Allow empty args to dataclass and field directives (#4957)

Part of the bug fixes in https://github.com/cython/cython/issues/4956

4 files changed, 29 insertions, 10 deletions

diff --git a/Cython/Compiler/Dataclass.py b/Cython/Compiler/Dataclass.py
index 609520004..327f11e19 100644
--- a/Cython/Compiler/Dataclass.py
+++ b/Cython/Compiler/Dataclass.py
@@ -217,14 +217,16 @@ def process_class_get_fields(node):
                     and assignment.function.as_cython_attribute() == "dataclasses.field"):
                 # I believe most of this is well-enforced when it's treated as a directive
                 # but it doesn't hurt to make sure
-                if (not isinstance(assignment, ExprNodes.GeneralCallNode)
-                        or not isinstance(assignment.positional_args, ExprNodes.TupleNode)
-                        or assignment.positional_args.args
-                        or not isinstance(assignment.keyword_args, ExprNodes.DictNode)):
+                valid_general_call = (isinstance(assignment, ExprNodes.GeneralCallNode)
+                        and isinstance(assignment.positional_args, ExprNodes.TupleNode)
+                        and not assignment.positional_args.args
+                        and (assignment.keyword_args is None or isinstance(assignment.keyword_args, ExprNodes.DictNode)))
+                valid_simple_call = (isinstance(assignment, ExprNodes.SimpleCallNode) and not assignment.args)
+                if not (valid_general_call or valid_simple_call):
                     error(assignment.pos, "Call to 'cython.dataclasses.field' must only consist "
                           "of compile-time keyword arguments")
                     continue
-                keyword_args = assignment.keyword_args.as_python_dict()
+                keyword_args = assignment.keyword_args.as_python_dict() if valid_general_call and assignment.keyword_args else {}
                 if 'default' in keyword_args and 'default_factory' in keyword_args:
                     error(assignment.pos, "cannot specify both default and default_factory")
                     continue
diff --git a/Cython/Compiler/ParseTreeTransforms.py b/Cython/Compiler/ParseTreeTransforms.py
index baf5b4ef7..54d861d8a 100644
--- a/Cython/Compiler/ParseTreeTransforms.py
+++ b/Cython/Compiler/ParseTreeTransforms.py
@@ -1225,7 +1225,7 @@ class InterpretCompilerDirectives(CythonTransform):
             return (optname, directivetype(optname, str(args[0].value)))
         elif directivetype is Options.DEFER_ANALYSIS_OF_ARGUMENTS:
             # signal to pass things on without processing
-            return (optname, (args, kwds.as_python_dict()))
+            return (optname, (args, kwds.as_python_dict() if kwds else {}))
         else:
             assert False
 
diff --git a/Tools/make_dataclass_tests.py b/Tools/make_dataclass_tests.py
index 6a3cee7ac..25f43cc2d 100644
--- a/Tools/make_dataclass_tests.py
+++ b/Tools/make_dataclass_tests.py
@@ -111,6 +111,7 @@ skip_tests = frozenset(
         ("TestInit", "test_base_has_init"),  # needs __dict__ for vars
         # Requires arbitrary attributes to be writeable
         ("TestCase", "test_post_init_super"),
+        ('TestCase', 'test_init_in_order'),
         # Cython being strict about argument types - expected difference
         ("TestDescriptors", "test_getting_field_calls_get"),
         ("TestDescriptors", "test_init_calls_set"),
@@ -129,10 +130,6 @@ skip_tests = frozenset(
         # not possible to add attributes on extension types
         ("TestCase", "test_post_init_classmethod"),
         # Bugs
-        # ====
-        ("TestCase", "test_no_options"),  # @dataclass()
-        ("TestCase", "test_field_no_default"),  # field()
-        ("TestCase", "test_init_in_order"),  # field()
         ("TestCase", "test_hash_field_rules"),  # compiler crash
         ("TestCase", "test_class_var"),  # not sure but compiler crash
         ("TestCase", "test_field_order"),  # invalid C code (__pyx_base?)
diff --git a/tests/run/test_dataclasses.pyx b/tests/run/test_dataclasses.pyx
index 8321b9de0..5ea83f82a 100644
--- a/tests/run/test_dataclasses.pyx
+++ b/tests/run/test_dataclasses.pyx
@@ -66,6 +66,11 @@ class C_TestCase_test_1_field_compare:
 
 @dataclass
 @cclass
+class C_TestCase_test_field_no_default:
+    x: int = field()
+
+@dataclass
+@cclass
 class C_TestCase_test_not_in_compare:
     x: int = 0
     y: int = field(compare=False, default=4)
@@ -80,6 +85,11 @@ class Mutable_TestCase_test_deliberately_mutable_defaults:
 class C_TestCase_test_deliberately_mutable_defaults:
     x: Mutable_TestCase_test_deliberately_mutable_defaults
 
+@dataclass()
+@cclass
+class C_TestCase_test_no_options:
+    x: int
+
 @dataclass
 @cclass
 class Point_TestCase_test_not_tuple:
@@ -580,6 +590,12 @@ class TestCase(unittest.TestCase):
         self.assertGreaterEqual(C(1), C(0))
         self.assertGreaterEqual(C(1), C(1))
 
+    def test_field_no_default(self):
+        C = C_TestCase_test_field_no_default
+        self.assertEqual(C(5).x, 5)
+        with self.assertRaises(TypeError):
+            C()
+
     def test_not_in_compare(self):
         C = C_TestCase_test_not_in_compare
         self.assertEqual(C(), C(0, 20))
@@ -599,6 +615,10 @@ class TestCase(unittest.TestCase):
         self.assertEqual(o1.x.l, [1, 2])
         self.assertIs(o1.x, o2.x)
 
+    def test_no_options(self):
+        C = C_TestCase_test_no_options
+        self.assertEqual(C(42).x, 42)
+
     def test_not_tuple(self):
         Point = Point_TestCase_test_not_tuple
         self.assertNotEqual(Point(1, 2), (1, 2))