November 2014 - ghc-tickets

[GHC] #9765: Strange behavior of GC under ghci
by GHC 06 Nov '14

06 Nov '14

#9765: Strange behavior of GC under ghci -------------------------------------+------------------------------------- Reporter: remdezx | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Incorrect Blocked By: | result at runtime Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Releasing the result of `newForeignPtr nullFunPtr nullPtr` end in core dump, due to the fact that finalizer function is set to null pointer. When I run something like this in GHCI: {{{#!hs > import System.Mem > import Foreign.Ptr > import Foreign.ForeignPtr > import System.IO.Unsafe > import qualified Data.Map as Map > a <- return $ Map.singleton 1 (unsafePerformIO $ newForeignPtr nullFunPtr nullPtr) Loading package array-0.5.0.0 ... linking ... done. Loading package deepseq-1.3.0.2 ... linking ... done. Loading package containers-0.5.5.1 ... linking ... done. > print a fromList [(1,0x0000000000000000)] > performGC > ^D Leaving GHCi. [1] 3782 segmentation fault (core dumped) ghci }}} it wont crash until exit from ghci which is correct. But if I do something similar but using `let` binding it will crash even if variable `a` didn't lose its scope {{{#!hs > import System.Mem > import Foreign.Ptr > import Foreign.ForeignPtr > import System.IO.Unsafe > import qualified Data.Map as Map > let a = Map.singleton 1 (unsafePerformIO $ newForeignPtr nullFunPtr nullPtr) Loading package array-0.5.0.0 ... linking ... done. Loading package deepseq-1.3.0.2 ... linking ... done. Loading package containers-0.5.5.1 ... linking ... done. > print a fromList [(1,0x0000000000000000)] [1] 3842 segmentation fault (core dumped) ghci }}} Why is there a difference between doing it with `do` notation and with `let` binding? I also expected that if I rebind variable `a` it will lose it's scope and will be released but it is not (see below) {{{#!hs > import System.Mem > import Foreign.Ptr > import Foreign.ForeignPtr > import System.IO.Unsafe > import qualified Data.Map as Map > a <- return $ Map.singleton 1 (unsafePerformIO $ newForeignPtr nullFunPtr nullPtr) Loading package array-0.5.0.0 ... linking ... done. Loading package deepseq-1.3.0.2 ... linking ... done. Loading package containers-0.5.5.1 ... linking ... done. > print a fromList [(1,0x0000000000000000)] > a <- return () -- rebinding varable a, it is no longer used > performGC > -- no crash, varaible a not released }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9765> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7192: Bug in -fregs-graph with -fnew-codegen
by GHC 05 Nov '14

05 Nov '14

#7192: Bug in -fregs-graph with -fnew-codegen -------------------------------------+------------------------------------- Reporter: simonmar | Owner: benl Type: bug | Status: closed Priority: highest | Milestone: 7.8.1 Component: Compiler | Version: 7.7 Resolution: fixed | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Unknown Type of failure: | Blocked By: None/Unknown | Related Tickets: Test Case: | Blocking: 4258 | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by jstolarek): This is marked as fixed, but the `-fregs-graph` flag is still disabled for `-O` and `-O2`. Can I re-enabled it? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7192#comment:16> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9773: Binding ImplicitParams in lambda results in parse error
by GHC 05 Nov '14

05 Nov '14

#9773: Binding ImplicitParams in lambda results in parse error -------------------------------------+------------------------------------- Reporter: SimonHengel | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Parser) | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: GHC Blocked By: | rejects valid program Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- {{{ImplicitParams}}} currently do not play well with lambdas :( == Steps to reproduce Create a file {{{Foo.hs}}} with the following content: {{{ {-# LANGUAGE ImplicitParams #-} import Control.Monad foo :: (?bar :: Int) => IO () foo = print ?bar main = do forM_ [1..3] $ \ ?bar -> foo }}} === Expected result {{{ $ runhaskell Foo.hs 1 2 3 }}} === Actual result {{{ $ runhaskell Foo.hs Foo.hs:9:21: Parse error in pattern: ?bar }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9773> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7942: aarch64 support in ghc
by GHC 05 Nov '14

05 Nov '14

#7942: aarch64 support in ghc -------------------------------------+------------------------------------- Reporter: jcapik | Owner: Type: bug | Status: patch Priority: high | Milestone: 7.10.1 Component: Compiler | Version: Resolution: | Keywords: Operating System: Linux | Architecture: arm Type of failure: GHC | Difficulty: Unknown doesn't work at all | Blocked By: Test Case: | Related Tickets: 7623, 8664 Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by lukexi): * status: new => patch Comment: Hello! This patch finishes ARM64 support including SMP and means we can now run on the newest 64-bit iOS devices. Would be awesome to get this into 7.10. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7942#comment:51> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7942: aarch64 support in ghc
by GHC 05 Nov '14

05 Nov '14

#7942: aarch64 support in ghc -------------------------------------+------------------------------------- Reporter: jcapik | Owner: Type: bug | Status: new Priority: high | Milestone: 7.10.1 Component: Compiler | Version: Resolution: | Keywords: Operating System: Linux | Architecture: arm Type of failure: GHC | Difficulty: Unknown doesn't work at all | Blocked By: Test Case: | Related Tickets: 7623, 8664 Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by lukexi): * cc: lukexi@… (added) * priority: normal => high * status: closed => new * resolution: fixed => * type: feature request => bug -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7942#comment:50> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4114: Add a flag to remove/delete intermediate files generated by GHC
by GHC 05 Nov '14

05 Nov '14

#4114: Add a flag to remove/delete intermediate files generated by GHC -------------------------------------+------------------------------------- Reporter: guest | Owner: VictorDenisov Type: feature | Status: new request | Milestone: 7.10.1 Priority: low | Version: 6.10.4 Component: Compiler | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: | Related Tickets: #2258 None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by VictorDenisov): * owner: => VictorDenisov -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4114#comment:16> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9768: reify returns only first instance of class
by GHC 04 Nov '14

04 Nov '14

#9768: reify returns only first instance of class -------------------------------------+------------------------------------- Reporter: qnikst | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | https://gist.github.com/qnikst/b93e7154e78bcc159be2 | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- In ghc-7.8 reify returns only first data type that have an instance, here is a code: Test.hs {{{ {-# LANGUAGE TemplateHaskell #-} module Test where import Language.Haskell.TH class C a inner :: ExpQ inner = do ClassI _ instances <- reify ''C let sh = show instances [| sh |] def :: String -> DecsQ def x = let dn = mkName x in do dt <- dataD (cxt []) dn [] [] [] i <- instanceD (cxt []) (appT (conT ''C) (conT dn)) [] -- [d| instance C $(cn) |] return [dt,i] test :: ExpQ test = [| print $inner |] }}} test.hs {{{ {-# LANGUAGE TemplateHaskell #-} import Test def "A" def "B" main = $(test) }}} running test returns: "[InstanceD [] (AppT (ConT Test.C) (ConT Main.A)) []]" under 7.6 test returns: "[InstanceD [] (AppT (ConT Test.C) (ContT Main.B) [], InstanceD [] (AppT (ConT Test.C) (ConT Main.A) []]" -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9768> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9750: Core lint failure with TypeLits Symbol
by GHC 04 Nov '14

04 Nov '14

#9750: Core lint failure with TypeLits Symbol -------------------------------------+------------------------------------- Reporter: dreixel | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.9 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- The following module: {{{ {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE DataKinds #-} {-# LANGUAGE ScopedTypeVariables #-} module Bug where import GHC.TypeLits ( Symbol, KnownSymbol ) -------------------------------------------------------------------------------- data Meta = MetaCons Symbol data M1 (c :: Meta) = M1 class Generic a where type Rep a :: * from :: a -> Rep a -------------------------------------------------------------------------------- data A = A1 instance Generic A where type Rep A = M1 ('MetaCons "test") from A1 = M1 class GShow' f where gshowsPrec' :: f -> ShowS instance (KnownSymbol c) => GShow' (M1 ('MetaCons c)) instance GShow' A where gshowsPrec' = gshowsPrec' . from }}} fails `-dcore-lint` in HEAD with: {{{ *** Core Lint errors : in result of Desugar (after optimization) *** <no location info>: Warning: [RHS of $dKnownSymbol_azn :: GHC.TypeLits.KnownSymbol "test"] From-type of Cast differs from type of enclosed expression From-type: GHC.TypeLits.KnownSymbol "test" Type of enclosed expr: [GHC.Types.Char] Actual enclosed expr: GHC.CString.unpackCString# "test"# Coercion used in cast: GHC.TypeLits.NTCo:KnownSymbol[0] <"test">_N ; GHC.TypeLits.NTCo:SSymbol[0] <"test">_P }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9750> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9728: ghci: internal error: ASSERTION FAILED: file rts/Interpreter.c, line 773
by GHC 04 Nov '14

04 Nov '14

#9728: ghci: internal error: ASSERTION FAILED: file rts/Interpreter.c, line 773 -------------------------------------+------------------------------------- Reporter: slyfox | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.9 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Runtime Blocked By: | crash Related Tickets: | Test Case: ghcirun002 | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- It's a ghc-HEAD on amd64 ./configure --enable-unregisterised. One of faulty tests is a: {{{ ghc-unreg/testsuite/tests/ghci/should_run $ '/home/slyfox/dev/git/ghc- unreg/inplace/bin/ghc-stage2' -fforce-recomp -dcore-lint -dcmm-lint -dno- debug-output -no-user-package-db -rtsopts -optc-fno-builtin -fno-warn-tabs -fno-ghci-history ghcirun002.hs --interactive -v0 -ignore-dot-ghci +RTS -I0.1 -RTS *Main> main (<interactive>: internal error: ASSERTION FAILED: file rts/Interpreter.c, line 773 (GHC version 7.9.20141020 for x86_64_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Aborted }}} The assertion failure is triggered by stack overflow check when handling ... stack overflow! {{{ // Stack check if (Sp - INTERP_STACK_CHECK_THRESH < SpLim) { Sp -= 2; Sp[1] = (W_)obj; Sp[0] = (W_)&stg_apply_interp_info; // placeholder, really /* 773 */ RETURN_TO_SCHEDULER(ThreadInterpret, StackOverflow); } /* ... RETURN_TO_SCHEDULER decl: */ #define RETURN_TO_SCHEDULER(todo,retcode) \ /* this triggers assert */ SAVE_STACK_POINTERS; \ cap->r.rCurrentTSO->what_next = (todo); \ threadPaused(cap,cap->r.rCurrentTSO); \ cap->r.rRet = (retcode); \ return cap; /* ... SAVE_STACK_POINTERS decl: */ #define SAVE_STACK_POINTERS \ ASSERT(Sp > SpLim); \ cap->r.rCurrentTSO->stackobj->sp = Sp }}} In our case '''Sp == SpLim'''. That means we have written one word out-of-stack-bounds, right? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9728> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9211: Untouchable type variable (regression from 7.6)
by GHC 04 Nov '14

04 Nov '14

#9211: Untouchable type variable (regression from 7.6) ------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Oleg says: what used to type check in GHC 7.4.1 (and I think in 7.6.2, although I no longer have access to that version) fails in GHC 7.8.2. The following program type-checks with GHC 7.4.1 and GHC 7.8.2: {{{ {-# LANGUAGE RankNTypes #-} {-# LANGUAGE TypeFamilies #-} module T where foo :: (forall f g. (Functor f) => f a -> f b) -> [a] -> [b] -- foo :: (forall f g. (Functor f, g ~ f) => g a -> g b) -> [a] -> [b] foo tr x = tr x t = foo (fmap not) [True] }}} The following code (which differs only in the signature of foo) {{{ {-# LANGUAGE RankNTypes #-} {-# LANGUAGE TypeFamilies #-} module T where -- foo :: (forall f g. (Functor f) => f a -> f b) -> [a] -> [b] foo :: (forall f g. (Functor f, g ~ f) => g a -> g b) -> [a] -> [b] foo tr x = tr x t = foo (fmap not) [True] }}} type-checks with 7.4.1 but not with 7.8.2. The latter reports the error {{{ Couldn't match type `b' with `Bool' `b' is untouchable inside the constraints (Functor f, g ~ f) bound by a type expected by the context: (Functor f, g ~ f) => g Bool -> g b at /tmp/t.hs:12:5-25 `b' is a rigid type variable bound by the inferred type of t :: [b] at /tmp/t.hs:12:1 Expected type: Bool -> b Actual type: Bool -> Bool Relevant bindings include t :: [b] (bound at /tmp/t.hs:12:1) In the first argument of `fmap', namely `not' In the first argument of `foo', namely `(fmap not)' }}} Giving `t` the type signature `[Bool]` fixes the problem. Alas, I come across the similar untouchable error in situations where giving the type signature is quite difficult (in local bindings, with quite large types). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9211> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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