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-notes.rst?ref_type=heads&plain=1
[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
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