Merge pull request #315167 from NixOS/haskell-updates

  documentation). This dramatically reduces the closure size of the resulting

  derivation. Note that the executables are only statically linked against their

  Haskell dependencies, but will still link dynamically against libc, GMP and

other system library dependencies. If dependencies use their Cabal-generated

`Paths_*` module, this may not work as well if GHC's dead code elimination

is unable to remove the references to the dependency's store path that module

contains.

  other system library dependencies.

  If the library being built or its dependencies use their Cabal-generated

  `Paths_*` module, this may not work as well if GHC's dead code elimination is

  unable to remove the references to the dependency's store path that module

  contains. (See [nixpkgs#164630][164630] for more information.)

  Importing the `Paths_*` module may cause builds to fail with this message:

  ```

  error: output '/nix/store/64k8iw0ryz76qpijsnl9v87fb26v28z8-my-haskell-package-1.0.0.0' is not allowed to refer to the following paths:

           /nix/store/5q5s4a07gaz50h04zpfbda8xjs8wrnhg-ghc-9.6.3

  ```

  If that happens, first disable the check for GHC references and rebuild the

  derivation:

  ```nix

  pkgs.haskell.lib.overrideCabal

    (pkgs.haskell.lib.justStaticExecutables my-haskell-package)

    (drv: {

      disallowGhcReference = false;

    })

  ```

  Then use `strings` to determine which libraries are responsible:

  ```

  $ nix-build ...

  $ strings result/bin/my-haskell-binary | grep /nix/store/

  ...

  /nix/store/n7ciwdlg8yyxdhbrgd6yc2d8ypnwpmgq-hs-opentelemetry-sdk-0.0.3.6/bin

  ...

  ```

  Finally, use `remove-references-to` to delete those store paths from the produced output:

  ```nix

  pkgs.haskell.lib.overrideCabal

    (pkgs.haskell.lib.justStaticExecutables my-haskell-package)

    (drv: {

      postInstall = ''

        ${drv.postInstall or ""}

        remove-references-to -t ${pkgs.haskellPackages.hs-opentelemetry-sdk}

      '';

    })

  ```

[164630]: https://github.com/NixOS/nixpkgs/issues/164630

`enableSeparateBinOutput drv`

: Install executables produced by `drv` to a separate `bin` output. This

  before changing the package to `pkgs.stalwart-mail` in

  [`services.stalwart-mail.package`](#opt-services.stalwart-mail.package).

- `haskell.lib.compose.justStaticExecutables` now disallows references to GHC in the

  output by default, to alert users to closure size issues caused by

  [#164630](https://github.com/NixOS/nixpkgs/issues/164630). See ["Packaging

  Helpers" in the Haskell section of the Nixpkgs

  manual](https://nixos.org/manual/nixpkgs/unstable/#haskell-packaging-helpers)

  for information on working around `output '...' is not allowed to refer to

  the following paths` errors caused by this change.

- The `stalwart-mail` module now uses RocksDB as the default storage backend

  for `stateVersion` ≥ 24.11. (It was previously using SQLite for structured

  data and the filesystem for blobs).

{ lib, haskellPackages, haskell, removeReferencesTo

{ lib, stdenv, haskellPackages, haskell

# “Plugins” are a fancy way of saying gitit will invoke

# GHC at *runtime*, which in turn makes it pull GHC

# into its runtime closure. Only enable if you really need

, pluginSupport ? false

}:

# this is similar to what we do with the pandoc executable

let

  plain = haskellPackages.gitit;

  plugins =

    if pluginSupport

    then plain

    else haskell.lib.compose.disableCabalFlag "plugins" plain;

  static = haskell.lib.compose.justStaticExecutables plugins;

  inherit (haskell.lib.compose)

    enableCabalFlag

    disableCabalFlag

    justStaticExecutables

    overrideCabal

  ;

in

  (haskell.lib.compose.overrideCabal (drv: {

    buildTools = (drv.buildTools or []) ++ [ removeReferencesTo ];

  }) static).overrideAttrs (drv: {

  base = (if pluginSupport then enableCabalFlag else disableCabalFlag)

    "plugins"

    haskellPackages.gitit;

    # These libraries are still referenced, because they generate

    # a `Paths_*` module for figuring out their version.

    # The `Paths_*` module is generated by Cabal, and contains the

    # version, but also paths to e.g. the data directories, which

    # lead to a transitive runtime dependency on the whole GHC distribution.

    # This should ideally be fixed in haskellPackages (or even Cabal),

    # but a minimal gitit is important enough to patch it manually.

    disallowedReferences = [

      haskellPackages.pandoc-types

      haskellPackages.HTTP

      haskellPackages.pandoc

      haskellPackages.happstack-server

      haskellPackages.filestore

    ];

  # Removes erroneous references from dead code that GHC can't eliminate

  aarch64DarwinFix = overrideCabal (drv:

    lib.optionalAttrs (stdenv.hostPlatform.isDarwin && stdenv.hostPlatform.isAarch64) {

      postInstall = ''

      remove-references-to \

        -t ${haskellPackages.pandoc-types} \

        $out/bin/gitit

      remove-references-to \

        -t ${haskellPackages.HTTP} \

        $out/bin/gitit

      remove-references-to \

        -t ${haskellPackages.pandoc} \

        $out/bin/gitit

      remove-references-to \

        -t ${haskellPackages.happstack-server} \

        $out/bin/gitit

      remove-references-to \

        -t ${haskellPackages.filestore} \

        $out/bin/gitit

        ${drv.postInstall or ""}

        remove-references-to -t ${haskellPackages.HTTP} "$out/bin/gitit"

        remove-references-to -t ${haskellPackages.HTTP} "$out/bin/expireGititCache"

        remove-references-to -t ${haskellPackages.happstack-server} "$out/bin/gitit"

        remove-references-to -t ${haskellPackages.hoauth2} "$out/bin/gitit"

        remove-references-to -t ${haskellPackages.pandoc} "$out/bin/gitit"

        remove-references-to -t ${haskellPackages.pandoc-types} "$out/bin/gitit"

      '';

    });

in

    meta = drv.meta // {

      maintainers = drv.meta.maintainers or []

        ++ [ lib.maintainers.Profpatsch ];

    };

  })

if pluginSupport

then base

else lib.pipe (base.override { ghc-paths = null; }) [

  justStaticExecutables

  aarch64DarwinFix

]

          # These cause problems as they're not eliminated by GHC's dead code

          # elimination on aarch64-darwin. (see

          # https://github.com/NixOS/nixpkgs/issues/140774 for details).

          ./Cabal-at-least-3.6-paths-fix-cycle-aarch64-darwin.patch

          (if lib.versionOlder version "9.10"

           then ./Cabal-at-least-3.6-paths-fix-cycle-aarch64-darwin.patch

           else ./Cabal-3.12-paths-fix-cycle-aarch64-darwin.patch)

        ]

        # Prevents passing --hyperlinked-source to haddock. This is a custom

        # workaround as we wait for this to be configurable via userSettings or

    "--disable-large-address-space"

  ] ++ lib.optionals enableDwarf [

    "--enable-dwarf-unwind"

    "--with-libdw-includes=${lib.getDev elfutils}/include"

    "--with-libdw-libraries=${lib.getLib elfutils}/lib"

    "--with-libdw-includes=${lib.getDev targetPackages.elfutils}/include"

    "--with-libdw-libraries=${lib.getLib targetPackages.elfutils}/lib"

  ] ++ lib.optionals targetPlatform.isDarwin [

    # Darwin uses llvm-ar. GHC will try to use `-L` with `ar` when it is `llvm-ar`

    # but it doesn’t currently work because Cabal never uses `-L` on Darwin. See: