tvl-depot/nix/emptyDerivation/emptyDerivation.nix

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{ stdenv, system, pkgs, getBins }:
# The empty derivation. All it does is touch $out.
# Basically the unit value for derivations.
#
# In addition to simple test situations which require
# a derivation, we set __functor, so you can call it
# as a function and pass an attrset. The set you pass
# is `//`-merged with the attrset before calling derivation,
# so you can use this to add more fields.
let
bins = getBins pkgs.s6-portable-utils [ "s6-touch" ]
// getBins pkgs.execline [ "importas" "exec" ];
emptiness = {
name = "empty-derivation";
inherit system;
builder = bins.exec;
args = [
bins.importas
"out"
"out"
bins.s6-touch
"$out"
];
};
in
(derivation emptiness) // {
# This allows us to call the empty derivation
# like a function and override fields/add new fields.
__functor = _: overrides:
derivation (emptiness // overrides);
}