Allow submodules to use custom lib/evalModules

lib/tests/modules.sh

@@ -179,6 +179,13 @@ checkConfigOutput "true" config.submodule.outer ./declare-submoduleWith-modules.
 ## Paths should be allowed as values and work as expected
 checkConfigOutput "true" config.submodule.enable ./declare-submoduleWith-path.nix
 
+## evalModules should be settable
+checkConfigOutput 10 config.submodule.value ./submoduleWithLib.nix
+
+# Check the file location information is propagated into submodules
+checkConfigOutput the-file.nix config.submodule.internalFiles.0 ./submoduleFiles.nix
+
+
 # Check that disabledModules works recursively and correctly
 checkConfigOutput "true" config.enable ./disable-recursive/main.nix
 checkConfigOutput "true" config.enable ./disable-recursive/{main.nix,disable-foo.nix}

lib/tests/modules/submoduleFiles.nix

@@ -0,0 +1,21 @@
+{ lib, ... }: {
+  options.submodule = lib.mkOption {
+    default = {};
+    type = lib.types.submoduleWith {
+      modules = [ ({ options, ... }: {
+        options.value = lib.mkOption {};
+
+        options.internalFiles = lib.mkOption {
+          default = options.value.files;
+        };
+      })];
+    };
+  };
+
+  imports = [
+    {
+      _file = "the-file.nix";
+      submodule.value = 10;
+    }
+  ];
+}

lib/tests/modules/submoduleWithLib.nix

@@ -0,0 +1,13 @@
+{ lib, ... }: {
+  options.submodule = lib.mkOption {
+    default = {};
+    type = lib.types.submoduleWith {
+      evalModules = ((import ../..).extend (self: super: { value = 10; })).evalModules;
+      modules = [ ({ lib, ... }: {
+        options.value = lib.mkOption {
+          default = lib.value;
+        };
+      })];
+    };
+  };
+}

lib/types.nix

@@ -408,27 +408,23 @@ rec {
 
     submoduleWith =
       { modules
+      , evalModules ? lib.modules.evalModules
       , specialArgs ? {}
       , shorthandOnlyDefinesConfig ? false
       }@attrs:
       let
-        inherit (lib.modules) evalModules;
-
-        coerce = unify: value: if isFunction value
-          then setFunctionArgs (args: unify (value args)) (functionArgs value)
-          else unify (if shorthandOnlyDefinesConfig then { config = value; } else value);
 
         allModules = defs: modules ++ imap1 (n: { value, file }:
-          if isAttrs value || isFunction value then
-            # Annotate the value with the location of its definition for better error messages
-            coerce (lib.modules.unifyModuleSyntax file "${toString file}-${toString n}") value
-          else value
+          if isAttrs value && shorthandOnlyDefinesConfig
+          then { _file = file; config = value; }
+          else { _file = file; imports = [ value ]; }
         ) defs;
 
         freeformType = (evalModules {
           inherit modules specialArgs;
           args.name = "‹name›";
-        })._module.freeformType;
+        })._module.freeformType or null;
+        # `or null` in case the given evalModules doesn't have that attribute yet
 
       in
       mkOptionType rec {
@@ -477,6 +473,10 @@ rec {
             modules = modules;
             specialArgs = specialArgs;
             shorthandOnlyDefinesConfig = shorthandOnlyDefinesConfig;
+          } // optionalAttrs (attrs ? evalModules) {
+            # We need to be able to detect whether evalModules was set or not in
+            # the binOp function, to throw an error if it was set multiple times
+            inherit (attrs) evalModules;
           };
           binOp = lhs: rhs: {
             modules = lhs.modules ++ rhs.modules;
@@ -489,6 +489,10 @@ rec {
               if lhs.shorthandOnlyDefinesConfig == rhs.shorthandOnlyDefinesConfig
               then lhs.shorthandOnlyDefinesConfig
               else throw "A submoduleWith option is declared multiple times with conflicting shorthandOnlyDefinesConfig values";
+          } // optionalAttrs (lhs ? evalModules || rhs ? evalModules) {
+            evalModules = if lhs ? evalModules && rhs ? evalModules
+              then throw "A submoduleWith option is declared multiple times with conflicting evalModules values"
+              else lhs.evalModules or rhs.evalModules;
           };
         };
       };

nixos/doc/manual/development/option-types.xml

@@ -319,6 +319,7 @@
      <term>
        <varname>types.submoduleWith</varname> {
         <replaceable>modules</replaceable>,
+        <replaceable>evalModules</replaceable> ? lib.evalModules,
         <replaceable>specialArgs</replaceable> ? {},
         <replaceable>shorthandOnlyDefinesConfig</replaceable> ? false }
      </term>
@@ -335,6 +336,14 @@
                Only options defined with this argument are included in rendered documentation.
              </para></note>
            </para></listitem>
+           <listitem><para>
+             <replaceable>evalModules</replaceable>
+             The function used to evaluate the given modules. This can be set to a
+             <literal>lib.evalModules</literal> from another nixpkgs version if
+             the modules require that version for evaluation. This also causes
+             the <literal>lib</literal> module argument for the submodules to
+             point to the <literal>lib</literal> from <literal>evalModules</literal>.
+           </para></listitem>
            <listitem><para>
              <replaceable>specialArgs</replaceable>
              An attribute set of extra arguments to be passed to the module functions.