The GHC developers are very pleased to announce the availability
of the release candidate for GHC 9.14.2. Binary distributions, source
distributions, and documentation are available at [downloads.haskell.org][] and
via [GHCup](https://www.haskell.org/ghcup/).
GHC 9.14.2 is a bug-fix release fixing many issues of a variety of
severities and scopes, including:
* Fixed a CorePrep miscompilation that could project a field out of an absent
dictionary, resulting in a segfault (#25924)
* Fixed demand analysis giving an absent demand to an argument that was still
used by the function's stable unfolding, which could cause a run-time crash
(#26416)
* Numerous fixes for register allocation and Cmm register-conflict analysis
bugs, preventing incorrect code generation and corruption of vector registers
when spilling and reloading (#26411, #26526, #26537, #26542, #26550, #26668)
* Many NGG fixes on AArch64: `MOVK` clobbering live values (#26980), register
clobbering and an incorrect overflow bit in `MUL2` (#27046, #27047), and
incorrect sign extension (#26978) and unsigned right shift (#26979) at sub-word
widths
* Fixed several black hole handling bugs that could lead to deadlocks or crashes
in multithreaded programs, showing up as hangs or "END_TSO_QUEUE object
entered" errors (#26922, #26936)
* Fixed a stack alignment bug on x86 that could cause segfaults or corrupted
registers when using AVX/AVX-512 vector code (#26595, #26822)
* Fixed an "unknown/strange object" crash in the compacting garbage collector
(#27434)
* Fixed a regression that caused overloaded functions to no longer be
specialised as effectively as in previous releases, hurting runtime
performance (#26831)
* Fixed exponential-time desugaring of nested `case` expressions (#27383, #20251)
* Fixes for several compiler panics, including issues with SetLevels (#26681),
the type-class specialiser (#26682), `mkTick` (#26772, #27121) and
CoreToStg (#27182, #27386)
* Fixed cast worker/wrapper incorrectly firing on INLINE functions (#26903)
* Fixed negative type literals causing the compiler to hang (#26861)
* Fixed associated type family and data family instance changes not triggering
recompilation (#26183, #26705)
* Improvements to determinism of compiler output, including the order in which
`:info` lists instances (#26846, #26858, #26877, #27532)
* Fixed split sections support on Windows (#26696, #26494) and the LLVM
backend (#26770)
* The JavaScript backend now supports more than 128 registers, fixing runtime
`ReferenceError` failures for functions taking very many arguments (#26558)
* Fixes for the Wasm backend, and the RISC-V and PowerPC native code generators
* ... 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 13 August 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-9.14/docs/users_guide/9.14.2-…
[status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status
[downloads.haskell.org] https://downloads.haskell.org/ghc/9.14.2-rc1
[ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new
