March 2017 - ghc-tickets

[GHC] #13415: Instance declarations don't recognize named wildcards
by GHC 22 Mar '17

22 Mar '17

#13415: Instance declarations don't recognize named wildcards -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.0.1 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Poor/confusing Unknown/Multiple | error message Test Case: | Blocked By: Blocking: | Related Tickets: #13324 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- While exploring a fix for #13324, I was blocked pretty quickly by this limitation: instance declarations don't properly recognize named wildcards. Here is an example to demonstrate: {{{#!hs {-# LANGUAGE NamedWildCards #-} module Bug where instance _x => Show (Maybe a) }}} {{{ Bug.hs:4:10: error: • Illegal constraint: _x (Use ConstraintKinds to permit this) • In the context: _x While checking an instance declaration In the instance declaration for ‘Show (Maybe a)’ | 4 | instance _x => Show (Maybe a) | ^^^^^^^^^^^^^^^^^^^^ }}} GHC doesn't recognize that `_x` is just a type variable, not a named wildcard. I believe fixing this is just a matter of changing the ASTs for instance declarations to use `LHsSigWcType` instead of `LHsSigType`. Patch incoming. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13415> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13467: ghc: panic! (the 'impossible' happened), initTc: unsolved constraints
by GHC 22 Mar '17

22 Mar '17

#13467: ghc: panic! (the 'impossible' happened), initTc: unsolved constraints ----------------------------------------+--------------------------------- Reporter: jhjonsson | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Keywords: | Operating System: MacOS X Architecture: Unknown/Multiple | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ----------------------------------------+--------------------------------- NB! I'm no expert on the compiler and have not used GHC/GHCi very much. I have istaller the Haskell Platform and then run GHCi from within Aquamacs (emacs) using tthe Haskell mode already available there. I should say that everything worked fine and I could both load and run code. But then this happend when I started with the type Char and the functions ord and chr, so maybe the error has to do with them(?) Please change the subject to something relevant; I really have no clue what has happened here. Just like to help. /Håkan --- This is the error message: "GHCi, version 8.0.2: http://www.haskell.org/ghc/ :? for help Prelude> :load "/Users/hj/Downloads/d7012e-vt17/test.hs" [1 of 1] Compiling Main ( /Users/hj/Downloads/d7012e- vt17/test.hs, interpreted ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-apple-darwin): initTc: unsolved constraints WC {wc_insol = [W] –_a2n2 :: t_a2n1[tau:1] (CHoleCan: –)} Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug > " --- This is my Haskell code (putting together examples for a first lecture on declarative languages/functional languages): module Main (main) where import Data.Char (ord,chr) square :: Int -> Int square n = n * n primes :: [Int] primes = filterPrime [2..] where filterPrime (p:xs) = p : filterPrime [x | x <- xs, x `mod` p /= 0] -- take :: Int -> [a] -> [a] double :: Int -> Int double n = 2*n dubSq1 :: Int -> Int dubSq1 n = double (square n) dubSq2 :: Int -> Int dubSq2 = double . square -- Bool nAnd :: Bool -> Bool -> Bool nAnd x y = not (x && y) nAnd2 :: Bool -> Bool -> Bool nAnd2 True True = False nAnd2 False False = False nAnd2 x y = True -- if, the, else max2 :: Int -> Int -> Int max2 x y = if x >= y then x else y -- Int max3 :: Int -> Int -> Int -> Int max3 a b c = max2 (max2 a b) c f :: Int -> Int f 1 = 0 f n = if n `mod` 2 == 0 then n `div` 2 else 3*n + 1 isDigit :: Char -> Bool isDigit ch = ('0' <= ch) && (ch <= '9') isLower :: Char -> Bool isLower ch = ('a' <= ch) && (ch <= 'z') -- no åäö in ASCII offset :: Int offset = ord 'A' – ord 'a' toUpper :: Char -> Char toUpper ch = chr (ord ch + offset) f' 1 = 0 f' n | n `mod` 2 == 0 = n `div` 2 | otherwise = 3*n + 1 life_length x | x == 1 = 0 | otherwise = 1 + life_length(f' x) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13467> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1409: Allow recursively dependent modules transparently (without .hs-boot or anything)
by GHC 22 Mar '17

22 Mar '17

#1409: Allow recursively dependent modules transparently (without .hs-boot or anything) -------------------------------------+------------------------------------- Reporter: Isaac Dupree | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: 6.10.2 Resolution: | Keywords: backpack Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #9256 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by Tritlo): * cc: Tritlo (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1409#comment:71> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13463: Deriving Functor / Foldable / Traversable for co-pattern type
by GHC 21 Mar '17

21 Mar '17

#13463: Deriving Functor / Foldable / Traversable for co-pattern type -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: feature | Status: new request | 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: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This is probably asking too much, but could GHC derive `Functor`, `Foldable` ... for this [https://www.reddit.com/r/haskell/comments/4aju8f/simple_example_of_emulatin… co-pattern] data type? {{{#!hs data ListTag :: Type -> Type -> Type where HeadTag :: ListTag a a TailTag :: ListTag a (Stream a) newtype Stream a = S (forall res. ListTag a res -> res) instance Functor Stream where fmap :: (a -> a') -> (Stream a -> Stream a') fmap f (S stream) = S $ \case HeadTag -> f (stream HeadTag) TailTag -> fmap f (stream TailTag) instance Foldable Stream where foldMap :: Monoid m => (a -> m) -> (Stream a -> m) foldMap f (S stream) = f (stream HeadTag) <> foldMap f (stream TailTag) }}} I'm guessing it's not worth it in any case, but is it uniquely determined? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13463> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13343: Levity polymorphism-related GHC panic: expectJust zonkTcTyVarToVar
by GHC 21 Mar '17

21 Mar '17

#13343: Levity polymorphism-related GHC panic: expectJust zonkTcTyVarToVar -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 (Type checker) | Keywords: | Operating System: Unknown/Multiple LevityPolymorphism | Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Reproducible with GHC 8.0.2 and HEAD: {{{#!hs {-# LANGUAGE RankNTypes #-} {-# LANGUAGE TypeInType #-} module Bug where import GHC.Exts type Bad = forall (v1 :: RuntimeRep) (a1 :: TYPE v). a1 }}} {{{ [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.1.20170223 for x86_64-unknown-linux): expectJust zonkTcTyVarToVar CallStack (from HasCallStack): error, called at compiler/utils/Maybes.hs:53:27 in ghc:Maybes expectJust, called at compiler/typecheck/TcType.hs:1576:21 in ghc:TcType }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13343> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12709: GHC panic
by GHC 21 Mar '17

21 Mar '17

#12709: GHC panic -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: 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: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I get {{{ $ ./ghc-stage2 -ignore-dot-ghci --interactive /tmp/tEZm.hs GHCi, version 8.1.20160930: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( /tmp/tEZm.hs, interpreted ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.1.20160930 for x86_64-unknown-linux): kindPrimRep.go rep_a13E Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1076:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1080:37 in ghc:Outputable pprPanic, called at compiler/simplStg/RepType.hs:369:9 in ghc:RepType kindPrimRep, called at compiler/simplStg/RepType.hs:337:18 in ghc:RepType typePrimRep, called at compiler/ghci/ByteCodeGen.hs:1541:15 in ghc:ByteCodeGen Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug > }}} running {{{#!hs {-# Language MagicHash, PolyKinds, ViewPatterns, TypeInType, RebindableSyntax, NoImplicitPrelude #-} import GHC.Types import Prelude hiding (Num (..)) import qualified Prelude as P import GHC.Prim data BoxUnbox = BUB Int Int# class Num (a :: TYPE rep) where (+) :: a -> a -> a fromInteger :: Integer -> a instance Num Int where (+) = (P.+) fromInteger = P.fromInteger instance Num Int# where (+) = (+#) fromInteger (fromInteger -> I# n) = n a :: BoxUnbox a = let u :: Num (a :: TYPE rep) => a u = 1 + 2 + 3 + 4 in BUB u u }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12709> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13202: Levity polymorphism panic in GHCi
by GHC 21 Mar '17

21 Mar '17

#13202: Levity polymorphism panic in GHCi -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: high | Milestone: 8.2.1 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: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- With current `master`, {{{ $ ghci GHCi, version 8.1.20170126: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/ben/.ghci λ> import GHC.Exts λ> :set -XTypeApplications -XMagicHash -XTypeInType λ> data TypeRep (a :: k) = TypeRep λ> let typeRepKind = undefined :: TypeRep (a :: k) -> TypeRep k λ> let typeRep = undefined :: TypeRep (a :: k) λ> let x = typeRepKind (typeRep @(Maybe Int#)) ghc: panic! (the 'impossible' happened) (GHC version 8.1.20170126 for x86_64-unknown-linux): isUnliftedType forall (a :: TYPE q). a :: TYPE q Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1166:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1170:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:1869:10 in ghc:Type Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13202> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13413: GHC HEAD panic: collectNBinders
by GHC 21 Mar '17

21 Mar '17

#13413: GHC HEAD panic: collectNBinders -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.2.1 Component: Compiler | Version: 8.1 Keywords: JoinPoints | 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: -------------------------------------+------------------------------------- `repa-eval-4.2.3.1` currently fails to build on GHC HEAD because of this issue. Trying to build it leads to several `collectNBinders` panics is various modules. You can reproduce this by compiling this module: {{{#!hs {-# LANGUAGE BangPatterns #-} {-# LANGUAGE MagicHash #-} module Data.Repa.Eval.Generic.Seq.Chunked where import GHC.Exts (Int#, (+#), (*#), (>=#)) ------------------------------------------------------------------------------- -- | Fill a block in a rank-2 array, sequentially. -- -- * Blockwise filling can be more cache-efficient than linear filling for -- rank-2 arrays. -- -- * The block is filled in row major order from top to bottom. -- fillBlock2 :: (Int# -> a -> IO ()) -- ^ Update function to write into result buffer. -> (Int# -> Int# -> a) -- ^ Function to get the value at an (x, y) index. -> Int# -- ^ Width of the whole array. -> Int# -- ^ x0 lower left corner of block to fill. -> Int# -- ^ y0 -> Int# -- ^ w0 width of block to fill -> Int# -- ^ h0 height of block to fill -> IO () fillBlock2 write getElem !imageWidth !x0 !y0 !w0 h0 = do fillBlock y0 ix0 where !x1 = x0 +# w0 !y1 = y0 +# h0 !ix0 = x0 +# (y0 *# imageWidth) {-# INLINE fillBlock #-} fillBlock !y !ix | 1# <- y >=# y1 = return () | otherwise = do fillLine1 x0 ix fillBlock (y +# 1#) (ix +# imageWidth) where {-# INLINE fillLine1 #-} fillLine1 !x !ix' | 1# <- x >=# x1 = return () | otherwise = do write ix' (getElem x y) fillLine1 (x +# 1#) (ix' +# 1#) {-# INLINE [0] fillBlock2 #-} }}} This compiles on GHC 8.0.2, but on GHC HEAD: {{{ $ ~/Software/ghc4/inplace/bin/ghc-stage2 -fforce-recomp Bug.hs [1 of 1] Compiling Data.Repa.Eval.Generic.Seq.Chunked ( Bug.hs, Bug.o ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.1.20170201 for x86_64-unknown-linux): collectNBinders 2 Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1179:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1183:37 in ghc:Outputable pprPanic, called at compiler/coreSyn/CoreSyn.hs:1970:25 in ghc:CoreSyn }}} Interestingly, compiling this triggers the panic at any optimization level, but loading the module into GHCi does not cause it to panic. This regression was introduced in 8d5cf8bf584fd4849917c29d82dcf46ee75dd035 (Join points). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13413> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13464: Pattern match checker runs even when not needed
by GHC 21 Mar '17

21 Mar '17

#13464: Pattern match checker runs even when not needed -------------------------------------+------------------------------------- Reporter: jstolarek | 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: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I have code that triggers pattern match checker warning: {{{ Pattern match checker exceeded (2000000) iterations in a case alternative. (Use -fmax-pmcheck-iterations=n to set the maximun number of iterations to n) }}} I would like to silence that warning. Alas, `-Wno-incomplete-patterns` does nothing - the warning still appears. I would expect that if I do not want to check for incomplete patterns then pattern match checker is not run at all and thus does not exceed maximum number of iterations! I can only use `-w` to silence all the warnings but this is an overkill - definitely not what I want. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13464> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13462: stack upgrade failed, version 1.0.4 at macosx
by GHC 21 Mar '17

21 Mar '17

#13462: stack upgrade failed, version 1.0.4 at macosx -------------------------------------+------------------------------------- Reporter: chinaxing | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Keywords: panic | Operating System: MacOS X Architecture: x86_64 | Type of failure: Compile-time (amd64) | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- os: Darwin lambda-cat.local 16.4.0 Darwin Kernel Version 16.4.0: Thu Dec 22 22:53:21 PST 2016; root:xnu-3789.41.3~3/RELEASE_X86_64 x86_64 macOS sierra, 10.12.3 stack version: Version 1.0.4, Git revision cf18703b1392a96a5a4896a560309e501af63260 (3220 commits) x86_64 ghc: panic! (the 'impossible' happened) (GHC version 7.10.3 for x86_64-apple-darwin): Loading temp shared object failed: dlopen(/var/folders/79/l2kk9s8572gdvzc8r5jq2pf40000gn/T/ghc39735_0/libghc_68.dylib, 5): no suitable image found. Did find: /var/folders/79/l2kk9s8572gdvzc8r5jq2pf40000gn/T/ghc39735_0/libghc_68.dylib: malformed mach-o: load commands size (50048) > 32768 Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Completed 28 action(s). -- While building package stack-1.4.0 using: /private/var/folders/79/l2kk9s8572gdvzc8r5jq2pf40000gn/T/stack- upgrade36593/stack-1.4.0/.stack- work/dist/x86_64-osx/Cabal-1.22.5.0/setup/setup --builddir=.stack- work/dist/x86_64-osx/Cabal-1.22.5.0 build lib:stack exe:stack --ghc- options " -ddump-hi -ddump-to-file" Process exited with code: ExitFailure 1 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13462> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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