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[GHC] #12818: Allow reify to find top-level bindings in later declaration groups
by GHC 09 Nov '16

09 Nov '16

#12818: Allow reify to find top-level bindings in later declaration groups -------------------------------------+------------------------------------- Reporter: | Owner: facundo.dominguez | Type: bug | Status: new Priority: normal | Milestone: Component: Template | Version: 8.0.1 Haskell | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): Phab:D2519 | Wiki Page: -------------------------------------+------------------------------------- Some time ago, at Tweag we were considering inspecting the types of declarations added with `addTopDecls` like this: {{{ {-# LANGUAGE TemplateHaskell #-} import Language.Haskell.TH.Syntax main :: IO () main = $(do ds <- [d| f = True |] addTopDecls ds addModFinalizer $ do VarI _ t _ <- reify (mkName "f") runIO $ hPutStrLn stderr ("f :: " ++ show t) [| return () |] ) }}} `f` is not in scope when the finalizer is added. But its type would be known when the finalizer runs. This worked before the patch https://phabricator.haskell.org/D2286. There is a patch that we submitted to address this https://phabricator.haskell.org/D2519, but it turned out later that we didn't need it and the patch was considered less than ideal. We are opening this ticket to keep track of the nuance in case someone finds the patch useful later. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12818> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12748: BFD linker issue with GHCi
by GHC 08 Nov '16

08 Nov '16

#12748: BFD linker issue with GHCi ------------------------------------------+------------------------------- Reporter: hsyl20 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Linking) | Version: 8.0.1 Keywords: bfd,linker,ghci | Operating System: Linux Architecture: Unknown/Multiple | Type of failure: GHCi crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ------------------------------------------+------------------------------- On my project, GHCi seems to hang waiting for the BFD linker to complete the link of `libghc_1.so`. The hanging command has the form: `/usr/bin/ld @/tmp/ccHQ8Uzc` Using gdb, it seems the BFD linker `ld` is looping (infinitely?) into `bfd_elf_link_add_symbols`. I have tried to use the GOLD linker `ld.gold` instead on the `ccHQ8Uzc` file (removing the unsupported parameters `--hash-size=31` and `--reduce- memory-overhead`) and it links instantly. Could it be that GHC 8.0.1 generates too many symbols for the BFD linker or something like this? The BFD linker worked with GHC 7.10.3. I build the project with stack, the hanging happens with `stack repl` (GHCi's prompt never shows): {{{ @(Stack/Exec.hs:76:10) 2016-10-21 12:57:53.747332: [debug] Creating process: /usr/bin/ghc --interactive -i -odir=/home/hsyl20/travail/code/ViperVM/.stack-work/odir -hidir=/home/hsyl20/travail/code/ViperVM/.stack-work/odir -hide-all- packages -i/home/hsyl20/travail/code/ViperVM/src/lib -i/home/hsyl20/travail/code/ViperVM/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/autogen -i/home/hsyl20/travail/code/ViperVM/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build -stubdir=/home/hsyl20/travail/code/ViperVM/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build /home/hsyl20/travail/code/ViperVM/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/src/lib/ViperVM/Arch/X86_64/Linux/syscall.o /home/hsyl20/travail/code/ViperVM/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/src/lib/ViperVM/Arch/X86_64/cpuid.o -package-id=base-4.9.0.0 -package-id=containers-0.5.7.1 -package- id=list-t-1-z6InD0gw7C2QDNkG2mqUf -package- id=stm-2.4.4.1-9HlGYelGmT69YkepeDjuRg -package-id=stm- containers-0.2.15-JTVESCf1d8uCXyJbMCLfQJ -package-id=stm- linkedlist-0.1.0.0-GCpyrfjLFyWFZy8qotX7VW -package- id=hashable-1.2.4.0-GnltDttmBjG9qGzcjuPOH4 -package- id=cereal-0.5.3.0-JHJQkHEuvBGFx8XwIB7eX0 -package-id=bytestring-0.10.8.1 -package-id=system-fileio-0.3.16.3-EDef2a4Ximk1z04PLLp95q -package-id =system-filepath-0.4.13.4-24DUGoIUqZu3MxGDhYLfCN -package- id=pureMD5-2.1.3-HBUMOqRjfoe6ZpLefZBT34 -package- id=text-1.2.2.1-FgcR4Xf0VlEHD9HLxzq9WJ -package-id=filepath-1.4.1.0 -package-id=either-4.4.1.1-H4kagIugHGeIf0psi4Z0to -package- id=vector-0.11.0.0-BEDZb5o2QOhGbIm6ky7rl6 -package-id=directory-1.2.6.2 -package-id=megaparsec-5.0.1-25EMPYC0AB61WKE0MffPOR -package- id=transformers-0.5.2.0 -package-id=unix-2.7.2.0 -package- id=criterion-1.1.1.0-Hq6Gg6oBMXcJvBdkiC2CBq -package-id=c-storable- deriving-0.1.3-DIL5UpBe3Em7XwOYU01lXH -package- id=pqueue-1.3.1.1-A3EjwMk8dUf7l1Swzqrred -package- id=mtl-2.2.1-6qsR1PHUy5lL47Hpoa4jCM -package-id=template-haskell-2.11.0.0 -package-id=text-format-0.3.1.1-IMczxQgUdKA8it9OEumLMx -package- id=diagrams-1.3.0.1-9gEbAUMmu7DEIEOtgBTN65 -package-id=diagrams- lib-1.3.1.4-EWFz1jRqz29KScpInBNJM4 -package-id=diagrams- core-1.3.0.8-GGXo5v7JBpPFzOrVLJC9nc -package-id=diagrams- rasterific-1.3.1.8-2NQiYfE0qFP7UFNV120Viv -package- id=JuicyPixels-3.2.8-GcqBxM3ZIJ83rYx9ygJ0bm -package- id=loop-0.3.0-98VH1UqsOHy2KxBxA55ICY -package- id=Rasterific-0.6.1.1-3xSOfexAru5AQFIj4yXZ8f -package- id=colour-2.3.3-1clKnMqHWhQAElTFd8Ydyp -package-id=file- embed-0.0.10-IXfudWSq57y1Athysk5ifZ -i/home/hsyl20/travail/code/ViperVM/src/apps -i/home/hsyl20/travail/code/ViperVM/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/Disass/Disass-tmp -i/home/hsyl20/travail/code/ViperVM/src/apps/Elf -i/home/hsyl20/travail/code/ViperVM/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/ElfWeb/ElfWeb-tmp -package-id =happstack-server-7.4.6.2-8UX7Pc8fxznJjPPJjgBwca -package- id=lucid-2.9.6-FZpI2dlNE9n8QXjEeTfhJW -package-id=optparse- applicative-0.12.1.0-4FckWvtE7Gp1EYdm7OVbJw -i/home/hsyl20/travail/code/ViperVM/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/MemoryTest/MemoryTest-tmp -i/home/hsyl20/travail/code/ViperVM/src/apps/PlatformWeb -i/home/hsyl20/travail/code/ViperVM/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/PlatformWeb/PlatformWeb-tmp -package-id=blaze-html-0.8.1.2-2ceCZ3Fm7x67ZwaaR7uQ3C -package-id=blaze- markup-0.7.1.0-BKRb0wHFpEyDJWTsyjQqnp -package- id=network-2.6.3.1-G4Up1CPKbp7DeFsnywOnGG -i/home/hsyl20/travail/code/ViperVM/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/TestSyscalls/TestSyscalls-tmp -i/home/hsyl20/travail/code/ViperVM/src/apps/X86Web -i/home/hsyl20/travail/code/ViperVM/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/X86Web/X86Web-tmp -package- id=HTTP-4000.3.3-Fl4VtSZsPE4A3kSlCM2M0U -i/home/hsyl20/travail/code/ViperVM/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/gunzip/gunzip-tmp -i/home/hsyl20/travail/code/ViperVM/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/huffman/huffman-tmp -i/home/hsyl20/travail/code/ViperVM/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/udev/udev-tmp -i/home/hsyl20/travail/code/dynamic-linker-template -i/home/hsyl20/travail/code/dynamic-linker-template/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build/autogen -i/home/hsyl20/travail/code/dynamic-linker-template/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build -stubdir=/home/hsyl20/travail/code/dynamic-linker-template/.stack- work/dist/x86_64-linux/Cabal-1.24.0.0/build -Wall -Wall -Wall -Wall -Wall -Wall -Wall -Wall -Wall -Wall -Wall -optP-include -optP/tmp/ghci13379/cabal_macros.h -ghci-script=/tmp/ghci13379/ghci-script @(System/Process/Run.hs:103:5) GHCi, version 8.0.1: http://www.haskell.org/ghc/ :? for help }}} This is on ArchLinux, binutils-2.27, stack 1.2.0, GHC 8.0.1. Steps to reproduce (I don't have a smaller reproducing example for now): {{{ git clone https://github.com/hsyl20/ViperVM cd ViperVM stack repl # wait... the compilation is quite long # press enter when stack asks for the main module to load }}} `stack build` doesn't trigger this linker issue. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12748> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3384: Add HsSyn prettyprinter tests
by GHC 08 Nov '16

08 Nov '16

#3384: Add HsSyn prettyprinter tests -------------------------------------+------------------------------------- Reporter: igloo | Owner: Type: task | Status: new Priority: normal | Milestone: ⊥ Component: Test Suite | Version: 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 alanz): Updating https://github.com/alanz/ghc-exactprint/blob/no- annotations/tests/Test/NoAnnotations.hs#L119 to be {{{#!hs let !printed = pragmaStr ++ "\n" ++ (showSDoc_ $ GHC.ppr parsedOrig) }}} i.e. to simply `ppr` the `ParsedSource` and compare the resulting re- parsed AST. The initial results are for ghc-8.0.1, of the 823 test cases in ghc- exactprint, the straight GHC ppr fails to roundtrip 106 where it cannot be reparsed, and another 84 where the re-parsed AST does not match the original. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3384#comment:7> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12815: ghc: panic Loading temp shared object failed
by GHC 08 Nov '16

08 Nov '16

#12815: ghc: panic Loading temp shared object failed -------------------------------------+------------------------------------- Reporter: brodyberg | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: osx | Operating System: MacOS X Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I ran 'stack upgrade' and after downloading, configuring, building and registering all 178 required packages I got this: {{{ [1 of 1] Compiling Main ( /private/var/folders/23/f9jzgvns2378jgmdt5v42sj00000gn/T/stack- upgrade11535/stack-1.2.0/Setup.hs, /private/var/folders/23/f9jzgvns2378jgmdt5v42sj00000gn/T/stack- upgrade11535/stack-1.2.0/.stack- work/dist/x86_64-osx/Cabal-1.22.5.0/setup/Main.o ) Linking /private/var/folders/23/f9jzgvns2378jgmdt5v42sj00000gn/T/stack- upgrade11535/stack-1.2.0/.stack- work/dist/x86_64-osx/Cabal-1.22.5.0/setup/setup ... Configuring stack-1.2.0... stack-1.2.0: build Preprocessing library stack-1.2.0... [ 1 of 96] Compiling Text.PrettyPrint.Leijen.Extended ( src/Text/PrettyPrint/Leijen/Extended.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Text/PrettyPrint/Leijen/Extended.o ) [ 2 of 96] Compiling Stack.Ghci.Script ( src/Stack/Ghci/Script.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Stack/Ghci/Script.o ) [ 3 of 96] Compiling Stack.FileWatch ( src/Stack/FileWatch.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Stack/FileWatch.o ) [ 4 of 96] Compiling System.Process.PagerEditor ( src/System/Process/PagerEditor.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/System/Process/PagerEditor.o ) [ 5 of 96] Compiling System.Process.Log ( src/System/Process/Log.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.5.0/build/System/Process/Log.o ) [ 6 of 96] Compiling Paths_stack ( .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/autogen/Paths_stack.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Paths_stack.o ) [ 7 of 96] Compiling Path.Find ( src/Path/Find.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Path/Find.o ) [ 8 of 96] Compiling Path.Extra ( src/Path/Extra.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Path/Extra.o ) [ 9 of 96] Compiling System.Process.Read ( src/System/Process/Read.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.5.0/build/System/Process/Read.o ) ghc: panic! (the 'impossible' happened) (GHC version 7.10.3 for x86_64-apple-darwin): Loading temp shared object failed: dlopen(/var/folders/23/f9jzgvns2378jgmdt5v42sj00000gn/T/ghc29794_0/libghc_55.dylib, 5): no suitable image found. Did find: /var/folders/23/f9jzgvns2378jgmdt5v42sj00000gn/T/ghc29794_0/libghc_55.dylib: malformed mach-o: load commands size (47248) > 32768 Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Completed 178 action(s). -- While building package stack-1.2.0 using: /private/var/folders/23/f9jzgvns2378jgmdt5v42sj00000gn/T/stack- upgrade11535/stack-1.2.0/.stack- work/dist/x86_64-osx/Cabal-1.22.5.0/setup/setup --builddir=.stack- work/dist/x86_64-osx/Cabal-1.22.5.0 build lib:stack exe:stack --ghc- options " -ddump-hi -ddump-to-file" Process exited with code: ExitFailure 1 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12815> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[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] #12728: setnumcapabilities001 sometimes fails on Windows
by GHC 07 Nov '16

07 Nov '16

#12728: setnumcapabilities001 sometimes fails on Windows --------------------------------------+---------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Runtime System | Version: 8.0.1 Keywords: | Operating System: Windows Architecture: x86_64 (amd64) | Type of failure: Runtime crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: --------------------------------------+---------------------------------- I have seen the `setnumcapabilities001` test fail at least once on Windows ([[https://phabricator.haskell.org/harbormaster/build/14178/?l=0]] It seems that the assertion `ASSERT(n_idle == 0);` in `Schedule.scheduleDoGC` is to blame in this particular case. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12728> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12746: Assertion failed with BuildFlavour = devel2 (one more)
by GHC 07 Nov '16

07 Nov '16

#12746: Assertion failed with BuildFlavour = devel2 (one more) -------------------------------------+------------------------------------- Reporter: pacak | 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 or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Affected versions: ghc 8.0.1 and ghc git master as of 21 Oct 2016 (c23dc61) It compiles fine on first time but fails to compile on second attempt. Using -fforce-recomp recompiles both files and bug is not triggered. {{{ % ls A.hs B.hs % cat A.hs }}} {{{#!hs module A where import B foo a = case a of Foo -> True _ -> False }}} {{{ % cat B.hs }}} {{{#!hs {-# LANGUAGE PatternSynonyms, ScopedTypeVariables #-} module B where pattern Foo = 0x00000001 :: Int }}} {{{ % ghc -O2 A.hs ; touch A.hs ; ghc -O2 A.hs [1 of 2] Compiling B ( B.hs, B.o ) [2 of 2] Compiling A ( A.hs, A.o ) [2 of 2] 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/iface/BuildTyCl.hs:195:404 in ghc:BuildTyCl [] ~ [] [] ~ [] Int ~ Int [] ~ [] [] ~ [] [] ~ [Void#] Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12746> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12738: GHC drops -optl flags
by GHC 07 Nov '16

07 Nov '16

#12738: GHC drops -optl flags -------------------------------------+------------------------------------- Reporter: niteria | Owner: Type: bug | Status: new Priority: high | 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: -------------------------------------+------------------------------------- This is a regression between GHC 7.10 and GHC 8.0. Repro script: {{{ GHC_ROOT=$HOME/local/ghc-8.0.1-facebook # built 8.0.1 branch, fails with recent HEAD as well GHC=$GHC_ROOT/inplace/bin/ghc-stage2 GPP=g++ touch build_info.o # irrelevant "$GHC" -no-auto-link-packages -pgml"$GPP" -o a.out build_info.o -optl- Xlinker -optl$GHC_ROOT/libraries/ghc-prim/dist-install/build/libHSghc- prim-0.5.0.0.a -optl-Xlinker -optl-u -optl-Xlinker -optlghczmprim_GHCziTypes_Izh_static_info -v }}} Output from GHC 7.10 (expected): {{{ Glasgow Haskell Compiler, Version 7.10.2, stage 2 booted by GHC version 7.8.4 Using binary package database: /usr/local/haskell/ghc-7.10.2-x86_64/lib/ghc-7.10.2/package.conf.d/package.cache Using binary package database: /home/bnitka/.ghc/x86_64-linux-7.10.2/package.conf.d/package.cache wired-in package ghc-prim mapped to ghc- prim-0.4.0.0-af16264bc80979d06e37ac63e3ba9a21 wired-in package integer-gmp mapped to integer- gmp-1.0.0.0-8e0f14d0262184533b417ca1f8b44482 wired-in package base mapped to base-4.8.1.0-4f7206fd964c629946bb89db72c80011 wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template- haskell-2.10.0.0-90e8393d65f4ae44cb2026177a257f28 wired-in package ghc mapped to ghc-7.10.2-787f1a784665fb3ac2a1be1d9d85245b wired-in package dph-seq not found. wired-in package dph-par not found. Hsc static flags: Created temporary directory: /tmp/ghc2775839_0 *** C Compiler: /usr/bin/gcc -fno-stack-protector -DTABLES_NEXT_TO_CODE -c /tmp/ghc2775839_0/ghc_1.c -o /tmp/ghc2775839_0/ghc_2.o -I/usr/local/haskell/ghc-7.10.2-x86_64/lib/ghc-7.10.2/include *** C Compiler: /usr/bin/gcc -fno-stack-protector -DTABLES_NEXT_TO_CODE -c /tmp/ghc2775839_0/ghc_3.s -o /tmp/ghc2775839_0/ghc_4.o -I/usr/local/haskell/ghc-7.10.2-x86_64/lib/ghc-7.10.2/include *** Linker: 'g++' '-Wl,--hash-size=31' -Wl,--reduce-memory-overheads -Wl,--no-as- needed -Xlinker /home/bnitka/local/ghc-8.0.1-facebook/libraries/ghc-prim /dist-install/build/libHSghc-prim-0.5.0.0.a -Xlinker -u -Xlinker ghczmprim_GHCziTypes_Izh_static_info -o a.out build_info.o /tmp/ghc2775839_0/ghc_2.o /tmp/ghc2775839_0/ghc_4.o build_info.o: file not recognized: File truncated collect2: ld returned 1 exit status *** Deleting temp files: Deleting: /tmp/ghc2775839_0/ghc_4.o /tmp/ghc2775839_0/ghc_3.s /tmp/ghc2775839_0/ghc_2.o /tmp/ghc2775839_0/ghc_1.c *** Deleting temp dirs: Deleting: /tmp/ghc2775839_0 }}} Output from GHC 8.0: {{{ Glasgow Haskell Compiler, Version 8.0.1.20160729, stage 2 booted by GHC version 7.10.2 Using binary package database: /data/users/bnitka/ghc-8.0.1-facebook/inplace/lib/package.conf.d/package.cache loading package database /data/users/bnitka/ghc-8.0.1-facebook/inplace/lib/package.conf.d wired-in package ghc-prim mapped to ghc-prim-0.5.0.0 wired-in package integer-gmp mapped to integer-gmp-1.0.0.1 wired-in package base mapped to base-4.9.0.0 wired-in package rts mapped to rts wired-in package template-haskell mapped to template-haskell-2.11.0.0 wired-in package ghc mapped to ghc-8.0.1.20160729 wired-in package dph-seq not found. wired-in package dph-par not found. Hsc static flags: Created temporary directory: /tmp/ghc2778573_0 *** C Compiler: /usr/bin/gcc -fno-stack-protector -DTABLES_NEXT_TO_CODE -c /tmp/ghc2778573_0/ghc_1.c -o /tmp/ghc2778573_0/ghc_2.o -I/data/users/bnitka/ghc-8.0.1-facebook/rts/dist/build -I/data/users/bnitka/ghc-8.0.1-facebook/includes -I/data/users/bnitka/ghc-8.0.1-facebook/includes/dist- derivedconstants/header *** C Compiler: /usr/bin/gcc -fno-stack-protector -DTABLES_NEXT_TO_CODE -c /tmp/ghc2778573_0/ghc_4.s -o /tmp/ghc2778573_0/ghc_5.o *** Linker: 'g++' '-Wl,--hash-size=31' -Wl,--reduce-memory-overheads -Wl,--no-as- needed -Xlinker -Xlinker -u -Xlinker ghczmprim_GHCziTypes_Izh_static_info -o a.out -Wl,--gc-sections build_info.o /tmp/ghc2778573_0/ghc_2.o /tmp/ghc2778573_0/ghc_5.o /home/bnitka/local/ghc-8.0.1-facebook/libraries /ghc-prim/dist-install/build/libHSghc-prim-0.5.0.0.a g++: ghczmprim_GHCziTypes_Izh_static_info: No such file or directory *** Deleting temp files: Deleting: /tmp/ghc2778573_0/ghc_7.rsp /tmp/ghc2778573_0/ghc_6.rsp /tmp/ghc2778573_0/ghc_5.o /tmp/ghc2778573_0/ghc_4.s /tmp/ghc2778573_0/ghc_3.rsp /tmp/ghc2778573_0/ghc_2.o /tmp/ghc2778573_0/ghc_1.c *** Deleting temp dirs: Deleting: /tmp/ghc2778573_0 `g++' failed in phase `Linker'. (Exit code: 1) }}} The relevant difference is in the flags passed to `g++`. {{{ 'g++' '-Wl,--hash-size=31' -Wl,--reduce-memory-overheads -Wl,--no-as- needed -Xlinker /home/bnitka/local/ghc-8.0.1-facebook/libraries/ghc-prim /dist-install/build/libHSghc-prim-0.5.0.0.a -Xlinker -u -Xlinker ghczmprim_GHCziTypes_Izh_static_info -o a.out build_info.o /tmp/ghc2775839_0/ghc_2.o /tmp/ghc2775839_0/ghc_4.o }}} vs {{{ 'g++' '-Wl,--hash-size=31' -Wl,--reduce-memory-overheads -Wl,--no-as- needed -Xlinker -Xlinker -u -Xlinker ghczmprim_GHCziTypes_Izh_static_info -o a.out -Wl,--gc-sections build_info.o /tmp/ghc2778573_0/ghc_2.o /tmp/ghc2778573_0/ghc_5.o /home/bnitka/local/ghc-8.0.1-facebook/libraries /ghc-prim/dist-install/build/libHSghc-prim-0.5.0.0.a }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12738> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12810: -Wredundant-constraints doesn't factor in associated type families
by GHC 07 Nov '16

07 Nov '16

#12810: -Wredundant-constraints doesn't factor in associated type families -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect Unknown/Multiple | error/warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- If I compile this code: {{{#!hs {-# LANGUAGE TypeFamilies #-} module M where class C a where type T a instance C a => C [a] where type T [a] = T a }}} with `-Wredundant-constraints` enabled, it complains: {{{ $ /opt/ghc/head/bin/ghc -Wredundant-constraints M.hs [1 of 1] Compiling M ( M.hs, M.o ) M.hs:7:10: warning: [-Wredundant-constraints] • Redundant constraint: C a • In the instance declaration for ‘C [a]’ }}} I don't think this is right. The RHS of `T [a]` won't be able to reduce unless there's a `T a` instance available–that is, unless there's a `C a` instance available, which is what the context provides, making it non- redundant. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12810> 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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