Thanks Magnus! I installed it on my MacOS 26.5.1 with an M4 chip. I smoke
tested it with llvm 22.1.8 and it works fine.
I did get some mysterious (to me at least) messages at install
- checking for 'ar'...
Entering: checking for 'ar'
aarch64-apple-darwin-ar not found in search path
aarch64-apple-darwin-llvm-ar not found in search path
- checking for 'ranlib'...
Entering: checking for 'ranlib'
aarch64-apple-darwin-ranlib not found in search path
aarch64-apple-darwin-llvm-ranlib not found in search path
- Entering: checking for 'nm'
aarch64-apple-darwin-nm not found in search path
aarch64-apple-darwin-llvm-nm not found in search path
- checking for linker for merging objects...
Entering: checking for linker for merging objects
aarch64-apple-darwin-ld not found in search path
Maybe the above is connected with the following for which I will be
reporting a bug in the next day or two:
configure: WARNING:
There are some differences between the toolchain configured by "configure"
(default.target) and the toolchain configured by the "ghc-toolchain"
program (default.target.ghc-toolchain).
16c16
< , tgtCxxCompiler = Cxx {cxxProgram = Program { prgPath = "g++" ,
prgFlags = [] }}
---
> , tgtCxxCompiler = Cxx {cxxProgram = Program { prgPath = "g++" ,
prgFlags = ["--target=arm64-apple-darwin"] }}
Don't worry! This won't affect your ghc in any way.
However, in a near future, we will move to configuring toolchains with
"ghc-toolchain" by default, so you might have discovered a future bug.
In light of it, if you've spotted this difference, please report a GHC bug
at https://www.haskell.org/ghc/reportabug
Thanks again,
George
On Wed, Jun 24, 2026 at 7:01 AM Magnus Viernickel via ghc-devs <
[email protected]> wrote:
> Dear GHC users, distributors and devs,
>
> I'm pleased to announce that the second release candidate for GHC 9.12.5
> is now available from downloads.haskell.org and on GHCup.
>
> GHC 9.12.5 is a bug fix release. For a long form announcement, check out
> https://discourse.haskell.org/t/ghc-9-12-5-rc2-is-now-available/14313/1.
>
> Mind that the very important overhaul of the semaphore-compat library to
> v2 is included in this release and that the semaphore feature will only
> start working with cabal-install 3.18 again, which is sadly a breaking
> but necessary change.
>
> Your testing of the release is much appreciated. Many thanks to the
> nixpkgs and stackage package set distributors for testing the first
> release candidate.
>
> If you find any issues with the candidate, please open an issue on the
> ghc issue tracker.
>
> If there are no critical regressions are discovered within this release
> candidate, it will be published in about 2 weeks of time (the week of 8
> July 2026).
>
> Best
>
> Magnus
>
> _______________________________________________
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>
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