From 6c0d67769d99800cbbc294abba722d9ba3b19fcc Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 6 Oct 2025 11:29:15 +0200
Subject: [PATCH] ExternalDerivationBuilder: Pass inputPaths

---
 src/libstore/include/nix/store/globals.hh     | 45 +++----------------
 .../unix/build/external-derivation-builder.cc |  6 +++
 2 files changed, 12 insertions(+), 39 deletions(-)

diff --git a/src/libstore/include/nix/store/globals.hh b/src/libstore/include/nix/store/globals.hh
index ae8990eab..f97b261f8 100644
--- a/src/libstore/include/nix/store/globals.hh
+++ b/src/libstore/include/nix/store/globals.hh
@@ -1401,48 +1401,15 @@ public:
               "builder": "/nix/store/s1qkj0ph…-bash-5.2p37/bin/bash",
               "env": {
                 "HOME": "/homeless-shelter",
-                "NIX_BUILD_CORES": "14",
-                "NIX_BUILD_TOP": "/build",
-                "NIX_LOG_FD": "2",
-                "NIX_STORE": "/nix/store",
-                "PATH": "/path-not-set",
-                "PWD": "/build",
-                "TEMP": "/build",
-                "TEMPDIR": "/build",
-                "TERM": "xterm-256color",
-                "TMP": "/build",
-                "TMPDIR": "/build",
-                "__structuredAttrs": "",
-                "buildInputs": "",
                 "builder": "/nix/store/s1qkj0ph…-bash-5.2p37/bin/bash",
-                "cmakeFlags": "",
-                "configureFlags": "",
-                "depsBuildBuild": "",
-                "depsBuildBuildPropagated": "",
-                "depsBuildTarget": "",
-                "depsBuildTargetPropagated": "",
-                "depsHostHost": "",
-                "depsHostHostPropagated": "",
-                "depsTargetTarget": "",
-                "depsTargetTargetPropagated": "",
-                "doCheck": "1",
-                "doInstallCheck": "1",
-                "mesonFlags": "",
-                "name": "hello-2.12.2",
                 "nativeBuildInputs": "/nix/store/l31j72f1…-version-check-hook",
-                "out": "/nix/store/2yx2prgx…-hello-2.12.2",
-                "outputs": "out",
-                "patches": "",
-                "pname": "hello",
-                "postInstallCheck": "stat \"${!outputBin}/bin/hello\"\n",
-                "propagatedBuildInputs": "",
-                "propagatedNativeBuildInputs": "",
-                "src": "/nix/store/dw402azx…-hello-2.12.2.tar.gz",
-                "stdenv": "/nix/store/i8bw5nqg…-stdenv-linux",
-                "strictDeps": "",
-                "system": "aarch64-linux",
-                "version": "2.12.2"
+                …
               },
+              "inputPaths": [
+                "/nix/store/14dciax3mm8j70hjy4c0d68mds9ppx2s-glibc-2.32-54-dev",
+                "/nix/store/1azs5s8zc0z7m6sssvq1np0m7z873zml-gettext-0.21",
+                …
+              ],
               "realStoreDir": "/nix/store",
               "storeDir": "/nix/store",
               "system": "aarch64-linux",
diff --git a/src/libstore/unix/build/external-derivation-builder.cc b/src/libstore/unix/build/external-derivation-builder.cc
index 4d3eba6db..e30a92db7 100644
--- a/src/libstore/unix/build/external-derivation-builder.cc
+++ b/src/libstore/unix/build/external-derivation-builder.cc
@@ -68,6 +68,12 @@ struct ExternalDerivationBuilder : DerivationBuilderImpl
         json.emplace("storeDir", store.storeDir);
         json.emplace("realStoreDir", store.config->realStoreDir.get());
         json.emplace("system", drv.platform);
+        {
+            auto l = nlohmann::json::array();
+            for (auto & i : inputPaths)
+                l.push_back(store.printStorePath(i));
+            json.emplace("inputPaths", std::move(l));
+        }
 
         // TODO(cole-h): writing this to stdin is too much effort right now, if we want to revisit
         // that, see this comment by Eelco about how to make it not suck: