From ccf442b0996acf186e1da756378e455e489d66b3 Mon Sep 17 00:00:00 2001
From: Kiara Grouwstra <kiara@procolix.eu>
Date: Fri, 1 Aug 2025 20:38:43 +0200
Subject: [PATCH] reproduce infinite recursion
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the challenge here seems to stem from a mutual dependency between imports and `inputs`:

```
  at /nix/store/zid48nap5bh52n8d2gc5kbnzhxy3cm0k-source/deployment/data-model.nix:31:7:
    30|     staticModules = [
    31|       inputs.nixops4.modules.nixops4Deployment.default
      |       ^
    32|
… while calling anonymous lambda
  at /nix/store/hjb1rqv2mfs5ny47amj2gsc8xk05x5g6-source/lib/modules.nix:513:35:
   512|       context = name: ''while evaluating the module argument `${name}' in "${key}":'';
   513|       extraArgs = mapAttrs (name: _:
      |                                   ^
   514|         addErrorContext (context name)
… while evaluating the module argument `inputs' in "/nix/store/zid48nap5bh52n8d2gc5kbnzhxy3cm0k-source/deployment/data-model.nix":
… while evaluating the attribute 'inputs'
  at /nix/store/zid48nap5bh52n8d2gc5kbnzhxy3cm0k-source/deployment/check/data-model/deployment.nix:15:17:
    14|       specialArgs = {
    15|         inherit inputs;
      |                 ^
    16|       };
… from call site
  at /nix/store/zid48nap5bh52n8d2gc5kbnzhxy3cm0k-source/deployment/check/data-model/deployment.nix:15:17:
    14|       specialArgs = {
    15|         inherit inputs;
      |                 ^
    16|       };
```
---
 deployment/check/data-model/deployment.nix    | 75 ++++++++++++-------
 .../check/data-model/flake-under-test.nix     |  4 +-
 deployment/check/data-model/nixosTest.nix     |  6 +-
 3 files changed, 56 insertions(+), 29 deletions(-)

diff --git a/deployment/check/data-model/deployment.nix b/deployment/check/data-model/deployment.nix
index 14a35ac6..6e81b46c 100644
--- a/deployment/check/data-model/deployment.nix
+++ b/deployment/check/data-model/deployment.nix
@@ -2,35 +2,60 @@
   inputs,
   sources,
   lib,
-  providers,
   ...
 }:
 
 let
   inherit (import ./constants.nix) targetMachines pathToRoot pathFromRoot;
-in
-
-{
-  providers = {
-    inherit (inputs.nixops4.modules.nixops4Provider) local;
-  };
-
-  resources = lib.genAttrs targetMachines (nodeName: {
-    type = providers.local.exec;
-
-    imports = [
-      inputs.nixops4-nixos.modules.nixops4Resource.nixos
-      ../common/targetResource.nix
-    ];
-
-    _module.args = { inherit inputs sources; };
-
-    inherit nodeName pathToRoot pathFromRoot;
-
-    nixos.module =
-      { pkgs, ... }:
-      {
-        environment.systemPackages = [ pkgs.${nodeName} ];
+  eval =
+    module:
+    (lib.evalModules {
+      specialArgs = {
+        inherit inputs;
       };
-  });
+      modules = [
+        module
+        ../../data-model.nix
+      ];
+    }).config;
+  fediversity = eval (
+    { ... }:
+    {
+      config = {
+        environments.single-nixos-vm =
+          { ... }:
+          {
+            implementation = requests: {
+              input = requests;
+              output =
+                { providers, ... }:
+                {
+                  providers = {
+                    inherit (inputs.nixops4.modules.nixops4Provider) local;
+                  };
+                  resources = lib.genAttrs targetMachines (nodeName: {
+                    type = providers.local.exec;
+                    imports = [
+                      inputs.nixops4-nixos.modules.nixops4Resource.nixos
+                      ../../data-model.nix
+                      ../../function.nix
+                      ../common/targetResource.nix
+                    ];
+                    _module.args = { inherit inputs sources; };
+                    inherit nodeName pathToRoot pathFromRoot;
+                    nixos.module =
+                      { pkgs, ... }:
+                      {
+                        environment.systemPackages = [ pkgs.${nodeName} ];
+                      };
+                  });
+                };
+            };
+          };
+      };
+    }
+  );
+in
+fediversity.environments.single-nixos-vm.deployment {
+  enable = true;
 }
diff --git a/deployment/check/data-model/flake-under-test.nix b/deployment/check/data-model/flake-under-test.nix
index b9e3fb4b..94d37ab8 100644
--- a/deployment/check/data-model/flake-under-test.nix
+++ b/deployment/check/data-model/flake-under-test.nix
@@ -13,8 +13,8 @@
           inputs.nixops4.modules.flake.default
         ];
 
-        nixops4Deployments.check-deployment-basic = {
-          imports = [ ./deployment/check/basic/deployment.nix ];
+        nixops4Deployments.check-deployment-model = {
+          imports = [ ./deployment/check/data-model/deployment.nix ];
           _module.args = { inherit inputs sources; };
         };
       }
diff --git a/deployment/check/data-model/nixosTest.nix b/deployment/check/data-model/nixosTest.nix
index 93c8ad23..50f41039 100644
--- a/deployment/check/data-model/nixosTest.nix
+++ b/deployment/check/data-model/nixosTest.nix
@@ -3,9 +3,11 @@
 {
   _class = "nixosTest";
 
-  name = "deployment-basic";
+  name = "deployment-model";
 
   sourceFileset = lib.fileset.unions [
+    ../../data-model.nix
+    ../../function.nix
     ./constants.nix
     ./deployment.nix
   ];
@@ -39,7 +41,7 @@
       cowsay.fail("cowsay 1>&2")
 
     with subtest("Run the deployment"):
-      deployer.succeed("nixops4 apply check-deployment-basic --show-trace --no-interactive 1>&2")
+      deployer.succeed("nixops4 apply check-deployment-model --show-trace --no-interactive 1>&2")
 
     with subtest("Check the deployment"):
       hello.succeed("hello 1>&2")