From 023fa7b9239e645f7dfcbbe3ee82ab0093f9978d Mon Sep 17 00:00:00 2001
From: Silvan Mosberger <contact@infinisil.com>
Date: Wed, 8 Dec 2021 19:13:14 +0100
Subject: [PATCH] lib.modules: Use types.optionType for _module.freeformType

This ensures that the module file locations are propagated to the
freeform type, which makes it so that submodules in freeform types now
have their declaration location shown in the manual, fixing
https://github.com/NixOS/nixpkgs/issues/132085.

In addition, this also newly allows freeformTypes to be declared
multiple times and all declarations being merged together according to
normal option merging.

This also removes some awkwardness regarding the type of `freeformType`
---
 lib/modules.nix                           |  3 +--
 lib/tests/modules.sh                      |  5 +++++
 lib/tests/modules/freeform-submodules.nix | 22 ++++++++++++++++++++++
 3 files changed, 28 insertions(+), 2 deletions(-)
 create mode 100644 lib/tests/modules/freeform-submodules.nix

diff --git a/lib/modules.nix b/lib/modules.nix
index e9fc1007fc20..79d54e4a5387 100644
--- a/lib/modules.nix
+++ b/lib/modules.nix
@@ -151,8 +151,7 @@ rec {
           };
 
           _module.freeformType = mkOption {
-            # Disallow merging for now, but could be implemented nicely with a `types.optionType`
-            type = types.nullOr (types.uniq types.attrs);
+            type = types.nullOr types.optionType;
             internal = true;
             default = null;
             description = ''
diff --git a/lib/tests/modules.sh b/lib/tests/modules.sh
index d11f32e59964..e4bb7ad21900 100755
--- a/lib/tests/modules.sh
+++ b/lib/tests/modules.sh
@@ -240,6 +240,11 @@ checkConfigOutput '^"24"$' config.foo ./freeform-attrsOf.nix ./freeform-str-dep-
 checkConfigError 'infinite recursion encountered' config.foo ./freeform-attrsOf.nix ./freeform-unstr-dep-str.nix
 checkConfigError 'The option .* is used but not defined' config.foo ./freeform-lazyAttrsOf.nix ./freeform-unstr-dep-str.nix
 checkConfigOutput '^"24"$' config.foo ./freeform-lazyAttrsOf.nix ./freeform-unstr-dep-str.nix ./define-value-string.nix
+# submodules in freeformTypes should have their locations annotated
+checkConfigOutput '/freeform-submodules.nix"$' config.fooDeclarations.0 ./freeform-submodules.nix
+# freeformTypes can get merged using `types.type`, including submodules
+checkConfigOutput '^10$' config.free.xxx.foo ./freeform-submodules.nix
+checkConfigOutput '^10$' config.free.yyy.bar ./freeform-submodules.nix
 
 ## types.anything
 # Check that attribute sets are merged recursively
diff --git a/lib/tests/modules/freeform-submodules.nix b/lib/tests/modules/freeform-submodules.nix
new file mode 100644
index 000000000000..3910435a7b5c
--- /dev/null
+++ b/lib/tests/modules/freeform-submodules.nix
@@ -0,0 +1,22 @@
+{ lib, options, ... }: with lib.types; {
+
+  options.fooDeclarations = lib.mkOption {
+    default = (options.free.type.getSubOptions [])._freeformOptions.foo.declarations;
+  };
+
+  options.free = lib.mkOption {
+    type = submodule {
+      config._module.freeformType = lib.mkMerge [
+        (attrsOf (submodule {
+          options.foo = lib.mkOption {};
+        }))
+        (attrsOf (submodule {
+          options.bar = lib.mkOption {};
+        }))
+      ];
+    };
+  };
+
+  config.free.xxx.foo = 10;
+  config.free.yyy.bar = 10;
+}