October 2017 - ghc-tickets

[GHC] #12479: build fail of commercialhaskell.com with stack build on mac os x sierra beta 4
by GHC 20 Oct '17

20 Oct '17

#12479: build fail of commercialhaskell.com with stack build on mac os x sierra beta 4 -------------------------------------+------------------------------------- Reporter: stephenb | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Hi, git clone (commit dfe55e97ed86567aafca2e5f3c19096e2a4cb50f - Sep 20th 2016) of commercialhaskell.com from github: {{{ https://github.com/commercialhaskell/commercialhaskell.com.git }}} follow instructions from that repo exactly for os x (stacksetup installed ghc-7.10.2, but i have seen similar issue with 8): {{{ $ brew install icu4c Add the following to your ~/.stack/stack.yaml: extra-include-dirs: - /usr/local/opt/icu4c/include extra-lib-dirs: - /usr/local/opt/icu4c/lib Now: $ stack build }}} Hit one minor issue in build process with icu4c, resolving with following stack build: {{{ stack build --extra-lib-dirs=/usr/local/opt/icu4c/lib --extra-include- dirs=/usr/local/opt/icu4c/include }}} reach build of yesod-auth, with a failure: {{{ yesod-auth-1.4.6: configure yesod-auth-1.4.6: build texmath-0.8.2.2: copy/register Progress: 35/38 -- While building package yesod-auth-1.4.6 using: /Users/stephen/.stack/setup-exe-cache/x86_64-osx/setup-Simple- Cabal-1.22.4.0-ghc-7.10.2 --builddir=.stack- work/dist/x86_64-osx/Cabal-1.22.4.0 build --ghc-options " -ddump-hi -ddump-to-file" Process exited with code: ExitFailure 1 Logs have been written to: /Users/stephen/Documents/github/commercialhaskell.com/.stack-work/logs /yesod-auth-1.4.6.log Configuring yesod-auth-1.4.6... Building yesod-auth-1.4.6... Preprocessing library yesod-auth-1.4.6... [ 1 of 11] Compiling Yesod.PasswordStore ( Yesod/PasswordStore.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build/Yesod/PasswordStore.o ) /private/var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/stack49268 /yesod-auth-1.4.6/Yesod/PasswordStore.hs:166:31: Warning: Defaulting the following constraint(s) to type ‘Integer’ (Integral b0) arising from a use of ‘^’ at Yesod/PasswordStore.hs:166:31 (Num b0) arising from the literal ‘32’ at Yesod/PasswordStore.hs:166:32-33 In the first argument of ‘(-)’, namely ‘2 ^ 32’ In the first argument of ‘(*)’, namely ‘(2 ^ 32 - 1)’ In the second argument of ‘(>)’, namely ‘(2 ^ 32 - 1) * hLen’ /private/var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/stack49268 /yesod-auth-1.4.6/Yesod/PasswordStore.hs:419:1: Warning: Defined but not used: ‘toStrict’ /private/var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/stack49268 /yesod-auth-1.4.6/Yesod/PasswordStore.hs:422:1: Warning: Defined but not used: ‘fromStrict’ [ 2 of 11] Compiling Yesod.Auth.Message ( Yesod/Auth/Message.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build/Yesod/Auth/Message.o ) /private/var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/stack49268 /yesod-auth-1.4.6/Yesod/Auth/Message.hs:22:1: Warning: The import of ‘Data.Monoid’ is redundant except perhaps to import instances from ‘Data.Monoid’ To import instances alone, use: import Data.Monoid() [ 3 of 11] Compiling Yesod.Auth.Routes ( Yesod/Auth/Routes.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.4.0/build/Yesod/Auth/Routes.o ) [ 4 of 11] Compiling Yesod.Auth ( Yesod/Auth.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.4.0/build/Yesod/Auth.o ) ghc: panic! (the 'impossible' happened) (GHC version 7.10.2 for x86_64-apple-darwin): Loading temp shared object failed: dlopen(/var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/ghc64990_0/libghc_21.dylib, 5): no suitable image found. Did find: /var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/ghc64990_0/libghc_21.dylib: malformed mach-o: load commands size (34176) > 32768 Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} So reporting.... I've seen the same error attempting to brew install haskell-stack on sierra betas 3 and 4, but on those occasions, an issue with libghc_44.dylib causing the problem. {{{ [ 4 of 87] Compiling System.Process.Read ( src/System/Process/Read.hs, dist/dist-sandbox-558713ad/build/System/Process/Read.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.1 for x86_64-apple-darwin): Loading temp shared object failed: dlopen(/var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/ghc67839_0/libghc_44.dylib, 5): no suitable image found. Did find: /var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/ghc67839_0/libghc_44.dylib: malformed mach-o: load commands size (40560) > 32768 Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} stack version: {{{ Version 1.1.2, Git revision cebe10e845fed4420b6224d97dcabf20477bbd4b (3646 commits) x86_64 hpack-0.14.0 }}} stack exec env returns: {{{ stack exec env Apple_PubSub_Socket_Render=/private/tmp/com.apple.launchd.tEAdTiAWFI/Render GHC_PACKAGE_PATH=/Users/stephen/Documents/github/commercialhaskell.com /.stack- work/install/x86_64-osx/lts-3.0/7.10.2/pkgdb:/Users/stephen/.stack/snapshots/x86_64-osx/lts-3.0/7.10.2/pkgdb:/Users/stephen/.stack/programs/x86_64-osx/ghc-7.10.2/lib/ghc-7.10.2/package.conf.d HASKELL_DIST_DIR=.stack-work/dist/x86_64-osx/Cabal-1.22.4.0 HASKELL_PACKAGE_SANDBOX=/Users/stephen/.stack/snapshots/x86_64-osx/lts-3.0/7.10.2/pkgdb HASKELL_PACKAGE_SANDBOXES=/Users/stephen/Documents/github/commercialhaskell… /.stack- work/install/x86_64-osx/lts-3.0/7.10.2/pkgdb:/Users/stephen/.stack/snapshots/x86_64-osx/lts-3.0/7.10.2/pkgdb: HOME=/Users/stephen LANG=en_IE.UTF-8 LOGNAME=stephen NAME=Stephen Barrett OLDPWD=/Users/stephen/Documents/github PATH=/Users/stephen/Documents/github/commercialhaskell.com/.stack- work/install/x86_64-osx/lts-3.0/7.10.2/bin:/Users/stephen/.stack/snapshots/x86_64-osx/lts-3.0/7.10.2/bin:/Users/stephen/.stack/programs/x86_64-osx/ghc-7.10.2/bin:/Users/stephen/Library/Haskell/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin PWD=/Users/stephen/Documents/github/commercialhaskell.com SECURITYSESSIONID=186a6 SHELL=/bin/bash SHLVL=1 SSH_AUTH_SOCK=/private/tmp/com.apple.launchd.RTM6V8Lo2y/Listeners STACK_EXE=/Library/Haskell/ghc-8.0.1-x86_64/bin/stack TERM=xterm-256color TERM_PROGRAM=Apple_Terminal TERM_PROGRAM_VERSION=377 TERM_SESSION_ID=020844C9-1E8A-410E-8892-43DC0C5A8C0B TMPDIR=/var/folders/3k/ycnfbqgx33n7qdytkl9ryx7m0000gn/T/ USER=stephen XPC_FLAGS=0x0 XPC_SERVICE_NAME=0 _=/usr/local/bin/stack __CF_USER_TEXT_ENCODING=0x1F5:0x0:0x6C }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12479> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14368: GHC 8.2.1 doesn't inform you when the monomorphism restriction kicks in anymore
by GHC 20 Oct '17

20 Oct '17

#14368: GHC 8.2.1 doesn't inform you when the monomorphism restriction kicks in anymore -------------------------------------+------------------------------------- Reporter: RyanGlScott | 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: Poor/confusing Unknown/Multiple | error message Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This program doesn't typecheck due to the monomorphism restriction: {{{#!hs f = (==) }}} In GHC 8.0.2, the error message was quite helpful in informing you of this fact: {{{ GHCi, version 8.0.2: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Main ( Bug.hs, interpreted ) Bug.hs:1:1: error: • Ambiguous type variable ‘a0’ arising from a use of ‘==’ prevents the constraint ‘(Eq a0)’ from being solved. Probable fix: use a type annotation to specify what ‘a0’ should be. These potential instances exist: instance Eq Ordering -- Defined in ‘GHC.Classes’ instance Eq Integer -- Defined in ‘integer-gmp-1.0.0.1:GHC.Integer.Type’ instance Eq a => Eq (Maybe a) -- Defined in ‘GHC.Base’ ...plus 22 others ...plus 7 instances involving out-of-scope types (use -fprint-potential-instances to see them all) • When instantiating ‘f’, initially inferred to have this overly-general type: forall a. Eq a => a -> a -> Bool NB: This instantiation can be caused by the monomorphism restriction. }}} Notice the `NB: This instantiation can be caused by the monomorphism restriction` part. But in GHC 8.2.1, this advice has mysteriously vanished! {{{ GHCi, version 8.2.1: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Main ( Bug.hs, interpreted ) Bug.hs:1:5: error: • Ambiguous type variable ‘a0’ arising from a use of ‘==’ prevents the constraint ‘(Eq a0)’ from being solved. Relevant bindings include f :: a0 -> a0 -> Bool (bound at Bug.hs:1:1) Probable fix: use a type annotation to specify what ‘a0’ should be. These potential instances exist: instance Eq Ordering -- Defined in ‘GHC.Classes’ instance Eq Integer -- Defined in ‘integer-gmp-1.0.1.0:GHC.Integer.Type’ instance Eq a => Eq (Maybe a) -- Defined in ‘GHC.Base’ ...plus 22 others ...plus 9 instances involving out-of-scope types (use -fprint-potential-instances to see them all) • In the expression: (==) In an equation for ‘f’: f = (==) | 1 | f = (==) | ^^^^ }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14368> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14363: :type hangs on coerce
by GHC 20 Oct '17

20 Oct '17

#14363: :type hangs on coerce -------------------------------------+------------------------------------- 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: -------------------------------------+------------------------------------- This works {{{ ghci -ignore-dot-ghci GHCi, version 8.2.1: http://www.haskell.org/ghc/ :? for help Prelude> import Data.Coerce Prelude Data.Coerce> :t [fmap, coerce] <interactive>:1:8: error: • Occurs check: cannot construct the infinite type: b ~ f b arising from a use of ‘coerce’ • In the expression: coerce In the expression: [fmap, coerce] }}} But doing it with `contra` {{{ Prelude Data.Coerce> contra = undefined :: Functor f => (b -> a) -> (f a -> f b) }}} it hangs {{{ Prelude Data.Coerce> :t [coerce, contra] ^CInterrupted. Prelude Data.Coerce> :t [contra, coerce] ^CInterrupted. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14363> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7259: Eta expansion of products in System FC
by GHC 20 Oct '17

20 Oct '17

#7259: Eta expansion of products in System FC -------------------------------------+------------------------------------- Reporter: simonpj | Owner: simonpj Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): > What is the status of this? It's parked at the moment. No one actually working on it that I know of. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7259#comment:21> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7259: Eta expansion of products in System FC
by GHC 20 Oct '17

20 Oct '17

#7259: Eta expansion of products in System FC -------------------------------------+------------------------------------- Reporter: simonpj | Owner: simonpj Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Iceland_jack): What is the status of this? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7259#comment:20> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14374: group by using groupWith seems stricter than it need be
by GHC 20 Oct '17

20 Oct '17

#14374: group by using groupWith seems stricter than it need be -------------------------------------+------------------------------------- Reporter: newthin | 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: -------------------------------------+------------------------------------- Using TransformListComps: {{{#!hs is = [1..10] fs = map ((,) False) is ts = map ((,) True ) is a = [(the b, take 5 n) | (b,n) <- ts ++ fs, then group by b using groupWith] b = [(the b, take 5 n) | (b,n) <- ts ++ fs ++ [undefined], then group by b using groupWith] c = take 2 b }}} As of GHC 8.2.1, both b and c fail. While getting b to work seems difficult - it would require realizing that the domain of Bool has been satisfied - c seems like it might be more feasible to get working. As a motivator, this pattern is pretty common in data science, where we want to map elements of a large list to a small result domain and get examples of those elements with each result without iterating through the whole list. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14374> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13613: Simplify fixIO
by GHC 20 Oct '17

20 Oct '17

#13613: Simplify fixIO -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.4.1 Component: Core | Version: 8.0.1 Libraries | 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: -------------------------------------+------------------------------------- Now that we have `noDuplicate#`, I think we can make `fixIO` much simpler, and perhaps also faster, using something like what we do for `ST`. {{{#!hs data Res a = Res (# State# RealWorld, a #) fixIO f = IO $ \s -> let Res r@(# _s', a #) = unIO (noDuplicate >> f a) s in r }}} If `f` forks an `IO` thread demanding `a`, the `noDuplicate` should ensure that the computation is not re-entered, and the thread should wait for the main computation to complete. So I believe, anyway. The comment about eager blackholing here is a bit vague and doesn't give an example. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13613> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14342: ghci fails to start with RebindableSyntax and OverloadedStrings
by GHC 19 Oct '17

19 Oct '17

#14342: ghci fails to start with RebindableSyntax and OverloadedStrings ----------------------------------------+------------------------------- Reporter: NeilMitchell | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.2.1 Keywords: | Operating System: Windows Architecture: Unknown/Multiple | Type of failure: GHCi crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ----------------------------------------+------------------------------- {{{ C:\Neil>ghci -XRebindableSyntax -XOverloadedStrings GHCi, version 8.2.1: http://www.haskell.org/ghc/ :? for help <interactive>:1:39: error: Not in scope: `fromString' }}} GHCi exits immediately with the above error if using both rebindable syntax and overloaded strings. This behaviour prevents starting projects which use both extensions. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14342> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14369: GHC warns an injective type family "may not be injective"
by GHC 19 Oct '17

19 Oct '17

#14369: GHC warns an injective type family "may not be injective" -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 (Type checker) | Keywords: | Operating System: Unknown/Multiple InjectiveFamilies | Architecture: | Type of failure: Poor/confusing Unknown/Multiple | error message Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{#!hs {-# LANGUAGE AllowAmbiguousTypes #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeApplications #-} {-# LANGUAGE TypeFamilyDependencies #-} {-# LANGUAGE TypeInType #-} {-# LANGUAGE TypeOperators #-} data family Sing (a :: k) data instance Sing (z :: Maybe a) where SNothing :: Sing Nothing SJust :: Sing x -> Sing (Just x) class SingKind k where type Demote k = r | r -> k fromSing :: Sing (a :: k) -> Demote k instance SingKind a => SingKind (Maybe a) where type Demote (Maybe a) = Maybe (Demote a) fromSing SNothing = Nothing fromSing (SJust x) = Just (fromSing x) f :: forall (x :: forall a. Maybe a) a. SingKind a => Sing x -> Maybe (Demote a) f = fromSing }}} {{{ GHCi, version 8.2.1: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Main ( Bug.hs, interpreted ) Bug.hs:26:5: error: • Couldn't match type ‘Demote a’ with ‘Demote a1’ Expected type: Sing (x a) -> Maybe (Demote a1) Actual type: Sing (x a) -> Demote (Maybe a) NB: ‘Demote’ is a type function, and may not be injective • In the expression: fromSing In an equation for ‘f’: f = fromSing • Relevant bindings include f :: Sing (x a) -> Maybe (Demote a1) (bound at Bug.hs:26:1) | 26 | f = fromSing | ^^^^^^^^ }}} That `NB: ‘Demote’ is a type function, and may not be injective` suggestion shouldn't be shown here, since `Demote` is definitely injective. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14369> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14365: Panic with (bogus?) deriving in hs-boot: newTyConEtadArity
by GHC 19 Oct '17

19 Oct '17

#14365: Panic with (bogus?) deriving in hs-boot: newTyConEtadArity -------------------------------------+------------------------------------- Reporter: happykitten | 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: -------------------------------------+------------------------------------- {{{ $ cat A.hs module Main where import {-# SOURCE #-} B main = return () $ cat B.hs module B where data Foo a = Foo a deriving (Functor) $ cat B.hs-boot module B where data Foo a deriving (Functor) $ ghc --make A.hs [1 of 3] Compiling B[boot] ( B.hs-boot, B.o-boot ) ghc: panic! (the 'impossible' happened) (GHC version 8.2.1 for i386-unknown-linux): newTyConEtadArity Foo 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/TyCon.hs:2149:27 in ghc:TyCon Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14365> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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