pkgs/build-support: refactor drvs using __structuredAttrs = true

Derivations affected by this patch set `__structuredAttrs = true;` and
provide their own `builder`, i.e. it's necessary to `source .attrs.sh`.

Rather than adding even more `if`-`source` monstrums, I decided to
modify all of those derivations to use `buildCommand` or `runCommand`,
without `builder` being set.

Then, `$stdenv/setup` is sourced already and as a result it's safe to
assume that `NIX_ATTRS_JSON_FILE`/`NIX_ATTRS_SH_FILE` point to a usable
location both in a build and a shell session.

pkgs/build-support/binary-cache/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, buildPackages }:
+{ lib, stdenv, coreutils, jq, python3, nix, xz }:
 
 # This function is for creating a flat-file binary cache, i.e. the kind created by
 # nix copy --to file:///some/path and usable as a substituter (with the file:// prefix).
@@ -19,15 +19,10 @@ stdenv.mkDerivation {
 
   preferLocalBuild = true;
 
-  PATH = lib.makeBinPath (with buildPackages; [ coreutils jq python3 nix xz ]);
+  nativeBuildInputs = [ coreutils jq python3 nix xz ];
 
-  builder = builtins.toFile "builder" ''
-    . .attrs.sh
-
-    export out=''${outputs[out]}
-
-    mkdir $out
-    mkdir $out/nar
+  buildCommand = ''
+    mkdir -p $out/nar
 
     python ${./make-binary-cache.py}
 

pkgs/build-support/binary-cache/make-binary-cache.py

@@ -3,7 +3,7 @@
 import os
 import subprocess
 
-with open(".attrs.json", "r") as f:
+with open(os.environ["NIX_ATTRS_JSON_FILE"], "r") as f:
   closures = json.load(f)["closure"]
 
 os.chdir(os.environ["out"])

pkgs/build-support/closure-info.nix

@@ -4,7 +4,7 @@
 # "nix-store --load-db" and "nix-store --register-validity
 # --hash-given".
 
-{ stdenv, buildPackages }:
+{ stdenv, coreutils, jq }:
 
 { rootPaths }:
 
@@ -19,18 +19,16 @@ stdenv.mkDerivation {
 
   preferLocalBuild = true;
 
-  PATH = "${buildPackages.coreutils}/bin:${buildPackages.jq}/bin";
+  nativeBuildInputs = [ coreutils jq ];
 
-  builder = builtins.toFile "builder"
+  buildCommand =
     ''
-      . .attrs.sh
-
       out=''${outputs[out]}
 
       mkdir $out
 
-      jq -r ".closure | map(.narSize) | add" < .attrs.json > $out/total-nar-size
-      jq -r '.closure | map([.path, .narHash, .narSize, "", (.references | length)] + .references) | add | map("\(.)\n") | add' < .attrs.json | head -n -1 > $out/registration
-      jq -r .closure[].path < .attrs.json > $out/store-paths
+      jq -r ".closure | map(.narSize) | add" < "$NIX_ATTRS_JSON_FILE" > $out/total-nar-size
+      jq -r '.closure | map([.path, .narHash, .narSize, "", (.references | length)] + .references) | add | map("\(.)\n") | add' < "$NIX_ATTRS_JSON_FILE" | head -n -1 > $out/registration
+      jq -r '.closure[].path' < "$NIX_ATTRS_JSON_FILE" > $out/store-paths
     '';
 }

pkgs/build-support/references-by-popularity/default.nix

@@ -6,11 +6,8 @@ path: runCommand "closure-paths"
   exportReferencesGraph.graph = path;
   __structuredAttrs = true;
   preferLocalBuild = true;
-  PATH = "${coreutils}/bin:${python3}/bin";
-  builder = builtins.toFile "builder"
-    ''
-      . .attrs.sh
-      python3 ${./closure-graph.py} .attrs.json graph > ''${outputs[out]}
-    '';
-  }
-  ""
+  nativeBuildInputs = [ coreutils python3 ];
+}
+''
+  python3 ${./closure-graph.py} "$NIX_ATTRS_JSON_FILE" graph > ''${outputs[out]}
+''