- ghc-devs - Haskell.org

in-tree API Annotations
by Alan & Kim Zimmerman 26 May '20

26 May '20

I am trying to get my head around the best way to put the API annotations into the GHC ParsedSource directly, so ghc-exactprint can move in to GHC and make the development/testing process easier. Prior to API Annotations, there were very few locations in the AST, as they were added as anchor points for the annotations, being separate from the AST and indexed to it by the SrcSpan. I am intending to strip out the superfluous ones, in particular all the (Located RdrName), replacing them with something like data ApiAnnName a = N ApiAnn a instead. So they would still be wrapped, but the annotations would be only ones that can occur for a RdrName, such a backticks, parens, and so on. Does anything actually need these locations now they are there? I am thinking specifically of the .hie files, as the `toHie` instances seem to make use of locations extensively. Regards Alan

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8.12 plans
by Ben Gamari 24 May '20

24 May '20

Hi everyone, The time is again upon us to start thinking about release planning for the next major release: GHC 8.12. In keeping with our 6-month release schedule, I propose the following schedule: * Mid-June 2020: Aim to have all major features in the tree * Late-June 2020: Cut the ghc-8.12 branch * June - August 2020: 3 alpha releases * 1 September 2020: beta release * 25 September 2020: Final 8.12.1 release So, if you have any major features which you would like to merge for 8.12, now is the time to start planning how to wrap them up in the next month or so. As always, do let me know if you think this may be problematic and we can discuss options. Cheers, - Ben

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profiling a constructor?
by Richard Eisenberg 24 May '20

24 May '20

Hi devs, Is there a way to count the number of times a particular constructor is allocated? I might want to know, say, the total number of cons cells allocated over the course of a program, or (in my actual case) the total number of FunTy cells allocated over the course of a program. I can try to do this with an SCC. But it's very clunky: * The constructor may be used in a number of places; each such place would need the SCC. * SCCs can interfere with optimizations. In my use case, this would negate the usefulness of the exercise entirely, as I think some of the structures I wish to observe should never come into being, due to optimizations (e.g. case-of-known-constructor after inlining). Surely, the RTS must be able to count the number of times a constructor is used. But is there any way to access such a feature? If others agree that this would sometimes be helpful, perhaps we can build the feature. Now is not the first time I've wanted this. Thanks! Richard

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How to use the compact regions API to write a compact to a file?
by Matthew Pickering 22 May '20

22 May '20

Dear devs, I have been under the impression for a while that you can write a compact region to a file and the functions in GHC.Compact.Serialized also seem to suggest this is possible. https://hackage.haskell.org/package/ghc-compact-0.1.0.0/docs/GHC-Compact-Se… It seems like there are some functions missing from the API. There is "importCompactByteStrings" but no function in the API which produces ByteStrings. So in order to use this function you have to convert a SerializedCompact into a ByteString, but in what specific way? Has anyone got any code where they have tried to do this? Cheers, Matt

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build ghc with make (ghc-boot-th broken deps)
by Daneel Yaitskov 21 May '20

21 May '20

Hi List, I pulled ghc repo (568d7279a) and trying to build with following env: Ghc from stack (8.8.3). I made links to ghc and ghc-pkg in /usr/bin ./boot is passing well, but ./configure breaks on ghc-boot step. I have no idea how could I fix this issue. I manually modified dep versions in to what I have for ghc-8.8.3 and issue with ghc-boot-th disappeared and appeared parsec libraries/bootstrapping.conf/binary-0.8.7.0.conf depends: array-0.5.4.0 base-4.13.0.0 bytestring-0.10.10.0 containers-0.6.2.1 but there was depends: array-0.5.3.0 base-4.12.0.0 bytestring-0.10.8.2 containers-0.6.0.1 Where is actual problem? Old cabal? 10:45$ cabal --version cabal-install version 1.24.0.2 compiled using version 1.24.2.0 of the Cabal library Configuring ghc-boot-th-8.11.0.20200520... "/usr/bin/ghc-pkg" update -v0 --force --package-db=libraries/bootstrapping.conf libraries/ghc-boot-th/dist-boot/inplace-pkg-config "inplace/bin/ghc-cabal" configure libraries/ghc-boot dist-boot --with-ghc="/usr/bin/ghc" --with-ghc-pkg="/usr/bin/ghc-pkg" --package-db=/home/dan/demo/haskell/compiler/ghc/libraries/bootstrapping.conf --disable-library-for-ghci --enable-library-vanilla --enable-library-for-ghci --disable-library-profiling --disable-shared --with-hscolour="/home/dan/.cabal/bin/HsColour" --configure-option=CFLAGS="-Wall -Werror=unused-but-set-variable -Wno-error=inline -iquote /home/dan/demo/haskell/compiler/ghc/libraries/ghc-boot" --configure-option=LDFLAGS=" " --configure-option=CPPFLAGS=" " --gcc-options="-Wall -Werror=unused-but-set-variable -Wno-error=inline -iquote /home/dan/demo/haskell/compiler/ghc/libraries/ghc-boot " --constraint "binary == 0.8.7.0" --constraint "transformers == 0.5.6.2" --constraint "mtl == 2.2.2" --constraint "hpc == 0.6.1.0" --constraint "ghc-boot-th == 8.11.0.20200520" --constraint "ghc-boot == 8.11.0.20200520" --constraint "template-haskell == 2.17.0.0" --constraint "text == 1.2.4.0" --constraint "parsec == 3.1.14.0" --constraint "Cabal == 3.3.0.0" --constraint "ghc-heap == 8.11.0.20200520" --constraint "exceptions == 0.10.4" --constraint "ghci == 8.11.0.20200520" --constraint "terminfo == 0.4.1.4" --with-gcc="gcc" --with-ld="ld.gold" --with-ar="ar" --with-alex="/home/dan/.cabal/bin/alex" --with-happy="/home/dan/.cabal/bin/happy" Configuring ghc-boot-8.11.0.20200520... Error: The following packages are broken because other packages they depend on are missing. These broken packages must be rebuilt before they can be used. installed package binary-0.8.7.0 is broken due to missing package array-0.5.3.0, base-4.12.0.0, bytestring-0.10.8.2, containers-0.6.0.1 libraries/ghc-boot/ghc.mk:3: recipe for target 'libraries/ghc-boot/dist-boot/package-data.mk' failed make[1]: *** [libraries/ghc-boot/dist-boot/package-data.mk] Error 1 Makefile:123: recipe for target 'all' failed make: *** [all] Error 2 -- Best regards, Daniil Iaitskov

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Brief GitLab reboot
by Ben Gamari 19 May '20

19 May '20

Hi all, GitLab will be down for about 10 minutes for a quick reboot. Apologies for the inconvenience. Cheers, - Ben

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GitLab is down ?
by Richard Eisenberg 19 May '20

19 May '20

Hi devs, gitlab.haskell.org is reporting an error 500. :( Help? Thanks! Richard

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[ANNOUNCE] Glasgow Haskell Compiler 8.10.1 released
by Ben Gamari 18 May '20

18 May '20

Hello all, The GHC team is happy to announce the availability of GHC 8.10.1. Source and binary distributions are available at the usual place: https://downloads.haskell.org/ghc/8.10.1/ GHC 8.10.1 brings a number of new features including: * The new UnliftedNewtypes extension allowing newtypes around unlifted types. * The new StandaloneKindSignatures extension allows users to give top-level kind signatures to type, type family, and class declarations. * A new warning, -Wderiving-defaults, to draw attention to ambiguous deriving clauses * A number of improvements in code generation, including changes * A new GHCi command, :instances, for listing the class instances available for a type. * An upgraded Windows toolchain lifting the MAX_PATH limitation * A new, low-latency garbage collector. * Improved support profiling, including support for sending profiler samples to the eventlog, allowing correlation between the profile and other program events Note that at the moment we still require that macOS Catalina users exempt the binary distribution from the notarization requirement by running `xattr -cr .` on the unpacked tree before running `make install`. This situation will hopefully be improved for GHC 8.10.2 with the resolution of #17418 [1]. Cheers, - Ben [1] https://gitlab.haskell.org/ghc/ghc/issues/17418

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Iface loading type reflection module bindings
by Josh Meredith 17 May '20

17 May '20

Hi, In attempting to implement an extensible interface field for Core bindings based on my previous interfaces patch, I've run into problems with deserialising the special type reflection `$trModule` bindings generated by `GHC.Tc.Instance.Typeable.mkTypeableBinds`. These bindings are then stored in the `ModGuts.mg_binds` along with the real exported top-level bindings of the module. Specifically, attempting to load the iface right-hand side expressions with `tcIfaceExpr` results in the error "Iface id out of scope" from `GHC.Iface.Env.tcIfaceLclId`. My understanding is that this may be because the binding is attempting to look itself up within the interface loading environment, without being bound yet - though it's unclear to me whether this is the correct behaviour for these special type reflection bindings, or if there's some special treatment that should be instead applied to load these. Any advice on how I should proceed would be greatly appreciated. Cheers, Josh

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Strange library git glitch
by Simon Peyton Jones 15 May '20

15 May '20

I'm getting this strange output from 'git diff' bash$ git diff diff --git a/libraries/exceptions b/libraries/exceptions --- a/libraries/exceptions +++ b/libraries/exceptions @@ -1 +1 @@ -Subproject commit fe4166f8d23d8288ef2cbbf9e36118b6b99e0d7d +Subproject commit fe4166f8d23d8288ef2cbbf9e36118b6b99e0d7d-dirty No amount of git submodule update makes it go away. Any ideas? Thanks Simon

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