Add the addPassthru library function

With multiple outputs, adding attributes to a derivation without
changing the {drv,out}Path is no longer as trivial as simply using the
`//' operator, as we usually want to add the attribute to _each_ output,
and even if we only care about one that one output can be reached via
multiple paths.

For stdenv.mkDerivation, we already had code in place to add passthru
and meta attributes to derivations. This commit simply factors part of
that code out into a lib function addPassthru, which takes a derivation
and an attribute set and appends the attribute set to each output of the
derivation.

Signed-off-by: Shea Levy <shea@shealevy.com>

1 files changed, 38 insertions, 53 deletions

diff --git a/pkgs/stdenv/generic/default.nix b/pkgs/stdenv/generic/default.nix
index fd7b3218e34..fe4bbbc94dd 100644
--- a/pkgs/stdenv/generic/default.nix
+++ b/pkgs/stdenv/generic/default.nix
@@ -52,59 +52,44 @@ let
           if !allowUnfree && (let l = attrs.meta.license or ""; in l == "unfree" || l == "unfree-redistributable" || l == lib.licenses.proprietary) then
             throw "package ‘${attrs.name}’ has an unfree license, refusing to evaluate"
           else
-            let
-              drv = derivation (
-                (removeAttrs attrs ["meta" "passthru" "crossAttrs"])
-                // (let
-                  buildInputs = attrs.buildInputs or [];
-                  nativeBuildInputs = attrs.nativeBuildInputs or [];
-                  propagatedBuildInputs = attrs.propagatedBuildInputs or [];
-                  propagatedNativeBuildInputs = attrs.propagatedNativeBuildInputs or [];
-                  crossConfig = attrs.crossConfig or null;
-                in
-                {
-                  builder = attrs.realBuilder or shell;
-                  args = attrs.args or ["-e" (attrs.builder or ./default-builder.sh)];
-                  stdenv = result;
-                  system = result.system;
-                  userHook = config.stdenv.userHook or null;
-
-                  # Inputs built by the cross compiler.
-                  buildInputs = lib.optionals (crossConfig != null) buildInputs;
-                  propagatedBuildInputs = lib.optionals (crossConfig != null)
-                      propagatedBuildInputs;
-                  # Inputs built by the usual native compiler.
-                  nativeBuildInputs = nativeBuildInputs ++ lib.optionals
-                    (crossConfig == null) buildInputs;
-                  propagatedNativeBuildInputs = propagatedNativeBuildInputs ++
-                    lib.optionals (crossConfig == null) propagatedBuildInputs;
-              }));
-
-              outputs = drv.outputs or [ "out" ];
-
-              commonAttrs = drv // (builtins.listToAttrs outputsList) //
-                ({ all = map (x: x.value) outputsList;
-                  # The meta attribute is passed in the resulting attribute set,
-                  # but it's not part of the actual derivation, i.e., it's not
-                  # passed to the builder and is not a dependency.  But since we
-                  # include it in the result, it *is* available to nix-env for
-                  # queries.
-                  meta = attrs.meta or {};
-                }) //
-                # Pass through extra attributes that are not inputs, but
-                # should be made available to Nix expressions using the
-                # derivation (e.g., in assertions).
-                (attrs.passthru or {});
-
-              outputToAttrListElement = outputName:
-                { name = outputName;
-                  value = commonAttrs // {
-                    inherit (builtins.getAttr outputName drv) outPath drvPath type outputName;
-                  };
-                };
-
-              outputsList = map outputToAttrListElement outputs;
-            in (builtins.head outputsList).value;
+            lib.addPassthru (derivation (
+              (removeAttrs attrs ["meta" "passthru" "crossAttrs"])
+              // (let
+                buildInputs = attrs.buildInputs or [];
+                nativeBuildInputs = attrs.nativeBuildInputs or [];
+                propagatedBuildInputs = attrs.propagatedBuildInputs or [];
+                propagatedNativeBuildInputs = attrs.propagatedNativeBuildInputs or [];
+                crossConfig = attrs.crossConfig or null;
+              in
+              {
+                builder = attrs.realBuilder or shell;
+                args = attrs.args or ["-e" (attrs.builder or ./default-builder.sh)];
+                stdenv = result;
+                system = result.system;
+                userHook = config.stdenv.userHook or null;
+
+                # Inputs built by the cross compiler.
+                buildInputs = lib.optionals (crossConfig != null) buildInputs;
+                propagatedBuildInputs = lib.optionals (crossConfig != null)
+                    propagatedBuildInputs;
+                # Inputs built by the usual native compiler.
+                nativeBuildInputs = nativeBuildInputs ++ lib.optionals
+                  (crossConfig == null) buildInputs;
+                propagatedNativeBuildInputs = propagatedNativeBuildInputs ++
+                  lib.optionals (crossConfig == null) propagatedBuildInputs;
+            }))) (
+            {
+              # The meta attribute is passed in the resulting attribute set,
+              # but it's not part of the actual derivation, i.e., it's not
+              # passed to the builder and is not a dependency.  But since we
+              # include it in the result, it *is* available to nix-env for
+              # queries.
+              meta = attrs.meta or {};
+            } //
+            # Pass through extra attributes that are not inputs, but
+            # should be made available to Nix expressions using the
+            # derivation (e.g., in assertions).
+            (attrs.passthru or {}));
 
         # Utility flags to test the type of platform.
         isDarwin = result.system == "x86_64-darwin";