March 2016 - ghc-tickets

[GHC] #11732: Deriving Generic1 interacts poorly with TypeInType
by GHC 11 Apr '16

11 Apr '16

#11732: Deriving Generic1 interacts poorly with TypeInType -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 Keywords: TypeInType, | Operating System: Unknown/Multiple Generics | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- From @RyanGlScott, comment:9:ticket:11357: Vanilla datatypes and data family instances are still inconsistent w.r.t. which type variables are considered "instantiated" in a `Generic1` instance. For instance, this is rejected: {{{ λ> data Proxy k (a :: k) = ProxyCon deriving Generic1 }}} {{{ <interactive>:32:43: error: • Can't make a derived instance of ‘Generic1 (Proxy *)’: Proxy must not be instantiated; try deriving `Proxy k a' instead • In the data declaration for ‘Proxy’ }}} And rightfully so, since the visible kind binder `k` is instantiated to `*`. But now it's possible to have an equivalent instance for a data family that squeaks past this check! {{{ λ> data family ProxyFam (a :: y) (b :: z) λ> data instance ProxyFam k (a :: k) = ProxyFamCon deriving Generic1 ==================== Derived instances ==================== Derived instances: instance GHC.Generics.Generic1 (Ghci13.ProxyFam *) where ... }}} [Ryan needs] to investigate further to see why this is the case. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11732> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11546: Compiler warning: cast from pointer to integer of different size
by GHC 09 Apr '16

09 Apr '16

#11546: Compiler warning: cast from pointer to integer of different size -------------------------------------+------------------------------------- Reporter: wereHamster | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 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 building the stage1 compiler: {{{ In file included from rts/Capability.h:25:0, from includes/dist-derivedconstants/header/tmp.c:15: rts/Task.h: In function 'serialiseTaskId': rts/Task.h:318:12: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] return (TaskId) taskID; ^ }}} I'm building a cross-compiler with build/host=x86_64-linux-gnu and target =mips-unknown-linux-musl -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11546> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11529: Show instance of Char should print literals for non-ascii printable charcters
by GHC 08 Apr '16

08 Apr '16

#11529: Show instance of Char should print literals for non-ascii printable charcters -------------------------------------+------------------------------------- Reporter: nushio | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 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: -------------------------------------+------------------------------------- Show instance for non-ascii characters prints their character codes. This is sad for Haskell users that speaks language other than English. {{{#!hs > 'A' 'A' > 'Ä' '\196' > '漢' '\28450' > print $ [(++"'s dad"), (++"'s mom")] <*> ["Simon", "John"] ["Simon's dad","John's dad","Simon's mom","John's mom"] > print $ [(++"の父"), (++"の母")] <*> ["田中", "山田"] ["\30000\20013\12398\29238","\23665\30000\12398\29238","\30000\20013\12398\27597","\23665\30000\12398\27597"] }}} The function that needs improvement is showLitChar in GHC.Show, which currently prints any character larger than ASCII code 127 by its character code: http://haddock.stackage.org/lts-5.1/base-4.8.2.0/src/GHC-Show.html {{{#!hs showLitChar :: Char -> ShowS showLitChar c s | c > '\DEL' = showChar '\\' (protectEsc isDec (shows (ord c)) s) }}} On the other hand, there is GHC.Unicode.isPrint, the predicate for printable Unicode characters, that is calling on a foreign function u_iswprint for the knowledge. https://hackage.haskell.org/package/base-4.8.2.0/docs/src/GHC.Unicode.html#… I think one of the solution is to import and call u_iswprint from GHC.Show, too, but I don't know it's against any design choices. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11529> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8468: ghc panic in deriving Generic1 on Array#
by GHC 07 Apr '16

07 Apr '16

#8468: ghc panic in deriving Generic1 on Array# -----------------------------------+--------------------------------------- Reporter: ghorn | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time crash Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | -----------------------------------+--------------------------------------- Compiling the following code {{{ {-# Language DeriveGeneric, MagicHash #-} module Test where import GHC.Generics import GHC.Prim data Array a = Array (Array# a) newtype Vec a = MkVec {unVec :: Array a} deriving Generic1 }}} causes panic: {{{ [1 of 1] Compiling Test ( Test.hs, Test.o ) ghc: panic! (the 'impossible' happened) (GHC version 7.6.3 for x86_64-unknown-linux): No match in record selector tyConTyVars Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} some comments from IRC: <monoidal> with deriving Generic1 we get "Can't make a derived instance of `Generic1 Array': Array must not have unlifted or polymorphic arguments" - so it seems the check is not done recursively on used types <monoidal> * deriving Generic1 on Array -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8468> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8416: GHC.Generics needs more documentation
by GHC 07 Apr '16

07 Apr '16

#8416: GHC.Generics needs more documentation -------------------------------------+------------------------------------- Reporter: tibbe | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: libraries (other) | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- Recently I tried to used `GHC.Generics` "in anger" for the first time, to fix some code in hashable that wasn't originally written by me. After a while I just gave up (and the generics support in hashable is now somewhat broken). The documentation for `GHC.Generics` is too incomprehensible for mere mortals. In particular, I find the documentation for `M1` and `K1` not very helpful. The documentation needs examples, more in-depth explanations of what each of the data types/constructors is used for, and finally an explanation of the up to 4 type parameters! -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8416> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8797: Generics instances for monoid and applicative newtypes
by GHC 07 Apr '16

07 Apr '16

#8797: Generics instances for monoid and applicative newtypes -------------------------------------------+------------------------------- Reporter: jcristovao | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: libraries/base | Version: 7.6.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Easy (less than 1 hour) | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: -------------------------------------------+------------------------------- Hi, Is there any particular reason why there aren't Generic instances for the newtypes under Data.Monoid and Control.Applicative (for example)? I've tried adding them to GHC/Generics.hs and base compiles without problems. Could this addition be considered? Best Regards, João -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8797> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8929: Deriving Generics broken
by GHC 07 Apr '16

07 Apr '16

#8929: Deriving Generics broken ----------------------------------+------------------------------------- Reporter: guest | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: x86_64 (amd64) | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------------+------------------------------------- I load the following code into ghci: == {-# LANGUAGE DeriveGeneric #-} import GHC.Generics import Data.Binary data Foo = Foo deriving (Show, Generic) instance Binary Foo == Then I execute: (decode . encode $ Foo) :: Foo In 7.6.3 (stage 2 booted 7.6.3), I get an error. In 7.6.3 (stage 2 booted 7.6.2), the desired result "Foo" is shown. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8929> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9523: Typo in GHC Generics documentation
by GHC 07 Apr '16

07 Apr '16

#9523: Typo in GHC Generics documentation -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.8.4 Component: Documentation | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Easy (less than 1 | Type of failure: hour) | None/Unknown Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- In `GHC.Generics`: The types `S`, `C` and `R` are once again type-level proxies, just used to create several variants of `M1`. The `R`, it seems, is supposed to be a `D`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9523> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9527: Add Generic instances for Language.Haskell.TH
by GHC 07 Apr '16

07 Apr '16

#9527: Add Generic instances for Language.Haskell.TH -------------------------------------+------------------------------------- Reporter: nh2 | Owner: Type: feature request | Status: new Priority: normal | Milestone: 7.10.1 Component: libraries/base | 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: 9526 | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Template Haskell has a number of huge data types that would be much easier to work with if they had `Generic` instances. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9527> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9563: Support for deriving Generic1 for data families
by GHC 07 Apr '16

07 Apr '16

#9563: Support for deriving Generic1 for data families -------------------------------------+------------------------------------- Reporter: mnislaih | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: MacOS X Architecture: Unknown/Multiple | Type of failure: GHC Difficulty: Unknown | rejects valid program Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- The following code: {{{#!hs import GHC.Generics data family F typ :: * -> * data A data instance F A a = AData a deriving Generic1 }}} produces an error when run with ghc 7.8.2 or 7.8.3: {{{ Couldn't match type ‘Rep1 (F A)’ with ‘M1 t0 t1 (M1 t2 t3 (M1 t4 t5 Par1))’ The type variables ‘t0’, ‘t1’, ‘t2’, ‘t3’, ‘t4’, ‘t5’ are ambiguous Expected type: Rep1 (F A) a Actual type: M1 t0 t1 (M1 t2 t3 (M1 t4 t5 Par1)) a In the pattern: M1 (M1 (M1 g1)) In an equation for ‘to1’: to1 (M1 (M1 (M1 g1))) = AData (unPar1 g1) In the instance declaration for ‘Generic1 (F A)’ }}} whereas ghc 7.6.3 simply refuses to go ahead with the message: {{{ generic1.hs:14:40: Derived instance `Generic1 (F A)' requires illegal partial application of data type family F In the data instance declaration for `F' }}} Either a check has gone missing in 7.8.x, or a bug has crept up in the Generic1 support. I have gone through past tickets and https://ghc.haskell.org/trac/ghc/ticket/5936 suggests that it is the latter. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9563> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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