June 2017 - ghc-tickets

[GHC] #13752: Odd pattern synonym type errors
by GHC 15 Jan '18

15 Jan '18

#13752: Odd pattern synonym type errors -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.2.1-rc2 (Type checker) | Keywords: | Operating System: Unknown/Multiple PatternSynonyms | Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Suppose we have {{{#!hs newtype Arrange = Arrange {getArrange :: [Int] -> [Int]} }}} If I write {{{#!hs pattern Heh :: (c ~ ((~) Int)) => (forall a. c a => [a] -> [a]) -> Arrange pattern Heh f <- Arrange f }}} I get {{{ • Couldn't match type ‘[Int] -> [Int]’ with ‘forall a. Int ~ a => [a] -> [a]’ Expected type: forall a. c a => [a] -> [a] Actual type: [Int] -> [Int] • In the declaration for pattern synonym ‘Heh’ }}} It surprises me that these don't match. I can hack around that a bit: {{{#!hs newtype Help = Help {getHelp :: forall a. Int ~ a => [a] -> [a]} pattern Heh :: (c ~ ((~) Int)) => (forall a. c a => [a] -> [a]) -> Arrange pattern Heh f <- ((\x -> Help (getArrange x)) -> Help f) }}} Now this compiles, and I can use it in a variety of ways, but not quite all. If I write {{{#!hs pattern Heh' :: ([Int] -> [Int]) -> Arrange pattern Heh' f <- Heh f }}} I get {{{ Haha.hs:78:23: error: • Couldn't match expected type ‘[Int] -> [Int]’ with actual type ‘forall a. Int ~ a => [a] -> [a]’ • In the declaration for pattern synonym ‘Heh'’ | 78 | pattern Heh' f <- Heh f | ^ }}} This strikes me as perhaps even more surprising. I can hack around that too, of course, but yuck! {{{#!hs pattern Heh' :: ([Int] -> [Int]) -> Arrange pattern Heh' f <- ((\(Heh g) -> g @ Int) -> f) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13752> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10634: Type class with bijective type functions
by GHC 15 Jan '18

15 Jan '18

#10634: Type class with bijective type functions -------------------------------------+------------------------------------- Reporter: Lemming | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- See the attached module. {{{ $ cat TypeFunctionBijection.hs {-# LANGUAGE TypeFamilies #-} module TypeFunctionBijection where import Data.Int (Int8, Int16, Int32) type family Up a type instance Up Int8 = Int16 type instance Up Int16 = Int32 class (Up (Down a) ~ a) => Convert a where type Down a down :: a -> Down a instance Convert Int16 where type Down Int16 = Int8 down = fromIntegral instance Convert Int32 where type Down Int32 = Int16 down = fromIntegral x :: Int8 x = down 8 }}} {{{ $ ghci-7.8.4 -Wall TypeFunctionBijection.hs GHCi, version 7.8.4: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. [1 of 1] Compiling TypeFunctionBijection ( TypeFunctionBijection.hs, interpreted ) Ok, modules loaded: TypeFunctionBijection. *TypeFunctionBijection> :q Leaving GHCi. }}} {{{ $ ghci-7.10.1 -Wall TypeFunctionBijection.hs GHCi, version 7.10.1: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling TypeFunctionBijection ( TypeFunctionBijection.hs, interpreted ) TypeFunctionBijection.hs:24:5: Couldn't match expected type ‘Int8’ with actual type ‘Down a0’ The type variable ‘a0’ is ambiguous In the expression: down 8 In an equation for ‘x’: x = down 8 Failed, modules loaded: none. Prelude> :q Leaving GHCi. }}} Up to GHC-7.8.4 I could make a type function like `Down` a bijection by adding equality constraints to the `Convert` class. In GHC-7.10.1 this fails. Is this a bug or a feature? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10634> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13903: KQueue evtmgr backend fails to register for write events
by GHC 14 Jan '18

14 Jan '18

#13903: KQueue evtmgr backend fails to register for write events -------------------------------------+------------------------------------- Reporter: waldheinz | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Runtime | Version: 8.0.2 System | Keywords: | Operating System: FreeBSD Architecture: | Type of failure: Incorrect result Unknown/Multiple | at runtime Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The root of the problem is that the `GHC.Event.KQueue.toFilter` function has type `GHC.Event.Internal.Event -> Filter` with GHC's `Event` being a bitmask which can represent read events, write events or a combination of those. It happens that the event manager requests it's backend to be notified about read ''and'' write events on some fd, and because the kqueue `EVFILT_*`s are ''not'' bitmasks, the above function cannot capture this, silently dropping the desire to be notified about write events. The following program triggers the problematic behaviour: {{{ import Control.Concurrent ( forkIO, killThread ) import Control.Exception ( finally ) import Control.Monad.Trans.Resource ( runResourceT ) import Control.Monad.IO.Class ( liftIO ) import qualified Data.ByteString as BS import Data.Conduit ( ($$), ($=) ) import qualified Data.Conduit.Binary as CB import qualified Data.Conduit.List as CL import qualified Data.Conduit.Network as CN import Data.IORef ( newIORef, modifyIORef', readIORef) main :: IO () main = CN.runTCPClient (CN.clientSettings 5555 "192.168.2.11") client where logMsg cnt = CL.mapM $ \bs -> liftIO $ do modifyIORef' cnt (+ 1) readIORef cnt >>= \x -> putStrLn $ "msg #" ++ show x ++ " of size: " ++ show (BS.length bs) return bs client ad = do reader <- forkIO (runResourceT $ CN.appSource ad $$ CL.mapM_ ( \bs -> (liftIO . putStrLn) $ "read " ++ show (BS.length bs) ++ " bytes")) cnt <- newIORef ( 0 :: Int ) let runPipe = runResourceT $ CB.sourceFile "cool-linux-distro.iso" $$ logMsg cnt $= CN.appSink ad runPipe `finally` (killThread reader) }}} Having a `nc -l -p 5555 > /dev/null` running on another machine is sufficient to sink the data. Assuming that we can read `bigfile.iso` faster than we can send out over the socket, the `send` syscall will at some point give an `EAGAIN` as can be seen in the `truss` output: {{{ write(1,"msg #20 of size: 32752\n",23) = 23 (0x17) sendto(12,"\f\2409\0\M^RA\^T\M-&A\M-'\M-d8"...,32752,0x0,NULL,0x0) = 32752 (0x7ff0) read(13,"\M^?\0'\\\M-B\M-:+\^]D\M-0\M-="...,32752) = 32752 (0x7ff0) poll({ 1/POLLOUT },1,0) = 1 (0x1) msg #21 of size: 32752 write(1,"msg #21 of size: 32752\n",23) = 23 (0x17) sendto(12,"\M^?\0'\\\M-B\M-:+\^]D\M-0\M-="...,32752,0x0,NULL,0x0) = 19204 (0x4b04) sendto(12,"\M-j$2\M^BH\M-#-\^A\M-E\^O\M^Y\a"...,13548,0x0,NULL,0x0) ERR#35 'Resource temporarily unavailable' SIGNAL 26 (SIGVTALRM) sigprocmask(SIG_SETMASK,{ SIGVTALRM },0x0) = 0 (0x0) sigreturn(0x7fffffff9c60) ERR#35 'Resource temporarily unavailable' kevent(3,{ 12,EVFILT_READ,EV_ADD|EV_ONESHOT,0x0,0x0,0x0 },1,0x0,0,{ 0.000000000 }) = 0 (0x0) _umtx_op(0x800c71ed0,UMTX_OP_WAIT_UINT_PRIVATE,0x0,0x0,0x0) ERR#4 'Interrupted system call' SIGNAL 26 (SIGVTALRM) sigprocmask(SIG_SETMASK,{ SIGVTALRM },0x0) = 0 (0x0) sigreturn(0x7fffffffdc00) ERR#4 'Interrupted system call' _umtx_op(0x800c71ed0,UMTX_OP_WAIT_UINT_PRIVATE,0x0,0x0,0x0) ERR#4 'Interrupted system call' SIGNAL 26 (SIGVTALRM) }}} Not the `sendto` call on fd 12 resulting in `ERR#35`, soon followed by an `kevent` call for that same fd and only `EVFILT_READ` set. This makes little sense as it was an attempt to ''write'' that just failed. This is caused by `toFilter` giving precedence to `read` events, dropping the write event. Not starting the `reader` thread prevents bad things from happening as then the `write` events are properly passed thru to kqueue. I have an initial version of a patch fixing this. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13903> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13554: Allow the user to provide a C function that is called on each thread the RTS creates before running any Haskell code
by GHC 14 Jan '18

14 Jan '18

#13554: Allow the user to provide a C function that is called on each thread the RTS creates before running any Haskell code -------------------------------------+------------------------------------- Reporter: dobenour | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: 8.4.1 Component: Runtime | Version: 8.0.1 System | 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: -------------------------------------+------------------------------------- Currently, it is very difficult to use the MySQL/MariaDB client library with Haskell. One must use bound threads, which comes at a performance penalty. The reason is that the underlying library requires a certain initialization function to be called on each OS thread before any other functions are called. Similarly, it is difficult to optimally use libcurl with GHC. The best- performing way to use libcurl is to have one multi handle per thread and to use `curl_multi_socket_action` to respond to events. This is currently not possible from Haskell, at least not easily. (There are other issues with using libcurl from Haskell; most notably libcurl’s event support makes heavy use of callbacks, which are slow, to tell the application which file descriptors to wait for. But that is a separate issue.) Setting milestone to 8.4.1 because I don’t think that this is difficult. This is a feature requ -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13554> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10245: panic in new integer switch logic with "out-of-range" literals
by GHC 08 Jan '18

08 Jan '18

#10245: panic in new integer switch logic with "out-of-range" literals -------------------------------------+------------------------------------- Reporter: rwbarton | Owner: Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 7.11 (CodeGen) | Operating System: Unknown/Multiple Keywords: | Type of failure: Compile-time Architecture: x86_64 | crash (amd64) | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Compiling this module {{{ module D (f) where f :: Int -> String f n = case n of 0x8000000000000000 -> "yes" _ -> "no" }}} crashes with the error {{{ [1 of 1] Compiling D ( /tmp/D.hs, /tmp/D.o ) ghc-stage1: panic! (the 'impossible' happened) (GHC version 7.11.20150403 for x86_64-unknown-linux): Map.findMin: empty map has no minimal element }}} The constant does not have to be exactly `0x8000000000000000`, everything I tested from there up to `0xffffffffffffffff` yields the same crash. Also occurs with `Word` and negative literals. The bug seems to be tied to the target's word size somehow, though: a 64-bit compiler does not panic on `Int32` and `0x80000000`, but a 32-bit compiler does. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10245> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10731: System.IO.openTempFile is not thread safe on Windows
by GHC 05 Jan '18

05 Jan '18

#10731: System.IO.openTempFile is not thread safe on Windows -------------------------------------+------------------------------------- Reporter: | Owner: NeilMitchell | Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 7.10.1 libraries/base | Keywords: | Operating System: Windows Architecture: | Type of failure: Runtime crash Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Given the test program: {{{#!hs import Control.Concurrent import System.IO import Control.Monad import System.Directory main = do putStrLn "Starting" var <- newEmptyMVar tdir <- getTemporaryDirectory xs <- replicateM 10 $ do var <- newEmptyMVar flip forkFinally (\s -> do print s; putMVar var ()) $ do replicateM_ 100000 $ do (file, h) <- openTempFile tdir "test.txt" hClose h removeFile file return var mapM_ takeMVar xs }}} If I compile and run that with {{{ghc --make TmpFile.hs -threaded && tmpfile +RTS -N5}}} I get: {{{ Starting Left C:\Users\NDMIT_~1\AppData\Local\Temp\: openTempFile: permission denied (Permission denied) Left C:\Users\NDMIT_~1\AppData\Local\Temp\: openTempFile: permission denied (Permission denied) ... }}} I've reproduced this on GHC 7.8 and 7.10.1. We hit this in production about twice a day. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10731> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12022: unsafeShiftL and unsafeShiftR are not marked as INLINE
by GHC 03 Jan '18

03 Jan '18

#12022: unsafeShiftL and unsafeShiftR are not marked as INLINE -------------------------------------+------------------------------------- Reporter: Rufflewind | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: | Version: 7.10.3 libraries/base | Keywords: performance, | Operating System: Unknown/Multiple inline, bits | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Given that they are fairly essential operations in core libraries such as containers, I think it would be useful to have them marked as INLINE (or INLINABLE at the very least). See also: https://github.com/haskell/containers/pull/216 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12022> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13201: Type-level naturals aren't instantiate with GHCi debugger
by GHC 03 Jan '18

03 Jan '18

#13201: Type-level naturals aren't instantiate with GHCi debugger -------------------------------------+------------------------------------- Reporter: konn | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 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: -------------------------------------+------------------------------------- GHCi debugger cannot use the information of specific value type-level natural number, even if it is explicitly specified. For example, consider the following code: {{{#!hs {-# LANGUAGE DataKinds, KindSignatures, StandaloneDeriving, TypeOperators #-} module Main where import GHC.TypeLits data Foo (n :: Nat) = Foo deriving instance KnownNat n => Show (Foo n) fooSucc :: Foo n -> Foo (n + 1) fooSucc Foo = Foo foos :: Foo n -> [Foo (n + 1)] foos f = loop 5 where loop 0 = [] loop n = fooSucc f : loop (n - 1) main :: IO () main = print $ foos (Foo :: Foo 5) }}} Loading it with GHCi Debugger, we cannot `show` the value of `f`, because GHCi debugger doesn't know the specific value of `n` (in`Foo n`), even though we specify it in `main`! {{{#!hs ghci> :l tmp.hs [1 of 1] Compiling Main ( tmp.hs, interpreted ) Ok, modules loaded: Main. ghci> :break foos Breakpoint 0 activated at tmp.hs:13:10-15 ghci> :set stop :list ghci> main Stopped in Main.foos, tmp.hs:13:10-15 _result :: [Foo (n + 1)] = _ loop :: (Num t, Eq t) => t -> [Foo (n + 1)] = _ 12 foos :: Foo n -> [Foo (n + 1)] 13 foos f = loop 5 14 where ghci> :step Stopped in Main.foos.loop, tmp.hs:16:14-37 _result :: [Foo (n + 1)] = _ f :: Foo n = _ n :: Integer = 5 15 loop 0 = [] 16 loop n = fooSucc f : loop (n - 1) 17 ghci> :t f f :: Foo n ghci> f <interactive>:8:1: error: • No instance for (KnownNat n) arising from a use of ‘print’ • In a stmt of an interactive GHCi command: print it }}} Of course, we can inspect the internal representation via `:print` or `:force` command, but it is rather impractical when we cannot easily read its pretty form from its internal representation . I tested this with GHC 7.0.1 and 7.0.2. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13201> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10617: Panic in GHCi debugger with GADTs, PolyKinds and Phantom types
by GHC 03 Jan '18

03 Jan '18

#10617: Panic in GHCi debugger with GADTs, PolyKinds and Phantom types -----------------------------------------+------------------------------- Reporter: bjmprice | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.10.1 Keywords: | Operating System: Linux Architecture: x86_64 (amd64) | Type of failure: GHCi crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -----------------------------------------+------------------------------- Potentially related: #10616 (I noticed this one first, and in simplifying the code it changed to that error - note TcUnify.hs vs TcType.hs) The code {{{#!hs {-# LANGUAGE GADTs , PolyKinds #-} data AppTreeT (a::k) where Con :: AppTreeT a App :: AppTreeT a -> AppTreeT b -> AppTreeT (a b) tmt :: AppTreeT (Maybe Bool) tmt = App (Con :: AppTreeT Maybe) Con f :: AppTreeT a -> Bool f (App (c@Con) _) = const True c f _ = False }}} when loaded in ghci runs fine without breakpoints, but panics when breaking on {{{f (App )c@Con) _) = ...}}}: {{{ *Main> f tmt True *Main> :break 11 Breakpoint 0 activated at DebuggerCrash2.hs:11:21-32 *Main> f tmt ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.11.20150708 for x86_64-unknown-linux): ASSERT failed! file compiler/typecheck/TcType.hs line 739 k_anx }}} It fails to load in 7.4.1: {{{DebuggerCrash2.hs:3:19: parse error on input `k'}}} It fails to load in 7.8.2: {{{ DebuggerCrash2.hs:5:50: Kind occurs check The first argument of ‘a’ should have kind ‘k0’, but ‘b’ has kind ‘k0 -> k1’ In the type ‘AppTreeT (a b)’ In the definition of data constructor ‘App’ In the data declaration for ‘AppTreeT’ }}} It has the panic in both 7.10.1 and HEAD@d71b65f53a1daa2631d2c818c7ea6add77813532 {{{uname -a: Linux cam-05-unx 3.5.0-54-generic #81~precise1-Ubuntu SMP Tue Jul 15 04:02:22 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux}}} {{{ gcc -v: Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.6/lto-wrapper Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.6.3-1ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program- suffix=-4.6 --enable-shared --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.6 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable- libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --enable- objc-gc --disable-werror --with-arch-32=i686 --with-tune=generic --enable- checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5) }}} With {{{ghci-7.10.1 -v}}} {{{ GHCi, version 7.10.1: http://www.haskell.org/ghc/ :? for help Glasgow Haskell Compiler, Version 7.10.1, stage 2 booted by GHC version 7.8.2 Using binary package database: /5playpen/t-bepric/ghc-7.10.1-build/inplace/lib/package.conf.d/package.cache wired-in package ghc-prim mapped to ghc-prim-0.4.0.0-inplace wired-in package integer-gmp mapped to integer-gmp-1.0.0.0-inplace wired-in package base mapped to base-4.8.0.0-inplace wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template- haskell-2.10.0.0-inplace wired-in package ghc mapped to ghc-7.10.1-inplace wired-in package dph-seq not found. wired-in package dph-par not found. Hsc static flags: Loading package ghc-prim-0.4.0.0 ... linking ... done. *** gcc: /usr/bin/gcc -fno-stack-protector -DTABLES_NEXT_TO_CODE -L/5playpen/t-bepric/ghc-7.10.1-build/libraries/integer-gmp2/dist- install/build --print-file-name libgmp.so Loading package integer-gmp-1.0.0.0 ... linking ... done. Loading package base-4.8.0.0 ... linking ... done. wired-in package ghc-prim mapped to ghc-prim-0.4.0.0-inplace wired-in package integer-gmp mapped to integer-gmp-1.0.0.0-inplace wired-in package base mapped to base-4.8.0.0-inplace wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template- haskell-2.10.0.0-inplace wired-in package ghc mapped to ghc-7.10.1-inplace wired-in package dph-seq not found. wired-in package dph-par not found. *** Chasing dependencies: Chasing modules from: Stable obj: [] Stable BCO: [] unload: retaining objs [] unload: retaining bcos [] Ready for upsweep [] Upsweep completely successful. *** Deleting temp files: Deleting: *** Chasing dependencies: Chasing modules from: *DebuggerCrash2.hs Stable obj: [] Stable BCO: [] unload: retaining objs [] unload: retaining bcos [] Ready for upsweep [NONREC ModSummary { ms_hs_date = 2015-07-08 13:56:59 UTC ms_mod = Main, ms_textual_imps = [import (implicit) Prelude] ms_srcimps = [] }] *** Deleting temp files: Deleting: compile: input file DebuggerCrash2.hs Created temporary directory: /tmp/ghc22446_0 *** Checking old interface for Main: [1 of 1] Compiling Main ( DebuggerCrash2.hs, interpreted ) *** Parser: *** Renamer/typechecker: *** Desugar: Result size of Desugar (before optimization) = {terms: 32, types: 72, coercions: 1} Result size of Desugar (after optimization) = {terms: 26, types: 55, coercions: 0} *** Simplifier: Result size of Simplifier iteration=1 = {terms: 24, types: 79, coercions: 2} Result size of Simplifier = {terms: 21, types: 76, coercions: 2} *** Tidy Core: Result size of Tidy Core = {terms: 31, types: 109, coercions: 4} *** CorePrep: Result size of CorePrep = {terms: 45, types: 157, coercions: 5} *** ByteCodeGen: Upsweep completely successful. *** Deleting temp files: Deleting: /tmp/ghc22446_0/ghc22446_2.c /tmp/ghc22446_0/ghc22446_1.o Warning: deleting non-existent /tmp/ghc22446_0/ghc22446_2.c Warning: deleting non-existent /tmp/ghc22446_0/ghc22446_1.o Ok, modules loaded: Main. *Main> f tmt *** Parser: *** Desugar: *** Simplify: *** CorePrep: *** ByteCodeGen: True *Main> :break 11 Breakpoint 0 activated at DebuggerCrash2.hs:11:21-32 *Main> f tmt *** Parser: *** Desugar: *** Simplify: *** CorePrep: *** ByteCodeGen: ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.10.1 for x86_64-unknown-linux): ASSERT failed! file compiler/typecheck/TcType.hs line 730 k_an3 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10617> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10616: Panic in ghci debugger with PolyKinds and PhantomTypes
by GHC 03 Jan '18

03 Jan '18

#10616: Panic in ghci debugger with PolyKinds and PhantomTypes -----------------------------------------+------------------------------- Reporter: bjmprice | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.10.1 Keywords: | Operating System: Linux Architecture: x86_64 (amd64) | Type of failure: GHCi crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -----------------------------------------+------------------------------- The code {{{#!hs {-# LANGUAGE PolyKinds #-} data D a = A | B f d@A = const True d f B = False }}} when loaded in ghci, runs fine without breakpoints, but panics when breaking on {{{f A}}}, thus: {{{ *Main> f A True *Main> :break 5 Breakpoint 0 activated at DebuggerCrash.hs:5:9-20 *Main> f A ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.10.1 for x86_64-unknown-linux): ASSERT failed! file compiler/typecheck/TcUnify.hs line 1138 k_amp }}} It is fine in 7.4.1 and 7.8.1. It panics in 7.10.1 and HEAD@d71b65f53a1daa2631d2c818c7ea6add77813532 Without one (or both) of PolyKinds or the phantom type it runs fine. {{{uname -a: Linux cam-05-unx 3.5.0-54-generic #81~precise1-Ubuntu SMP Tue Jul 15 04:02:22 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux}}} {{{ gcc -v: Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.6/lto-wrapper Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.6.3-1ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program- suffix=-4.6 --enable-shared --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.6 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable- libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --enable- objc-gc --disable-werror --with-arch-32=i686 --with-tune=generic --enable- checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5) }}} With {{{ghci-7.10.1 -v}}} {{{ ghci-7.10.1 -v ./DebuggerCrash.hs GHCi, version 7.10.1: http://www.haskell.org/ghc/ :? for help Glasgow Haskell Compiler, Version 7.10.1, stage 2 booted by GHC version 7.8.2 Using binary package database: /5playpen/t-bepric/ghc-7.10.1-build/inplace/lib/package.conf.d/package.cache wired-in package ghc-prim mapped to ghc-prim-0.4.0.0-inplace wired-in package integer-gmp mapped to integer-gmp-1.0.0.0-inplace wired-in package base mapped to base-4.8.0.0-inplace wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template- haskell-2.10.0.0-inplace wired-in package ghc mapped to ghc-7.10.1-inplace wired-in package dph-seq not found. wired-in package dph-par not found. Hsc static flags: Loading package ghc-prim-0.4.0.0 ... linking ... done. *** gcc: /usr/bin/gcc -fno-stack-protector -DTABLES_NEXT_TO_CODE -L/5playpen/t-bepric/ghc-7.10.1-build/libraries/integer-gmp2/dist- install/build --print-file-name libgmp.so Loading package integer-gmp-1.0.0.0 ... linking ... done. Loading package base-4.8.0.0 ... linking ... done. wired-in package ghc-prim mapped to ghc-prim-0.4.0.0-inplace wired-in package integer-gmp mapped to integer-gmp-1.0.0.0-inplace wired-in package base mapped to base-4.8.0.0-inplace wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template- haskell-2.10.0.0-inplace wired-in package ghc mapped to ghc-7.10.1-inplace wired-in package dph-seq not found. wired-in package dph-par not found. *** Chasing dependencies: Chasing modules from: Stable obj: [] Stable BCO: [] unload: retaining objs [] unload: retaining bcos [] Ready for upsweep [] Upsweep completely successful. *** Deleting temp files: Deleting: *** Chasing dependencies: Chasing modules from: *DebuggerCrash.hs Stable obj: [] Stable BCO: [] unload: retaining objs [] unload: retaining bcos [] Ready for upsweep [NONREC ModSummary { ms_hs_date = 2015-07-08 14:18:11 UTC ms_mod = Main, ms_textual_imps = [import (implicit) Prelude] ms_srcimps = [] }] *** Deleting temp files: Deleting: compile: input file DebuggerCrash.hs Created temporary directory: /tmp/ghc22370_0 *** Checking old interface for Main: [1 of 1] Compiling Main ( DebuggerCrash.hs, interpreted ) *** Parser: *** Renamer/typechecker: *** Desugar: Result size of Desugar (before optimization) = {terms: 16, types: 26, coercions: 0} Result size of Desugar (after optimization) = {terms: 12, types: 18, coercions: 0} *** Simplifier: Result size of Simplifier iteration=1 = {terms: 12, types: 20, coercions: 0} Result size of Simplifier = {terms: 12, types: 20, coercions: 0} *** Tidy Core: Result size of Tidy Core = {terms: 12, types: 20, coercions: 0} *** CorePrep: Result size of CorePrep = {terms: 16, types: 30, coercions: 0} *** ByteCodeGen: Upsweep completely successful. *** Deleting temp files: Deleting: /tmp/ghc22370_0/ghc22370_2.c /tmp/ghc22370_0/ghc22370_1.o Warning: deleting non-existent /tmp/ghc22370_0/ghc22370_2.c Warning: deleting non-existent /tmp/ghc22370_0/ghc22370_1.o Ok, modules loaded: Main. *Main> f A *** Parser: *** Desugar: *** Simplify: *** CorePrep: *** ByteCodeGen: True *Main> :break 5 Breakpoint 0 activated at DebuggerCrash.hs:5:9-20 *Main> f A *** Parser: *** Desugar: *** Simplify: *** CorePrep: *** ByteCodeGen: ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.10.1 for x86_64-unknown-linux): ASSERT failed! file compiler/typecheck/TcUnify.hs line 1138 k_amp }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10616> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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