August 2017 - ghc-tickets

[GHC] #14128: Possible bug in Renamer when dealing with orphans
by GHC 21 Sep '17

21 Sep '17

#14128: Possible bug in Renamer when dealing with orphans -------------------------------------+------------------------------------- Reporter: Shayan-Najd | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 (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: -------------------------------------+------------------------------------- In a [https://github.com/shayan-najd/GrowableGHC branch] of GHC with [https://ghc.haskell.org/trac/ghc/wiki/ImplementingTreesThatGrow Growable ASTs], the code compiles with `devel2` configuration, but fails with `./validate`. It passes all the test cases, except two that already fail in HEAD (see [https://ghc.haskell.org/trac/ghc/ticket/14126 #14126]). Especifically, the compiler returns the following error: {{{ ghc-stage1: panic! (the 'impossible' happened) (GHC version 8.3.20170806 for x86_64-unknown-linux): ASSERT failed! HsPat [GHC.Base, GHC.Float, Data.Binary.Generic, Data.ByteString.Builder, HsBinds, HsDoc, HsExpr, HsLit, HsPat, HsTypes, PprCore, GHC.LanguageExtensions, Data.Time.Calendar.Gregorian, Data.Time.Format.Parse, Data.Time.LocalTime.Internal.LocalTime, Data.Time.LocalTime.Internal.ZonedTime] Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1133:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1188:22 in ghc:Outputable assertPprPanic, called at compiler/rename/RnNames.hs:364:99 in ghc:RnNames 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/utils/Outputable.hs:1186:5 in ghc:Outputable assertPprPanic, called at compiler/rename/RnNames.hs:364:99 in ghc:RnNames Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} I suspect (as hinted above) it has to do with a bug in the renamer when dealing with orphan instances (and probably in conjunction with boot files). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14128> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13964: Pattern-match warnings for datatypes with COMPLETE sets break abstraction
by GHC 21 Sep '17

21 Sep '17

#13964: Pattern-match warnings for datatypes with COMPLETE sets break abstraction -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple PatternSynonyms, | PatternMatchWarnings | Architecture: | Type of failure: Poor/confusing Unknown/Multiple | error message Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Here's a file: {{{#!hs {-# LANGUAGE PatternSynonyms #-} {-# LANGUAGE ViewPatterns #-} module Bug (Boolean(F, TooGoodToBeTrue), catchAll) where data Boolean = F | T deriving Eq pattern TooGoodToBeTrue :: Boolean pattern TooGoodToBeTrue <- ((== T) -> True) where TooGoodToBeTrue = T {-# COMPLETE F, TooGoodToBeTrue #-} catchAll :: Boolean -> Int catchAll F = 0 -- catchAll TooGoodToBeTrue = 1 }}} If you compile this with `-Wall`, the warning will warn about `T`, not `TooGoodToBeTrue` (the other conlike in the `COMPLETE` set): {{{ $ /opt/ghc/8.2.1/bin/ghc -fforce-recomp -Wall Bug.hs [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) Bug.hs:15:1: warning: [-Wincomplete-patterns] Pattern match(es) are non-exhaustive In an equation for ‘catchAll’: Patterns not matched: T | 15 | catchAll F = 0 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ }}} Perhaps this isn't so bad, since it's intra-module. But the problem persists even across modules: {{{#!hs module Foo where import Bug catchAll2 :: Boolean -> Int catchAll2 F = 0 -- catchAll2 TooGoodToBeTrue = 1 }}} {{{ $ /opt/ghc/8.2.1/bin/ghc -fforce-recomp -c Bug.hs $ /opt/ghc/8.2.1/bin/ghc -fforce-recomp -c -Wall Foo.hs Foo.hs:6:1: warning: [-Wincomplete-patterns] Pattern match(es) are non-exhaustive In an equation for ‘catchAll2’: Patterns not matched: Bug.T | 6 | catchAll2 F = 0 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ }}} This one is really bad, since it's warning about `Bug.T`, which should be hidden! -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13964> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13959: substTyVar's definition is highly dubious
by GHC 21 Sep '17

21 Sep '17

#13959: substTyVar's definition is highly dubious -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Currently, we have: {{{#!hs substTyVar :: TCvSubst -> TyVar -> Type substTyVar (TCvSubst _ tenv _) tv = ASSERT( isTyVar tv ) case lookupVarEnv tenv tv of Just ty -> ty Nothing -> TyVarTy tv }}} But as Richard pointed out to me, the `Nothing` case is flat-out wrong. If `tv` isn't in the substitution, we need to check if any of the variables in `tv`'s kind are in the substitution, and if so, apply the substitution to them. Fixing this might seem straightforward enough: {{{#!diff diff --git a/compiler/types/TyCoRep.hs b/compiler/types/TyCoRep.hs index 5ac63e5..4f7d650 100644 --- a/compiler/types/TyCoRep.hs +++ b/compiler/types/TyCoRep.hs @@ -2191,11 +2191,11 @@ subst_ty subst ty go (CoercionTy co) = CoercionTy $! (subst_co subst co) substTyVar :: TCvSubst -> TyVar -> Type -substTyVar (TCvSubst _ tenv _) tv +substTyVar subst@(TCvSubst _ tenv _) tv = ASSERT( isTyVar tv ) case lookupVarEnv tenv tv of Just ty -> ty - Nothing -> TyVarTy tv + Nothing -> TyVarTy (updateTyVarKind (substTyUnchecked subst) tv) substTyVars :: TCvSubst -> [TyVar] -> [Type] substTyVars subst = map $ substTyVar subst }}} But note that I'm using `substTyUnchecked`, not `substTy`, since if you try using the latter, GHC will pretty quickly fall over on a `./validate --slow` build, as `substTy`'s assertions are violated all over the place. I'm fairly certain I know why the assertions would be tripping up, however. To build most of the in-scope sets used for `substTyVar`'s substitutions, the `mkVarSet :: [Var] -> VarSet` function is used. But `mkVarSet` only grabs the `Unique`s of the type variables themselves, not the variables in the kind of each type variable. This means the in-scope sets will frequently be too narrow to encompass the kind variables, which absolutely must be in the set if we want to change `substTyVar` as described above. I'm not sure what the solution is here. Perhaps we should be using a variant of `mkVarSet` called `mkTyVarSet` that grabs the `Unique`s of the kind variables as well? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13959> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8919: Why is xhtml library installed but not exported to users?
by GHC 20 Sep '17

20 Sep '17

#8919: Why is xhtml library installed but not exported to users? ------------------------------------+------------------------------------- Reporter: simons | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.8.1 Component: Build System | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Other Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- GHC 7.8.1-rc2 installs the xhtml library, but doesn't export it, i.e. it's completely invisible to users. Is there a particular reason why this setup is necessary? If GHC needs that library internally anywhere, would it be possible to link it statically and *not* install it? Or, if that's not possible, if the library needs to be installed, please make it visible to users. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8919> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9281: Rewrite `integer-gmp` to use only non-allocating GMP functions
by GHC 19 Sep '17

19 Sep '17

#9281: Rewrite `integer-gmp` to use only non-allocating GMP functions -------------------------------------+------------------------------------- Reporter: hvr | Owner: hvr Type: task | Status: new Priority: normal | Milestone: 7.10.1 Component: libraries (other) | Version: Keywords: integer-gmp | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- After some promising results with a proof-of-concept implementation, I'm optimistic we can rewrite `integer-gmp` to use only non-allocating GMP lib functions without suffering from serious regressions. If successful, this would - allow to avoid the custom GMP allocator hack, and thus - avoid issues when linking against other C libraries using GMP, - simplify code, as we would perform all heap allocations in Haskell code (and never inside Cmm/C code as its done now), - and finally maybe even remove a few more superfluous temporary heap allocations. This rewrite can be done incrementally. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9281> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13481: T12622 fails in ghci way
by GHC 19 Sep '17

19 Sep '17

#13481: T12622 fails in ghci way -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: 8.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- `T12622`, which is intended to test StaticPointers, fails in the GHCi way with a core lint warning, {{{ *** Core Lint errors : in result of Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = False}) *** <no location info>: warning: In the expression: >>= @ IO $fMonadIO @ (Bool -> Bool) @ () (break<10>(s_a1DF) lvl_s3bD) lvl_s3bE s_a1DF :: StaticPtr (Bool -> Bool) [LclId, Unf=Unf{Src=<vanilla>, TopLvl=False, Value=False, ConLike=False, WorkFree=False, Expandable=False, Guidance=IF_ARGS [] 70 0}] is out of scope *** Offending Program *** g :: Bool [LclIdX] g = break<15>() True $trModule_s3b7 :: Addr# [LclId] $trModule_s3b7 = "main"# $trModule_s3b6 :: TrName [LclId] $trModule_s3b6 = TrNameS $trModule_s3b7 $trModule_s3b9 :: Addr# [LclId] $trModule_s3b9 = "Main"# $trModule_s3b8 :: TrName [LclId] $trModule_s3b8 = TrNameS $trModule_s3b9 $trModule :: Module [LclIdX] $trModule = Module $trModule_s3b6 $trModule_s3b8 lvl_s3bj :: Addr# [LclId] lvl_s3bj = "error"# lvl_s3bk :: [Char] [LclId] lvl_s3bk = unpackCString# lvl_s3bj lvl_s3bl :: Addr# [LclId] lvl_s3bl = "main"# lvl_s3bm :: [Char] [LclId] lvl_s3bm = unpackCString# lvl_s3bl lvl_s3bn :: Addr# [LclId] lvl_s3bn = "Main"# lvl_s3bo :: [Char] [LclId] lvl_s3bo = unpackCString# lvl_s3bn lvl_s3bp :: Addr# [LclId] lvl_s3bp = "T12622.hs"# lvl_s3bq :: [Char] [LclId] lvl_s3bq = unpackCString# lvl_s3bp lvl_s3br :: Int [LclId] lvl_s3br = I# 21# lvl_s3bs :: Int [LclId] lvl_s3bs = I# 14# lvl_s3bt :: Int [LclId] lvl_s3bt = I# 21# lvl_s3bu :: Int [LclId] lvl_s3bu = I# 64# lvl_s3bv :: SrcLoc [LclId] lvl_s3bv = SrcLoc lvl_s3bm lvl_s3bo lvl_s3bq lvl_s3br lvl_s3bs lvl_s3bt lvl_s3bu lvl_s3bw :: ([Char], SrcLoc) [LclId] lvl_s3bw = (lvl_s3bk, lvl_s3bv) $dIP_s3bc :: CallStack [LclId] $dIP_s3bc = pushCallStack lvl_s3bw emptyCallStack lvl_s3bx :: Addr# [LclId] lvl_s3bx = "couldn't find "# lvl_s3by :: [Char] [LclId] lvl_s3by = unpackCString# lvl_s3bx lookupKey :: forall a. StaticPtr a -> IO a [LclIdX, Arity=1] lookupKey = \ (@ a_a23X) (p_X1DX :: StaticPtr a_a23X) -> break<8>(p_X1DX) >>= @ IO $fMonadIO @ (Maybe (StaticPtr a_a23X)) @ a_a23X (break<1>(p_X1DX) unsafeLookupStaticPtr @ a_a23X (break<0>(p_X1DX) staticKey @ a_a23X p_X1DX)) (\ (ds_d3as :: Maybe (StaticPtr a_a23X)) -> case ds_d3as of { Nothing -> break<7>(p_X1DX) error @ 'LiftedRep @ (IO a_a23X) ($dIP_s3bc `cast` (Sym (N:IP[0] <"callStack">_N <CallStack>_N) :: (CallStack :: *) ~R# ((?callStack::CallStack) :: Constraint))) (break<6>(p_X1DX) ++ @ Char lvl_s3by (break<5>(p_X1DX) show @ StaticPtrInfo $fShowStaticPtrInfo (break<4>(p_X1DX) staticPtrInfo @ a_a23X p_X1DX))); Just p_a1DI -> break<3>(p_a1DI) return @ IO $fMonadIO @ a_a23X (break<2>(p_a1DI) deRefStaticPtr @ a_a23X p_a1DI) }) $dTypeable_s3bA :: TypeRep Bool [LclId] $dTypeable_s3bA = mkTrCon @ * @ Bool $tcBool ([] @ SomeTypeRep) s_s3bC :: StaticPtr (Bool -> Bool) [LclId] s_s3bC = case break<9>() sg @ Bool ($dTypeable_s3bA `cast` (Sym N:Typeable[0] <*>_N <Bool>_N :: (TypeRep Bool :: *) ~R# (Typeable Bool :: Constraint))) of { T s_a38b -> s_a38b } lvl_s3bD :: IO (Bool -> Bool) [LclId] lvl_s3bD = lookupKey @ (Bool -> Bool) s_s3bC lvl_s3bE :: (Bool -> Bool) -> IO () [LclId] lvl_s3bE = \ (f_a1DG :: Bool -> Bool) -> break<12>(f_a1DG) print @ Bool $fShowBool (break<11>(f_a1DG) f_a1DG True) main :: IO () [LclIdX] main = break<14>() break<13>(s_s3bC) >>= @ IO $fMonadIO @ (Bool -> Bool) @ () (break<10>(s_a1DF) lvl_s3bD) lvl_s3bE main :: IO () [LclIdX] main = runMainIO @ () main *** End of Offense *** <no location info>: error: Compilation had errors *** Exception: ExitFailure 1 ===== program output begins here ===== program output begins here T12622:6:30: error: Not in scope: ‘Main.main’ No module named ‘Main’ is imported. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13481> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14096: Residency profiling with eventlog enabled breaks
by GHC 19 Sep '17

19 Sep '17

#14096: Residency profiling with eventlog enabled breaks -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.2.1 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: -------------------------------------+------------------------------------- The RTS panics when a program compiled with `-eventlog` is run with `+RTS -l -h`, {{{ trec-car-graph-expansion: internal error: getHeapProfBreakdown: unknown heap profiling mode Stack trace: 0x2122e2f set_initial_registers (rts/Libdw.c:288.0) 0x7f98bbdfb8b8 dwfl_thread_getframes (/usr/lib/x86_64 -linux-gnu/libdw-0.168.so) 0x7f98bbdfb347 (null) (/usr/lib/x86_64-linux- gnu/libdw-0.168.so) 0x7f98bbdfb673 dwfl_getthreads (/usr/lib/x86_64-linux- gnu/libdw-0.168.so) 0x7f98bbdfbc30 dwfl_getthread_frames (/usr/lib/x86_64 -linux-gnu/libdw-0.168.so) 0x212342d libdwGetBacktrace (rts/Libdw.c:259.0) 0x2127aab rtsFatalInternalErrorFn (rts/RtsMessages.c:169.0) 0x2127c6d barf (rts/RtsMessages.c:47.0) 0x2136824 postHeapProfBegin (rts/eventlog/EventLog.c:1147.0) 0x21443bb initHeapProfiling.part.5 (rts/ProfHeap.c:464.0) 0x211cc16 hs_init_ghc (rts/RtsStartup.c:268.0) 0x2128bb3 hs_main (rts/RtsMain.c:63.0) 0x4cfc8d (null) (/home/ben/trec-car/mediawiki- annotate/dist-newstyle/build/x86_64-linux/ghc-8.2.1/trec-car-graph- expansion-0.1.0.0/c/trec-car-graph-expansion/bu ild/trec-car-graph-expansion/trec-car-graph-expansion) 0x7f98bba4a2b1 __libc_start_main (../csu/libc- start.c:325.0) 0x40ba1a _start (/home/ben/trec-car/mediawiki- annotate/dist-newstyle/build/x86_64-linux/ghc-8.2.1/trec-car-graph- expansion-0.1.0.0/c/trec-car-graph-expansion/bu ild/trec-car-graph-expansion/trec-car-graph-expansion) (GHC version 8.2.1 for x86_64_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14096> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14163: Stack Overflow with ApplicativeDo
by GHC 19 Sep '17

19 Sep '17

#14163: Stack Overflow with ApplicativeDo -------------------------------------+------------------------------------- Reporter: lippling | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Keywords: | Operating System: MacOS X Architecture: x86_64 | Type of failure: Compile-time (amd64) | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I tried to compile one of our server applications with 8.2.1 (which compiles fine with 8.0.2). The compilation runs smooth, but when it reaches a specific file, the RAM usage goes up to > 20GB pretty fast on my 16GB machine and the GHC process gets terminated with a stack overflow error. I tried to find a minimal example that causes this behavior: {{{ #!/usr/bin/env stack -- stack --resolver nightly-2017-08-25 script {-# LANGUAGE ApplicativeDo #-} x = do (a, _) <- undefined (b, _) <- undefined (c, _) <- undefined undefined main = undefined }}} It only happens with at least 3 of these pattern matches. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14163> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14158: (Control.Category.id @(->) >>=) causes GHC panic
by GHC 19 Sep '17

19 Sep '17

#14158: (Control.Category.id @(->) >>=) causes GHC panic -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 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: -------------------------------------+------------------------------------- {{{ $ ghci -ignore-dot-ghci -XTypeApplications GHCi, version 8.3.20170605: http://www.haskell.org/ghc/ :? for help Prelude> import qualified Control.Category as Cat Prelude Cat> :t (Cat.id @(->) >>=) ghc: panic! (the 'impossible' happened) (GHC version 8.3.20170605 for x86_64-unknown-linux): repSplitAppTy_maybe a0_a1qW[tau:2] a0_a1qW[tau:2] 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/types/Type.hs:699:5 in ghc:Type Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Prelude Cat> }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14158> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13525: hWaitForInput with timeout causes program to abort
by GHC 19 Sep '17

19 Sep '17

#13525: hWaitForInput with timeout causes program to abort --------------------------------------+---------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler | Version: 8.0.2 Keywords: | Operating System: Linux Architecture: x86_64 (amd64) | Type of failure: Runtime crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: --------------------------------------+---------------------------------- This program, {{{#!hs import System.IO import System.Timeout main = hWaitForInput stdin (5 * 1000) }}} causes the program to abort (tested on Linux), {{{ $ ghc hi.hs [1 of 1] Compiling Main ( hi.hs, hi.o ) Linking hi ... $ ./hi fdReady: msecs != 0, this shouldn't happenAborted }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13525> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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