Allow singleton(C) as module self type constraint

config.yml

@@ -151,6 +151,16 @@ nodes:
     locations:
       - required: name
       - optional: args
+  - name: RBS::AST::Declarations::Module::SingletonSelf
+    rust_name: ModuleSingletonSelfNode
+    fields:
+      - name: name
+        c_type: rbs_type_name
+      - name: args
+        c_type: rbs_node_list
+    locations:
+      - required: name
+      - optional: args
   - name: RBS::AST::Declarations::ModuleAlias
     rust_name: ModuleAliasNode
     fields:

docs/syntax.md

@@ -637,8 +637,9 @@ _class-alias-decl_ ::= `class` _class-name_ `=` _class-name_
 
 _module-alias-decl_ ::= `module` _module-name_ `=` _module-name_
 
-_module-self-types_ ::= _class-name_ _type-arguments_ `,` _module-self-types_            (Class instance)
-                      | _interface-name_ _type-arguments_ `,` _module-self-types_        (Interface)
+_module-self-types_ ::= _class-name_ _type-arguments_ `,` _module-self-types_                     (Class instance)
+                      | _interface-name_ _type-arguments_ `,` _module-self-types_                 (Interface)
+                      | `singleton(` _class-name_ `)` _type-arguments_ `,` _module-self-types_    (Class singleton)
 
 _interface-decl_ ::= `interface` _interface-name_ _module-type-parameters_ _interface-members_ `end`
 
@@ -681,6 +682,22 @@ end
 
 The `Enumerable` module above requires `each` method for enumerating objects.
 
+The self type can be a class singleton type, which declares that the module is `extend`ed to the class (or its subclasses).
+
+```rbs
+class Model
+  def self.find: (Integer) -> instance
+end
+
+module ClassMethods : singleton(Model)
+  def find_or_raise: (Integer) -> Model   # Can call `find` of `singleton(Model)`
+end
+
+class User < Model
+  extend ClassMethods
+end
+```
+
 * Self type arguments and generic class bounds are not *classish-context* nor *self-context*
 
 ### Class/module alias declaration

ext/rbs_extension/ast_translation.c

@@ -487,6 +487,29 @@ VALUE rbs_struct_to_ruby_value(rbs_translation_context_t ctx, rbs_node_t *instan
         rb_hash_aset(h, ID2SYM(rb_intern("args")), arg_args);
         return CLASS_NEW_INSTANCE(RBS_AST_Declarations_Module_Self, 1, &h);
     }
+    case RBS_AST_DECLARATIONS_MODULE_SINGLETON_SELF: {
+        rbs_ast_declarations_module_singleton_self_t *node = (rbs_ast_declarations_module_singleton_self_t *) instance;
+
+        // Compute child VALUEs into locals variables first, before any recursion into `rbs_struct_to_ruby_value()`.
+        VALUE arg_location = rbs_location_range_to_ruby_location(ctx, node->base.location);
+        rbs_loc *loc = rbs_check_location(arg_location);
+        {
+            rbs_loc_legacy_alloc_children(loc, 2);
+            rbs_loc_legacy_add_required_child(loc, rb_intern("name"), (rbs_loc_range) { .start = node->name_range.start_char, .end = node->name_range.end_char });
+            rbs_loc_legacy_add_optional_child(loc, rb_intern("args"), (rbs_loc_range) { .start = node->args_range.start_char, .end = node->args_range.end_char });
+        }
+        VALUE arg_name = rbs_struct_to_ruby_value(ctx, (rbs_node_t *) node->name); // rbs_type_name
+        VALUE arg_args = rbs_node_list_to_ruby_array(ctx, node->args);
+
+        // Claim the shared kwargs hash, clear it, fill it, and hand it to `.new`.
+        // Must not recurse between `rb_hash_clear()` and `CLASS_NEW_INSTANCE()`.
+        VALUE h = ctx.reusable_kwargs_hash;
+        rb_hash_clear(h);
+        rb_hash_aset(h, ID2SYM(rb_intern("location")), arg_location);
+        rb_hash_aset(h, ID2SYM(rb_intern("name")), arg_name);
+        rb_hash_aset(h, ID2SYM(rb_intern("args")), arg_args);
+        return CLASS_NEW_INSTANCE(RBS_AST_Declarations_Module_SingletonSelf, 1, &h);
+    }
     case RBS_AST_DECLARATIONS_MODULE_ALIAS: {
         rbs_ast_declarations_module_alias_t *node = (rbs_ast_declarations_module_alias_t *) instance;
 

ext/rbs_extension/class_constants.c

@@ -28,6 +28,7 @@ VALUE RBS_AST_Declarations_Global;
 VALUE RBS_AST_Declarations_Interface;
 VALUE RBS_AST_Declarations_Module;
 VALUE RBS_AST_Declarations_Module_Self;
+VALUE RBS_AST_Declarations_Module_SingletonSelf;
 VALUE RBS_AST_Declarations_ModuleAlias;
 VALUE RBS_AST_Declarations_TypeAlias;
 VALUE RBS_AST_Directives_Use;
@@ -123,6 +124,7 @@ void rbs__init_constants(void) {
     IMPORT_CONSTANT(RBS_AST_Declarations_Interface, RBS_AST_Declarations, "Interface");
     IMPORT_CONSTANT(RBS_AST_Declarations_Module, RBS_AST_Declarations, "Module");
     IMPORT_CONSTANT(RBS_AST_Declarations_Module_Self, RBS_AST_Declarations_Module, "Self");
+    IMPORT_CONSTANT(RBS_AST_Declarations_Module_SingletonSelf, RBS_AST_Declarations_Module, "SingletonSelf");
     IMPORT_CONSTANT(RBS_AST_Declarations_ModuleAlias, RBS_AST_Declarations, "ModuleAlias");
     IMPORT_CONSTANT(RBS_AST_Declarations_TypeAlias, RBS_AST_Declarations, "TypeAlias");
     IMPORT_CONSTANT(RBS_AST_Directives_Use, RBS_AST_Directives, "Use");

ext/rbs_extension/class_constants.h

@@ -36,6 +36,7 @@ extern VALUE RBS_AST_Declarations_Global;
 extern VALUE RBS_AST_Declarations_Interface;
 extern VALUE RBS_AST_Declarations_Module;
 extern VALUE RBS_AST_Declarations_Module_Self;
+extern VALUE RBS_AST_Declarations_Module_SingletonSelf;
 extern VALUE RBS_AST_Declarations_ModuleAlias;
 extern VALUE RBS_AST_Declarations_TypeAlias;
 extern VALUE RBS_AST_Directives_Use;

include/rbs/ast.h

@@ -71,73 +71,74 @@ enum rbs_node_type {
     RBS_AST_DECLARATIONS_INTERFACE = 9,
     RBS_AST_DECLARATIONS_MODULE = 10,
     RBS_AST_DECLARATIONS_MODULE_SELF = 11,
-    RBS_AST_DECLARATIONS_MODULE_ALIAS = 12,
-    RBS_AST_DECLARATIONS_TYPE_ALIAS = 13,
-    RBS_AST_DIRECTIVES_USE = 14,
-    RBS_AST_DIRECTIVES_USE_SINGLE_CLAUSE = 15,
-    RBS_AST_DIRECTIVES_USE_WILDCARD_CLAUSE = 16,
-    RBS_AST_INTEGER = 17,
-    RBS_AST_MEMBERS_ALIAS = 18,
-    RBS_AST_MEMBERS_ATTR_ACCESSOR = 19,
-    RBS_AST_MEMBERS_ATTR_READER = 20,
-    RBS_AST_MEMBERS_ATTR_WRITER = 21,
-    RBS_AST_MEMBERS_CLASS_INSTANCE_VARIABLE = 22,
-    RBS_AST_MEMBERS_CLASS_VARIABLE = 23,
-    RBS_AST_MEMBERS_EXTEND = 24,
-    RBS_AST_MEMBERS_INCLUDE = 25,
-    RBS_AST_MEMBERS_INSTANCE_VARIABLE = 26,
-    RBS_AST_MEMBERS_METHOD_DEFINITION = 27,
-    RBS_AST_MEMBERS_METHOD_DEFINITION_OVERLOAD = 28,
-    RBS_AST_MEMBERS_PREPEND = 29,
-    RBS_AST_MEMBERS_PRIVATE = 30,
-    RBS_AST_MEMBERS_PUBLIC = 31,
-    RBS_AST_RUBY_ANNOTATIONS_BLOCK_PARAM_TYPE_ANNOTATION = 32,
-    RBS_AST_RUBY_ANNOTATIONS_CLASS_ALIAS_ANNOTATION = 33,
-    RBS_AST_RUBY_ANNOTATIONS_COLON_METHOD_TYPE_ANNOTATION = 34,
-    RBS_AST_RUBY_ANNOTATIONS_DOUBLE_SPLAT_PARAM_TYPE_ANNOTATION = 35,
-    RBS_AST_RUBY_ANNOTATIONS_INSTANCE_VARIABLE_ANNOTATION = 36,
-    RBS_AST_RUBY_ANNOTATIONS_METHOD_TYPES_ANNOTATION = 37,
-    RBS_AST_RUBY_ANNOTATIONS_MODULE_ALIAS_ANNOTATION = 38,
-    RBS_AST_RUBY_ANNOTATIONS_MODULE_SELF_ANNOTATION = 39,
-    RBS_AST_RUBY_ANNOTATIONS_NODE_TYPE_ASSERTION = 40,
-    RBS_AST_RUBY_ANNOTATIONS_PARAM_TYPE_ANNOTATION = 41,
-    RBS_AST_RUBY_ANNOTATIONS_RETURN_TYPE_ANNOTATION = 42,
-    RBS_AST_RUBY_ANNOTATIONS_SKIP_ANNOTATION = 43,
-    RBS_AST_RUBY_ANNOTATIONS_SPLAT_PARAM_TYPE_ANNOTATION = 44,
-    RBS_AST_RUBY_ANNOTATIONS_TYPE_APPLICATION_ANNOTATION = 45,
-    RBS_AST_STRING = 46,
-    RBS_AST_TYPE_PARAM = 47,
-    RBS_METHOD_TYPE = 48,
-    RBS_NAMESPACE = 49,
-    RBS_SIGNATURE = 50,
-    RBS_TYPE_NAME = 51,
-    RBS_TYPES_ALIAS = 52,
-    RBS_TYPES_BASES_ANY = 53,
-    RBS_TYPES_BASES_BOOL = 54,
-    RBS_TYPES_BASES_BOTTOM = 55,
-    RBS_TYPES_BASES_CLASS = 56,
-    RBS_TYPES_BASES_INSTANCE = 57,
-    RBS_TYPES_BASES_NIL = 58,
-    RBS_TYPES_BASES_SELF = 59,
-    RBS_TYPES_BASES_TOP = 60,
-    RBS_TYPES_BASES_VOID = 61,
-    RBS_TYPES_BLOCK = 62,
-    RBS_TYPES_CLASS_INSTANCE = 63,
-    RBS_TYPES_CLASS_SINGLETON = 64,
-    RBS_TYPES_FUNCTION = 65,
-    RBS_TYPES_FUNCTION_FORWARDING_PARAM = 66,
-    RBS_TYPES_FUNCTION_PARAM = 67,
-    RBS_TYPES_INTERFACE = 68,
-    RBS_TYPES_INTERSECTION = 69,
-    RBS_TYPES_LITERAL = 70,
-    RBS_TYPES_OPTIONAL = 71,
-    RBS_TYPES_PROC = 72,
-    RBS_TYPES_RECORD = 73,
-    RBS_TYPES_RECORD_FIELD_TYPE = 74,
-    RBS_TYPES_TUPLE = 75,
-    RBS_TYPES_UNION = 76,
-    RBS_TYPES_UNTYPED_FUNCTION = 77,
-    RBS_TYPES_VARIABLE = 78,
+    RBS_AST_DECLARATIONS_MODULE_SINGLETON_SELF = 12,
+    RBS_AST_DECLARATIONS_MODULE_ALIAS = 13,
+    RBS_AST_DECLARATIONS_TYPE_ALIAS = 14,
+    RBS_AST_DIRECTIVES_USE = 15,
+    RBS_AST_DIRECTIVES_USE_SINGLE_CLAUSE = 16,
+    RBS_AST_DIRECTIVES_USE_WILDCARD_CLAUSE = 17,
+    RBS_AST_INTEGER = 18,
+    RBS_AST_MEMBERS_ALIAS = 19,
+    RBS_AST_MEMBERS_ATTR_ACCESSOR = 20,
+    RBS_AST_MEMBERS_ATTR_READER = 21,
+    RBS_AST_MEMBERS_ATTR_WRITER = 22,
+    RBS_AST_MEMBERS_CLASS_INSTANCE_VARIABLE = 23,
+    RBS_AST_MEMBERS_CLASS_VARIABLE = 24,
+    RBS_AST_MEMBERS_EXTEND = 25,
+    RBS_AST_MEMBERS_INCLUDE = 26,
+    RBS_AST_MEMBERS_INSTANCE_VARIABLE = 27,
+    RBS_AST_MEMBERS_METHOD_DEFINITION = 28,
+    RBS_AST_MEMBERS_METHOD_DEFINITION_OVERLOAD = 29,
+    RBS_AST_MEMBERS_PREPEND = 30,
+    RBS_AST_MEMBERS_PRIVATE = 31,
+    RBS_AST_MEMBERS_PUBLIC = 32,
+    RBS_AST_RUBY_ANNOTATIONS_BLOCK_PARAM_TYPE_ANNOTATION = 33,
+    RBS_AST_RUBY_ANNOTATIONS_CLASS_ALIAS_ANNOTATION = 34,
+    RBS_AST_RUBY_ANNOTATIONS_COLON_METHOD_TYPE_ANNOTATION = 35,
+    RBS_AST_RUBY_ANNOTATIONS_DOUBLE_SPLAT_PARAM_TYPE_ANNOTATION = 36,
+    RBS_AST_RUBY_ANNOTATIONS_INSTANCE_VARIABLE_ANNOTATION = 37,
+    RBS_AST_RUBY_ANNOTATIONS_METHOD_TYPES_ANNOTATION = 38,
+    RBS_AST_RUBY_ANNOTATIONS_MODULE_ALIAS_ANNOTATION = 39,
+    RBS_AST_RUBY_ANNOTATIONS_MODULE_SELF_ANNOTATION = 40,
+    RBS_AST_RUBY_ANNOTATIONS_NODE_TYPE_ASSERTION = 41,
+    RBS_AST_RUBY_ANNOTATIONS_PARAM_TYPE_ANNOTATION = 42,
+    RBS_AST_RUBY_ANNOTATIONS_RETURN_TYPE_ANNOTATION = 43,
+    RBS_AST_RUBY_ANNOTATIONS_SKIP_ANNOTATION = 44,
+    RBS_AST_RUBY_ANNOTATIONS_SPLAT_PARAM_TYPE_ANNOTATION = 45,
+    RBS_AST_RUBY_ANNOTATIONS_TYPE_APPLICATION_ANNOTATION = 46,
+    RBS_AST_STRING = 47,
+    RBS_AST_TYPE_PARAM = 48,
+    RBS_METHOD_TYPE = 49,
+    RBS_NAMESPACE = 50,
+    RBS_SIGNATURE = 51,
+    RBS_TYPE_NAME = 52,
+    RBS_TYPES_ALIAS = 53,
+    RBS_TYPES_BASES_ANY = 54,
+    RBS_TYPES_BASES_BOOL = 55,
+    RBS_TYPES_BASES_BOTTOM = 56,
+    RBS_TYPES_BASES_CLASS = 57,
+    RBS_TYPES_BASES_INSTANCE = 58,
+    RBS_TYPES_BASES_NIL = 59,
+    RBS_TYPES_BASES_SELF = 60,
+    RBS_TYPES_BASES_TOP = 61,
+    RBS_TYPES_BASES_VOID = 62,
+    RBS_TYPES_BLOCK = 63,
+    RBS_TYPES_CLASS_INSTANCE = 64,
+    RBS_TYPES_CLASS_SINGLETON = 65,
+    RBS_TYPES_FUNCTION = 66,
+    RBS_TYPES_FUNCTION_FORWARDING_PARAM = 67,
+    RBS_TYPES_FUNCTION_PARAM = 68,
+    RBS_TYPES_INTERFACE = 69,
+    RBS_TYPES_INTERSECTION = 70,
+    RBS_TYPES_LITERAL = 71,
+    RBS_TYPES_OPTIONAL = 72,
+    RBS_TYPES_PROC = 73,
+    RBS_TYPES_RECORD = 74,
+    RBS_TYPES_RECORD_FIELD_TYPE = 75,
+    RBS_TYPES_TUPLE = 76,
+    RBS_TYPES_UNION = 77,
+    RBS_TYPES_UNTYPED_FUNCTION = 78,
+    RBS_TYPES_VARIABLE = 79,
     RBS_AST_SYMBOL,
 };
 
@@ -317,6 +318,16 @@ typedef struct rbs_ast_declarations_module_self {
     rbs_location_range args_range; /* Optional */
 } rbs_ast_declarations_module_self_t;
 
+typedef struct rbs_ast_declarations_module_singleton_self {
+    rbs_node_t base;
+
+    struct rbs_type_name *RBS_NONNULL name;
+    struct rbs_node_list *RBS_NONNULL args;
+
+    rbs_location_range name_range; /* Required */
+    rbs_location_range args_range; /* Optional */
+} rbs_ast_declarations_module_singleton_self_t;
+
 typedef struct rbs_ast_declarations_module_alias {
     rbs_node_t base;
 
@@ -984,6 +995,7 @@ rbs_ast_declarations_global_t *RBS_NONNULL rbs_ast_declarations_global_new(rbs_a
 rbs_ast_declarations_interface_t *RBS_NONNULL rbs_ast_declarations_interface_new(rbs_allocator_t *RBS_NONNULL allocator, rbs_location_range location, rbs_type_name_t *RBS_NONNULL name, rbs_node_list_t *RBS_NONNULL type_params, rbs_node_list_t *RBS_NONNULL members, rbs_node_list_t *RBS_NONNULL annotations, rbs_ast_comment_t *RBS_NULLABLE comment, rbs_location_range keyword_range, rbs_location_range name_range, rbs_location_range end_range);
 rbs_ast_declarations_module_t *RBS_NONNULL rbs_ast_declarations_module_new(rbs_allocator_t *RBS_NONNULL allocator, rbs_location_range location, rbs_type_name_t *RBS_NONNULL name, rbs_node_list_t *RBS_NONNULL type_params, rbs_node_list_t *RBS_NONNULL self_types, rbs_node_list_t *RBS_NONNULL members, rbs_node_list_t *RBS_NONNULL annotations, rbs_ast_comment_t *RBS_NULLABLE comment, rbs_location_range keyword_range, rbs_location_range name_range, rbs_location_range end_range);
 rbs_ast_declarations_module_self_t *RBS_NONNULL rbs_ast_declarations_module_self_new(rbs_allocator_t *RBS_NONNULL allocator, rbs_location_range location, rbs_type_name_t *RBS_NONNULL name, rbs_node_list_t *RBS_NONNULL args, rbs_location_range name_range);
+rbs_ast_declarations_module_singleton_self_t *RBS_NONNULL rbs_ast_declarations_module_singleton_self_new(rbs_allocator_t *RBS_NONNULL allocator, rbs_location_range location, rbs_type_name_t *RBS_NONNULL name, rbs_node_list_t *RBS_NONNULL args, rbs_location_range name_range);
 rbs_ast_declarations_module_alias_t *RBS_NONNULL rbs_ast_declarations_module_alias_new(rbs_allocator_t *RBS_NONNULL allocator, rbs_location_range location, rbs_type_name_t *RBS_NONNULL new_name, rbs_type_name_t *RBS_NONNULL old_name, rbs_ast_comment_t *RBS_NULLABLE comment, rbs_node_list_t *RBS_NONNULL annotations, rbs_location_range keyword_range, rbs_location_range new_name_range, rbs_location_range eq_range, rbs_location_range old_name_range);
 rbs_ast_declarations_type_alias_t *RBS_NONNULL rbs_ast_declarations_type_alias_new(rbs_allocator_t *RBS_NONNULL allocator, rbs_location_range location, rbs_type_name_t *RBS_NONNULL name, rbs_node_list_t *RBS_NONNULL type_params, rbs_node_t *RBS_NONNULL type, rbs_node_list_t *RBS_NONNULL annotations, rbs_ast_comment_t *RBS_NULLABLE comment, rbs_location_range keyword_range, rbs_location_range name_range, rbs_location_range eq_range);
 rbs_ast_directives_use_t *RBS_NONNULL rbs_ast_directives_use_new(rbs_allocator_t *RBS_NONNULL allocator, rbs_location_range location, rbs_node_list_t *RBS_NONNULL clauses, rbs_location_range keyword_range);

lib/rbs/ast/declarations.rb

@@ -156,6 +156,10 @@ def initialize(name:, args:, location:)
             @location = location
           end
 
+          def update(name: self.name, args: self.args, location: self.location)
+            self.class.new(name: name, args: args, location: location)
+          end
+
           def ==(other)
             other.is_a?(Self) && other.name == name && other.args == args
           end
@@ -183,6 +187,49 @@ def to_s
           end
         end
 
+        class SingletonSelf
+          attr_reader :name
+          attr_reader :args
+          attr_reader :location
+
+          def initialize(name:, args:, location:)
+            @name = name
+            @args = args
+            @location = location
+          end
+
+          def update(name: self.name, args: self.args, location: self.location)
+            self.class.new(name: name, args: args, location: location)
+          end
+
+          def ==(other)
+            other.is_a?(SingletonSelf) && other.name == name && other.args == args
+          end
+
+          alias eql? ==
+
+          def hash
+            self.class.hash ^ name.hash ^ args.hash
+          end
+
+          def to_json(state = nil)
+            {
+              singleton: true,
+              name: name,
+              args: args,
+              location: location
+            }.to_json(state)
+          end
+
+          def to_s
+            if args.empty?
+              "singleton(#{name})"
+            else
+              "singleton(#{name})[#{args.join(", ")}]"
+            end
+          end
+        end
+
         include NestedDeclarationHelper
         include MixinHelper
 

lib/rbs/definition.rb

@@ -228,10 +228,11 @@ def hash
       end
 
       class Singleton
-        attr_reader :name
+        attr_reader :name, :source
 
-        def initialize(name:)
+        def initialize(name:, source: nil)
           @name = name
+          @source = source
         end
 
         def ==(other)