January 2018 - ghc-tickets

[GHC] #14605: Core Lint error
by GHC 03 Jan '18

03 Jan '18

#14605: Core Lint error -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Keywords: TypeInType, | Operating System: Unknown/Multiple DeferredTypeErrors | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This piece of code fails when run with `ghci -ignore-dot-ghci -fdefer- type-errors -dcore-lint bug.hs`, maybe same as my previous #14584. {{{#!hs {-# Language DerivingStrategies #-} {-# Language GeneralizedNewtypeDeriving #-} {-# Language InstanceSigs #-} {-# Language KindSignatures #-} {-# Language PolyKinds #-} {-# Language ScopedTypeVariables #-} {-# Language TypeApplications #-} {-# Language TypeFamilies #-} {-# Language TypeInType #-} {-# Language TypeOperators #-} {-# Language UndecidableInstances #-} import Data.Kind import Data.Functor.Identity import Data.Functor.Product type a <-> b = a -> b -> Type class Iso (iso :: a <-> b) where iso :: a -> b osi :: b -> a data Iso_Bool :: Either () () <-> Bool instance Iso Iso_Bool where class Representable f where type Rep f :: Type index :: f a -> (Rep f -> a) tabulate :: (Rep f -> a) -> f a class Comonad w where extract :: w a -> a duplicate :: w a -> w (w a) newtype Co f a = Co (f a) deriving newtype (Functor, Representable) instance (Representable f, Monoid (Rep f)) => Comonad (Co f) where extract = (`index` mempty) newtype WRAP (iso::old <-> new) f a = WRAP (f a) instance (Representable f, Rep f ~ old, Iso iso) => Representable (WRAP (iso :: old <-> new) f) where type Rep (WRAP (iso :: old <-> new) f) = new index :: WRAP iso f a -> (new -> a) index (WRAP fa) = index fa . osi @old @new @iso tabulate :: (new -> a) -> WRAP iso f a tabulate gen = WRAP $ tabulate (gen . iso @old @new @iso) newtype PAIR a = PAIR (Co (WRAP Iso_Bool (Product Identity Identity)) a) deriving newtype Comonad }}} I unfortunately don't have time to find a more minimal example. Core linter vomits a lot of errors on 8.2.1 & 8.3.20171208. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14605> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14629: Seemingly unused qualified import affects method visibility
by GHC 03 Jan '18

03 Jan '18

#14629: Seemingly unused qualified import affects method visibility -------------------------------------+------------------------------------- Reporter: gelisam | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Poor/confusing Unknown/Multiple | error message Test Case: | Blocked By: Blocking: | Related Tickets: ticket:3992, | ticket:10890 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Here is a simple test case: {{{#!hs module MyLib where class MyClass a where myMethod :: a -> a }}} {{{#!hs module MyModule where import MyLib (MyClass) --import qualified MyLib as L data Foo = Foo instance MyClass Foo where -- error: ‘myMethod’ is not a (visible) method of class ‘MyClass’ myMethod Foo = Foo }}} Since I have only imported `MyClass` and not its methods (that would be `import MyLib (MyClass(..))`), the error is correct, `myMethod` is not visible. But if I uncomment the `import qualified MyLib as L` line, the error disappears even though I do not use `L` anywhere. Writing `L.myMethod Foo = Foo` is not even legal! ----- I filed this under "confusing error message", so let me show you the conditions under which the above behaviour was confusing. We were using [https://hackage.haskell.org/package/classy- prelude-1.3.1/docs/ClassyPrelude.html classy-prelude] instead of `Prelude`, but we were not familiar with all the differences between the two preludes. We started with code like this, which did not compile: {{{#!hs {-# LANGUAGE NoImplicitPrelude #-} module MyModule import ClassyPrelude data Foo a = Foo instance Foldable Foo where -- 'foldMap' is not a (visible) method of class 'Foldable' foldMap = undefined }}} So we clarified that we meant `Prelude.Foldable`, in case `ClassyFoldable.Foldable` meant something different. {{{#!hs {-# LANGUAGE NoImplicitPrelude #-} module MyModule import ClassyPrelude import qualified Prelude data Foo a = Foo instance Prelude.Foldable Foo where foldMap = undefined }}} This compiled, so we first thought that `Prelude.Foldable` and `ClassyPrelude.Foldable` were two different type classes, but we later discovered that `ClassyPrelude.Foldable` is a re-export of `Prelude.Foldable`. So the following means the same thing and also compiles: {{{#!hs {-# LANGUAGE NoImplicitPrelude #-} module MyModule import ClassyPrelude import qualified Prelude data Foo a = Foo instance ClassyPrelude.Foldable Foo where foldMap = undefined }}} At this point, the qualified `Prelude` import doesn't seem used anywhere, so we thought it was safe to remove it: {{{#!hs {-# LANGUAGE NoImplicitPrelude #-} import ClassyPrelude data Foo a = Foo instance ClassyPrelude.Foldable Foo where -- 'foldMap' is not a (visible) method of class 'Foldable' foldMap = undefined }}} But `ClassyPrelude.foldMap` is ''not'' the same as `Prelude.foldMap`, so this did not compile and it wasn't clear why. One way to make this less confusing would be to allow qualified method names; this way, we would have tried both `Prelude.foldMap = undefined` and `ClassyPrelude.foldMap = undefined`, and we would have discovered the source of the problem. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14629> 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] #14628: Panic (No skolem Info) in GHCi
by GHC 03 Jan '18

03 Jan '18

#14628: Panic (No skolem Info) in GHCi -------------------------------------+------------------------------------- Reporter: AndreasK | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.2.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: #13393 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Loading the following code in GHCi causes a panic. Versions affected at least 8.2.2 and 8.0.2 {{{ module Main where import System.IO import Control.Monad.IO.Class import Control.Monad.Trans.State import Text.Printf putArrayBytes :: Handle -- ^ output file handle -> [String] -- ^ byte-strings -> IO Int -- ^ total number of bytes written putArrayBytes outfile xs = do let writeCount x = modify' (+ length x) >> liftIO (putLine x) :: MonadIO m => StateT Int m () execStateT (mapM_ writeCount xs) 0 where putLine = hPutStrLn outfile . (" "++) . concatMap (printf "0x%02X,") {- ghci: :break 12 46 :trace putArrayBytes stdout [['1'..'9'],['2'..'8'],['3'..'7']] snd $ runStateT _result 0 -} main = undefined }}} {{{ Configuring GHCi with the following packages: GHCi, version 8.2.2: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( C:\test\test.hs, interpreted ) Ok, one module loaded. Loaded GHCi configuration from C:\Users\Andi\AppData\Local\Temp\ghci34988 \ghci-script *Main> :break 12 46 Breakpoint 0 activated at C:\test\test.hs:12:46-63 *Main> :trace putArrayBytes stdout [['1'..'9'],['2'..'8'],['3'..'7']] Stopped in Main.putArrayBytes.writeCount, C:\test\test.hs:12:46-63 _result :: StateT Int m () = _ putLine :: [Char] -> IO () = _ x :: [Char] = "123456789" [C:\test\test.hs:12:46-63] [C:\test\test.hs:12:46-63] *Main> snd $ runStateT _result 0 <interactive>:3:7: error:<interactive>: panic! (the 'impossible' happened) (GHC version 8.2.2 for x86_64-unknown-mingw32): No skolem info: m_I5Cm[rt] Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler\utils\Outputable.hs:1133:58 in ghc:Outputable callStackDoc, called at compiler\utils\Outputable.hs:1137:37 in ghc:Outputable pprPanic, called at compiler\typecheck\TcErrors.hs:2653:5 in ghc:TcErrors Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug [C:\test\test.hs:12:46-63] [C:\test\test.hs:12:46-63] *Main> :r [1 of 1] Compiling Main ( C:\test\test.hs, interpreted ) Ok, one module loaded. *Main> :break 12 46 Breakpoint 1 activated at C:\test\test.hs:12:46-63 *Main> :trace putArrayBytes stdout [['1'..'9'],['2'..'8'],['3'..'7']] Stopped in Main.putArrayBytes.writeCount, C:\test\test.hs:12:46-63 _result :: StateT Int m () = _ putLine :: [Char] -> IO () = _ x :: [Char] = "123456789" [C:\test\test.hs:12:46-63] [C:\test\test.hs:12:46-63] *Main> snd $ runStateT _result 0 <interactive>:7:7: error:<interactive>: panic! (the 'impossible' happened) (GHC version 8.2.2 for x86_64-unknown-mingw32): No skolem info: m_I5Nz[rt] Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler\utils\Outputable.hs:1133:58 in ghc:Outputable callStackDoc, called at compiler\utils\Outputable.hs:1137:37 in ghc:Outputable pprPanic, called at compiler\typecheck\TcErrors.hs:2653:5 in ghc:TcErrors Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug [C:\test\test.hs:12:46-63] [C:\test\test.hs:12:46-63] *Main> }}} Maybe related to #13393. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14628> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1620: ModBreaks.modBreaks_array not initialised
by GHC 03 Jan '18

03 Jan '18

#1620: ModBreaks.modBreaks_array not initialised -------------------------------------+------------------------------------- Reporter: guest | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.8.2 Resolution: | Keywords: debugger Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * keywords: => debugger -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1620#comment:10> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1379: Allow breakpoints and single-stepping for functions defined interactively
by GHC 03 Jan '18

03 Jan '18

#1379: Allow breakpoints and single-stepping for functions defined interactively -------------------------------------+-------------------------------- Reporter: Michael D. Adams | Owner: (none) Type: feature request | Status: new Priority: lowest | Milestone: Component: GHCi | Version: 6.7 Resolution: | Keywords: debugger Operating System: Linux | Architecture: x86 Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+-------------------------------- Changes (by RyanGlScott): * keywords: => debugger -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1379#comment:21> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1377: GHCi debugger tasks
by GHC 03 Jan '18

03 Jan '18

#1377: GHCi debugger tasks -------------------------------------+------------------------------------- Reporter: simonmar | Owner: mnislaih Type: task | Status: new Priority: lowest | Milestone: Component: GHCi | Version: 6.7 Resolution: | Keywords: debugger Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * keywords: => debugger -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1377#comment:25> 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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