2 a) instance Cs Int where C1.c = pred C2.c = succ }}} This won't work currently because you can't use qualified names in a binding position, but without the qualification you can't distinguish between the different `c` methods on the classes. I also can't say I'm a fan of having multiple instances defined in the same block. For example, the following would bother me {{{ newtype MyInt = MyInt Int type OrdNum a = (Num a, Ord a) instance OrdNum MyInt where compare (MyInt x) (MyInt y) = compare x y fromInteger = MyInt ... -- Results in -- instance Num MyInt -- instance Ord MyInt }}} Considering that the argument for being able use constraints like this is that it would slightly improve the usability of a handful of libraries, I'm personally leaning towards a fix that would simply disallow instancing anything that is not a class. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7543#comment:11> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7543: Constraint synonym instances
by GHC 16 Mar '15

16 Mar '15

#7543: Constraint synonym instances -------------------------------------+------------------------------------- Reporter: monoidal | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by simonpj): > This would be easier to explain, at least, and wouldn't require much upheaval either. Actually, this is probably simpler than my idea in comment:7. I don't think so. {{{ type C a = X a Num type X a b = b a }}} I really don't want to put enough cleverness in the renamer to expand type synonyms on the fly. Let's see how keen our users are. Simon -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7543#comment:10> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7543: Constraint synonym instances
by GHC 16 Mar '15

16 Mar '15

#7543: Constraint synonym instances -------------------------------------+------------------------------------- Reporter: monoidal | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by goldfire): The other thing we could do is support this feature at synonym-definition time. When defining a type synonym such that the head of the RHS is a class, record this fact in the `TyCon` and corresponding iface info. If such a synonym appears as the head of an instance declaration, we use this tidbit to do the name lookup. This would be easier to explain, at least, and wouldn't require much upheaval either. Actually, this is probably simpler than my idea in comment:7. About looking up instances: we really need to move beyond `grep` for this sort of thing! Of course, I exclusively use `grep` for this sort of thing... because I don't have a better option to hand. But that's a story for another day. In the meantime, worrying about obfuscation via synonyms is valid, but also not something that (I believe) should hold this up. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7543#comment:9> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7543: Constraint synonym instances
by GHC 16 Mar '15

16 Mar '15

#7543: Constraint synonym instances -------------------------------------+------------------------------------- Reporter: monoidal | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by simonpj): Yes we could do as Richard suggests. It'd be one more thing to explain in the user manual. And I'm a little suspicious, because now if I'm hunting for instances of some class I need to take synonyms into account. I grant that we already allow ''type'' synonyms in the instance head, and that too makes hunting for instances harder in a similar way. Are these disadvantages outweighed by the advantages? Do more than two people want this? Simon -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7543#comment:8> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10156: Unable to coerce with flipped Coercible context
by GHC 16 Mar '15

16 Mar '15

#10156: Unable to coerce with flipped Coercible context -------------------------------------+------------------------------------- Reporter: ekmett | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.10.1-rc2 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 coerce' :: Coercible a b => b -> a coerce' = coerce }}} doesn't compile, forcing workarounds like: {{{#!hs coerce' :: forall a b. Coercible a b => b -> a coerce' = coerce (id :: a -> a) }}} This arises in practice in several places in the `profunctors` package and `lens`. https://github.com/ekmett/profunctors/blob/1c3508e5274a0ed03765c569596a8fda… http://hackage.haskell.org/package/lens-4.8/docs/src/Control-Lens- Internal-Coerce.html#coerce%27 Ideally we'd be able to retire `coerce'` entirely and just use `coerce` in those contexts. The tricky part is of course avoiding infinite loops once you add symmetry. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10156> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7934: usleep hangs, no threads
by GHC 15 Mar '15

15 Mar '15

#7934: usleep hangs, no threads -------------------------------------+------------------------------------- Reporter: gelisam | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 7.4.2 Resolution: | Keywords: Operating System: MacOS X | Architecture: x86_64 Type of failure: Incorrect result | (amd64) at runtime | Test Case: Blocked By: | Blocking: Related Tickets: 1156 | Differential Revisions: -------------------------------------+------------------------------------- Comment (by gelisam): Yes, it still occurs with ghc 7.8.3 on my OS X 10.6.8 machine. However, it does not occur with ghc 7.8.2 on my OS X 10.9.2 machine, so it's probably an OS X bug which since got fixed. I think we can finally close this issue :) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7934#comment:3> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7353: Make system IO interruptible on Windows
by GHC 15 Mar '15

15 Mar '15

#7353: Make system IO interruptible on Windows -------------------------------------+------------------------------------- Reporter: joeyadams | Owner: ekmett Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Core Libraries | Version: 7.6.1 Resolution: | Keywords: Operating System: Windows | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by Phyx-): * cc: Phyx-, core-libraries-committee@… (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7353#comment:23> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1820: Windows segfault-catching only works for the main thread
by GHC 15 Mar '15

15 Mar '15

#1820: Windows segfault-catching only works for the main thread -------------------------------------+------------------------------------- Reporter: simonmar | Owner: Type: bug | Status: closed Priority: lowest | Milestone: 7.12.1 Component: Runtime System | Version: 6.8.1 Resolution: fixed | Keywords: Operating System: Windows | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: #6079 | derefnull(ghci), divbyzero(ghci) | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by Phyx-): * related: 6079 => #6079 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1820#comment:20> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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