May 2025 - ghc-devs - Haskell.org

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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RTS: mmap fails on RISC-V with Linux 6.8
by Heinrich Schuchardt 20 Jun '25

20 Jun '25

The following bug related to the Haskell runtime was reported in Launchpad: Haskell's default behaviour of using large-address-space is causing pandoc to stuck in an infinite loop on QEMU 10 Edit https://bugs.launchpad.net/ubuntu/+source/ghc/+bug/2111581 The problem seems to relate to the following loop in osReserveHeapMemory(): https://gitlab.haskell.org/ghc/ghc/-/blob/master/rts/posix/OSMem.c?ref_type… According to the mmap() manpage the address passed to the kernel in only a hint there is no guarantee that the same address will be used for allocation. As shown in the strace logs attached in Launchpad this code can lead to an endless loop when the kernel decides always to return an address below 8 GiB. It might make sense to round up the address to 8 GiB if the returned address is below 8 GiB and reduce *len accordingly instead of retrying. Best regards Heinrich

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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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GitLab account request
by Florian Ragwitz 16 May '25

16 May '25

Hi, I'd like for the gitlab.haskell.org account request for the account "rafl" to be approved, so that I can participate in issue discussions and submit changes for review, please. Thanks!

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GitLab Account creation request
by Iris 14 May '25

14 May '25

Dear GHC developers, I am interested in contributing to the GHC project and would like to have an account(iris) on the GitLab instance. Best regards, Iris

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LINE and COLUMN pragmas
by Alan & Kim Zimmerman 12 May '25

12 May '25

I recently discovered the `UsePosPragsBit` in the lexer, which can allow emitting the LINE and COLUMN pragmas as tokens instead of processing them directly in the Lexer, updating the position. When exact printing, this behaviour is not desirable. So I am putting together an MR to parse them if they appear, so they do not cause a parser crash, and they can then be exact printed. Question: Where should these pragmas appear in HsDecl Options are - TTG, XXHsDecl - A new HsDecl constructor, with all its concomitant matching everywhere - tuck it in elsewhere, e.g. in `AnnDecl` (or `XXAnnDecl`). Alan

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GHC 9.10.2 is now available
by Zubin Duggal 03 May '25

03 May '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, including: * Significantly improved performance when dynamically loading Haskell symbols (#23415). * Fixing a bug where the simplifier sometimes destroyed join points during float out, which could impact performance (#24768). * Reduced memory fragmentation in the non-moving GC's segment allocator, improving resident set size by up to 26% for some applications (#24150). * Added new flags to control speculative evaluation (-fspec-eval and -fspec-eval-dictfun) to work around performance regressions (#25606). * Fixed several platform-specific issues, including segfaults with FFI on PowerPC (#23034) and improved code generation for AArch64 with multiway branches now using jump tables (#19912) * And many more! 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][]. 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, Zubin [release notes]: https://downloads.haskell.org/~ghc/9.10.2/docs/users_guide/9.10.2-notes.html [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.10.2 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new

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