August 2017 - ghc-tickets

[GHC] #14118: stg2stg passes appear to produce invalid STG
by GHC 29 Nov '17

29 Nov '17

#14118: stg2stg passes appear to produce invalid STG -------------------------------------+------------------------------------- Reporter: bgamari | 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: -------------------------------------+------------------------------------- While building with GHC with `-dstg-lint -g3 -O0` (after fixing #14116 and #14117) I encountered a rather peculiar error, {{{ "inplace/bin/ghc-stage1" -hisuf hi -osuf o -hcsuf hc -static -O -H64m -Wall -this-unit-id integer-gmp-1.0.1.0 -hide-all-packages -i -ilibraries/integer-gmp/src/ -ilibraries/integer-gmp/dist-install/build -Ilibraries/integer-gmp/dist-install/build -ilibraries/integer-gmp/dist- install/build/./autogen -Ilibraries/integer-gmp/dist- install/build/./autogen -Ilibraries/integer-gmp/include -optP-include -optPlibrari es/integer-gmp/dist-install/build/./autogen/cabal_macros.h -package-id ghc-prim-0.5.1.0 -this-unit-id integer-gmp -Wall -XHaskell2010 -O -dcore- lint -g3 -ddump-to-file -ddump-stg -dcore-lint -dstg-lint -dcmm-lin t -no-user-package-db -rtsopts -Wno-deprecated-flags -Wnoncanonical- monad-instances -odir libraries/integer-gmp/dist-install/build -hidir libraries/integer-gmp/dist-install/build -stubdir libraries/intege r-gmp/dist-install/build -dynamic-too -c libraries/integer- gmp/src//GHC/Integer/Type.hs -o libraries/integer-gmp/dist- install/build/GHC/Integer/Type.o -dyno libraries/integer-gmp/dist- install/build/GHC/Integer /Type.dyn_o ghc-stage1: panic! (the 'impossible' happened) (GHC version 8.3.20170815 for x86_64-unknown-linux): *** Stg Lint ErrMsgs: in Stg2Stg *** <no location info>: warning: [in body of lambda with binders m0_scBy :: State# s_a2Em -> State# s_a2Em, s1_scBz :: State# s_a2Em] s'_scBA is out of scope <no location info>: warning: [in body of lambda with binders wild1_sdUv :: Int#] qr_sdUp is out of scope }}} Looking at the STG it appears that these warnings are absolutely correct, {{{#!hs svoid [InlPrag=INLINE (sat-args=1)] :: forall s. (State# s -> State# s) -> S s () [GblId, Arity=2, Caf=NoCafRefs, Str=<C(S),1*C1(U)><S,U>, Unf=OtherCon []] = \r [m0_scBy s1_scBz] src<libraries/integer-gmp/src/GHC/Integer/Type.hs:1957:1-48> case m0_scBy s1_scBz of s'_scBA { __DEFAULT -> src<libraries/integer- gmp/src/GHC/Integer/Type.hs:1957:37-48> (#,#) [s'_scBA ()]; }; }}} This is quite strange given that `s'_scBA` is clearly in scope, being bound as the case binder. We had the following from Core Prep, {{{#!hs -- RHS size: {terms: 10, types: 17, coercions: 0, joins: 0/0} GHC.Integer.Type.svoid [InlPrag=INLINE (sat-args=1)] :: forall s. (GHC.Prim.State# s -> GHC.Prim.State# s) -> GHC.Integer.Type.S s () [GblId, Arity=2, Caf=NoCafRefs, Str=<C(S),1*C1(U)><S,U>, Unf=OtherCon []] GHC.Integer.Type.svoid = \ (@ s_a2Em) (m0_scBy [Occ=Once!] :: GHC.Prim.State# s_a2Em -> GHC.Prim.State# s_a2Em) (s1_scBz [Occ=Once] :: GHC.Prim.State# s_a2Em) -> src<libraries/integer-gmp/src/GHC/Integer/Type.hs:1957:1-48> case m0_scBy s1_scBz of s'_scBA { __DEFAULT -> src<libraries/integer-gmp/src/GHC/Integer/Type.hs:1957:37-48> (# s'_scBA, GHC.Tuple.() #) } }}} The reason the linter fails here is due to the following logic in `lintStgExpr`, {{{#!hs in_scope <- MaybeT $ liftM Just $ case alts_type of AlgAlt tc -> check_bndr (tyConPrimRep tc) >> return True PrimAlt rep -> check_bndr [rep] >> return True MultiValAlt _ -> return False -- Binder is always dead in this case PolyAlt -> return True MaybeT $ addInScopeVars [bndr | in_scope] $ lintStgAlts alts scrut_ty }}} In the `svoid` case above we hit `MultiValAlt` path, which causes us to ignore the case binder. The fact that we hit `MultiValAlt` at all is a bit surprising given that the result is not an unboxed sum or tuple. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14118> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14120: stg-lint is hopelessly broken
by GHC 29 Nov '17

29 Nov '17

#14120: stg-lint is hopelessly broken -------------------------------------+------------------------------------- Reporter: bgamari | 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: -------------------------------------+------------------------------------- Today I spent a fair amount of time looking at the STG linter, having encountered a number of times in the past six months where I noticed it broke. While I thought fixing it would just be a few small tweaks, it seems that with every issue I fix another bug rears its ugly head. So far I have encountered and fixed, * #14116 * #14117 * #14118 The solutions to each of these has seemed rather obvious. However, now I seem to have run into a bit of a more fundamental issue: Consider this excerpt extracted from `Foreign.Storable`, {{{#!hs {-# LANGUAGE BangPatterns #-} module Hi where import GHC.Word import GHC.Ptr import GHC.Base import GHC.Num import Data.Bits import GHC.Fingerprint.Type peekFingerprint :: Ptr Fingerprint -> IO Fingerprint peekFingerprint p0 = do let peekW64 :: Ptr Word8 -> Int -> Word64 -> IO Word64 peekW64 _ 0 !i = return i peekW64 !p !n !i = peekW64 (p `plusPtr` 1) (n-1) (i `shiftL` 8) high <- peekW64 (castPtr p0) 8 0 low <- peekW64 (castPtr p0 `plusPtr` 8) 8 0 return (Fingerprint high low) }}} In particular notice the `castPtr` application. This triggers the STG linter with, {{{ ghc-stage1: panic! (the 'impossible' happened) (GHC version 8.3.20170815 for x86_64-unknown-linux): *** Stg Lint ErrMsgs: in Stg2Stg *** <no location info>: warning: [in body of lambda with binders p0_s2zB :: Ptr Fingerprint, eta_s2zC :: State# RealWorld] In a function application, function type doesn't match arg types: Function type: Ptr Word8 -> Int# -> Word# -> State# RealWorld -> (# State# RealWorld, Word64 #) Arg types: Ptr Fingerprint Int# Word# State# RealWorld Expression: $wpeekW64 p0_s2zB 8# 0## eta_s2zC }}} This is because by the time we are in Core Prep the `castPtr` is turned into a cast, which we discard in STG. Consequently, it seems that the comment attached to `stgEqType`, {{{#!hs stgEqType :: Type -> Type -> Bool -- Compare types, but crudely because we have discarded -- both casts and type applications, so types might look -- different but be the same. So reply "True" if in doubt. -- "False" means that the types are definitely different. -- -- Fundamentally this is a losing battle because of unsafeCoerce }}} is quite an understatement. Rather, there are exceedingly few cases where we can catch any type errors in STG. I think the only case which we can reliably catch is that of two types with explicitly different primreps. It's not clear what we can/should do about this. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14120> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14116: Core lint error while compiling master
by GHC 29 Nov '17

29 Nov '17

#14116: Core lint error while compiling master -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: high | 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: -------------------------------------+------------------------------------- While compiling e054c5f06451def4437d9d770ae156f034796c59 with the following `build.mk`, {{{ BuildFlavour = devel2 include mk/flavours/$(BuildFlavour).mk GhcStage2HcOpts += -eventlog GhcStage1HcOpts += -eventlog GhcLibHcOpts += -g3 -ddump-to-file -ddump-stg -dcore-lint -dstg-lint -dcmm-lint GhcRtsHcOpts += -g3 GhcStage2HcOpts += -g3 -ddump-to-file -ddump-stg -dcore-lint -dstg-lint -dcmm-lint }}} I encountered this Core lint failure while compiling `PprColour`, {{{ stgEqType: unequal PprColour [Char] ghc-stage1: panic! (the 'impossible' happened) (GHC version 8.3.20170815 for x86_64-unknown-linux): *** Stg Lint ErrMsgs: in Stg2Stg *** compiler/utils/PprColour.hs:62:1: warning: [RHS of defaultScheme :: Scheme] In a RHS constructor application, con type doesn't match arg types: Constructor type: PprColour -> PprColour -> PprColour -> PprColour -> PprColour -> PprColour -> Scheme Arg types: [Char] PprColour String String String String *** Offending Program *** ... }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14116> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13110: GHC API allocates memory which is never GC'd
by GHC 28 Nov '17

28 Nov '17

#13110: GHC API allocates memory which is never GC'd -------------------------------------+------------------------------------- Reporter: DanielG | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHC API | 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: -------------------------------------+------------------------------------- I've run into a very strange sort of memory leak it seems. GHC seems to manage to allocate memory which I cannot get rid of no matter what I try even after all references have disappeared. The allocated memory doesn't show up in heap profiles but is still visibly allocated (as seen in ps or pmap). I discovered this while investigating reports of large memory usage in ghc-mod where this issue is forcing us to dump completion information in a separate process to avoid the allocated memory sticking around for the rest of the user's session. The attached test case demonstrates this problem by first calling `getModuleInfo` for all modules in all visible packages and then just looping forever in `main`. I would expect all memory GHC allocated to be GC'd at this point but this does not happen. When run as {{{ $ ./Leaky -hide-all-packages }}} the test case consumes around 30M of memory on my system, if we however load some large package, say GHC itself {{{ $ ./Leaky -hide-all-packages -package ghc }}} the program will consume around 2-300M of memory which are never deallocated. The behaviour is not related to the loaded package though I tried it with `Cabal` too with the same result though smaller memory usage. At first I thought this might be related to large CAFs with IORefs inside not being GCd for some reason so I tried calling `resetCAFs` from the RTS before entering the loop. This however makes no difference whatsoever. I also tried forcing a major GC just to be save to no avail. Next I speculated that maybe the allocated memory is beyond the GC's control (malloc()ed or something) but looking at the memory map of the process with `pmap $(pgrep Leaky)` that the majority of the memory usage I'm seeing comes from address `0x0000000200000000` which is where the RTS allocates memory AFAIK. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13110> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13157: Opportunity to improve case-of-case
by GHC 25 Nov '17

25 Nov '17

#13157: Opportunity to improve case-of-case -------------------------------------+------------------------------------- Reporter: simonpj | Owner: 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: -------------------------------------+------------------------------------- Consider this code {{{ f g x = (case g x of True -> not False -> id) `seq` True }}} With GHC 8 (and -O) we get this Core {{{ f = \ (@ t_a1rk) (g_aqD :: t -> Bool) (x_aqE :: t) -> case case g_aqD x_aqE of { False -> id @ Bool; True -> not } of { __DEFAULT -> GHC.Types.True } }}} This is obviously bad. The reasoning is in the long, complicated `Note [Single-alternative cases]` in `Simplify.hs`. Happily with join points the entire Note becomes unnecessary; we can delete the special case that this Note describes, and the Note itself. Result: simpler compiler, and more optimal code. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13157> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12159: Record-like GADTs with repeated fields (of same type) rejected
by GHC 22 Nov '17

22 Nov '17

#12159: Record-like GADTs with repeated fields (of same type) rejected -------------------------------------+------------------------------------- Reporter: heisenbug | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I came across a curious bug with record-like GADTs and repeated fields. Consider following code: {{{#!hs {-# LANGUAGE GADTs #-} data Foo p where Bar :: { quux' :: Bool } -> Foo Char Baz :: { quux'' :: Bool } -> Foo Int quux :: Foo p -> Bool quux (Bar q) = q quux (Baz q) = q quuxSetter :: Foo p -> Bool -> Foo p quuxSetter old@Bar{} q = old{quux' = q} quuxSetter old@Baz{} q = old{quux'' = q} }}} This compiles and all is fine. *But* GHC is supposed to create the nice `quux` and `quuxSetter` accessors for me, right? So, let's try: {{{#!hs data Foo p where Bar :: { quux :: Bool } -> Foo Char Baz :: { quux :: Bool } -> Foo Int }}} It does not compile! Instead I get: {{{ T12159.hs:3:1: error: Constructors Bar and Baz have a common field quux , but have different result types In the data type declaration for Foo Failed, modules loaded: none. }}} This is not very polite :-) It should simply create the accessors like I did above. It obviously can be done! Testcase is attached. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12159> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11721: GADT-syntax data constructors don't work well with TypeApplications
by GHC 21 Nov '17

21 Nov '17

#11721: GADT-syntax data constructors don't work well with TypeApplications -------------------------------------+------------------------------------- Reporter: goldfire | Owner: goldfire Type: bug | Status: new Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: 8.1 Keywords: | Operating System: Unknown/Multiple TypeApplications | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Consider {{{ data X a where MkX :: b -> Proxy a -> X a }}} According to the rules around specified vs. generalized variables around `TypeApplications`, the type of `MkX` should be {{{ MkX :: forall {k} (b :: *) (a :: k). b -> Proxy a -> X a }}} A few things to note: * The `k` isn't available for `TypeApplications` (that's why it's in braces), because it is not user-written. * The `b` is quantified before the `a`, because `b` comes before `a` in the user-written type signature for `MkX`. Both of these bullets are currently violated. GHCi reports `MkX`'s type as {{{ MkX :: forall k (a :: k) b. b -> Proxy a -> X a }}} It turns out that this is a hard to fix. The problem is that GHC expects data constructors to have their universal variables followed by their existential variables, always. And yet that's violated in the desired type for `MkX`. Furthermore, given the way that GHC deals with GADT return types ("rejigging", in technical parlance), it's inconvenient to get the specified/generalized distinction correct. Given time constraints, I'm afraid fixing this all won't make it for 8.0. Happily, there is are easy-to-articulate rules governing GHC's current (wrong) behavior. In a GADT-syntax data constructor: * All kind and type variables are considered specified and available for visible type application. * Universal variables always come first, in precisely the order they appear in the tycon. Note that universals that are constrained by a GADT return type are missing from the datacon. * Existential variables come next. Their order is determined by a user- written `forall`; or, if there is none, by taking the left-to-right order in the datacon's type and doing a stable topological sort. (This stable topological sort step is the same as for other user-written type signatures.) Despite the existence of these rules, it would still be better not to have special rules for GADT-syntax data constructors. This ticket is intended to capture that eventual goal. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11721> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9118: Can't eta-reduce representational coercions
by GHC 19 Nov '17

19 Nov '17

#9118: Can't eta-reduce representational coercions ------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- When I say {{{ import Data.Type.Coercion import Data.Coerce import Data.Proxy eta2 :: Coercible (f a) (g a) => Proxy a -> Coercion f g eta2 _ = Coercion }}} I get {{{ Could not coerce from ‘f’ to ‘g’ because ‘f’ and ‘g’ are different types. arising from a use of ‘Coercion’ from the context (Coercible (f a) (g a)) bound by the type signature for eta2 :: Coercible (f a) (g a) => Proxy a -> Coercion f g at /Users/rae/temp/Roles.hs:5:9-56 In the expression: Coercion In an equation for ‘eta2’: eta2 _ = Coercion }}} Unlike the case for #9116, this one is ''not'' expressible in Core. (At least, I don't see a way to do it.) So, to do this, we would have to update Core and then update the constraint solver. I ''do'' think this would be type safe. But, I also think it's reasonable to wait for someone with a real use case to shout before doing this. The only use case I have is to be able to do this: {{{ -- says that a's parameter is representational class Rep (a :: k1 -> k2) where co :: Coercible x y => Coercible (a x) (a x) instance Rep f => Rep (Compose f) where ... }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9118> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11392: Decide and document how semicolons are supposed to work in GHCi
by GHC 19 Nov '17

19 Nov '17

#11392: Decide and document how semicolons are supposed to work in GHCi -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: task | Status: new Priority: normal | Milestone: 8.2.1 Component: GHCi | Version: 7.10.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #10663 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Currently there is a fair bit of confusion surrounding the intended function of semicolons in GHCi (see #10663 and Phab:D1726), * the users guide doesn't discuss the matter at all * sometimes the content after semicolons work as expected {{{ λ> let x=2; y=5 λ> x+y 7 }}} * other times it is silently ignored (see #10663), {{{ λ> import Data.List; 684 λ> }}} * other times it works but the parser state is subtly wrong, resulting in (arguably) incorrect line numbers later in the session, {{{ λ> data Infix a b = a :@: b; infixl 4 :@: λ> a <interactive>:3:1: error: Variable not in scope: a }}} * some times the only way to accomplish a given task is with a semicolon, {{{ Prelude> data Infix a b = a :@: b; infixl 4 :@: -- this is OK, but: Prelude> data Infix a b = a :@: b Prelude> infixl 4 :@: <interactive>:12:10: error: The fixity signature for `:@:' lacks an accompanying binding (The fixity signature must be given where `:@:' is declared) }}} This inconsistency is surprising and at times frustrating. Let's decide how we want semicolons to work and stick with it. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11392> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14168: Installing math-functions with GHC-8.2.1 on windows crashed
by GHC 14 Nov '17

14 Nov '17

#14168: Installing math-functions with GHC-8.2.1 on windows crashed -------------------------------------+------------------------------------- Reporter: Qinka | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Keywords: | Operating System: Unknown/Multiple Architecture: x86_64 | Type of failure: None/Unknown (amd64) | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I use the ghc-8.2.1 in Windows. When install math-functions, ghc crash. The following is the output. {{{ λ stack install math-functions math-functions-0.2.1.0: configure math-functions-0.2.1.0: build -- While building package math-functions-0.2.1.0 using: C:\sr\setup-exe-cache\x86_64-windows\Cabal- simple_Z6RU0evB_2.0.0.2_ghc-8.2.1.exe --builddir=.stack-work\dist\e53504d9 build --ghc-options " -ddump-hi -ddump-to-file" Process exited with code: ExitFailure 255 Logs have been written to: A:\Glob\.stack-work\logs\math- functions-0.2.1.0.log Configuring math-functions-0.2.1.0... Preprocessing library for math-functions-0.2.1.0.. Building library for math-functions-0.2.1.0.. [ 1 of 10] Compiling Numeric.MathFunctions.Comparison ( Numeric\MathFunctions\Comparison.hs, .stack- work\dist\e53504d9\build\Numeric\MathFunctions\Comparison.o ) [ 2 of 10] Compiling Numeric.MathFunctions.Constants ( Numeric\MathFunctions\Constants.hs, .stack- work\dist\e53504d9\build\Numeric\MathFunctions\Constants.o ) [ 3 of 10] Compiling Numeric.Polynomial ( Numeric\Polynomial.hs, .stack-work\dist\e53504d9\build\Numeric\Polynomial.o ) [ 4 of 10] Compiling Numeric.Polynomial.Chebyshev ( Numeric\Polynomial\Chebyshev.hs, .stack- work\dist\e53504d9\build\Numeric\Polynomial\Chebyshev.o ) [ 5 of 10] Compiling Numeric.RootFinding ( Numeric\RootFinding.hs, .stack-work\dist\e53504d9\build\Numeric\RootFinding.o ) [ 6 of 10] Compiling Numeric.Series ( Numeric\Series.hs, .stack- work\dist\e53504d9\build\Numeric\Series.o ) [ 7 of 10] Compiling Numeric.SpecFunctions.Internal ( Numeric\SpecFunctions\Internal.hs, .stack- work\dist\e53504d9\build\Numeric\SpecFunctions\Internal.o ) C:\Users\qinka\AppData\Local\Temp\stack12716\math- functions-0.2.1.0\Numeric\SpecFunctions\Internal.hs:24:1: warning: [-Wunused-imports] The import of 鈥榚xpm1鈥?from module 鈥楪HC.Float鈥?is redundant | 24 | import GHC.Float (log1p,expm1) | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ [ 8 of 10] Compiling Numeric.SpecFunctions.Extra ( Numeric\SpecFunctions\Extra.hs, .stack- work\dist\e53504d9\build\Numeric\SpecFunctions\Extra.o ) [ 9 of 10] Compiling Numeric.SpecFunctions ( Numeric\SpecFunctions.hs, .stack-work\dist\e53504d9\build\Numeric\SpecFunctions.o ) [10 of 10] Compiling Numeric.Sum ( Numeric\Sum.hs, .stack- work\dist\e53504d9\build\Numeric\Sum.o ) ghc.EXE: internal error: mkPath failed converting char* to wchar_t* (GHC version 8.2.1 for x86_64_unknown_mingw32) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14168> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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