August 2014 - ghc-devs

Trouble committing
by Andreas Voellmy 14 Dec '14

14 Dec '14

Hi GHCers, I just fixed a bug (#9423) and went through the Phab workflow. Then I did a fresh checkout from git and ran: $ git checkout master $ arc patch --nobranch D129 $ git push origin master as explained on https://ghc.haskell.org/trac/ghc/wiki/Phabricator, but on the last command I get this error: fatal: remote error: access denied or repository not exported: /ghc.git Maybe I just no longer have commit access to ghc? If so, could someone restore my access? Or I'd be happy if someone else can push the patch. Thanks, Andi

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Core libraries bug tracker
by Simon Peyton Jones 03 Nov '14

03 Nov '14

Edward, and core library colleagues, This came up in our weekly GHC discussion * Does the Core Libraries Committee have a Trac? Surely, surely you should, else you'll lose track of issues. * Would you like to use GHC's Trac for the purpose? Advantages: o People often report core library issues on GHC's Trac anyway, so telling them to move it somewhere else just creates busy-work --- and maybe they won't bother, which leaves it in our pile. o Several of these libraries are closely coupled to GHC, and you might want to milestone some library tickets with an upcoming GHC release * If so we'd need a canonical way to identify tickets as CLC issues. Perhaps by making "core-libraries" the owner? Or perhaps the "Component" field? * Some core libraries (e.g. random) have a maintainer that isn't the committee. So that maintainer should be the owner of the ticket. Or the CLC might like a particular member to own a ticket. Either way, that suggest using the "Component" field to identify CLC tickets * Or maybe you want a Trac of your own? The underlying issue from our end is that we'd like a way to * filter out tickets that you are dealing with * and be sure you are dealing with them * without losing track of milestones... i.e. when building a release we want to be sure that important tickets are indeed fixed before releasing Simon

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old-time.git/tests/time004.hs is DST-sensitive :-/
by Herbert Valerio Riedel 26 Oct '14

26 Oct '14

Hi *, if anyone wonders, why TEST=time004 suddenly fails: it's sensitive to DST (and depends on your system's TZ-config): http://git.haskell.org/packages/old-time.git/blob/HEAD:/tests/time004.hs For me, the comparison this unit-test checks now suddenly fails, because the DST-switch occurs on different days in 2012 and 2013 in my TZ, i.e. length "Sun Oct 27 10:56:42 CET 2013" /= length "Sat Oct 27 11:56:42 CEST 2012" Does anyone happen to know what the rationale behind this 'time004' unit test was? Cheers, hvr

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I'm going to disable DPH until someone starts maintaining it
by Austin Seipp 16 Oct '14

16 Oct '14

Everyone, I'm still working on the AMP, and of course, things aren't going as planned. Why is that? I'm attempting to update `vector` to the latest version from GitHub, as it has some fixes we need for AMP. Mostly, it has some instances we need. Unfortunately, this is basically impossible because dph is locked into a vector fork of ours that we have been maintaining for *months*, and doesn't work with the latest vector upstream (0.11) due to changes in the stream representation. This means I can either: 1) Fix everything in DPH to work with vector 0.11, which is probably going to take a lot of work. 2) Merely fix our fork of vector and let things continue working. This is much easier than #1. Now, you might say that #2 is clearly a preferable solution, and it's very easy - so just do that, Austin! But I don't want to do it. You could say this is the straw that has broken the camel's back. Why? Because I'm afraid I just don't have any more patience for DPH, I'm tired of fixing it, and it takes up a lot of extra time to build, and time to maintain. In fact I'm the only person who's committed to it in *months*, and that has only been to fix breakage. The hackage packages are out of date and sync with what's in the repository (I can't upload them, nor can anyone else besides Ben I believe). So - why are we still building it, exactly? We had a conversation about this months ago. The concern was that things would break and we don't want it to fall out of sync. We're at that point right now - things are breaking, it's out of sync, and it's a pain to keep fixing it, and the actual *benefits* we get from doing so are completely unclear to me. It basically just seems like extra work for nothing, honestly. Unless someone speaks[1] up *very* soon, I'm going to disable DPH during ./validate and the regular build. It will be possible to build it with a '--dph' flag (the dual of the current '--no-dph' flag), although it will be broken very soon with these incoming changes. Providing someone starts fixing it, I'm completely, 100% open to re-enabling it in ./validate by default. But I'm personally tired of fixing it. I'm CC'ing Manuel, Geoff & Ben for their inputs. [1] And by 'speak up', I mean I'd like to see someone actively step forward address my concerns above in a decisive manner. With patches. -- Regards, Austin Seipp, Haskell Consultant Well-Typed LLP, http://www.well-typed.com/

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FFI: c/c++ struct on stack as an argument or return value
by Yuras Shumovich 08 Oct '14

08 Oct '14

Hi, Right now ghc's FFI doesn't support c/c++ structures. Whenever we have foreign function that accepts or returns struct by value, we have to create wrapper that accepts or returns pointer to struct. It is inconvenient, but actually not a big deal. But there is no easy workaround when you want to export haskell function to use it with c/c++ API that requires structures to be passed by value (Usually it is a callback in c/c++ API. You can't change it's signature, and if it doesn't provide some kind of "void* userdata", then you are stuck.) I'm interested in fixing that. I'm going to start with 'foreign import "wrapper" ...' stuff. Calling conventions for passing c/c++ structures by value are pretty tricky and platform/compiler specific. So initially I'll use libffi for that (it will work when USE_LIBFFI_FOR_ADJUSTORS is defined, see rts/Adjustor.c). It will allow me to explore design space without bothering about low level implementation details. Later it could be implemented for native (non-libffi) adjustors. Is anybody interested it that? I appreciate any comments/ideas. Right now I don't have clear design. It would be nice to support plain haskell data types that are 1) not recursive, 2) has one constructor and 3) contains only c/c++ types. But it doesn't work with c/c++ unions. Any ideas are welcome. An example how to use libffi with structures: http://www.atmark-techno.com/~yashi/libffi.html#Structures Thanks, Yuras

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HEADS UP: Running cabal install with the latest GHC
by Edward Z. Yang 28 Sep '14

28 Sep '14

Hey all, SPJ pointed out to me today that if you try to run: cabal install --with-ghc=/path/to/inplace/bin/ghc-stage2 with the latest GHC HEAD, this probably will not actually work, because your system installed version of Cabal is probably too old to deal with the new package key stuff in HEAD. So, how do you get a version of cabal-install (and Cabal) which is new enough to do what you need it to? The trick is to compile Cabal using your /old/ GHC. Step-by-step, this involves cd'ing into libraries/Cabal/Cabal and running `cabal install` (or install it in a sandbox, if you like) and then cd'ing to libraries/Cabal/cabal-install and cabal install'ing that. Cabal devs, is cutting a new release of Cabal and cabal-install in the near future possible? In that case, users can just cabal update; cabal install cabal-install and get a version of Cabal which will work for them. Cheers, Edward

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GHC AST Annotations
by Alan & Kim Zimmerman 26 Sep '14

26 Sep '14

Now that the landmines have hopefully been cleared from the AST via [1] I would like to propose changing the location information in the AST. Right now the locations of syntactic markers such as do/let/where/in/of in the source are discarded from the AST, although they are retained in the rich token stream. The haskell-src-exts package deals with this by means of using the SrcSpanInfo data type [2] which contains the SrcSpan as per the current GHC Located type but also has a list of SrcSpan s for the syntactic markers, depending on the particular AST fragment being annotated. In addition, the annotation type is provided as a parameter to the AST, so that it can be changed as required, see [3]. The motivation for this change is then 1. Simplify the roundtripping and modification of source by explicitly capturing the missing location information for the syntactic markers. 2. Allow the annotation to be a parameter so that it can be replaced with a different one in tools, for example HaRe would include the tokens for the AST fragment leaves. 3. Aim for some level compatibility with haskell-src-exts so that tools developed for it could be easily ported to GHC, for example exactprint [4]. I would like feedback as to whether this would be acceptable, or if the same goals should be achieved a different way. Regards Alan [1] https://phabricator.haskell.org/D157 [2] http://hackage.haskell.org/package/haskell-src-exts-1.15.0.1/docs/Language-… [3] http://hackage.haskell.org/package/haskell-src-exts-1.15.0.1/docs/Language-… [4] http://hackage.haskell.org/package/haskell-src-exts-1.15.0.1/docs/Language-…

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Problems with building GHC 7.8.3 on Windows
by Marek Wawrzos 06 Sep '14

06 Sep '14

Hello, I am trying to compile GHC 7.8.3 on Windows. I was following the instructions from the GHC wiki, but I have encountered errors during the make process. I have filed a bug report describing my issue: https://ghc.haskell.org/trac/ghc/ticket/9513 Does anyone had working setup for building GHC and would be willing to share information on how to achieve it? -- Best regards, Marek Wawrzos

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Building HEAD (e83e873d) on mips64el: unknown package: old-locale-1.0.0.6
by Nikita Karetnikov 06 Sep '14

06 Sep '14

$ git clone git://github.com/ghc/ghc.git ghc-github $ cd ghc-github $ ./sync-all get $ perl boot $ ./configure $ make […] "inplace/bin/ghc-stage1" -this-package-key rts -shared -dynamic -dynload deploy -no-auto-link-packages -Lrts/dist/build -lffi -optl-Wl,-rpath -optl-Wl,'$ORIGIN' -optl-Wl,-zorigin `cat rts/dist/libs.depend` rts/dist/build/Adjustor.dyn_o rts/dist/build/Arena.dyn_o rts/dist/build/Capability.dyn_o rts/dist/build/CheckUnload.dyn_o rts/dist/build/ClosureFlags.dyn_o rts/dist/build/Disassembler.dyn_o rts/dist/build/FileLock.dyn_o rts/dist/build/Globals.dyn_o rts/dist/build/Hash.dyn_o rts/dist/build/Hpc.dyn_o rts/dist/build/HsFFI.dyn_o rts/dist/build/Inlines.dyn_o rts/dist/build/Interpreter.dyn_o rts/dist/build/LdvProfile.dyn_o rts/dist/build/Linker.dyn_o rts/dist/build/Messages.dyn_o rts/dist/build/OldARMAtomic.dyn_o rts/dist/build/Papi.dyn_o rts/dist/build/Printer.dyn_o rts/dist/build/ProfHeap.dyn_o rts/dist/build/Profiling.dyn_o rts/dist/build/Proftimer.dyn_o rts/dist/build/RaiseAsync.dyn_o rts/dist/build/RetainerProfile.dyn_o rts/dist/build/RetainerSet.dyn_o rts/dist/build/RtsAPI.dyn_o rts/dist/build/RtsDllMain.dyn_o rts/dist/build/RtsFlags.dyn_o rts/dist/build/RtsMain.dyn_o rts/dist/build/RtsMessages.dyn_o rts/dist/build/RtsStartup.dyn_o rts/dist/build/RtsUtils.dyn_o rts/dist/build/STM.dyn_o rts/dist/build/Schedule.dyn_o rts/dist/build/Sparks.dyn_o rts/dist/build/Stable.dyn_o rts/dist/build/Stats.dyn_o rts/dist/build/StgCRun.dyn_o rts/dist/build/StgPrimFloat.dyn_o rts/dist/build/Task.dyn_o rts/dist/build/ThreadLabels.dyn_o rts/dist/build/ThreadPaused.dyn_o rts/dist/build/Threads.dyn_o rts/dist/build/Ticky.dyn_o rts/dist/build/Timer.dyn_o rts/dist/build/Trace.dyn_o rts/dist/build/WSDeque.dyn_o rts/dist/build/Weak.dyn_o rts/dist/build/hooks/FlagDefaults.dyn_o rts/dist/build/hooks/MallocFail.dyn_o rts/dist/build/hooks/OnExit.dyn_o rts/dist/build/hooks/OutOfHeap.dyn_o rts/dist/build/hooks/StackOverflow.dyn_o rts/dist/build/sm/BlockAlloc.dyn_o rts/dist/build/sm/Compact.dyn_o rts/dist/build/sm/Evac.dyn_o rts/dist/build/sm/GC.dyn_o rts/dist/build/sm/GCAux.dyn_o rts/dist/build/sm/GCUtils.dyn_o rts/dist/build/sm/MBlock.dyn_o rts/dist/build/sm/MarkWeak.dyn_o rts/dist/build/sm/Sanity.dyn_o rts/dist/build/sm/Scav.dyn_o rts/dist/build/sm/Storage.dyn_o rts/dist/build/sm/Sweep.dyn_o rts/dist/build/eventlog/EventLog.dyn_o rts/dist/build/posix/GetEnv.dyn_o rts/dist/build/posix/GetTime.dyn_o rts/dist/build/posix/Itimer.dyn_o rts/dist/build/posix/OSMem.dyn_o rts/dist/build/posix/OSThreads.dyn_o rts/dist/build/posix/Select.dyn_o rts/dist/build/posix/Signals.dyn_o rts/dist/build/posix/TTY.dyn_o rts/dist/build/Apply.dyn_o rts/dist/build/Exception.dyn_o rts/dist/build/HeapStackCheck.dyn_o rts/dist/build/PrimOps.dyn_o rts/dist/build/StgMiscClosures.dyn_o rts/dist/build/StgStartup.dyn_o rts/dist/build/StgStdThunks.dyn_o rts/dist/build/Updates.dyn_o rts/dist/build/AutoApply.dyn_o -fPIC -dynamic -H32m -O -Iincludes -Iincludes/dist -Iincludes/dist-derivedconstants/header -Iincludes/dist-ghcconstants/header -Irts -Irts/dist/build -DCOMPILING_RTS -this-package-key rts -optc-DNOSMP -dcmm-lint -i -irts -irts/dist/build -irts/dist/build/autogen -Irts/dist/build -Irts/dist/build/autogen -O2 -fno-use-rpaths -optl-Wl,-zorigin -o rts/dist/build/libHSrts-ghc7.9.20140809.so /usr/bin/ld: rts/dist/build/Adjustor.dyn_o: relocation R_MIPS_HI16 against `__gnu_local_gp' can not be used when making a shared object; recompile with -fPIC rts/dist/build/Adjustor.dyn_o: could not read symbols: Bad value collect2: ld returned 1 exit status make[1]: *** [rts/dist/build/libHSrts-ghc7.9.20140809.so] Error 1 make[1]: *** Waiting for unfinished jobs.... make: *** [all] Error 2 After making this change (see #8857) $ diff -Nru config.mk.in-orig config.mk.in --- config.mk.in-orig 2014-08-11 04:39:24.257232224 +0000 +++ config.mk.in 2014-08-11 04:41:50.666057938 +0000 @@ -99,7 +99,8 @@ x86_64-unknown-mingw32 \ i386-unknown-mingw32 \ sparc-sun-solaris2 \ - sparc-unknown-linux + sparc-unknown-linux \ + mipsel-unknown-linux ifeq "$(SOLARIS_BROKEN_SHLD)" "YES" NoSharedLibsPlatformList += i386-unknown-solaris2 and running $ make distclean $ ./configure $ make it failed with a different error: "inplace/bin/ghc-stage1" -hisuf hi -osuf o -hcsuf hc -static -H32m -O -this-package-key time_KUji6QoLFw0LtcZkg4b7t4 -hide-all-packages -i -ilibraries/time/. -ilibraries/time/dist-install/build -ilibraries/time/dist-install/build/autogen -Ilibraries/time/dist-install/build -Ilibraries/time/dist-install/build/autogen -Ilibraries/time/include -optP-DLANGUAGE_Rank2Types -optP-DLANGUAGE_DeriveDataTypeable -optP-DLANGUAGE_StandaloneDeriving -optP-include -optPlibraries/time/dist-install/build/autogen/cabal_macros.h -package-key base_DiPQ1siqG3SBjHauL3L03p -package-key deeps_L0rJEVU1Zgn8x0Qs5aTOsU -package-key oldlo_EJWcQwUgW2gEwNtIuJl2P8 -Wall -XHaskell2010 -XCPP -XRank2Types -XDeriveDataTypeable -XStandaloneDeriving -O2 -no-user-package-db -rtsopts -odir libraries/time/dist-install/build -hidir libraries/time/dist-install/build -stubdir libraries/time/dist-install/build -c libraries/time/./Data/Time/Clock/CTimeval.hs -o libraries/time/dist-install/build/Data/Time/Clock/CTimeval.o <command line>: unknown package: old-locale-1.0.0.6 make[1]: *** [libraries/time/dist-install/build/Data/Time/Clock/CTimeval.o] Error 1 make[1]: *** Waiting for unfinished jobs.... make: *** [all] Error 2 ‘libraries/old-locale’ is present in the tree and is not empty. Is it necessary to run anything else after distclean? According to ‘MAKEHELP’, it is not needed, so I’m puzzled.

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Extending fold/build fusion
by Akio Takano 05 Sep '14

05 Sep '14

Hi, I have been thinking about how foldl' can be turned into a good consumer, and I came up with something that I thought would work. So I'd like to ask for opinions from the ghc devs: if this idea looks good, if it is a known bad idea, if there is a better way to do it, etc. The main idea is to have an extended version of foldr: -- | A mapping between @a@ and @b@. data Wrap a b = Wrap (a -> b) (b -> a) foldrW :: (forall e. Wrap (f e) (e -> b -> b)) -> (a -> b -> b) -> b -> [a] -> b foldrW (Wrap wrap unwrap) f z0 list0 = wrap go list0 z0 where go = unwrap $ \list z' -> case list of [] -> z' x:xs -> f x $ wrap go xs z' This allows the user to apply an arbitrary "worker-wrapper" transformation to the loop. Using this, foldl' can be defined as newtype Simple b e = Simple { runSimple :: e -> b -> b } foldl' :: (b -> a -> b) -> b -> [a] -> b foldl' f initial xs = foldrW (Wrap wrap unwrap) g id xs initial where wrap (Simple s) e k a = k $ s e a unwrap u = Simple $ \e -> u e id g x next acc = next $! f acc x The wrap and unwrap functions here ensure that foldl' gets compiled into a loop that returns a value of 'b', rather than a function 'b -> b', effectively un-CPS-transforming the loop. I put preliminary code and some more explanation on Github: https://github.com/takano-akio/ww-fusion Thank you, Takano Akio

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