Jan 26, 2023 · Jan 20, 2023 · Jan 25, 2023 · Jan 25, 2023 · Jan 25, 2023 · Jan 26, 2023
diff --git a/mypy/nodes.py b/mypy/nodes.py
        return visitor.visit_import_all(self)


 FUNCBASE_FLAGS: Final = ["is_property", "is_class", "is_static", "is_final"]
 FUNCBASE_FLAGS: Final = [
    "is_property",
    "is_class",
    "is_static",
    "is_final",
    "is_dataclass_transform",
 ]


 class FuncBase(Node):
        "is_static",  # Uses "@staticmethod"
        "is_final",  # Uses "@final"
        "_fullname",
        "is_dataclass_transform", # Is decorated with "@typing.dataclass_transform" or similar
    )

    def __init__(self) -> None:
        self.is_final = False
        # Name with module prefix
        self._fullname = ""
        self.is_dataclass_transform = False

    @property
    @abstractmethod
diff --git a/mypy/plugins/common.py b/mypy/plugins/common.py
 Var,
 )
 frommypy.pluginimportCheckerPluginInterface,ClassDefContext,SemanticAnalyzerPluginInterface
 frommypy.semanalimportALLOW_INCOMPATIBLE_OVERRIDE,set_callable_name
 frommypy.semanal_sharedimportALLOW_INCOMPATIBLE_OVERRIDE,set_callable_name
 frommypy.typeopsimport (# noqa: F401  # Part of public API
 try_getting_str_literalsastry_getting_str_literals,
 )
diff --git a/mypy/semanal.py b/mypy/semanal.py
    Plugin,
    SemanticAnalyzerPluginInterface,
 )
 from mypy.plugins import dataclasses as dataclasses_plugin
 from mypy.reachability import (
    ALWAYS_FALSE,
    ALWAYS_TRUE,
 from mypy.semanal_namedtuple import NamedTupleAnalyzer
 from mypy.semanal_newtype import NewTypeAnalyzer
 from mypy.semanal_shared import (
    ALLOW_INCOMPATIBLE_OVERRIDE,
    PRIORITY_FALLBACKS,
    SemanticAnalyzerInterface,
    calculate_tuple_fallback,
 from mypy.typeops import function_type, get_type_vars
 from mypy.types import (
    ASSERT_TYPE_NAMES,
    DATACLASS_TRANSFORM_NAMES,
    FINAL_DECORATOR_NAMES,
    FINAL_TYPE_NAMES,
    NEVER_NAMES,
 # available very early on.
 CORE_BUILTIN_CLASSES: Final = ["object", "bool", "function"]

 # Subclasses can override these Var attributes with incompatible types. This can also be
 # set for individual attributes using 'allow_incompatible_override' of Var.
 ALLOW_INCOMPATIBLE_OVERRIDE: Final = ("__slots__", "__deletable__", "__match_args__")


 # Used for tracking incomplete references
 Tag: _TypeAlias = int
                    removed.append(i)
                else:
                    self.fail("@final cannot be used with non-method functions", d)
            elif isinstance(d, CallExpr) and refers_to_fullname(
                d.callee, DATACLASS_TRANSFORM_NAMES
            ):
                dec.func.is_dataclass_transform = True
            elif not dec.var.is_property:
                # We have seen a "non-trivial" decorator before seeing @property, if
                # we will see a @property later, give an error, as we don't support this.
            decorator_name = self.get_fullname_for_hook(decorator)
            if decorator_name:
                hook = self.plugin.get_class_decorator_hook(decorator_name)
                # Special case: if the decorator is itself decorated with
                # typing.dataclass_transform, apply the hook for the dataclasses plugin
                # TODO: remove special casing here
                if hook is None and is_dataclass_transform_decorator(decorator):
                    hook = dataclasses_plugin.dataclass_tag_callback
                if hook:
                    hook(ClassDefContext(defn, decorator, self))

    return isinstance(stmt, PassStmt) or (
        isinstance(stmt, ExpressionStmt) and isinstance(stmt.expr, EllipsisExpr)
    )


 def is_dataclass_transform_decorator(node: Node | None) -> bool:
    if isinstance(node, RefExpr):
        return is_dataclass_transform_decorator(node.node)

    return isinstance(node, Decorator) and node.func.is_dataclass_transform
diff --git a/mypy/semanal_main.py b/mypy/semanal_main.py
 from mypy.nodes import Decorator, FuncDef, MypyFile, OverloadedFuncDef, TypeInfo, Var
 from mypy.options import Options
 from mypy.plugin import ClassDefContext
 from mypy.plugins import dataclasses as dataclasses_plugin
 from mypy.semanal import (
    SemanticAnalyzer,
    apply_semantic_analyzer_patches,
    is_dataclass_transform_decorator,
    remove_imported_names_from_symtable,
 )
 from mypy.semanal_classprop import (
    ok = True
    for decorator in defn.decorators:
        with self.file_context(file_node, options, info):
            hook = None

            decorator_name = self.get_fullname_for_hook(decorator)
            if decorator_name:
                hook = self.plugin.get_class_decorator_hook_2(decorator_name)
                if hook:
                    ok = ok and hook(ClassDefContext(defn, decorator, self))
            # Special case: if the decorator is itself decorated with
            # typing.dataclass_transform, apply the hook for the dataclasses plugin
            # TODO: remove special casing here
            if hook is None and is_dataclass_transform_decorator(decorator):
                hook = dataclasses_plugin.dataclass_class_maker_callback

            if hook:
                ok = ok and hook(ClassDefContext(defn, decorator, self))
    return ok


diff --git a/mypy/semanal_shared.py b/mypy/semanal_shared.py
    get_proper_type,
 )

 # Subclasses can override these Var attributes with incompatible types. This can also be
 # set for individual attributes using 'allow_incompatible_override' of Var.
 ALLOW_INCOMPATIBLE_OVERRIDE: Final = ("__slots__", "__deletable__", "__match_args__")


 # Priorities for ordering of patches within the "patch" phase of semantic analysis
 # (after the main pass):

diff --git a/mypy/types.py b/mypy/types.py
    "typing_extensions.Never",
 )

 DATACLASS_TRANSFORM_NAMES: Final = (
    "typing.dataclass_transform",
    "typing_extensions.dataclass_transform",
 )

 # A placeholder used for Bogus[...] parameters
 _dummy: Final[Any] = object()

diff --git a/test-data/unit/check-dataclass-transform.test b/test-data/unit/check-dataclass-transform.test
 [case testDataclassTransformReusesDataclassLogic]
 # flags: --python-version 3.7
 from typing import dataclass_transform, Type

 @dataclass_transform()
 def my_dataclass(cls: Type) -> Type:
    return cls

 @my_dataclass
 class Person:
    name: str
    age: int

    def summary(self):
        return "%s is %d years old." % (self.name, self.age)

 reveal_type(Person)  # N: Revealed type is "def (name: builtins.str, age: builtins.int) -> __main__.Person"
 Person('John', 32)
 Person('Jonh', 21, None)  # E: Too many arguments for "Person"

 [typing fixtures/typing-medium.pyi]
 [builtins fixtures/dataclasses.pyi]

 [case testDataclassTransformIsFoundInTypingExtensions]
 # flags: --python-version 3.7
 from typing import Type
 from typing_extensions import dataclass_transform

 @dataclass_transform()
 def my_dataclass(cls: Type) -> Type:
    return cls

 @my_dataclass
 class Person:
    name: str
    age: int

    def summary(self):
        return "%s is %d years old." % (self.name, self.age)

 reveal_type(Person)  # N: Revealed type is "def (name: builtins.str, age: builtins.int) -> __main__.Person"
 Person('John', 32)
 Person('Jonh', 21, None)  # E: Too many arguments for "Person"

 [typing fixtures/typing-full.pyi]
 [builtins fixtures/dataclasses.pyi]
diff --git a/test-data/unit/fixtures/dataclasses.pyi b/test-data/unit/fixtures/dataclasses.pyi
    def get(self, k: KT, default: Union[KT, _T]) -> Union[VT, _T]: pass
    def __len__(self) -> int: ...

 class list(Generic[_T], Sequence[_T]): pass
 class list(Generic[_T], Sequence[_T]):
    def __contains__(self, item: object) -> int: pass
    def __getitem__(self, key: int) -> _T: pass
    def __iter__(self) -> Iterator[_T]: pass

 class function: pass
 class classmethod: pass
 property = object()
diff --git a/test-data/unit/fixtures/typing-medium.pyi b/test-data/unit/fixtures/typing-medium.pyi
 class _SpecialForm: pass

 TYPE_CHECKING = 1

 def dataclass_transform() -> Callable[[T], T]: ...
diff --git a/test-data/unit/lib-stub/typing_extensions.pyi b/test-data/unit/lib-stub/typing_extensions.pyi
 def TypedDict(typename: str, fields: Dict[str, Type[_T]], *, total: Any = ...) -> Type[dict]: ...

 def reveal_type(__obj: T) -> T: pass

 def dataclass_transform() -> Callable[[T], T]: ...
Original file line number	Diff line number	Diff line change
Expand Up		@@ -480,7 +480,13 @@ def accept(self, visitor: StatementVisitor[T]) -> T:
		return visitor.visit_import_all(self)


		FUNCBASE_FLAGS: Final = ["is_property", "is_class", "is_static", "is_final"]
		FUNCBASE_FLAGS: Final = [
		"is_property",
		"is_class",
		"is_static",
		"is_final",
		"is_dataclass_transform",
		]


		class FuncBase(Node):
Expand All		@@ -506,6 +512,7 @@ class FuncBase(Node):
		"is_static", # Uses "@staticmethod"
		"is_final", # Uses "@final"
		"_fullname",
		"is_dataclass_transform", # Is decorated with "@typing.dataclass_transform" or similar
		)

		def __init__(self) -> None:
Expand All		@@ -524,6 +531,7 @@ def __init__(self) -> None:
		self.is_final = False
		# Name with module prefix
		self._fullname = ""
		self.is_dataclass_transform = False

		@property
		@abstractmethod
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -19,7 +19,7 @@
		Var,
		)
		frommypy.pluginimportCheckerPluginInterface,ClassDefContext,SemanticAnalyzerPluginInterface
		frommypy.semanalimportALLOW_INCOMPATIBLE_OVERRIDE,set_callable_name
		frommypy.semanal_sharedimportALLOW_INCOMPATIBLE_OVERRIDE,set_callable_name
Copy link CollaboratorAuthor wesleywrightJan 25, 2023 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. this move was needed to avoid a cyclic dependency between`semanal.py` and`plugins/common.py`
		frommypy.typeopsimport (# noqa: F401 # Part of public API
		try_getting_str_literalsastry_getting_str_literals,
		)
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -194,6 +194,7 @@
		Plugin,
		SemanticAnalyzerPluginInterface,
		)
		from mypy.plugins import dataclasses as dataclasses_plugin
		from mypy.reachability import (
		ALWAYS_FALSE,
		ALWAYS_TRUE,
Expand All		@@ -208,6 +209,7 @@
		from mypy.semanal_namedtuple import NamedTupleAnalyzer
		from mypy.semanal_newtype import NewTypeAnalyzer
		from mypy.semanal_shared import (
		ALLOW_INCOMPATIBLE_OVERRIDE,
		PRIORITY_FALLBACKS,
		SemanticAnalyzerInterface,
		calculate_tuple_fallback,
Expand All		@@ -234,6 +236,7 @@
		from mypy.typeops import function_type, get_type_vars
		from mypy.types import (
		ASSERT_TYPE_NAMES,
		DATACLASS_TRANSFORM_NAMES,
		FINAL_DECORATOR_NAMES,
		FINAL_TYPE_NAMES,
		NEVER_NAMES,
Expand DownExpand Up		@@ -304,10 +307,6 @@
		# available very early on.
		CORE_BUILTIN_CLASSES: Final = ["object", "bool", "function"]

		# Subclasses can override these Var attributes with incompatible types. This can also be
		# set for individual attributes using 'allow_incompatible_override' of Var.
		ALLOW_INCOMPATIBLE_OVERRIDE: Final = ("__slots__", "__deletable__", "__match_args__")


		# Used for tracking incomplete references
		Tag: _TypeAlias = int
Expand DownExpand Up		@@ -1505,6 +1504,10 @@ def visit_decorator(self, dec: Decorator) -> None:
		removed.append(i)
		else:
		self.fail("@final cannot be used with non-method functions", d)
		elif isinstance(d, CallExpr) and refers_to_fullname(
		d.callee, DATACLASS_TRANSFORM_NAMES
		):
		dec.func.is_dataclass_transform = True
		elif not dec.var.is_property:
		# We have seen a "non-trivial" decorator before seeing @property, if
		# we will see a @property later, give an error, as we don't support this.
Expand DownExpand Up		@@ -1706,6 +1709,11 @@ def apply_class_plugin_hooks(self, defn: ClassDef) -> None:
		decorator_name = self.get_fullname_for_hook(decorator)
		if decorator_name:
		hook = self.plugin.get_class_decorator_hook(decorator_name)
		# Special case: if the decorator is itself decorated with
		# typing.dataclass_transform, apply the hook for the dataclasses plugin
		# TODO: remove special casing here
		if hook is None and is_dataclass_transform_decorator(decorator):
		hook = dataclasses_plugin.dataclass_tag_callback
		if hook:
		hook(ClassDefContext(defn, decorator, self))

Expand DownExpand Up		@@ -6596,3 +6604,10 @@ def halt(self, reason: str = ...) -> NoReturn:
		return isinstance(stmt, PassStmt) or (
		isinstance(stmt, ExpressionStmt) and isinstance(stmt.expr, EllipsisExpr)
		)


		def is_dataclass_transform_decorator(node: Node \| None) -> bool:
		if isinstance(node, RefExpr):
		return is_dataclass_transform_decorator(node.node)

		return isinstance(node, Decorator) and node.func.is_dataclass_transform
Original file line number	Diff line number	Diff line change
Expand Up		@@ -37,9 +37,11 @@
		from mypy.nodes import Decorator, FuncDef, MypyFile, OverloadedFuncDef, TypeInfo, Var
		from mypy.options import Options
		from mypy.plugin import ClassDefContext
		from mypy.plugins import dataclasses as dataclasses_plugin
		from mypy.semanal import (
		SemanticAnalyzer,
		apply_semantic_analyzer_patches,
		is_dataclass_transform_decorator,
		remove_imported_names_from_symtable,
		)
		from mypy.semanal_classprop import (
Expand DownExpand Up		@@ -450,11 +452,19 @@ def apply_hooks_to_class(
		ok = True
		for decorator in defn.decorators:
		with self.file_context(file_node, options, info):
		hook = None

		decorator_name = self.get_fullname_for_hook(decorator)
		if decorator_name:
		hook = self.plugin.get_class_decorator_hook_2(decorator_name)
		if hook:
		ok = ok and hook(ClassDefContext(defn, decorator, self))
		# Special case: if the decorator is itself decorated with
		# typing.dataclass_transform, apply the hook for the dataclasses plugin
		# TODO: remove special casing here
		if hook is None and is_dataclass_transform_decorator(decorator):
		hook = dataclasses_plugin.dataclass_class_maker_callback

		if hook:
		ok = ok and hook(ClassDefContext(defn, decorator, self))
		return ok


Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -38,6 +38,11 @@
		get_proper_type,
		)

		# Subclasses can override these Var attributes with incompatible types. This can also be
		# set for individual attributes using 'allow_incompatible_override' of Var.
		ALLOW_INCOMPATIBLE_OVERRIDE: Final = ("__slots__", "__deletable__", "__match_args__")


		# Priorities for ordering of patches within the "patch" phase of semantic analysis
		# (after the main pass):

Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -150,6 +150,11 @@
		"typing_extensions.Never",
		)

		DATACLASS_TRANSFORM_NAMES: Final = (
		"typing.dataclass_transform",
		"typing_extensions.dataclass_transform",
		)

		# A placeholder used for Bogus[...] parameters
		_dummy: Final[Any] = object()

Expand Down
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,46 @@
		[case testDataclassTransformReusesDataclassLogic]
		# flags: --python-version 3.7
		from typing import dataclass_transform, Type

		@dataclass_transform()
		def my_dataclass(cls: Type) -> Type:
		return cls

		@my_dataclass
		class Person:
		name: str
		age: int

		def summary(self):
		return "%s is %d years old." % (self.name, self.age)

		reveal_type(Person) # N: Revealed type is "def (name: builtins.str, age: builtins.int) -> __main__.Person"
		Person('John', 32)
		Person('Jonh', 21, None) # E: Too many arguments for "Person"

		[typing fixtures/typing-medium.pyi]
		[builtins fixtures/dataclasses.pyi]

		[case testDataclassTransformIsFoundInTypingExtensions]
		# flags: --python-version 3.7
		from typing import Type
		from typing_extensions import dataclass_transform

		@dataclass_transform()
		def my_dataclass(cls: Type) -> Type:
		return cls

		@my_dataclass
		class Person:
		name: str
		age: int

		def summary(self):
		return "%s is %d years old." % (self.name, self.age)

		reveal_type(Person) # N: Revealed type is "def (name: builtins.str, age: builtins.int) -> __main__.Person"
		Person('John', 32)
		Person('Jonh', 21, None) # E: Too many arguments for "Person"

		[typing fixtures/typing-full.pyi]
		[builtins fixtures/dataclasses.pyi]
Original file line number	Diff line number	Diff line change
Expand Up		@@ -37,7 +37,11 @@ class dict(Mapping[KT, VT]):
		def get(self, k: KT, default: Union[KT, _T]) -> Union[VT, _T]: pass
		def __len__(self) -> int: ...

		class list(Generic[_T], Sequence[_T]): pass
		class list(Generic[_T], Sequence[_T]):
		def __contains__(self, item: object) -> int: pass
		def __getitem__(self, key: int) -> _T: pass
		def __iter__(self) -> Iterator[_T]: pass

Comment on lines +40 to +44 Copy link CollaboratorAuthor wesleywrightJan 25, 2023 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. needed to use`dataclasses.pyi` and`typing-full.pyi` at the same time in a test case
		class function: pass
		class classmethod: pass
		property = object()
Original file line number	Diff line number	Diff line change
Expand Up		@@ -71,3 +71,5 @@ class ContextManager(Generic[T]):
		class _SpecialForm: pass

		TYPE_CHECKING = 1

		def dataclass_transform() -> Callable[[T], T]: ...
Original file line number	Diff line number	Diff line change
Expand Up		@@ -57,3 +57,5 @@ class _TypedDict(Mapping[str, object]):
		def TypedDict(typename: str, fields: Dict[str, Type[_T]], *, total: Any = ...) -> Type[dict]: ...

		def reveal_type(__obj: T) -> T: pass

		def dataclass_transform() -> Callable[[T], T]: ...