Add GHC 9.4

[ocharles]

I'm sure this is on the radar, but adding an issue here for tracking purposes.

[MangoIV]

Has there been any work on this yet? If not, is there documentation on what has to be done and tested to upgrade to ghc942?

[hamishmack]

I have made a start on this and should have something to try soon. When I tried to build 9.4.1 with the make code we have been using I ran into problems. I've switched to trying with the hkm/hadrian branch, but got stuck on making windows cross compilation work.

[amesgen]

but got stuck on making windows cross compilation work.

At least for me, GHC 9.4 even without mingwW64 support would already be very useful. Also happy to try to help if there already is a WIP branch somewhere :smile:

[shlevy]

@hamishmack For GHC itself is there a reason we can't just use nixpkgs upstream when it's available?

[michaelpj]

@shlevy

• https://github.com/input-output-hk/haskell.nix/issues/1301
• https://github.com/input-output-hk/haskell.nix/issues/1531

[amesgen]

Another one: #1565

[MangoIV]

Hi, bumping this, it would be really neat to be able to use haskell.nix with ghc94 now that stackage nightly has moved to ghc94, too

@hamishmack, can I maybe help you with this? anything specific that is missing?

Thank you in advance.

[peterbecich]

work-in-progress https://github.com/input-output-hk/haskell.nix/pull/1787

[peterbecich]

See https://github.com/input-output-hk/haskell.nix/pull/1475

[sternenseemann]

Building GHC 9.4.* works fairly reliably with make by now which may be a path of less resistance for now. Some things don't even work with hadrian and 9.4, e.g. building a cross compiler.

[peterbecich]

Okay, in that case I will complete https://github.com/input-output-hk/haskell.nix/pull/1787

[ocharles]

Closing as GHC 9.4 is now available in Haskell.nix.