The GHC developers are very pleased to announce the release of GHC 9.12.4.
Binary distributions, source distributions, and documentation are available at
[downloads.haskell.org][] and via [GHCup](https://www.haskell.org/ghcup/).
GHC 9.12.4 is a bug-fix release fixing many issues of a variety of
severities and scopes, including:
* Fixed a critical code generation regression where sub-word division produced
incorrect results (#26711, #26668), similar to the bug fixed in 9.12.2
* Numerous fixes for register allocation bugs, preventing data corruption
when spilling and reloading registers
(#26411, #26526, #26537, #26542, #26550)
* Fixes for several compiler crashes, including issues with CSE (#25468),
and the simplifier(#26681), implicit parameters (#26451), and the type-class
specialiser (#26682)
* Fixed cast worker/wrapper incorrectly firing on INLINE functions (#26903)
* Fixed LLVM backend miscompilation of bit manipulation operations
(#20645, #26065, #26109)
* Fixed associated type family and data family instance changes not triggering
recompilation (#26183, #26705)
* Fixed negative type literals causing the compiler to hang (#26861)
* Improvements to determinism of compiler output (#26846, #26858)
* Fixes for eventlog shutdown deadlocks (#26573)
and lost wakeups in the RTS (#26324)
* Fixed split sections support on Windows (#26696, #26494) and the LLVM backend (#26770)
* Fixes for the bytecode compiler, PPC native code generator, and Wasm backend
* The runtime linker now supports COMMON symbols (#6107)
* Improved backtrace support: backtraces for `error` exceptions are now
evaluated at throw time
* `NamedDefaults` now correctly requires the class to be standard or have an
in-scope default declaration, and handles poly-kinded classes (#25775, #25778, #25882)
* ... 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][].
GHC development is sponsored by:
* [Juspay](https://juspay.com/)
* [QBayLogic](https://qbaylogic.com/)
* [Channable](https://www.channable.com/)
* [Haskell Foundation](https://haskell.foundation/)
* [Serokell](https://serokell.io/)
* [Well-Typed](https://well-typed.com/)
* [Tweag](https://www.tweag.io/)
* [Dotcom-Monitor](https://www.dotcom-monitor.com/)
* [LoadView](https://www.loadview-testing.com/)
* [Web Hosting Buddy](https://webhostingbuddy.com/)
* [Find My Electric](https://www.findmyelectric.com/)
* [Standard Chartered](https://www.sc.com)
* [UpCloud](https://upcloud.com)
* [Mercury](https://mercury.com)
We would like to thank these sponsors 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://gitlab.haskell.org/ghc/ghc/-/blob/ghc-9.12/docs/users_guide/9.12.4-…
[status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status
[downloads.haskell.org] https://downloads.haskell.org/ghc/9.12.4
[ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new
Can you clarify what behavior you are seeing? I just tested
with fresh install
❯ test/bin/ghc --version
The Glorious Glasgow Haskell Compilation System, version 9.12.3.20260311
❯ test/bin/ghc $PROJECT_DIR/Main.hs -fforce-recomp
[1 of 2] Compiling Main ( /home/zubin/ghcs/exprType/Main.hs, /home/zubin/ghcs/exprType/Main.o )
[2 of 2] Linking /home/zubin/ghcs/exprType/Main [Objects changed]
❯ cat $PROJECT_DIR/Main.hs
{-# OPTIONS_GHC -O #-}
import Data.Word
prop :: Word8 -> IO ()
prop x = do
print (x, x `quot` 7, x `rem` 7, x `quotRem` 7)
{-# NOINLINE prop #-}
main :: IO ()
main = prop 0
❯ /home/zubin/ghcs/exprType/Main
(0,0,0,(0,0))
On 26/03/18 11:01, George Colpitts wrote:
>Hello
>
>Below it states
>
> - Fixed a critical code generation regression where sub-word division
> produced incorrect results (#26711 </ghc/ghc/-/issues/26711>, #26668
> (closed) </ghc/ghc/-/issues/26668>), similar to the bug fixed in 9.12.2
>
>However when I test 26711 it on 9.12.3.20260311 ( 9.12.3.20260311) on my
>Apple Silicon Mac it is still broken, I've updated 26711. Maybe the above
>means that just 26668 is fixed but 26711 is not?
>
>On Fri, Mar 13, 2026 at 6:15 AM Zubin Duggal via ghc-devs <
>ghc-devs(a)haskell.org> wrote:
>
>> The GHC developers are very pleased to announce the availability
>> of the release candidate for GHC 9.12.4. Binary distributions, source
>> distributions, and documentation are available at [downloads.haskell.org][]
>> and
>> via [GHCup](https://www.haskell.org/ghcup/).
>>
>> GHC 9.12.4 is a bug-fix release fixing many issues of a variety of
>> severities and scopes, including:
>>
>> * Fixed a critical code generation regression where sub-word division
>> produced
>> incorrect results (#26711, #26668), similar to the bug fixed in 9.12.2
>> * Numerous fixes for register allocation bugs, preventing data corruption
>> when spilling and reloading registers
>> (#26411, #26526, #26537, #26542, #26550)
>> * Fixes for several compiler crashes, including issues with
>> CSE (#25468), SetLevels (#26681),
>> implicit parameters (#26451), and the type-class specialiser (#26682)
>> * Fixed cast worker/wrapper incorrectly firing on INLINE functions (#26903)
>> * Fixed LLVM backend miscompilation of bit manipulation operations
>> (#20645, #26065, #26109)
>> * Fixed associated type family and data family instance changes not
>> triggering
>> recompilation (#26183, #26705)
>> * Fixed negative type literals causing the compiler to hang (#26861)
>> * Improvements to determinism of compiler output (#26846, #26858)
>> * Fixes for eventlog shutdown deadlocks (#26573)
>> and lost wakeups in the RTS (#26324)
>> * Fixed split sections support on Windows (#26696, #26494) and the LLVM
>> backend (#26770)
>> * Fixes for the bytecode compiler, PPC native code generator, and Wasm
>> backend
>> * The runtime linker now supports COMMON symbols (#6107)
>> * Improved backtrace support: backtraces for `error` exceptions are now
>> evaluated at throw time
>> * `NamedDefaults` now correctly requires the class to be standard or have
>> an
>> in-scope default declaration, and handles poly-kinded classes (#25775,
>> #25778, #25882)
>> * ... 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][].
>>
>> This release candidate will have a two-week testing period. If all goes
>> well
>> the final release will be available the week of 26 March 2026.
>>
>> GHC development is sponsored by:
>>
>> * [Juspay](https://juspay.com/)
>> * [QBayLogic](https://qbaylogic.com/)
>> * [Channable](https://www.channable.com/)
>> * [Haskell Foundation](https://haskell.foundation/)
>> * [Serokell](https://serokell.io/)
>> * [Well-Typed](https://well-typed.com/)
>> * [Tweag](https://www.tweag.io/)
>> * [Dotcom-Monitor](https://www.dotcom-monitor.com/)
>> * [LoadView](https://www.loadview-testing.com/)
>> * [Web Hosting Buddy](https://webhostingbuddy.com/)
>> * [Find My Electric](https://www.findmyelectric.com/)
>> * [Standard Chartered](https://www.sc.com)
>> * [UpCloud](https://upcloud.com)
>> * [Mercury](https://mercury.com)
>>
>> We would like to thank these sponsors 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://gitlab.haskell.org/ghc/ghc/-/blob/ghc-9.12/docs/users_guide/9.12.4-…
>> [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status
>> [downloads.haskell.org] https://downloads.haskell.org/ghc/9.12.4-rc1
>> [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new
>> _______________________________________________
>> ghc-devs mailing list -- ghc-devs(a)haskell.org
>> To unsubscribe send an email to ghc-devs-leave(a)haskell.org
>>
The GHC developers are very pleased to announce the availability
of the release candidate for GHC 9.12.4. Binary distributions, source
distributions, and documentation are available at [downloads.haskell.org][] and
via [GHCup](https://www.haskell.org/ghcup/).
GHC 9.12.4 is a bug-fix release fixing many issues of a variety of
severities and scopes, including:
* Fixed a critical code generation regression where sub-word division produced
incorrect results (#26711, #26668), similar to the bug fixed in 9.12.2
* Numerous fixes for register allocation bugs, preventing data corruption
when spilling and reloading registers
(#26411, #26526, #26537, #26542, #26550)
* Fixes for several compiler crashes, including issues with
CSE (#25468), SetLevels (#26681),
implicit parameters (#26451), and the type-class specialiser (#26682)
* Fixed cast worker/wrapper incorrectly firing on INLINE functions (#26903)
* Fixed LLVM backend miscompilation of bit manipulation operations
(#20645, #26065, #26109)
* Fixed associated type family and data family instance changes not triggering
recompilation (#26183, #26705)
* Fixed negative type literals causing the compiler to hang (#26861)
* Improvements to determinism of compiler output (#26846, #26858)
* Fixes for eventlog shutdown deadlocks (#26573)
and lost wakeups in the RTS (#26324)
* Fixed split sections support on Windows (#26696, #26494) and the LLVM backend (#26770)
* Fixes for the bytecode compiler, PPC native code generator, and Wasm backend
* The runtime linker now supports COMMON symbols (#6107)
* Improved backtrace support: backtraces for `error` exceptions are now
evaluated at throw time
* `NamedDefaults` now correctly requires the class to be standard or have an
in-scope default declaration, and handles poly-kinded classes (#25775, #25778, #25882)
* ... 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][].
This release candidate will have a two-week testing period. If all goes well
the final release will be available the week of 26 March 2026.
GHC development is sponsored by:
* [Juspay](https://juspay.com/)
* [QBayLogic](https://qbaylogic.com/)
* [Channable](https://www.channable.com/)
* [Haskell Foundation](https://haskell.foundation/)
* [Serokell](https://serokell.io/)
* [Well-Typed](https://well-typed.com/)
* [Tweag](https://www.tweag.io/)
* [Dotcom-Monitor](https://www.dotcom-monitor.com/)
* [LoadView](https://www.loadview-testing.com/)
* [Web Hosting Buddy](https://webhostingbuddy.com/)
* [Find My Electric](https://www.findmyelectric.com/)
* [Standard Chartered](https://www.sc.com)
* [UpCloud](https://upcloud.com)
* [Mercury](https://mercury.com)
We would like to thank these sponsors 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://gitlab.haskell.org/ghc/ghc/-/blob/ghc-9.12/docs/users_guide/9.12.4-…
[status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status
[downloads.haskell.org] https://downloads.haskell.org/ghc/9.12.4-rc1
[ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new
Hello everyone,
time marches and so do our plans for future releases.
We plan to fork the 10.0 branch early on in April (likely the 1st).
If you have work you want to see land in 10.0 please try to land it on
ghc-master before that time,
as we plan to do no *feature* backports beyond that point. Bugfixes of
course will continue to be
backported beyond the fork date.
If you are maintaining a boot library and you expect any issues or want
to make a new release
specificly for the release please let us know. Ideally on the release
tracking ticket: https://gitlab.haskell.org/ghc/ghc/-/issues/26992
Unless we hear otherwise we plan to bump all boot libraries to their
latest published version over the next few weeks and
we will let you know if we run into any issues while doing so.
Cheers
Andreas
