Handle kw_only flag for dataclasses in Static Python

Summary: Doesn't handle it *well* but at least it no longer amounts to an exception.

Reviewed By: martindemello

Differential Revision: D96499729

fbshipit-source-id: 7accdef8aeb288567d4dc41cf054a12ab2b6913c

Author: alexmalyshev

cinderx/PythonLib/cinderx/compiler/static/types.py

@@ -5272,6 +5272,14 @@ def __init__(self, type_env: TypeEnvironment) -> None:
                 False,
                 ParamStyle.KWONLY,
             ),
+            Parameter(
+                "kw_only",
+                7,
+                ResolvedTypeRef(type_env.bool),
+                True,
+                False,
+                ParamStyle.KWONLY,
+            ),
         ]
         super().__init__(
             type_env.function,
@@ -5321,6 +5329,7 @@ def resolve_decorate_class(
             "order": False,
             "unsafe_hash": False,
             "frozen": False,
+            "kw_only": False,
         }
 
         for kw in decorator.keywords:
@@ -5582,6 +5591,7 @@ def __init__(
         order: bool = False,
         unsafe_hash: bool = False,
         frozen: bool = False,
+        kw_only: bool = False,
     ) -> None:
         super().__init__(
             type_name=klass.type_name,
@@ -5602,6 +5612,7 @@ def __init__(
         self.order = order
         self.unsafe_hash = unsafe_hash
         self.frozen = frozen
+        self.kw_only = kw_only
 
         self.fields: dict[str, DataclassField] = {}
 
@@ -5824,14 +5835,15 @@ def finish_bind(self, module: ModuleTable, klass: Class | None) -> Value | None:
                     default = ast.Name("_HAS_DEFAULT_FACTORY", ast.Load())
                 else:
                     default = None
+
                 init_params.append(
                     Parameter(
                         name,
                         len(init_params),
                         field.unwrapped_ref,
                         has_default,
                         default,
-                        ParamStyle.NORMAL,
+                        ParamStyle.KWONLY if self.kw_only else ParamStyle.NORMAL,
                     )
                 )
 

cinderx/PythonLib/test_cinderx/test_compiler/test_static/dataclass.py

@@ -1858,3 +1858,33 @@ def x(c: C):
             a = mod.C("foo")
             for _ in range(256):
                 self.assertEqual(mod.x(a), "fooFalseNoneNone")
+
+    def test_dataclass_kw_only(self) -> None:
+        codestr = """
+        from dataclasses import dataclass
+
+        @dataclass(kw_only=True)
+        class C:
+            x: int
+            y: float
+
+        c = C(x=10, y=2.0)
+        """
+        with self.in_module(codestr) as mod:
+            self.assertEqual(mod.c.x, 10)
+
+    def test_dataclass_kw_only_wrong(self) -> None:
+        codestr = """
+        from dataclasses import dataclass
+
+        @dataclass(kw_only=True)
+        class C:
+            x: int
+            y: float
+
+        c = C(10, y=2.0)
+        """
+
+        # TODO(T259691972): This should raise a TypedSyntaxError!
+        with self.in_module(codestr) as mod:
+            self.assertEqual(mod.c.x, 10)