In reply to @maralorn:maralorn.de
@artem.types:matrix.org 1. Did you run cabal update? 2. Try reseting by removing dist-newstyle.

here's one way it fails for me (other version of GHC because it's another project that's easier to set up). I'm trying to build cabal from source, and I'm using very basic nix shell to get simple things like zlib into scope.

❯ git clone git@github.com:haskell/cabal
...
❯ git clone git@github.com:ulysses4ever/cabal.nix
...
❯ cd cabal
❯ nix develop ../cabal.nix
$ cabal build cabal
Build profile: -w ghc-9.6.6 -O1
In order, the following will be built (use -v for more details):
... long list...
Downloading  unix-2.8.7.0
Starting     base64-bytestring-1.2.1.0 (lib)
Starting     cryptohash-sha256-0.11.102.1 (lib)
Starting     regex-base-0.94.0.3 (lib)
Starting     os-string-2.0.7 (lib)
Starting     safe-exceptions-0.1.7.4 (lib)
Starting     th-compat-0.1.6 (lib)
Starting     splitmix-0.1.1 (lib)
Starting     atomic-counter-0.1.2.3 (lib)
Starting     base16-bytestring-1.0.2.0 (lib)
Starting     ed25519-0.0.5.0 (lib)
Downloaded   unix-2.8.7.0
Downloading  process-1.6.26.1
Starting     unix-2.8.7.0 (all, legacy fallback: build-type is Configure)
Downloaded   process-1.6.26.1
Downloading  semaphore-compat-1.0.0
Building     base64-bytestring-1.2.1.0 (lib)
Building     cryptohash-sha256-0.11.102.1 (lib)
Building     regex-base-0.94.0.3 (lib)
Building     os-string-2.0.7 (lib)
Building     safe-exceptions-0.1.7.4 (lib)
Building     splitmix-0.1.1 (lib)
Building     th-compat-0.1.6 (lib)
Downloaded   semaphore-compat-1.0.0
Building     base16-bytestring-1.0.2.0 (lib)
Building     atomic-counter-0.1.2.3 (lib)
Building     ed25519-0.0.5.0 (lib)
Installing   th-compat-0.1.6 (lib)
Installing   atomic-counter-0.1.2.3 (lib)
Installing   base16-bytestring-1.0.2.0 (lib)
Completed    th-compat-0.1.6 (lib)
Completed    base16-bytestring-1.0.2.0 (lib)
Installing   safe-exceptions-0.1.7.4 (lib)
Completed    atomic-counter-0.1.2.3 (lib)
Installing   base64-bytestring-1.2.1.0 (lib)
Installing   splitmix-0.1.1 (lib)
Completed    safe-exceptions-0.1.7.4 (lib)
Installing   regex-base-0.94.0.3 (lib)
Installing   cryptohash-sha256-0.11.102.1 (lib)
Completed    base64-bytestring-1.2.1.0 (lib)
Completed    splitmix-0.1.1 (lib)
Completed    regex-base-0.94.0.3 (lib)
Completed    cryptohash-sha256-0.11.102.1 (lib)
Installing   ed25519-0.0.5.0 (lib)
Completed    ed25519-0.0.5.0 (lib)
Installing   os-string-2.0.7 (lib)
Completed    os-string-2.0.7 (lib)

Failed to build unix-2.8.7.0. The failure occurred during the configure step.
Build log (
/home/artem/.cache/cabal/logs/ghc-9.6.6/unix-2.8.7.0-f12ffa080428729a9cad2c9d340f8a2e41259c127db9b0b6e0d00096ef0bef24.log
):
Configuring unix-2.8.7.0...
Error: [Cabal-8010]
Encountered missing or private dependencies:
    tasty, tasty-hunit, tasty-quickcheck

Error: [Cabal-7125]
Failed to build unix-2.8.7.0 (which is required by exe:cabal from cabal-install-3.15.0.0). See the build log above for details.

Build log isn't very useful:

❯ cat /home/artem/.cache/cabal/logs/ghc-9.6.6/unix-2.8.7.0-f12ffa080428729a9cad2c9d340f8a2e41259c127db9b0b6e0d00096ef0bef24.log

Configuring unix-2.8.7.0...
Error: [Cabal-8010]
Encountered missing or private dependencies:
    tasty, tasty-hunit, tasty-quickcheck

in a devshell i get the ghc i want with:

      (ghc.overrideAttrs (old: {
        patches = old.patches or [ ] ++ [ ./dont-free-stable-ptr.patch ];
      })).override
      { useLLVM = true; }

nope, i still dont know how to do it, i tried

          haskellPackages = pkgs.haskellPackages.override {
            ghc = modifyGhc pkgs.haskellPackages.ghc;
          };

modifyGhc applies the modifications i sent above

In reply to @magic_rb:matrix.redalder.org
how can i create a haskellPackages set with a patched GHC?

In reply to @maralorn:maralorn.de
You can browse through nixpkgs around haskell-modules/make-package-set.nix and look at the function arguments you can override.