April 2025 - ghc-devs

openFile gives "file is locked" error on Linux when creating a non-existing file
by Harendra Kumar 06 Jul '25

06 Jul '25

Hi everyone, We have a long standing, elusive and intermittent test failure in streamly's file system event test suite. The code where the error emanates from looks like this: createFileWithParent :: FilePath -> FilePath -> IO () createFileWithParent file parent = do let filepath = parent </> file let dir = takeDirectory filepath putStrLn $ "createFileWithParent: file [" ++ file ++ "] dir [" ++ dir ++ "]" putStrLn $ "Ensuring dir: " ++ dir createDirectoryIfMissing True dir r <- doesDirectoryExist dir if r then do putStrLn $ "Ensured dir: " ++ dir when (not (null file)) $ do exists <- doesFileExist filepath if not exists then do putStrLn $ "Creating file: " ++ (parent </> file) openFile (parent </> file) WriteMode >>= hClose putStrLn $ "Created file: " ++ (parent </> file) else error $ "File exists: " ++ filepath else error $ "Could not create dir: " ++ dir The important thing in the code above is that we check that the file does not exist already, and we are creating it. Creating this new file intermittently fails with the following error messages, all of these are coming from prints in the above: createFileWithParent: file [file1] dir [/tmp/fsevent_dir-e1098325dc2b0880/watch-root] Ensuring dir: /tmp/fsevent_dir-e1098325dc2b0880/watch-root Ensured dir: /tmp/fsevent_dir-e1098325dc2b0880/watch-root Creating file: /tmp/fsevent_dir-e1098325dc2b0880/watch-root/file1 uncaught exception: IOException of type ResourceBusy /tmp/fsevent_dir-e1098325dc2b0880/watch-root/file1: openFile: resource busy (file is locked) How can a file that does not exist and being created be locked during creation? We see this only on Linux, the same tests always succeed on Windows and macOS. We are facing this in GHC 9.2.8, I am not sure if it is version specific because in the past I selectively disabled the tests for specific GHC versions and the error still surfaced in other GHC versions. Anything obvious that we may be missing here? Any pointers or more debug info to generate to debug this? I have not started looking into the openFile code yet, hoping someone else knowing it well might help here. Is this some other "resource busy" error which is being wrongly bucketed into "file is locked" error? Thanks, Harendra

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Request for approval of account
by Mark Seemann 24 Jun '25

24 Jun '25

Hello I’d like to report a bug in GHC because an error message tells me to do so. In order to do that, I’m trying to follow the guidelines in https://gitlab.haskell.org/ghc/ghc/-/wikis/report-a-bug, so I’ve created an account. The next step, as I understand it, is to use this mailing list to request approval for he account. I’m hereby doing that. TIA Mark Seemann

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can't move to latest version of llvm on ghc 9.12.2
by George Colpitts 25 May '25

25 May '25

llvm 20 is out but unlike in earlier versions of ghc moving to it means you can no longer use llvm: compiling: ghc -fllvm hello.hs Loaded package environment from /Users/avie/.ghc/aarch64-darwin-9.12.2/environments/default [1 of 2] Compiling Main ( hello.hs, hello.o ) <no location info>: error: [GHC-66599] GHC was not configured with a supported LLVM toolchain Make sure you have installed LLVM between [13 and 20) and reinstall GHC to make -fllvm work from configure: configure: We only support llvm 13 upto 20 (non-inclusive) (found 20.1.1). Can we move to llvm 20 on HEAD and can we revert to the old behavior on ghc 9.12.3? Should I file an ER? Thanks

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Marge
by Simon Peyton Jones 28 Apr '25

28 Apr '25

Colleagues Marge has failed to pick up !14242 for nearly 24 hrs. Is something stuck? Thanks Simon

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Questions regarding the RISCV native codegen & performance
by Daniel Trujillo Viedma 19 Apr '25

19 Apr '25

Hello, ghc-devs! My name is Daniel Trujillo, I'm a Haskell enthusiast from Spain and I'm trying to make my Master's thesis about accelerating Haskell programs with a custom ISA extension. Right now, my focus is in executing software written in Haskell within QEMU in order to get traces that tells me, basically, how many times each block (not exactly basic blocks, but sort of) of assembly code has been executed, with the hope of finding some patterns of RISCV instructions that I could implement together into 1 instruction. As you can see, my method is a bit crude, and I was wondering if the people involved with any of the different internal representations (STG, Cmm...) and/or native code generators (particularly RISCV) could provide me hints about assembly instructions that would have made the work easier, by removing the need of "massaging" the Cmm code to make CodeGen easier, or the need of particular optimizations, or in general, dirty tricks because of lacking of proper support of the standard RISCV ISA. And of course, I would also appreciate very much other hints from people involved in general performance (as oppossed to, for example, libraries for SIMD and parallel execution, or Haskell wrappers to lower-level code for performance reasons). P.D. I'm sorry if I broke any netiquette rule, but I'm very new to the email list, and haven't received yet any email from it. Looking forward to hear from you! Cheers, Dani.

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GHC 9.10.2-rc1 is now available
by Ben Gamari 18 Apr '25

18 Apr '25

The GHC developers are very pleased to announce the availability of the release candidate for GHC 9.10.2. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][] and via [GHCup](https://www.haskell.org/ghcup/). GHC 9.10.2 is a bug-fix release fixing over 50 issues of a variety of severities and scopes. A full accounting of these fixes can be found in the [release notes][]. As always, GHC's release status, including planned future releases, can be found on the GHC Wiki [status][]. This release candidate will have a two-week testing period. If all goes well the final release will be available the week of 1 May 2025. We would like to thank Well-Typed, Tweag I/O, Juspay, QBayLogic, Channable, Serokell, SimSpace, the Haskell Foundation, and other anonymous contributors whose on-going financial and in-kind support has facilitated GHC maintenance and release management over the years. Finally, this release would not have been possible without the hundreds of open-source contributors whose work comprise this release. As always, do give this release a try and open a [ticket][] if you see anything amiss. Cheers, - Ben [release notes]: https://gitlab.haskell.org/ghc/ghc/-/blob/ghc-9.10/docs/users_guide/9.10.2-… [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.10.2-rc1 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new

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GSoC 2025 proposal : Documenting and Improving Cmm
by Diego Antonio Rosario Palomino 16 Apr '25

16 Apr '25

Hi all, I've posted a thread on Discourse outlining my GSoC 2025 proposal, which focuses on documenting and improving GHC's Cmm backend. It covers two possible directions (LLVM and SSA), along with some refinements I've been exploring. You can find the full details here: 👉 https://discourse.haskell.org/t/gsoc-2025-documenting-and-improving-cmm/118… Feedback is very welcome! Best regards, Diego Antonio Rosario Palomino

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GitLab maintenance this evening
by Ben Gamari 14 Apr '25

14 Apr '25

Hello all, Tonight GitLab will be down for maintenance between 17:00 EDT and 18:00 EDT as part of the on-going infrastructure migration. Cheers, - Ben

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Testsuite tests
by Simon Peyton Jones 08 Apr '25

08 Apr '25

Friends In CI for !10479 I'm getting test failures for some call-stack tests e.g. `callstack001`. But if I try to run this in my build tree hadrian/build -j8 test --skip=_build/stage1/rts/** --skip=_build/stage1/** --skip=_build/stage0/** --docs=none --only=callstack001 I get SUMMARY for test run started at Fri Apr 4 22:22:47 2025 0:00:02.413942 spent to go through 1 total tests, which gave rise to 8 test cases, of which 8 were skipped 0 had missing libraries 0 expected passes 0 expected failures 0 caused framework failures 0 caused framework warnings 0 unexpected passes 0 unexpected failures 0 unexpected stat failures 0 fragile tests So I can't reproduce the failure. What am i doing wrong? Can anyone help? Thanks Simon

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Next steps forward for a stable Template Haskell
by Teo Camarasu 08 Apr '25

08 Apr '25

Hi folks, At Tuesday's GHC devs meeting, we talked about having a discussion about template-haskell stability. I've jotted down some notes to help focus our future discussion. It's mostly just a list of what I take to be the next most important issues to tackle, and some details about each. https://docs.google.com/document/d/1gui1YXOvrNihR3NpXuMVCKV3lTkKPL8y_HDRjbZ… Cheers, Teo

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