lib.modules: Add mergeAttrDefinitionsWithPrio

This will let us make assertions involving _module.args.pkgs, which
is not an option but a value attribute, and therefore doesn't have
its own highestPrio to inspect. The new function gives us that info.

2 files changed, 23 insertions, 0 deletions

diff --git a/lib/tests/modules.sh b/lib/tests/modules.sh
index 7aebba6b589..a60228198fd 100755
--- a/lib/tests/modules.sh
+++ b/lib/tests/modules.sh
@@ -61,6 +61,8 @@ checkConfigError() {
 # Shorthand meta attribute does not duplicate the config
 checkConfigOutput '^"one two"$' config.result ./shorthand-meta.nix
 
+checkConfigOutput '^true$' config.result ./test-mergeAttrDefinitionsWithPrio.nix
+
 # Check boolean option.
 checkConfigOutput '^false$' config.enable ./declare-enable.nix
 checkConfigError 'The option .* does not exist. Definition values:\n\s*- In .*: true' config.enable ./define-enable.nix
diff --git a/lib/tests/modules/test-mergeAttrDefinitionsWithPrio.nix b/lib/tests/modules/test-mergeAttrDefinitionsWithPrio.nix
new file mode 100644
index 00000000000..3233f415136
--- /dev/null
+++ b/lib/tests/modules/test-mergeAttrDefinitionsWithPrio.nix
@@ -0,0 +1,21 @@
+{ lib, options, ... }:
+
+let
+  defs = lib.modules.mergeAttrDefinitionsWithPrio options._module.args;
+  assertLazy = pos: throw "${pos.file}:${toString pos.line}:${toString pos.column}: The test must not evaluate this the assertLazy thunk, but it did. Unexpected strictness leads to unexpected errors and performance problems.";
+in
+
+{
+  options.result = lib.mkOption { };
+  config._module.args = {
+    default = lib.mkDefault (assertLazy __curPos);
+    regular = null;
+    force = lib.mkForce (assertLazy __curPos);
+    unused = assertLazy __curPos;
+  };
+  config.result =
+    assert defs.default.highestPrio == (lib.mkDefault (assertLazy __curPos)).priority;
+    assert defs.regular.highestPrio == lib.modules.defaultOverridePriority;
+    assert defs.force.highestPrio == (lib.mkForce (assertLazy __curPos)).priority;
+    true;
+}