October 2024 - 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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[ANNOUNCE] GHC 9.12.1-alpha1 is now available
by Zubin Duggal 05 Nov '24

05 Nov '24

The GHC developers are very pleased to announce the availability of the first alpha release of GHC 9.12.1. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][]. We hope to have this release available via ghcup shortly. GHC 9.12 will bring a number of new features and improvements, including: * The new language extension [OrPatterns] allowing you to combine multiple pattern clauses into one. * The [MultilineStrings] language extension to allow you to more easily write strings spanning multiple lines in your source code. * Improvements to the OverloadedRecordDot extension, allowing the built-in `HasField` class to be used for records with fields of non lifted representations. * The [NamedDefaults] language extension has been introduced allowing you to define defaults for typeclasses other than `Num`. * More deterministic object code output, controlled by the `-fobject-determinism` flag, which improves determinism of builds a lot (though does not fully do so) at the cost of some compiler performance (1-2%). See #12935 for the details * GHC now accepts type syntax in expressions as part of [GHC Proposal #281]. * ... and many more A full accounting of changes 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 GitHub, IOG, the Zw3rk stake pool, Well-Typed, Tweag I/O, Serokell, Equinix, 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. [release notes]: https://downloads.haskell.org/ghc/9.12.1-alpha1/docs/users_guide/9.12.1-not… [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.12.1-alpha1 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new [OrPatterns]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0522-o… [MultilineStrings]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0569-m… [GHC Proposal #281]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0281-v… [NamedDefaults]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0409-e… Cheers, Zubin

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What makes C++ FFI painful?
by Hécate 01 Nov '24

01 Nov '24

Hi devs, Pardon me for the naïve question. I know that C++ FFI is *hard* in Haskell. From the perspective of an end-user I have heard that `text`'s new UTF-8 validation caused problems when released, as it relied on C++ code, but I never had any problems with it personally. From the GHC perspective, what makes C++ a difficult language to interface with? Cheers, Hécate -- Hécate ✨ 🐦: @TechnoEmpress IRC: Hecate WWW: https://glitchbra.in RUN: BSD

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9.12.1-alpha2 and submodule status
by Zubin Duggal 01 Nov '24

01 Nov '24

Hi all, I am currently in the process of preparing 9.12.1-alpha2. I expect a release to be published by the end of this week. We are tracking the current status of the submodules in this spreadsheet: https://docs.google.com/spreadsheets/d/19WeWjXPh8Q64qoe3fjs8AswpTHk6uLBD8WG… I want to finalise submodule versions by the next alpha in 2 weeks. If you have any requests for newer versions of submodules/boot libraries, please update the spreadsheet and drop me a message. Cheers, Zubin

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`getSizeofMutableByteArray#` may return a negative number
by Adithya Kumar 30 Oct '24

30 Oct '24

The following test is done with `ghc-9.6.6`. ``` {-# LANGUAGE UnboxedTuples #-} {-# LANGUAGE MagicHash #-} import GHC.Base (IO(..)) import GHC.Exts import Prelude hiding (length) data MutByteArray = MutByteArray (MutableByteArray# RealWorld) {-# INLINE new #-} new :: Int -> IO MutByteArray new (I# nbytes) = IO $ \s -> case newByteArray# nbytes s of (# s', mbarr# #) -> let c = MutByteArray mbarr# in (# s', c #) {-# INLINE length #-} length :: MutByteArray -> IO Int length (MutByteArray arr) = IO $ \s -> case getSizeofMutableByteArray# arr s of (# s1, i #) -> (# s1, I# i #) test1 :: IO () test1 = do val <- new (-7) len <- length val print len test2 :: IO () test2 = do val <- new (-8) len <- length val print len ``` `test1` succeeds and prints `-7` The test prints the length for all `>= -7` `test2` fails with `Out of memory` If `length <= -8`, the test fails with `Out of memory` This is an interesting quirk. I expected `newByteArray#` to fail if the size given to it is `< 0` and I never expected `getSizeofMutableByteArray#` would return a negative number. Best, Adithya

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Can't build GHC any more
by Simon Peyton Jones 24 Oct '24

24 Oct '24

Friends On all my builds, using ./boot; ./configure; ./hadrian/build I am getting the crash below. What should I do? My boot compiler is ghc-9.6. I can't build GHC at all right now, so this is somewhat urgent. Thank you! Simon ]0;Running for 5m11s [11771/39023], predicted 49s (86%)(/home/simonpj/code/HEAD) ]0;Running for 5m16s [11771/39023], predicted 49s (86%)(/home/simonpj/code/HEAD) ghc/GHCi/UI.hs:1704:5: warning: [GHC-53633] [-Woverlapping-patterns] Pattern match is redundant In a case alternative: _ -> ... | 1704 | _ -> pure () | ^^^^^^^^^^^^ | Run Ghc CompileHs (Stage0 InTreeLibs): ghc/Main.hs => _build/stage0/ghc/build/Main.o | Run Ghc LinkHs (Stage0 InTreeLibs): _build/stage0/ghc/build/Main.o (and 6 more) => _build/stage0/bin/ghc Command line: /home/simonpj/.ghcup/bin/ghc -Wall -Wcompat -hisuf hi -osuf o -hcsuf hc -static -hide-all-packages -no-user-package-db '-package-env -' '-package-db _build/stage0/lib/package.conf.d' '-this-unit-id ghc-bin-9.13.20241015-inplace' '-this-package-name ghc-bin' '-package-id array-0.5.5.0' '-package-id base-4.18.0.0' '-package-id bytestring-0.11.4.0' '-package-id containers-0.6.7' '-package-id deepseq-1.4.8.1' '-package-id directory-1.3.9.0-inplace' '-package-id exceptions-0.10.7' '-package-id filepath-1.5.2.0-inplace' '-package-id ghc-9.13-inplace' '-package-id ghc-boot-9.13-inplace' '-package-id ghc-prim-0.10.0' '-package-id ghci-9.13-inplace' '-package-id haskeline-0.8.2.1' '-package-id process-1.6.25.0-inplace' '-package-id time-1.14-inplace' '-package-id transformers-0.6.1.0' '-package-id unix-2.8.5.1-inplace' -i -i/home/simonpj/code/HEAD/_build/stage0/ghc/build -i/home/simonpj/code/HEAD/_build/stage0/ghc/build/ghc/autogen -i/home/simonpj/code/HEAD/ghc -I_build/stage0/ghc/build -I/home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/x86_64-linux-ghc-9.6.2/process-1.6.17.0/include -I/home/simonpj/code/HEAD/compiler -I/home/simonpj/code/HEAD/_build/stage0/compiler/build -I/home/simonpj/code/HEAD/libraries/process/include -I/home/simonpj/code/HEAD/_build/stage0/libraries/process/build/include -I/home/simonpj/code/HEAD/libraries/directory -I/home/simonpj/code/HEAD/_build/stage0/libraries/directory/build -I/home/simonpj/code/HEAD/libraries/unix/include -I/home/simonpj/code/HEAD/_build/stage0/libraries/unix/build/include -I/home/simonpj/code/HEAD/libraries/time/lib/include -I/home/simonpj/code/HEAD/_build/stage0/libraries/time/build/lib/include -I/home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/x86_64-linux-ghc-9.6.2/directory-1.3.8.1/include -I/home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/x86_64-linux-ghc-9.6.2/unix-2.8.1.0/include -I/home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/x86_64-linux-ghc-9.6.2/time-1.12.2/include -I/home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/x86_64-linux-ghc-9.6.2/bytestring-0.11.4.0/include -I/home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/x86_64-linux-ghc-9.6.2/base-4.18.0.0/include -I/home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/x86_64-linux-ghc-9.6.2/ghc-bignum-1.3/include -I/home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/x86_64-linux-ghc-9.6.2/rts-1.0.2/include -optP-include -optP_build/stage0/ghc/build/ghc/autogen/cabal_macros.h -optP-DHAVE_INTERNAL_INTERPRETER -outputdir _build/stage0/ghc/build -fdiagnostics-color=always -Wall -Wnoncanonical-monad-instances -Wnoncanonical-monoid-instances -rtsopts=all '-with-rtsopts=-K512M -H -I5 -T' -threaded -XGHC2021 -XNoImplicitPrelude -XScopedTypeVariables -XBangPatterns -no-auto-link-packages -rtsopts -optc-Wno-error=inline _build/stage0/ghc/build/Main.o _build/stage0/ghc/build/GHCi/Leak.o _build/stage0/ghc/build/GHCi/UI.o _build/stage0/ghc/build/GHCi/UI/Info.o _build/stage0/ghc/build/GHCi/UI/Monad.o _build/stage0/ghc/build/GHCi/UI/Exception.o _build/stage0/ghc/build/GHCi/Util.o -o _build/stage0/bin/ghc -O -H32m -dcore-lint -fomit-interface-pragmas -I_build/stage0/compiler/build -DDEBUG ===> Command failed with error code: 1 /usr/bin/ld.gold: error: _build/stage0/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.5.1-inplace/libHSunix-2.8.5.1-inplace.a(HsUnix.o): multiple definition of '__hsunix_rtldNext' /usr/bin/ld.gold: /home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.1.0/libHSunix-2.8.1.0.a(HsUnix.o): previous definition here /usr/bin/ld.gold: error: _build/stage0/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.5.1-inplace/libHSunix-2.8.5.1-inplace.a(HsUnix.o): multiple definition of '__hsunix_rtldDefault' /usr/bin/ld.gold: /home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.1.0/libHSunix-2.8.1.0.a(HsUnix.o): previous definition here /usr/bin/ld.gold: error: _build/stage0/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.5.1-inplace/libHSunix-2.8.5.1-inplace.a(HsUnix.o): multiple definition of '__hsunix_push_module' /usr/bin/ld.gold: /home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.1.0/libHSunix-2.8.1.0.a(HsUnix.o): previous definition here /usr/bin/ld.gold: error: _build/stage0/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.5.1-inplace/libHSunix-2.8.5.1-inplace.a(HsUnix.o): multiple definition of '__hsunix_clocks_per_second' /usr/bin/ld.gold: /home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.1.0/libHSunix-2.8.1.0.a(HsUnix.o): previous definition here /usr/bin/ld.gold: error: _build/stage0/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.5.1-inplace/libHSunix-2.8.5.1-inplace.a(HsUnix.o): multiple definition of '__hscore_readdir' /usr/bin/ld.gold: /home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.1.0/libHSunix-2.8.1.0.a(HsUnix.o): previous definition here /usr/bin/ld.gold: error: _build/stage0/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.5.1-inplace/libHSunix-2.8.5.1-inplace.a(HsUnix.o): multiple definition of '__hscore_d_name' /usr/bin/ld.gold: /home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.1.0/libHSunix-2.8.1.0.a(HsUnix.o): previous definition here /usr/bin/ld.gold: error: _build/stage0/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.5.1-inplace/libHSunix-2.8.5.1-inplace.a(HsUnix.o): multiple definition of '__hscore_free_dirent' /usr/bin/ld.gold: /home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.1.0/libHSunix-2.8.1.0.a(HsUnix.o): previous definition here collect2: error: ld returned 1 exit status `gcc' failed in phase `Linker'. (Exit code: 1) ]0;Finished in 5m19s(/home/simonpj/code/HEAD) Command failed Build failed. make: *** [/home/simonpj/code/Makefile-spj:12: all] Error 1 simonpj@LHR-WD-22561:~/code/HEAD$

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How is ExitCode handled?
by Tom Ellis 21 Oct '24

21 Oct '24

Hello all, I'm not sure I understand how an `ExitCode` exception is used to terminate a running program. Can anyone clarify? When we call `exitWith`, what we're doing is `throw`ing an `ExitCode` exception: https://www.stackage.org/haddock/lts-22.38/base-4.18.2.1/src/System.Exit.ht… That exception must be caught somewhere, and used to cause the running program to exit with the exit code in question. But where? It's not in the default `uncaughtExceptionHandler`: https://hackage.haskell.org/package/base-4.20.0.0/docs/src/GHC-Conc-Sync.ht… That doesn't do anything special with exit code. It seems like real_handler does: https://hackage.haskell.org/package/ghc-internal-9.1001.0/docs/src/GHC.Inte… >From my experiements with a small program (below) I conclude that the default handler is installed on every thread, and real_handler is installed *on the main thread only* *below* the default handler, so that if an `ExitCode` exception is thrown the default handler never gets a chance to see it. Is that right? Thanks, Tom {-# LANGUAGE GHC2021 #-} {-# LANGUAGE LambdaCase #-} import System.Environment (getArgs) import System.Exit (ExitCode (ExitFailure)) import Control.Exception (Exception, SomeException (SomeException), throw) import GHC.Conc (forkIO, setUncaughtExceptionHandler, threadDelay) data MyEx = MyEx deriving Show instance Exception MyEx myHandler (SomeException e) = putStrLn $ "In myHandler: " <> show e run f = do setUncaughtExceptionHandler myHandler f main = do getArgs >>= \case -- Exits with exit code 1 ["1"] -> run (throw (ExitFailure 1)) -- Print: In myHandler: MyEx -- Exits with exit code 1 ["2"] -> run (throw MyEx) -- Print: In myHandler: ExitFailure 1 -- Exits with exit code 0 ["3"] -> run (forkIO (throw (ExitFailure 1))) -- Print: In myHandler: MyEx -- Exits with exit code 0 ["4"] -> run (forkIO (throw MyEx)) _ -> error "Need an argument" threadDelay (1000 * 1000)

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[ANNOUNCE] GHC 9.8.3 is now available
by Ben Gamari 20 Oct '24

20 Oct '24

The GHC developers are happy to announce the availability of GHC 9.8.3. Binary distributions, source distributions, and documentation are available on the [release] page. This release is primarily a bugfix release the 9.8 series. These include: * Significantly improve performance of code loading via dynamic linking (#23415) * Fix a variety of miscompilations involving sub-word-size FFI arguments (#25018, #24314) * Fix a rare miscompilation by the x86 native code generator (#24507) * Improve runtime performance of some applications of `runRW#` (#25055) * Reduce fragmentation when using the non-moving garbage collector (#23340) * Fix source links in Haddock's hyperlinked sources output (#24086) A full accounting of changes can be found in the [release notes]. As some of the fixed issues do affect correctness users are encouraged to upgrade promptly. We would like to thank Microsoft Azure, GitHub, IOG, the Zw3rk stake pool, Well-Typed, Tweag I/O, Serokell, Equinix, SimSpace, 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. Happy compiling! - Ben [release]: https://www.haskell.org/ghc/download_ghc_9_8_3.html [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new [release notes]: https://downloads.haskell.org/~ghc/9.8.3/docs/users_guide/9.8.3-notes.html

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Re: [Haskell-cafe] [ANNOUNCE] GHC 9.12.1-alpha1 is now available
by George Colpitts 16 Oct '24

16 Oct '24

Thanks Vanessa, it seems you had the same workaround: " remove and reinstall XCode command-line tools." Zubin What OS were the install tests run on? I'm running on 15.0.1. I think 15.1 is coming at the end of the month around the same time as alpha 2, hopefully 15.1 will be accompanied by a new version of XCode command-line tools that resolves these issues. On Wed, Oct 16, 2024 at 7:58 PM Vanessa McHale <vamchale(a)gmail.com> wrote: > I encountered something similar, Apple had been majorly slacking. > > [image: 89166504e40f4869ea825dd70048017861ec8578.png] > > Cabal can't find C++ headers for digest/text on Mac (Sequoia) > <https://discourse.haskell.org/t/cabal-cant-find-c-headers-for-digest-text-o…> > discourse.haskell.org > <https://discourse.haskell.org/t/cabal-cant-find-c-headers-for-digest-text-o…> > > <https://discourse.haskell.org/t/cabal-cant-find-c-headers-for-digest-text-o…> > > > On Oct 16, 2024, at 3:53 PM, George Colpitts <george.colpitts(a)gmail.com> > wrote: > > > It worked for me on my M2 mac but only after uninstalling and reinstalling > Command Line Tools. > > Hopefully the problem I had was unique to me. I got an error when I ran > ./configure on my M2 mac: > > checking C++ standard library flavour... actest.cpp:1:10: fatal error: > 'iostream' file not found > 1 | #include <iostream> > | ^~~~~~~~~~ > 1 error generated. > configure: error: Failed to compile test program > > Following is the complete output I got > > checking for opt-17... no > checking for opt-17.0... no > checking for opt17... no > checking for opt-16... no > checking for opt-16.0... no > checking for opt16... no > checking for opt-15... no > checking for opt-15.0... no > checking for opt15... no > checking for opt-14... no > checking for opt-14.0... no > checking for opt14... no > checking for opt-13... no > checking for opt-13.0... no > checking for opt13... no > checking for opt... opt > checking opt version (18.1.8) is between 13 and 20... yes > checking for clang-19... no > checking for clang-19.0... no > checking for clang19... no > checking for clang-18... clang-18 > checking clang-18 version (18.1.8) is between 13 and 20... yes > configure: $CC is not gcc; assuming it's a reasonably new C compiler > checking whether CC supports -no-pie... no > checking whether CC supports flags passed by GHC when compiling via C... > yes > checking Setting up CFLAGS, LDFLAGS, IGNORE_LINKER_LD_FLAGS and > CPPFLAGS... done > checking Setting up CONF_CC_OPTS_STAGE0, CONF_GCC_LINKER_OPTS_STAGE0, > CONF_LD_LINKER_OPTS_STAGE0 and CONF_CPP_OPTS_STAGE0... done > checking Setting up CONF_CC_OPTS_STAGE1, CONF_GCC_LINKER_OPTS_STAGE1, > CONF_LD_LINKER_OPTS_STAGE1 and CONF_CPP_OPTS_STAGE1... done > checking Setting up CONF_CC_OPTS_STAGE2, CONF_GCC_LINKER_OPTS_STAGE2, > CONF_LD_LINKER_OPTS_STAGE2 and CONF_CPP_OPTS_STAGE2... done > checking whether ld64 requires -no_fixup_chains... yes > checking whether ld64 requires -no_fixup_chains... yes > checking whether ld64 requires -no_fixup_chains... yes > checking whether ld64 requires -no_fixup_chains... yes > checking whether the linker requires -no_warn_duplicate_libraries... yes > checking whether the linker requires -no_warn_duplicate_libraries... yes > checking whether the linker requires -no_warn_duplicate_libraries... yes > checking whether ld supports response files... yes > checking C++ standard library flavour... actest.cpp:1:10: fatal error: > 'iostream' file not found > 1 | #include <iostream> > | ^~~~~~~~~~ > 1 error generated. > configure: error: Failed to compile test program > > On Wed, Oct 16, 2024 at 8:51 AM Zubin Duggal <zubin(a)well-typed.com> wrote: > >> The GHC developers are very pleased to announce the availability >> of the first alpha release of GHC 9.12.1. Binary distributions, source >> distributions, and documentation are available at [downloads.haskell.org >> ][]. >> >> >> We hope to have this release available via ghcup shortly. >> >> GHC 9.12 will bring a number of new features and improvements, including: >> >> * The new language extension [OrPatterns] allowing you to combine >> multiple >> pattern clauses into one. >> >> * The [MultilineStrings] language extension to allow you to more easily >> write >> strings spanning multiple lines in your source code. >> >> * Improvements to the OverloadedRecordDot extension, allowing the >> built-in >> `HasField` class to be used for records with fields of non lifted >> representations. >> >> * The [NamedDefaults] language extension has been introduced allowing >> you to >> define defaults for typeclasses other than `Num`. >> >> * More deterministic object code output, controlled by the >> `-fobject-determinism` >> flag, which improves determinism of builds a lot (though does not >> fully do so) >> at the cost of some compiler performance (1-2%). See #12935 for the >> details >> >> * GHC now accepts type syntax in expressions as part of [GHC Proposal >> #281]. >> >> * ... and many more >> >> A full accounting of changes 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 GitHub, IOG, the Zw3rk stake pool, >> Well-Typed, Tweag I/O, Serokell, Equinix, 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. >> >> >> [release notes]: >> https://downloads.haskell.org/ghc/9.12.1-alpha1/docs/users_guide/9.12.1-not… >> [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status >> [downloads.haskell.org] https://downloads.haskell.org/ghc/9.12.1-alpha1 >> [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new >> [OrPatterns]: >> https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0522-o… >> [MultilineStrings]: >> https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0569-m… >> [GHC Proposal #281]: >> https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0281-v… >> [NamedDefaults]: >> https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0409-e… >> >> >> Cheers, >> Zubin >> _______________________________________________ >> ghc-devs mailing list >> ghc-devs(a)haskell.org >> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs >> > _______________________________________________ > Haskell-Cafe mailing list > To (un)subscribe, modify options or view archives go to: > http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe > Only members subscribed via the mailman list are allowed to post. > >

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