pkgs.buildEnv

The following is the current implementation of this function.

finalAttrs:
      {
        # The manifest file (if any).  A symlink $out/manifest will be
        # created to it.
        manifest ? "",

        # The paths to symlink.
        paths,

        # Whether to ignore collisions or abort.
        ignoreCollisions ? false,

        # Whether to ignore outputs that are a single file instead of a directory.
        ignoreSingleFileOutputs ? false,

        # Whether to include closures of all input paths.
        includeClosures ? false,

        # If there is a collision, check whether the contents and permissions match
        # and only if not, throw a collision error.
        checkCollisionContents ? true,

        # The paths (relative to each element of `paths') that we want to
        # symlink (e.g., ["/bin"]).  Any file not inside any of the
        # directories in the list is not symlinked.
        pathsToLink ? [ "/" ],

        # The package outputs to include. By default, only the default
        # output is included.
        extraOutputsToInstall ? [ ],

        # Root the result in directory "$out${extraPrefix}", e.g. "/share".
        extraPrefix ? "",

        # Shell commands to run after building the symlink tree.
        postBuild ? "",

        passthru ? { },
        meta ? { },

        # Additional stdenv.mkDerivation arguments
        # such as nativeBuildInputs/buildInputs for postBuild dependencies.
        derivationArgs ? { },

        # Placeholder name arguments.
        name ? null,
        pname ? null,
        version ? null,

        # `stdenv.mkDerivation` args before introducing derivationArgs.
        nativeBuildInputs ? null,
        buildInputs ? null,
      }@args:
      let
        compatArgs = {
          ${if args ? nativeBuildInputs then "nativeBuildInputs" else null} = nativeBuildInputs;
          ${if args ? buildInputs then "buildInputs" else null} = buildInputs;
        };
      in
      compatArgs
      // derivationArgs
      // {
        # Explicitly opt in: builder.pl reads all configuration from file $ENV["NIX_ATTRS_JSON_FILE"].
        __structuredAttrs = true;

        inherit
          extraOutputsToInstall
          manifest
          ignoreCollisions
          checkCollisionContents
          ignoreSingleFileOutputs
          includeClosures
          meta
          pathsToLink
          extraPrefix
          postBuild
          ;

        chosenOutputs = map (drv: {
          paths =
            # First add the usual output(s): respect if user has chosen explicitly,
            # and otherwise use `meta.outputsToInstall`. The attribute is guaranteed
            # to exist in mkDerivation-created cases. The other cases (e.g. runCommand)
            # aren't expected to have multiple outputs.
            (
              if
                (!drv ? outputSpecified || !drv.outputSpecified) && drv.meta.outputsToInstall or null != null
              then
                map (outName: drv.${outName}) drv.meta.outputsToInstall
              else
                [ drv ]
            )
            # Add any extra outputs specified by the caller of `buildEnv`.
            ++ concatMap (
              outName: if drv ? ${outName} then [ drv.${outName} ] else [ ]
            ) finalAttrs.extraOutputsToInstall;
          priority = drv.meta.priority or lib.meta.defaultPriority;
          # Silently use the original `paths` if `passthru.paths` is missing.
        }) finalAttrs.passthru.paths or paths;

        extraPathsFrom = lib.optionalString finalAttrs.includeClosures (
          # filter all null elements and concatenate the output paths together
          # in the final closure
          writeClosure (lib.concatMap (p: if p == null then [ ] else p.paths) finalAttrs.chosenOutputs)
        );

        preferLocalBuild = derivationArgs.preferLocalBuild or true;
        allowSubstitutes = derivationArgs.allowSubstitutes or false;

        buildCommand = ''
          ${buildPackages.perl}/bin/perl -w ${builder}
          eval "$postBuild"
        '';

        passthru = {
          # The `paths` attribute is referenced and overridden from passthru
          inherit paths;
        }
        // derivationArgs.passthru or { }
        // passthru;
      }