[Haskell-cafe] [ANNOUNCE] GHC 9.6.3 is now available

Bryan Richter bryan at haskell.foundation
Mon Sep 25 19:30:06 UTC 2023

The GHC developers are happy to announce the availability of GHC 9.6.3.
Binary distributions, source distributions, and documentation are
available on the release page.


This release is primarily a bugfix release addressing a few issues
found in the 9.6 series. These include:

  * Disable Polymorphic Specialisation (a performance optimisation)
    by default. It was discovered that Polymorphic Specialisation as
    currently implemented in GHC can lead to hard to diagnose bugs
    resulting in incorrect runtime results. Users wishing to use this
    optimisation despite the caveats will now have to explicitly
    enable the new `-fpolymorphic-specialisation` flag. For more
    details see #23469 as well as #23109, #21229, #23445.

  * Improve compile time and code generation performance when
    `-finfo-table-map` is enabled (#23103).

  * Make the recompilation check more robust when code generation
    flags are changed (#23369).

  * Addition of memory barriers that improve soundness on platforms
    with weak memory ordering.

  * And dozens of other fixes.

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 [GHC ticket] if you see
anything amiss.



[release notes]:
[GHC ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new

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