Kwonly attributes are moved to the end in all cases, this behaviour does not depend on parent classes...

Author: sterliakov

mypy/plugins/dataclasses.py

@@ -263,7 +263,11 @@ def transform(self) -> bool:
             args = [
                 attr.to_argument(info, of="__init__")
                 for attr in attributes
-                if attr.is_in_init and not self._is_kw_only_type(attr.type)
+                if attr.is_in_init and not self._is_kw_only_type(attr.type) and not attr.kw_only
+            ] + [
+                attr.to_argument(info, of="__init__")
+                for attr in attributes
+                if attr.is_in_init and not self._is_kw_only_type(attr.type) and attr.kw_only
             ]
 
             if info.fallback_to_any:
@@ -546,7 +550,6 @@ def collect_attributes(self) -> list[DataclassAttribute] | None:
         # in the parent. We can implement this via a dict without disrupting the attr order
         # because dicts preserve insertion order in Python 3.7+.
         found_attrs: dict[str, DataclassAttribute] = {}
-        found_dataclass_supertype = False
         for info in reversed(cls.info.mro[1:-1]):
             if "dataclass_tag" in info.metadata and "dataclass" not in info.metadata:
                 # We haven't processed the base class yet. Need another pass.
@@ -556,7 +559,6 @@ def collect_attributes(self) -> list[DataclassAttribute] | None:
 
             # Each class depends on the set of attributes in its dataclass ancestors.
             self._api.add_plugin_dependency(make_wildcard_trigger(info.fullname))
-            found_dataclass_supertype = True
 
             for data in info.metadata["dataclass"]["attributes"]:
                 name: str = data["name"]
@@ -720,8 +722,7 @@ def collect_attributes(self) -> list[DataclassAttribute] | None:
             )
 
         all_attrs = list(found_attrs.values())
-        if found_dataclass_supertype:
-            all_attrs.sort(key=lambda a: a.kw_only)
+        all_attrs.sort(key=lambda a: a.kw_only)
 
         # Third, ensure that arguments without a default don't follow
         # arguments that have a default and that the KW_ONLY sentinel

test-data/unit/check-dataclasses.test

@@ -460,14 +460,16 @@ from dataclasses import dataclass, field, KW_ONLY
 class Application:
     _: KW_ONLY
     name: str = 'Unnamed'
-    rating: int = field(kw_only=False)  # E: Attributes without a default cannot follow attributes with one
+    rating: int = field(kw_only=False)
 
 Application(name='name', rating=5)
-Application()  # E: Missing positional argument "name" in call to "Application"
-Application('name')  # E: Too many positional arguments for "Application" # E: Too few arguments for "Application"
-Application('name', 123)  # E: Too many positional arguments for "Application"
-Application('name', rating=123)  # E: Too many positional arguments for "Application"
-
+Application()  # E: Missing positional argument "rating" in call to "Application"
+Application(123)
+Application('name')  # E: Argument 1 to "Application" has incompatible type "str"; expected "int"
+Application('name', 123)  # E: Too many positional arguments for "Application" \
+                          # E: Argument 1 to "Application" has incompatible type "str"; expected "int" \
+                          # E: Argument 2 to "Application" has incompatible type "int"; expected "str"
+Application(123, rating=123)  # E: "Application" gets multiple values for keyword argument "rating"
 [builtins fixtures/dataclasses.pyi]
 
 [case testDataclassesOrderingKwOnlyWithSentinelAndSubclass]
@@ -2610,3 +2612,14 @@ class B2(B1):  # E: A NamedTuple cannot be a dataclass
     pass
 
 [builtins fixtures/tuple.pyi]
+
+[case testDataclassKwOnlyArgsLast]
+from dataclasses import dataclass, field
+
+@dataclass
+class User:
+    id: int = field(kw_only=True)
+    name: str
+
+User("Foo", id=0)
+[builtins fixtures/tuple.pyi]