nixpkgs/pkgs/build-support/dev-shell-tools/default.nix

{
  lib,
  writeTextFile,
}:
let
  inherit (builtins) typeOf;
in
rec {
  # Docs: doc/build-helpers/dev-shell-tools.chapter.md
  # Tests: ./tests/default.nix
  # This function closely mirrors what this Nix code does:
  # https://github.com/NixOS/nix/blob/2.8.0/src/libexpr/primops.cc#L1102
  # https://github.com/NixOS/nix/blob/2.8.0/src/libexpr/eval.cc#L1981-L2036
  valueToString = value:
    # We can't just use `toString` on all derivation attributes because that
    # would not put path literals in the closure. So we explicitly copy
    # those into the store here
    if typeOf value == "path" then "${value}"
    else if typeOf value == "list" then toString (map valueToString value)
    else toString value;


  # Docs: doc/build-helpers/dev-shell-tools.chapter.md
  # Tests: ./tests/default.nix
  # https://github.com/NixOS/nix/blob/2.8.0/src/libstore/build/local-derivation-goal.cc#L992-L1004
  unstructuredDerivationInputEnv = { drvAttrs }:
    # FIXME: this should be `normalAttrs // passAsFileAttrs`
    lib.mapAttrs'
      (name: value:
        let str = valueToString value;
        in if lib.elem name (drvAttrs.passAsFile or [])
        then
          let
            nameHash =
              if builtins?convertHash
              then builtins.convertHash {
                hash = "sha256:" + builtins.hashString "sha256" name;
                toHashFormat = "nix32";
              }
              else
                builtins.hashString "sha256" name;
            basename = ".attr-${nameHash}";
          in
            lib.nameValuePair "${name}Path" "${
              writeTextFile {
                name = "shell-passAsFile-${name}";
                text = str;
                destination = "/${basename}";
              }
            }/${basename}"
        else lib.nameValuePair name str
      )
      (removeAttrs drvAttrs [
        # TODO: there may be more of these
        "args"
      ]);

  # Docs: doc/build-helpers/dev-shell-tools.chapter.md
  # Tests: ./tests/default.nix
  derivationOutputEnv = { outputList, outputMap }:
    # A mapping from output name to the nix store path where they should end up
    # https://github.com/NixOS/nix/blob/2.8.0/src/libexpr/primops.cc#L1253
    lib.genAttrs outputList (output: builtins.unsafeDiscardStringContext outputMap.${output}.outPath);

}