nixos/version: Only warn about unset stateVersion if used (lite)

nixos/modules/misc/version.nix

@@ -89,6 +89,12 @@ in
 
     stateVersion = mkOption {
       type = types.str;
+      # TODO Remove this and drop the default of the option so people are forced to set it.
+      # Doing this also means fixing the comment in nixos/modules/testing/test-instrumentation.nix
+      apply = v:
+        lib.warnIf (options.system.stateVersion.highestPrio == (lib.mkOptionDefault { }).priority)
+          "system.stateVersion is not set, defaulting to ${v}. Read why this matters on https://nixos.org/manual/nixos/stable/options.html#opt-system.stateVersion."
+          v;
       default = cfg.release;
       defaultText = literalExpression "config.${opt.release}";
       description = lib.mdDoc ''
@@ -149,14 +155,6 @@ in
       "os-release".text = attrsToText osReleaseContents;
     };
 
-    # We have to use `warnings` because when warning in the default of the option
-    # the warning would also be shown when building the manual since the manual
-    # has to evaluate the default.
-    #
-    # TODO Remove this and drop the default of the option so people are forced to set it.
-    # Doing this also means fixing the comment in nixos/modules/testing/test-instrumentation.nix
-    warnings = lib.optional (options.system.stateVersion.highestPrio == (lib.mkOptionDefault { }).priority)
-      "system.stateVersion is not set, defaulting to ${config.system.stateVersion}. Read why this matters on https://nixos.org/manual/nixos/stable/options.html#opt-system.stateVersion.";
   };
 
   # uses version info nixpkgs, which requires a full nixpkgs path

nixos/modules/profiles/macos-builder.nix

@@ -11,6 +11,17 @@ in
 
 { imports = [
     ../virtualisation/qemu-vm.nix
+
+    # Avoid a dependency on stateVersion
+    {
+      disabledModules = [
+        ../virtualisation/nixos-containers.nix
+        ../services/x11/desktop-managers/xterm.nix
+      ];
+      config = {
+      };
+      options.boot.isContainer = lib.mkOption { default = false; internal = true; };
+    }
   ];
 
   # The builder is not intended to be used interactively
@@ -97,7 +108,14 @@ in
     # To prevent gratuitous rebuilds on each change to Nixpkgs
     nixos.revision = null;
 
-    stateVersion = "22.05";
+    stateVersion = lib.mkDefault (throw ''
+      The macOS linux builder should not need a stateVersion to be set, but a module
+      has accessed stateVersion nonetheless.
+      Please inspect the trace of the following command to figure out which module
+      has a dependency on stateVersion.
+
+        nix-instantiate --attr darwin.builder --show-trace
+    '');
   };
 
   users.users."${user}"= {

nixos/modules/services/matrix/synapse.nix

@@ -507,6 +507,12 @@ in {
                 sqlite3 = null;
                 psycopg2 = "matrix-synapse";
               }.${cfg.settings.database.name};
+              defaultText = lib.literalExpression ''
+                {
+                  sqlite3 = null;
+                  psycopg2 = "matrix-synapse";
+                }.''${cfg.settings.database.name};
+              '';
               description = lib.mdDoc ''
                 Username to connect with psycopg2, set to null
                 when using sqlite3.