2 files changed, 31 insertions, 2 deletions

diff --git a/src/libexpr/flake/call-flake.nix b/src/libexpr/flake/call-flake.nix
new file mode 100644
index 000000000..c59a0c75f
--- /dev/null
+++ b/src/libexpr/flake/call-flake.nix
@@ -0,0 +1,22 @@
+locks: rootSrc: rootSubdir:
+
+let
+
+  callFlake = sourceInfo: subdir: locks:
+    let
+      flake = import (sourceInfo + "/" + subdir + "/flake.nix");
+
+      inputs = builtins.mapAttrs (n: v:
+        if v.flake or true
+        then callFlake (fetchTree (removeAttrs v.locked ["dir"])) (v.locked.dir or "") v.inputs
+        else fetchTree v.locked) locks;
+
+      outputs = flake.outputs (inputs // { self = result; });
+
+      result = outputs // sourceInfo // { inherit inputs; inherit outputs; inherit sourceInfo; };
+    in
+      assert flake.edition == 201909;
+
+      result;
+
+in callFlake rootSrc rootSubdir (builtins.fromJSON locks).inputs
diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 9d8a5f950..249ceba6c 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -623,7 +623,6 @@ void callFlake(EvalState & state,
     const LockedInputs & lockedInputs,
     Value & vRes)
 {
-    auto vCallFlake = state.allocValue();
     auto vLocks = state.allocValue();
     auto vRootSrc = state.allocValue();
     auto vRootSubdir = state.allocValue();
@@ -636,7 +635,15 @@ void callFlake(EvalState & state,
 
     mkString(*vRootSubdir, flake.lockedRef.subdir);
 
-    state.evalFile(canonPath(settings.nixDataDir + "/nix/corepkgs/call-flake.nix", true), *vCallFlake);
+    static Value * vCallFlake = nullptr;
+
+    if (!vCallFlake) {
+        vCallFlake = state.allocValue();
+        state.eval(state.parseExprFromString(
+            #include "call-flake.nix.gen.hh"
+            , "/"), *vCallFlake);
+    }
+
     state.callFunction(*vCallFlake, *vLocks, *vTmp1, noPos);
     state.callFunction(*vTmp1, *vRootSrc, *vTmp2, noPos);
     state.callFunction(*vTmp2, *vRootSubdir, vRes, noPos);