September 2016 - ghc-tickets

[GHC] #12630: Assertion failed with BuildFlavour = devel2
by GHC 07 Nov '16

07 Nov '16

#12630: Assertion failed with BuildFlavour = devel2 -------------------------------------+------------------------------------- Reporter: pacak | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Linux Architecture: x86_64 | Type of failure: Compile-time (amd64) | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I tried to reproduce random ghc panic we have in our codebase with ghc8 so I decided to compile ghc with debug enabled. Source file: ghc-8.0.1-src.tar.xz build.mk changes: {{{ BuildFlavour = devel2 GhcStage1HcOpts = -DDEBUG GhcStage2HcOpts = -DDEBUG }}} source: {{{#!hs {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE PolyKinds #-} module A where import GHC.Generics class B f where b :: [f a] toEnumDefault :: (B (Rep a)) => Int -> a toEnumDefault i = let l = b in to }}} result: {{{ [1 of 1] Compiling A ( a.hs, a.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.1 for x86_64-unknown-linux): ASSERT failed! CallStack (from HasCallStack): assertPprPanic, called at compiler/types/TyCoRep.hs:1974:56 in ghc:TyCoRep checkValidSubst, called at compiler/types/TyCoRep.hs:2010:17 in ghc:TyCoRep substTy, called at compiler/types/TyCoRep.hs:1952:3 in ghc:TyCoRep in_scope InScope [a1BD :-> a_a1BD[sk], a1BI :-> k_a1BI[tau:3], a1BJ :-> f_a1BJ[tau:3], a1BL :-> a_a1BL[sk]] tenv [a1BD :-> a_a1BL[sk]] tenvFVs [a1Bz :-> k_a1Bz[tau:5], a1BL :-> a_a1BL[sk]] cenv [] cenvFVs [] tys [[f_a1BJ[tau:3] a_a1BD[sk]]] cos [] Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12630> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11369: Suppress redundant-constraint warnings in case of empty classes
by GHC 07 Nov '16

07 Nov '16

#11369: Suppress redundant-constraint warnings in case of empty classes -------------------------------------+------------------------------------- Reporter: hvr | Owner: simonpj Type: bug | Status: new Priority: highest | Milestone: 8.0.1 Component: Compiler | Version: 8.1 (Type checker) | 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: -------------------------------------+------------------------------------- The technique described in http://www.well-typed.com/blog/2015/07/checked-exceptions/ makes use of a class without any methods, i.e. {{{#!hs class Throws e }}} However, this by definition results in redundant constraints, e.g. {{{#!hs readFoo :: Throws IOError => FilePath -> IO Foo readFoo fn = {- ... -} }}} which GHC 8.0 warns about. I propose to suppress warnings in case a class which has no methods is used as seemingly redundant constraint. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11369> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12220: TypeApplications and DefaultSignatures - problems deducing type variables.
by GHC 07 Nov '16

07 Nov '16

#12220: TypeApplications and DefaultSignatures - problems deducing type variables. -------------------------------------+------------------------------------- Reporter: mkloczko | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Linux DefaultSignatures, | TypeApplications | Architecture: x86_64 | Type of failure: None/Unknown (amd64) | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The following example code throws an error. The example code: {{{#!hs {-#LANGUAGE TypeApplications#-} {-#LANGUAGE MultiParamTypeClasses #-} {-#LANGUAGE AllowAmbiguousTypes #-} {-#LANGUAGE FlexibleInstances #-} {-#LANGUAGE ScopedTypeVariables #-} {-#LANGUAGE DefaultSignatures #-} module Test1 where -- | Type a is only used for -- type application. class ToUse a where toUse :: Int -> Int -- | The type used for -- type application data Default -- | The instance using Default as type application. -- To call use: -- > toUse @Default instance ToUse Default where toUse a = 3*a -- | Typeclass whose methods work -- only with type application. class (ToUse a) => Uses a b where uses :: b -> [b] -- | Default Signature, which generates the problem. -- It is the same as the normal one -- Comment it to 'fix' the bug. default uses :: b -> [b] uses v = [v] -- | Normal instances, nothing special instance Uses Default Int where uses v = take (toUse @Default 3) $ repeat v -- | Another normal one instance Uses Default String where uses v = take (toUse @Default 2) $ repeat v -- | This one works nicely instance (ToUse t, Uses t a, Uses t b) => Uses t (a,b) where uses (vl,vr) = zip ls rs where ls = uses @t vl rs = uses @t vr -- | But this one doesn't. -- Unless you comment the default signature. instance (ToUse t, Uses t a, Uses t b, Uses t c) => Uses t (a,b,c) }}} The error: {{{ • Could not deduce (Uses a0 a) arising from a use of ‘Test1.$dmuses’ from the context: (ToUse t, Uses t a, Uses t b, Uses t c) bound by the instance declaration at Test1.hs:47:10-66 The type variable ‘a0’ is ambiguous Relevant bindings include uses :: (a, b, c) -> [(a, b, c)] (bound at Test1.hs:47:10) • In the expression: Test1.$dmuses In an equation for ‘uses’: uses = Test1.$dmuses In the instance declaration for ‘Uses t (a, b, c)’ }}} Commenting out the default signature fixes the problem. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12220> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11571: Need more intelligent conditionalization of libgcc rts symbols for x32
by GHC 05 Nov '16

05 Nov '16

#11571: Need more intelligent conditionalization of libgcc rts symbols for x32 -------------------------------------+------------------------------------- Reporter: rwbarton | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Runtime | Version: 8.1 System (Linker) | Keywords: | Operating System: Unknown/Multiple Architecture: Other | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- In `rts/RtsSymbols.c` we have {{{ // 64-bit support functions in libgcc.a #if defined(__GNUC__) && SIZEOF_VOID_P <= 4 && !defined(_ABIN32) #define RTS_LIBGCC_SYMBOLS \ SymI_NeedsProto(__divdi3) \ SymI_NeedsProto(__udivdi3) \ ... }}} The purpose is to provide these symbols to `.o` files that use these symbols, expecting to be linked against libgcc. These symbols are for things like 64-bit integer division that aren't available as machine instructions on some platforms. But the `#if` is wrong on x32, which, despite having `sizeof(void *) == 4`, naturally has a full complement of 64-bit arithmetic instructions, since its registers are 64 bits wide. So libgcc does not provide these symbols, and as a result we eventually encounter missing symbol errors when linking the rts. Some possible solutions include * Figure out if there is a CPP variable set for x32 and don't include these symbols if that variable is set. I'm not sure whether `__ILP32__` is such a variable (after all x86 is also an architecture on which int, long and pointers are 32-bits). * Use autoconf to detect the presence of these symbols in libgcc. (Probably just pick one, like `__divdi3`, and hope they are all present or all missing.) * Use weak symbols somehow to add these symbols to the RTS's internal symbol table if and only if the RTS was linked against a libgcc that provides these symbols. My Android ghci also needs lots more of these, including `__modsi3`, `__umodsi3`, `__ctzdi2`, a bunch of `__aeabi_*` and `__sync_*`, and `__sF` (no idea what that is). So I'm inclined towards the last option. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11571> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12539: Possible typo causes Stack and Cabal installs to fail
by GHC 04 Nov '16

04 Nov '16

#12539: Possible typo causes Stack and Cabal installs to fail -------------------------------------+------------------------------------- Reporter: ConorIA | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Linux Architecture: | Type of failure: Compile-time Unknown/Multiple | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Hi, I have been trying to use https://github.com/thriqon/pandoc-docker or to add pandoc to https://github.com/mitchty/alpine-ghc. However, in both cases, install commands are running into an issue with the '-nopie' flag passed to GCC. The gist of the error thrown when using wither Cabal or Stack is: {{{ <no location info>: Warning: Couldn't figure out linker information! Make sure you're using GNU ld, GNU gold or the built in OS X linker, etc. gcc: error: unrecognized command line option '-nopie'; did you mean '-no- pie'? ) }}} I am not sure where the error is, as I am really a non-expert. But the gcc linking option is "-no-pie", so if there is indeed an option "-nopie" being passed, it seems like it is a typo. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12539> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9010: TemplateHaskell leads to an "unknown symbol" error
by GHC 04 Nov '16

04 Nov '16

#9010: TemplateHaskell leads to an "unknown symbol" error ------------------------------------+------------------------------------- Reporter: Feuerbach | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Code: {{{ {-# LANGUAGE TemplateHaskell #-} module M where import System.Console.Editline import Data.Lens.Template data S = S { _a :: EditLine } makeLens ''S }}} When compiled with `ghc link.hs`, everything is fine; {{{ [1 of 1] Compiling M ( link.hs, link.o ) Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package array-0.4.0.1 ... linking ... done. Loading package deepseq-1.3.0.1 ... linking ... done. Loading package containers-0.5.0.0 ... linking ... done. Loading package bytestring-0.10.0.2 ... linking ... done. Loading package tagged-0.7.1 ... linking ... done. Loading package transformers-0.3.0.0 ... linking ... done. Loading package transformers-compat-0.1.1.1 ... linking ... done. Loading package contravariant-0.4.4 ... linking ... done. Loading package distributive-0.4.3.1 ... linking ... done. Loading package mtl-2.1.3.1 ... linking ... done. Loading package text-1.1.0.1 ... linking ... done. Loading package hashable-1.2.1.0 ... linking ... done. Loading package nats-0.1.2 ... linking ... done. Loading package unordered-containers-0.2.3.3 ... linking ... done. Loading package semigroups-0.12.2 ... linking ... done. Loading package comonad-4.0.1 ... linking ... done. Loading package semigroupoids-4.0.1 ... linking ... done. Loading package data-lens-2.10.4 ... linking ... done. Loading package pretty-1.1.1.0 ... linking ... done. Loading package template-haskell ... linking ... done. Loading package data-lens-template-2.1.8 ... linking ... done. }}} However, when compiling with `ghc -package-id editline-0.2.1.1-ef91ae78e7ea1b9142c2fb0b84e85c11 link.hs`, I get {{{ [1 of 1] Compiling M ( link.hs, link.o ) Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package editline-0.2.1.1 ... linking ... ghc: /home/feuerbach/work /.cabal-sandbox/lib/i386-linux- ghc-7.6.3/editline-0.2.1.1/HSeditline-0.2.1.1.o: unknown symbol `el_reset' ghc: unable to load package `editline-0.2.1.1' }}} This is a problem because that's how cabal invokes ghc. This looks similar to #4899, except there's nothing "non-standard" here (no profiling or dynamic linking). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9010> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12584: Bug (or Unhelpful Error) with TemplateHaskell
by GHC 03 Nov '16

03 Nov '16

#12584: Bug (or Unhelpful Error) with TemplateHaskell -------------------------------------+------------------------------------- Reporter: Shayan-Najd | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 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: -------------------------------------+------------------------------------- To recreate this make a Haskell file say named 'T.hs', with the following code: {{{#!hs {-# LANGUAGE TemplateHaskell #-} (() -> ()) }}} Then try to compile it: {{{ $> ghc-stage2 T.hs [...] ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.1.20160617 for x86_64-unknown-linux): tcMonoExpr _ [...] }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12584> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11184: panic tcMonoExpr _ with bad indentation in TH code
by GHC 02 Nov '16

02 Nov '16

#11184: panic tcMonoExpr _ with bad indentation in TH code -------------------------------------+------------------------------------- Reporter: TeroLaitinen | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Runtime crash Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{#!hs {-# LANGUAGE TemplateHaskell #-} import Data.Aeson.TH data Record = Record { type_ :: Int } $(deriveJSON defaultOptions{ fieldLabelModifier = \x -> case x of "type_" -> "type" _ -> x } ''Record) }}} gives {{{ ghc: panic! (the 'impossible' happened) (GHC version 7.10.2 for x86_64-unknown-linux): tcMonoExpr _ }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11184> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12590: GHC panics, -XTypeInType, possibly "cobox" related
by GHC 01 Nov '16

01 Nov '16

#12590: GHC panics, -XTypeInType, possibly "cobox" related -------------------------------------+------------------------------------- Reporter: heisenbug | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 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 {{{ GHCi, version 8.1.20160902: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Tree ( src/Tree.hs, interpreted ) ghc: panic! (the 'impossible' happened) (GHC version 8.1.20160902 for x86_64-apple-darwin): tcTyVarDetails cobox_a15m :: (n_a159[ssk] :: Peano) ~# ('Z :: Peano) }}} on the attached file. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12590> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10221: LLVM does not work on OSX
by GHC 01 Nov '16

01 Nov '16

#10221: LLVM does not work on OSX -------------------------------------------+---------------------------- Reporter: yongqli | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: MacOS X Architecture: Unknown/Multiple | Type of failure: Other Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------------+---------------------------- I can't seem to be able to use the LLVM backend on OSX. I get the error: {{{ error: unknown directive .macosx_version_min 10, 0 ^ <no location info>: Error running clang! you need clang installed to use theLLVM backend (or GHC tried to execute clang incorrectly) <no location info>: ghc: phase `Clang (Assembler)' failed (exitcode = 1) }}} This is on GHC 7.10.1 {{{ % clang --version Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn) Target: x86_64-apple-darwin14.1.0 Thread model: posix yongqli@auxiliary ~/secrets/projects/stocvol % opt --version LLVM (http://llvm.org/) LLVM version 3.5.1 Optimized build with assertions. Built Jan 15 2015 (18:24:46). Default target: x86_64-apple-darwin14.1.0 Host CPU: core-avx2 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10221> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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