lib/types: init {types.attrsWith}

lib/modules.nix

@@ -751,17 +751,47 @@ let
           t' = opt.options.type;
           mergedType = t.typeMerge t'.functor;
           typesMergeable = mergedType != null;
-          typeSet = if (bothHave "type") && typesMergeable
-                       then { type = mergedType; }
-                       else {};
+
+          # TODO: Remove this when all downstream reliances of internals: 'functor.wrapped' are sufficiently migrated.
+          # A function that adds the deprecated wrapped message to a type.
+          addDeprecatedWrapped = t:
+            t // {
+              functor = t.functor // {
+                wrapped = t.functor.wrappedDeprecationMessage {
+                  inherit loc;
+                };
+              };
+            };
+
+          typeSet =
+            if opt.options ? type then
+              if res ? type then
+                if typesMergeable then
+                  {
+                    type =
+                      if mergedType ? functor.wrappedDeprecationMessage then
+                        addDeprecatedWrapped mergedType
+                      else
+                        mergedType;
+                  }
+                else
+                  # Keep in sync with the same error below!
+                  throw "The option `${showOption loc}' in `${opt._file}' is already declared in ${showFiles res.declarations}."
+              else if opt.options.type ? functor.wrappedDeprecationMessage then
+                { type = addDeprecatedWrapped opt.options.type; }
+              else
+                {}
+            else
+              {};
+
           bothHave = k: opt.options ? ${k} && res ? ${k};
       in
       if bothHave "default" ||
          bothHave "example" ||
          bothHave "description" ||
-         bothHave "apply" ||
-         (bothHave "type" && (! typesMergeable))
+         bothHave "apply"
       then
+        # Keep in sync with the same error above!
         throw "The option `${showOption loc}' in `${opt._file}' is already declared in ${showFiles res.declarations}."
       else
         let

lib/tests/modules.sh

@@ -386,6 +386,14 @@ checkConfigOutput '^true$' config.conditionalWorks ./declare-attrsOf.nix ./attrs
 checkConfigOutput '^false$' config.conditionalWorks ./declare-lazyAttrsOf.nix ./attrsOf-conditional-check.nix
 checkConfigOutput '^"empty"$' config.value.foo ./declare-lazyAttrsOf.nix ./attrsOf-conditional-check.nix
 
+# Check attrsWith type merging
+checkConfigError 'The option `mergedLazyNonLazy'\'' in `.*'\'' is already declared in `.*'\''\.' options.mergedLazyNonLazy ./lazy-attrsWith.nix
+checkConfigOutput '^11$' config.lazyResult ./lazy-attrsWith.nix
+checkConfigError 'infinite recursion encountered' config.nonLazyResult ./lazy-attrsWith.nix
+
+# Test the attrsOf functor.wrapped warning
+# shellcheck disable=2016
+NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `type.functor.wrapped` attribute of the option `mergedLazyLazy` is accessed, use `nestedTypes.elemType` instead.' options.mergedLazyLazy.type.functor.wrapped ./lazy-attrsWith.nix
 
 # Even with multiple assignments, a type error should be thrown if any of them aren't valid
 checkConfigError 'A definition for option .* is not of type .*' \
@@ -575,6 +583,7 @@ checkConfigOutput '^38|27$' options.submoduleLine38.declarationPositions.1.line
 # nested options work
 checkConfigOutput '^34$' options.nested.nestedLine34.declarationPositions.0.line ./declaration-positions.nix
 
+
 cat <<EOF
 ====== module tests ======
 $pass Pass

lib/tests/modules/lazy-attrsWith.nix

@@ -0,0 +1,57 @@
+# Check that AttrsWith { lazy = true; } is lazy
+{ lib, ... }:
+let
+  inherit (lib) types mkOption;
+
+  lazyAttrsOf = mkOption {
+    # Same as lazyAttrsOf
+    type = types.attrsWith {
+      lazy = true;
+      elemType = types.int;
+    };
+  };
+
+  attrsOf = mkOption {
+    # Same as lazyAttrsOf
+    type = types.attrsWith {
+      elemType = types.int;
+    };
+  };
+in
+{
+  imports = [
+    #  Module A
+    (
+      { ... }:
+      {
+        options.mergedLazyLazy = lazyAttrsOf;
+        options.mergedLazyNonLazy = lazyAttrsOf;
+        options.mergedNonLazyNonLazy = attrsOf;
+      }
+    )
+    # Module B
+    (
+      { ... }:
+      {
+        options.mergedLazyLazy = lazyAttrsOf;
+        options.mergedLazyNonLazy = attrsOf;
+        options.mergedNonLazyNonLazy = attrsOf;
+      }
+    )
+    # Result
+    (
+      { config, ... }:
+      {
+        # Can only evaluate if lazy
+        config.mergedLazyLazy.bar = config.mergedLazyLazy.baz + 1;
+        config.mergedLazyLazy.baz = 10;
+        options.lazyResult = mkOption { default = config.mergedLazyLazy.bar; };
+
+        # Can not only evaluate if not lazy
+        config.mergedNonLazyNonLazy.bar = config.mergedNonLazyNonLazy.baz + 1;
+        config.mergedNonLazyNonLazy.baz = 10;
+        options.nonLazyResult = mkOption { default = config.mergedNonLazyNonLazy.bar; };
+      }
+    )
+  ];
+}

lib/types.nix

@@ -83,35 +83,39 @@ rec {
   # Default type merging function
   # takes two type functors and return the merged type
   defaultTypeMerge = f: f':
-    let mergedWrapped = f.wrapped.typeMerge f'.wrapped.functor;
-        mergedPayload = f.binOp f.payload f'.payload;
+    let
+      mergedWrapped = f.wrapped.typeMerge f'.wrapped.functor;
+      mergedPayload = f.binOp f.payload f'.payload;
 
-        hasPayload = assert (f'.payload != null) == (f.payload != null); f.payload != null;
-        hasWrapped = assert (f'.wrapped != null) == (f.wrapped != null); f.wrapped != null;
+      hasPayload = assert (f'.payload != null) == (f.payload != null); f.payload != null;
+      hasWrapped = assert (f'.wrapped != null) == (f.wrapped != null); f.wrapped != null;
+
+      typeFromPayload = if mergedPayload == null then null else f.type mergedPayload;
+      typeFromWrapped = if mergedWrapped == null then null else f.type mergedWrapped;
     in
     # Abort early: cannot merge different types
     if f.name != f'.name
        then null
     else
 
     if hasPayload then
-      if hasWrapped then
+      # Just return the payload if returning wrapped is deprecated
+      if f ? wrappedDeprecationMessage then
+        typeFromPayload
+      else if hasWrapped then
         # Has both wrapped and payload
         throw ''
           Type ${f.name} defines both `functor.payload` and `functor.wrapped` at the same time, which is not supported.
 
           Use either `functor.payload` or `functor.wrapped` but not both.
 
-          If your code worked before remove `functor.payload` from the type definition.
+          If your code worked before remove either `functor.wrapped` or `functor.payload` from the type definition.
         ''
       else
-        # Has payload
-        if mergedPayload == null then null else f.type mergedPayload
+        typeFromPayload
     else
       if hasWrapped then
-        # Has wrapped
-        # TODO(@hsjobeki): This could also be a warning and removed in the future
-        if mergedWrapped == null then null else f.type mergedWrapped
+        typeFromWrapped
       else
         f.type;
 
@@ -582,48 +586,78 @@ rec {
         substSubModules = m: nonEmptyListOf (elemType.substSubModules m);
       };
 
-    attrsOf = elemType: mkOptionType rec {
-      name = "attrsOf";
-      description = "attribute set of ${optionDescriptionPhrase (class: class == "noun" || class == "composite") elemType}";
-      descriptionClass = "composite";
-      check = isAttrs;
-      merge = loc: defs:
-        mapAttrs (n: v: v.value) (filterAttrs (n: v: v ? value) (zipAttrsWith (name: defs:
-            (mergeDefinitions (loc ++ [name]) elemType defs).optionalValue
-          )
-          # Push down position info.
-          (map (def: mapAttrs (n: v: { inherit (def) file; value = v; }) def.value) defs)));
-      emptyValue = { value = {}; };
-      getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["<name>"]);
-      getSubModules = elemType.getSubModules;
-      substSubModules = m: attrsOf (elemType.substSubModules m);
-      functor = (defaultFunctor name) // { wrapped = elemType; };
-      nestedTypes.elemType = elemType;
-    };
+    attrsOf = elemType: attrsWith { inherit elemType; };
 
     # A version of attrsOf that's lazy in its values at the expense of
     # conditional definitions not working properly. E.g. defining a value with
     # `foo.attr = mkIf false 10`, then `foo ? attr == true`, whereas with
     # attrsOf it would correctly be `false`. Accessing `foo.attr` would throw an
     # error that it's not defined. Use only if conditional definitions don't make sense.
-    lazyAttrsOf = elemType: mkOptionType rec {
-      name = "lazyAttrsOf";
-      description = "lazy attribute set of ${optionDescriptionPhrase (class: class == "noun" || class == "composite") elemType}";
+    lazyAttrsOf = elemType: attrsWith { inherit elemType; lazy = true; };
+
+    # base type for lazyAttrsOf and attrsOf
+    attrsWith =
+    let
+      # Push down position info.
+      pushPositions = map (def: mapAttrs (n: v: { inherit (def) file; value = v; }) def.value);
+      binOp = lhs: rhs:
+        let
+          elemType = lhs.elemType.typeMerge rhs.elemType.functor;
+          lazy =
+            if lhs.lazy == rhs.lazy then
+              lhs.lazy
+            else
+              null;
+        in
+        if elemType == null || lazy == null then
+          null
+        else
+          {
+            inherit elemType lazy;
+          };
+    in
+    {
+      elemType,
+      lazy ? false,
+    }:
+    mkOptionType {
+      name = if lazy then "lazyAttrsOf" else "attrsOf";
+      description = (if lazy then "lazy attribute set" else "attribute set") + " of ${optionDescriptionPhrase (class: class == "noun" || class == "composite") elemType}";
       descriptionClass = "composite";
       check = isAttrs;
-      merge = loc: defs:
-        zipAttrsWith (name: defs:
-          let merged = mergeDefinitions (loc ++ [name]) elemType defs;
-          # mergedValue will trigger an appropriate error when accessed
-          in merged.optionalValue.value or elemType.emptyValue.value or merged.mergedValue
-        )
-        # Push down position info.
-        (map (def: mapAttrs (n: v: { inherit (def) file; value = v; }) def.value) defs);
+      merge = if lazy then (
+        # Lazy merge Function
+        loc: defs:
+          zipAttrsWith (name: defs:
+            let merged = mergeDefinitions (loc ++ [name]) elemType defs;
+            # mergedValue will trigger an appropriate error when accessed
+            in merged.optionalValue.value or elemType.emptyValue.value or merged.mergedValue
+          )
+          # Push down position info.
+          (pushPositions defs)
+      ) else (
+        # Non-lazy merge Function
+        loc: defs:
+          mapAttrs (n: v: v.value) (filterAttrs (n: v: v ? value) (zipAttrsWith (name: defs:
+              (mergeDefinitions (loc ++ [name]) elemType (defs)).optionalValue
+            )
+          # Push down position info.
+          (pushPositions defs)))
+      );
       emptyValue = { value = {}; };
       getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["<name>"]);
       getSubModules = elemType.getSubModules;
-      substSubModules = m: lazyAttrsOf (elemType.substSubModules m);
-      functor = (defaultFunctor name) // { wrapped = elemType; };
+      substSubModules = m: attrsWith { elemType = elemType.substSubModules m; inherit lazy; };
+      functor = defaultFunctor "attrsWith" // {
+        wrappedDeprecationMessage = { loc }: lib.warn ''
+          The deprecated `type.functor.wrapped` attribute of the option `${showOption loc}` is accessed, use `type.nestedTypes.elemType` instead.
+        '' elemType;
+        payload = {
+          # Important!: Add new function attributes here in case of future changes
+          inherit elemType lazy;
+        };
+        inherit binOp;
+      };
       nestedTypes.elemType = elemType;
     };