From 51bceb7afbae14495fc616bbec624489e7e6e682 Mon Sep 17 00:00:00 2001
From: Shantanu Jain <hauntsaninja@gmail.com>
Date: Fri, 28 Nov 2025 12:15:12 -0800
Subject: [PATCH 1/3] Use PEP 604 annotations everywhere

---
 mypy/binder.py                  |  4 ++--
 mypy/cache.py                   |  2 +-
 mypy/checker.py                 |  6 +++---
 mypy/checkexpr.py               |  2 +-
 mypy/checkstrformat.py          |  2 +-
 mypy/config_parser.py           |  4 +---
 mypy/constant_fold.py           |  4 ++--
 mypy/errors.py                  |  2 +-
 mypy/exportjson.py              |  2 +-
 mypy/fastparse.py               | 10 +++++-----
 mypy/literals.py                |  4 ++--
 mypy/modulefinder.py            |  6 +++---
 mypy/plugins/singledispatch.py  |  2 +-
 mypy/scope.py                   |  2 +-
 mypy/semanal_main.py            |  4 ++--
 mypy/server/astdiff.py          |  2 +-
 mypy/server/update.py           |  2 +-
 mypy/stubtest.py                |  2 +-
 mypy/test/data.py               |  2 +-
 mypy/treetransform.py           |  6 +++---
 mypy/types.py                   |  2 +-
 mypyc/build.py                  |  2 +-
 mypyc/codegen/emitmodule.py     |  2 +-
 mypyc/codegen/literals.py       |  8 ++++----
 mypyc/ir/ops.py                 |  4 ++--
 mypyc/ir/pprint.py              |  4 ++--
 mypyc/irbuild/builder.py        |  4 ++--
 mypyc/irbuild/constant_fold.py  |  4 ++--
 mypyc/irbuild/ll_builder.py     |  2 +-
 mypyc/irbuild/specialize.py     |  2 +-
 mypyc/lower/registry.py         |  2 +-
 mypyc/transform/ir_transform.py |  4 ++--
 32 files changed, 54 insertions(+), 56 deletions(-)

diff --git a/mypy/binder.py b/mypy/binder.py
index a83e65276ff4..2f56143c7870 100644
--- a/mypy/binder.py
+++ b/mypy/binder.py
@@ -39,7 +39,7 @@
 )
 from mypy.typevars import fill_typevars_with_any
 
-BindableExpression: _TypeAlias = Union[IndexExpr, MemberExpr, NameExpr]
+BindableExpression: _TypeAlias = IndexExpr | MemberExpr | NameExpr
 
 
 class CurrentType(NamedTuple):
@@ -81,7 +81,7 @@ def __repr__(self) -> str:
         return f"Frame({self.id}, {self.types}, {self.unreachable}, {self.conditional_frame})"
 
 
-Assigns = defaultdict[Expression, list[tuple[Type, Optional[Type]]]]
+Assigns = defaultdict[Expression, list[tuple[Type, Type | None]]]
 
 
 class ConditionalTypeBinder:
diff --git a/mypy/cache.py b/mypy/cache.py
index ad12fd96f1fa..92cf8609327b 100644
--- a/mypy/cache.py
+++ b/mypy/cache.py
@@ -391,7 +391,7 @@ def write_str_opt_list(data: WriteBuffer, value: list[str | None]) -> None:
         write_str_opt(data, item)
 
 
-JsonValue: _TypeAlias = Union[None, int, str, bool, list["JsonValue"], dict[str, "JsonValue"]]
+JsonValue: _TypeAlias = None | int | str | bool | list["JsonValue"] | dict[str, "JsonValue"]
 
 
 def read_json_value(data: ReadBuffer) -> JsonValue:
diff --git a/mypy/checker.py b/mypy/checker.py
index ad7eb3d35568..762e8268bd28 100644
--- a/mypy/checker.py
+++ b/mypy/checker.py
@@ -249,8 +249,8 @@
 # Maximum length of fixed tuple types inferred when narrowing from variadic tuples.
 MAX_PRECISE_TUPLE_SIZE: Final = 8
 
-DeferredNodeType: _TypeAlias = Union[FuncDef, OverloadedFuncDef, Decorator]
-FineGrainedDeferredNodeType: _TypeAlias = Union[FuncDef, MypyFile, OverloadedFuncDef]
+DeferredNodeType: _TypeAlias = FuncDef | OverloadedFuncDef | Decorator
+FineGrainedDeferredNodeType: _TypeAlias = FuncDef | MypyFile | OverloadedFuncDef
 
 
 # A node which is postponed to be processed during the next pass.
@@ -283,7 +283,7 @@ class FineGrainedDeferredNode(NamedTuple):
 # (such as two references to the same variable). TODO: it would
 # probably be better to have the dict keyed by the nodes' literal_hash
 # field instead.
-TypeMap: _TypeAlias = Optional[dict[Expression, Type]]
+TypeMap: _TypeAlias = dict[Expression, Type] | None
 
 
 # Keeps track of partial types in a single scope. In fine-grained incremental
diff --git a/mypy/checkexpr.py b/mypy/checkexpr.py
index 03ebc5058cee..85bde81013cd 100644
--- a/mypy/checkexpr.py
+++ b/mypy/checkexpr.py
@@ -217,7 +217,7 @@
 # Type of callback user for checking individual function arguments. See
 # check_args() below for details.
 ArgChecker: _TypeAlias = Callable[
-    [Type, Type, ArgKind, Type, int, int, CallableType, Optional[Type], Context, Context], None
+    [Type, Type, ArgKind, Type, int, int, CallableType, Type | None, Context, Context], None
 ]
 
 # Maximum nesting level for math union in overloads, setting this to large values
diff --git a/mypy/checkstrformat.py b/mypy/checkstrformat.py
index 45075bd37552..34cdc370d533 100644
--- a/mypy/checkstrformat.py
+++ b/mypy/checkstrformat.py
@@ -64,7 +64,7 @@
     get_proper_types,
 )
 
-FormatStringExpr: _TypeAlias = Union[StrExpr, BytesExpr]
+FormatStringExpr: _TypeAlias = StrExpr | BytesExpr
 Checkers: _TypeAlias = tuple[Callable[[Expression], None], Callable[[Type], bool]]
 MatchMap: _TypeAlias = dict[tuple[int, int], Match[str]]  # span -> match
 
diff --git a/mypy/config_parser.py b/mypy/config_parser.py
index 2bfd2a1e2eef..05daaafcfc5c 100644
--- a/mypy/config_parser.py
+++ b/mypy/config_parser.py
@@ -20,9 +20,7 @@
 from mypy import defaults
 from mypy.options import PER_MODULE_OPTIONS, Options
 
-_CONFIG_VALUE_TYPES: TypeAlias = Union[
-    str, bool, int, float, dict[str, str], list[str], tuple[int, int]
-]
+_CONFIG_VALUE_TYPES: TypeAlias = str | bool | int | float | dict[str, str] | list[str] | tuple[int, int]
 _INI_PARSER_CALLABLE: TypeAlias = Callable[[Any], _CONFIG_VALUE_TYPES]
 
 
diff --git a/mypy/constant_fold.py b/mypy/constant_fold.py
index 4582b2a7396d..e1b915df2298 100644
--- a/mypy/constant_fold.py
+++ b/mypy/constant_fold.py
@@ -5,7 +5,7 @@
 
 from __future__ import annotations
 
-from typing import Final, Union
+from typing import Final
 
 from mypy.nodes import (
     ComplexExpr,
@@ -20,7 +20,7 @@
 )
 
 # All possible result types of constant folding
-ConstantValue = Union[int, bool, float, complex, str]
+ConstantValue = int | bool | float | complex | str
 CONST_TYPES: Final = (int, bool, float, complex, str)
 
 
diff --git a/mypy/errors.py b/mypy/errors.py
index 69e4fb4cf065..8bd5f4dbd447 100644
--- a/mypy/errors.py
+++ b/mypy/errors.py
@@ -155,7 +155,7 @@ def __init__(
 
 # Type used internally to represent errors:
 #   (path, line, column, end_line, end_column, severity, message, code)
-ErrorTuple: _TypeAlias = tuple[Optional[str], int, int, int, int, str, str, Optional[ErrorCode]]
+ErrorTuple: _TypeAlias = tuple[str | None, int, int, int, int, str, str, ErrorCode | None]
 
 
 class ErrorWatcher:
diff --git a/mypy/exportjson.py b/mypy/exportjson.py
index dfc1cf5abbc6..0640f0a3eab6 100644
--- a/mypy/exportjson.py
+++ b/mypy/exportjson.py
@@ -69,7 +69,7 @@
     get_proper_type,
 )
 
-Json: _TypeAlias = Union[dict[str, Any], str]
+Json: _TypeAlias = dict[str, Any] | str
 
 
 class Config:
diff --git a/mypy/fastparse.py b/mypy/fastparse.py
index 0e7b418d0375..eb1cb8e2fbfa 100644
--- a/mypy/fastparse.py
+++ b/mypy/fastparse.py
@@ -714,7 +714,7 @@ def fix_function_overloads(self, stmts: list[Statement]) -> list[Statement]:
                     current_overload.extend(if_block_with_overload.body[-1].items)
                 else:
                     current_overload.append(
-                        cast(Union[Decorator, FuncDef], if_block_with_overload.body[0])
+                        cast(Decorator | FuncDef, if_block_with_overload.body[0])
                     )
             else:
                 if last_if_stmt is not None:
@@ -760,7 +760,7 @@ def fix_function_overloads(self, stmts: list[Statement]) -> list[Statement]:
                             cast(list[IfStmt], if_block_with_overload.body[:-1])
                         )
                         last_if_overload = cast(
-                            Union[Decorator, FuncDef, OverloadedFuncDef],
+                            Decorator | FuncDef | OverloadedFuncDef,
                             if_block_with_overload.body[-1],
                         )
                     last_if_unknown_truth_value = if_unknown_truth_value
@@ -807,7 +807,7 @@ def _check_ifstmt_for_overloads(
             return None
 
         overload_name = cast(
-            Union[Decorator, FuncDef, OverloadedFuncDef], stmt.body[0].body[-1]
+            Decorator | FuncDef | OverloadedFuncDef, stmt.body[0].body[-1]
         ).name
         if stmt.else_body is None:
             return overload_name
@@ -991,7 +991,7 @@ def do_func_def(
                         self.errors, line=lineno, override_column=n.col_offset
                     ).translate_expr_list(func_type_ast.argtypes)
                     # Use a cast to work around `list` invariance
-                    arg_types = cast(list[Optional[Type]], translated_args)
+                    arg_types = cast(list[Type | None], translated_args)
                 return_type = TypeConverter(self.errors, line=lineno).visit(func_type_ast.returns)
 
                 # add implicit self type
@@ -1646,7 +1646,7 @@ def visit_Call(self, n: Call) -> CallExpr:
             self.visit(n.func),
             arg_types,
             arg_kinds,
-            cast("list[Optional[str]]", [None] * len(args)) + keyword_names,
+            cast("list[str | None]", [None] * len(args)) + keyword_names,
         )
         return self.set_line(e, n)
 
diff --git a/mypy/literals.py b/mypy/literals.py
index fd17e0471440..c53a93c26433 100644
--- a/mypy/literals.py
+++ b/mypy/literals.py
@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 from collections.abc import Iterable
-from typing import Any, Final, Optional
+from typing import Any, Final
 from typing_extensions import TypeAlias as _TypeAlias
 
 from mypy.nodes import (
@@ -164,7 +164,7 @@ def extract_var_from_literal_hash(key: Key) -> Var | None:
     return None
 
 
-class _Hasher(ExpressionVisitor[Optional[Key]]):
+class _Hasher(ExpressionVisitor[Key | None]):
     def visit_int_expr(self, e: IntExpr) -> Key:
         return ("Literal", e.value)
 
diff --git a/mypy/modulefinder.py b/mypy/modulefinder.py
index 5176b7e1df52..78d8329f1fae 100644
--- a/mypy/modulefinder.py
+++ b/mypy/modulefinder.py
@@ -13,7 +13,7 @@
 import subprocess
 import sys
 from enum import Enum, unique
-from typing import Final, Optional, Union
+from typing import Final
 from typing_extensions import TypeAlias as _TypeAlias
 
 from pathspec import PathSpec
@@ -60,7 +60,7 @@ def asdict(self) -> dict[str, tuple[str, ...]]:
 PackageDirs = list[OnePackageDir]
 
 # Minimum and maximum Python versions for modules in stdlib as (major, minor)
-StdlibVersions: _TypeAlias = dict[str, tuple[tuple[int, int], Optional[tuple[int, int]]]]
+StdlibVersions: _TypeAlias = dict[str, tuple[tuple[int, int], tuple[int, int] | None]]
 
 PYTHON_EXTENSIONS: Final = [".pyi", ".py"]
 
@@ -118,7 +118,7 @@ def error_message_templates(self, daemon: bool) -> tuple[str, list[str]]:
 
 # If we found the module, returns the path to the module as a str.
 # Otherwise, returns the reason why the module wasn't found.
-ModuleSearchResult = Union[str, ModuleNotFoundReason]
+ModuleSearchResult = str | ModuleNotFoundReason
 
 
 class BuildSource:
diff --git a/mypy/plugins/singledispatch.py b/mypy/plugins/singledispatch.py
index eb2bbe133bf0..4b4fb61db54c 100644
--- a/mypy/plugins/singledispatch.py
+++ b/mypy/plugins/singledispatch.py
@@ -67,7 +67,7 @@ def make_fake_register_class_instance(
     return Instance(info, type_args)
 
 
-PluginContext: _TypeAlias = Union[FunctionContext, MethodContext]
+PluginContext: _TypeAlias = FunctionContext | MethodContext
 
 
 def fail(ctx: PluginContext, msg: str, context: Context | None) -> None:
diff --git a/mypy/scope.py b/mypy/scope.py
index 766048c41180..a95293648957 100644
--- a/mypy/scope.py
+++ b/mypy/scope.py
@@ -12,7 +12,7 @@
 
 from mypy.nodes import FuncBase, TypeInfo
 
-SavedScope: _TypeAlias = tuple[str, Optional[TypeInfo], Optional[FuncBase]]
+SavedScope: _TypeAlias = tuple[str, TypeInfo | None, FuncBase | None]
 
 
 class Scope:
diff --git a/mypy/semanal_main.py b/mypy/semanal_main.py
index b2c43e6becb8..2d07c0a7a5de 100644
--- a/mypy/semanal_main.py
+++ b/mypy/semanal_main.py
@@ -358,12 +358,12 @@ def process_top_level_function(
 
 
 TargetInfo: _TypeAlias = tuple[
-    str, Union[MypyFile, FuncDef, OverloadedFuncDef, Decorator], Optional[TypeInfo]
+    str, MypyFile | FuncDef | OverloadedFuncDef | Decorator, TypeInfo | None
 ]
 
 # Same as above but includes module as first item.
 FullTargetInfo: _TypeAlias = tuple[
-    str, str, Union[MypyFile, FuncDef, OverloadedFuncDef, Decorator], Optional[TypeInfo]
+    str, str, MypyFile | FuncDef | OverloadedFuncDef | Decorator, TypeInfo | None
 ]
 
 
diff --git a/mypy/server/astdiff.py b/mypy/server/astdiff.py
index 15d472b64886..74a2e5023f33 100644
--- a/mypy/server/astdiff.py
+++ b/mypy/server/astdiff.py
@@ -114,7 +114,7 @@ class level -- these are handled at attribute level (say, 'mod.Cls.method'
 # For example, the snapshot of the 'int' type is ('Instance', 'builtins.int', ()).
 
 # Type snapshots are strict, they must be hashable and ordered (e.g. for Unions).
-Primitive: _TypeAlias = Union[str, float, int, bool]  # float is for Literal[3.14] support.
+Primitive: _TypeAlias = str | float | int | bool  # float is for Literal[3.14] support.
 SnapshotItem: _TypeAlias = tuple[Union[Primitive, "SnapshotItem"], ...]
 
 # Symbol snapshots can be more lenient.
diff --git a/mypy/server/update.py b/mypy/server/update.py
index 86ccb57c2a3f..7401201baf7d 100644
--- a/mypy/server/update.py
+++ b/mypy/server/update.py
@@ -555,7 +555,7 @@ class BlockedUpdate(NamedTuple):
     messages: list[str]
 
 
-UpdateResult: _TypeAlias = Union[NormalUpdate, BlockedUpdate]
+UpdateResult: _TypeAlias = NormalUpdate | BlockedUpdate
 
 
 def update_module_isolated(
diff --git a/mypy/stubtest.py b/mypy/stubtest.py
index ada56a2489fe..570ae6e95d4d 100644
--- a/mypy/stubtest.py
+++ b/mypy/stubtest.py
@@ -59,7 +59,7 @@ def __repr__(self) -> str:
 MISSING: Final = Missing()
 
 T = TypeVar("T")
-MaybeMissing: typing_extensions.TypeAlias = Union[T, Missing]
+MaybeMissing: typing_extensions.TypeAlias = T | Missing
 
 
 class Unrepresentable:
diff --git a/mypy/test/data.py b/mypy/test/data.py
index 5b0ad84c0ba7..c4993f128160 100644
--- a/mypy/test/data.py
+++ b/mypy/test/data.py
@@ -43,7 +43,7 @@ class DeleteFile(NamedTuple):
     path: str
 
 
-FileOperation: _TypeAlias = Union[UpdateFile, DeleteFile]
+FileOperation: _TypeAlias = UpdateFile | DeleteFile
 
 
 def _file_arg_to_module(filename: str) -> str:
diff --git a/mypy/treetransform.py b/mypy/treetransform.py
index f5af5fb777b5..09187aeb5b94 100644
--- a/mypy/treetransform.py
+++ b/mypy/treetransform.py
@@ -194,7 +194,7 @@ def visit_func_def(self, node: FuncDef) -> FuncDef:
             node.name,
             [self.copy_argument(arg) for arg in node.arguments],
             self.block(node.body),
-            cast(Optional[FunctionLike], self.optional_type(node.type)),
+            cast(FunctionLike | None, self.optional_type(node.type)),
         )
 
         self.copy_function_attributes(new, node)
@@ -224,7 +224,7 @@ def visit_lambda_expr(self, node: LambdaExpr) -> LambdaExpr:
         new = LambdaExpr(
             [self.copy_argument(arg) for arg in node.arguments],
             self.block(node.body),
-            cast(Optional[FunctionLike], self.optional_type(node.type)),
+            cast(FunctionLike | None, self.optional_type(node.type)),
         )
         self.copy_function_attributes(new, node)
         return new
@@ -528,7 +528,7 @@ def visit_op_expr(self, node: OpExpr) -> OpExpr:
             node.op,
             self.expr(node.left),
             self.expr(node.right),
-            cast(Optional[TypeAliasExpr], self.optional_expr(node.analyzed)),
+            cast(TypeAliasExpr | None, self.optional_expr(node.analyzed)),
         )
         new.method_type = self.optional_type(node.method_type)
         return new
diff --git a/mypy/types.py b/mypy/types.py
index 09e4b74bb821..389c9f41e50f 100644
--- a/mypy/types.py
+++ b/mypy/types.py
@@ -84,7 +84,7 @@
 #
 # Note: Float values are only used internally. They are not accepted within
 # Literal[...].
-LiteralValue: _TypeAlias = Union[int, str, bool, float]
+LiteralValue: _TypeAlias = int | str | bool | float
 
 
 # If we only import type_visitor in the middle of the file, mypy
diff --git a/mypyc/build.py b/mypyc/build.py
index c9ddaa7dab1f..20da2e6a3aa2 100644
--- a/mypyc/build.py
+++ b/mypyc/build.py
@@ -119,7 +119,7 @@ class ModDesc(NamedTuple):
 
         from setuptools import Extension as _setuptools_Extension
 
-        Extension: TypeAlias = Union[_setuptools_Extension, _distutils_Extension]
+        Extension: TypeAlias = _setuptools_Extension | _distutils_Extension
 
 if sys.version_info >= (3, 12):
     # From setuptools' monkeypatch
diff --git a/mypyc/codegen/emitmodule.py b/mypyc/codegen/emitmodule.py
index 092b45c27e1c..53fc3743d782 100644
--- a/mypyc/codegen/emitmodule.py
+++ b/mypyc/codegen/emitmodule.py
@@ -94,7 +94,7 @@
 # its modules along with the name of the group. (Which can be None
 # only if we are compiling only a single group with a single file in it
 # and not using shared libraries).
-Group = tuple[list[BuildSource], Optional[str]]
+Group = tuple[list[BuildSource], str | None]
 Groups = list[Group]
 
 # A list of (file name, file contents) pairs.
diff --git a/mypyc/codegen/literals.py b/mypyc/codegen/literals.py
index 4cd41e0f4d32..4286bbea4840 100644
--- a/mypyc/codegen/literals.py
+++ b/mypyc/codegen/literals.py
@@ -1,13 +1,13 @@
 from __future__ import annotations
 
-from typing import Final, Union
+from typing import Final
 from typing_extensions import TypeGuard
 
 # Supported Python literal types. All tuple / frozenset items must have supported
 # literal types as well, but we can't represent the type precisely.
-LiteralValue = Union[
-    str, bytes, int, bool, float, complex, tuple[object, ...], frozenset[object], None
-]
+LiteralValue = (
+    str | bytes | int | bool | float | complex | tuple[object, ...] | frozenset[object] | None
+)
 
 
 def _is_literal_value(obj: object) -> TypeGuard[LiteralValue]:
diff --git a/mypyc/ir/ops.py b/mypyc/ir/ops.py
index 072892f776df..beb709adfbd0 100644
--- a/mypyc/ir/ops.py
+++ b/mypyc/ir/ops.py
@@ -27,7 +27,7 @@ class to enable the new behavior. Sometimes adding a new abstract
 
 from abc import abstractmethod
 from collections.abc import Sequence
-from typing import TYPE_CHECKING, Final, Generic, NamedTuple, TypeVar, Union, final
+from typing import TYPE_CHECKING, Final, Generic, NamedTuple, TypeVar, final
 
 from mypy_extensions import trait
 
@@ -1227,7 +1227,7 @@ def accept(self, visitor: OpVisitor[T]) -> T:
 
 
 # True steals all arguments, False steals none, a list steals those in matching positions
-StealsDescription = Union[bool, list[bool]]
+StealsDescription = bool | list[bool]
 
 
 @final
diff --git a/mypyc/ir/pprint.py b/mypyc/ir/pprint.py
index efefd76d15f0..e0a9e9d63208 100644
--- a/mypyc/ir/pprint.py
+++ b/mypyc/ir/pprint.py
@@ -4,7 +4,7 @@
 
 from collections import defaultdict
 from collections.abc import Sequence
-from typing import Any, Final, Union
+from typing import Any, Final
 
 from mypyc.common import short_name
 from mypyc.ir.func_ir import FuncIR, all_values_full
@@ -63,7 +63,7 @@
 )
 from mypyc.ir.rtypes import RType, is_bool_rprimitive, is_int_rprimitive
 
-ErrorSource = Union[BasicBlock, Op]
+ErrorSource = BasicBlock | Op
 
 
 class IRPrettyPrintVisitor(OpVisitor[str]):
diff --git a/mypyc/irbuild/builder.py b/mypyc/irbuild/builder.py
index 63930123135f..43e3d35d16b3 100644
--- a/mypyc/irbuild/builder.py
+++ b/mypyc/irbuild/builder.py
@@ -7,7 +7,7 @@
 
 from collections.abc import Iterator, Sequence
 from contextlib import contextmanager
-from typing import Any, Callable, Final, Union, overload
+from typing import Any, Callable, Final, overload
 
 from mypy.build import Graph
 from mypy.maptype import map_instance_to_supertype
@@ -146,7 +146,7 @@ class UnsupportedException(Exception):
     pass
 
 
-SymbolTarget = Union[AssignmentTargetRegister, AssignmentTargetAttr]
+SymbolTarget = AssignmentTargetRegister | AssignmentTargetAttr
 
 
 class IRBuilder:
diff --git a/mypyc/irbuild/constant_fold.py b/mypyc/irbuild/constant_fold.py
index b1133f95b18e..53274dd3f971 100644
--- a/mypyc/irbuild/constant_fold.py
+++ b/mypyc/irbuild/constant_fold.py
@@ -10,7 +10,7 @@
 
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Final, Union
+from typing import TYPE_CHECKING, Final
 
 from mypy.constant_fold import constant_fold_binary_op, constant_fold_unary_op
 from mypy.nodes import (
@@ -32,7 +32,7 @@
     from mypyc.irbuild.builder import IRBuilder
 
 # All possible result types of constant folding
-ConstantValue = Union[int, float, complex, str, bytes]
+ConstantValue = int | float | complex | str | bytes
 CONST_TYPES: Final = (int, float, complex, str, bytes)
 
 
diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index 6baff44f2f82..da5c8326dc42 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -202,7 +202,7 @@
 from mypyc.sametype import is_same_type
 from mypyc.subtype import is_subtype
 
-DictEntry = tuple[Optional[Value], Value]
+DictEntry = tuple[Value | None, Value]
 
 # If the number of items is less than the threshold when initializing
 # a list, we would inline the generate IR using SetMem and expanded
diff --git a/mypyc/irbuild/specialize.py b/mypyc/irbuild/specialize.py
index b64f51043b13..f1a838ddf1c8 100644
--- a/mypyc/irbuild/specialize.py
+++ b/mypyc/irbuild/specialize.py
@@ -122,7 +122,7 @@
 #
 # Specializers take three arguments: the IRBuilder, the CallExpr being
 # compiled, and the RefExpr that is the left hand side of the call.
-Specializer = Callable[["IRBuilder", CallExpr, RefExpr], Optional[Value]]
+Specializer = Callable[["IRBuilder", CallExpr, RefExpr], Value | None]
 
 # Dictionary containing all configured specializers.
 #
diff --git a/mypyc/lower/registry.py b/mypyc/lower/registry.py
index a20990fe39ae..8eb0501d5f3f 100644
--- a/mypyc/lower/registry.py
+++ b/mypyc/lower/registry.py
@@ -6,7 +6,7 @@
 from mypyc.irbuild.ll_builder import LowLevelIRBuilder
 
 LowerFunc = Callable[[LowLevelIRBuilder, list[Value], int], Value]
-LowerFuncOpt = Callable[[LowLevelIRBuilder, list[Value], int], Optional[Value]]
+LowerFuncOpt = Callable[[LowLevelIRBuilder, list[Value], int], Value | None]
 
 lowering_registry: Final[dict[str, LowerFuncOpt]] = {}
 
diff --git a/mypyc/transform/ir_transform.py b/mypyc/transform/ir_transform.py
index bcb6db9b0daf..4724e9d96fe8 100644
--- a/mypyc/transform/ir_transform.py
+++ b/mypyc/transform/ir_transform.py
@@ -2,7 +2,7 @@
 
 from __future__ import annotations
 
-from typing import Final, Optional
+from typing import Final
 
 from mypyc.ir.ops import (
     Assign,
@@ -52,7 +52,7 @@
 from mypyc.irbuild.ll_builder import LowLevelIRBuilder
 
 
-class IRTransform(OpVisitor[Optional[Value]]):
+class IRTransform(OpVisitor[Value | None]):
     """Identity transform.
 
     Subclass and override to perform changes to IR.

From 08490856d5a80654c8a0306776650b083c347467 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Fri, 28 Nov 2025 20:21:21 +0000
Subject: [PATCH 2/3] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 mypy/binder.py                 | 2 +-
 mypy/cache.py                  | 2 +-
 mypy/checker.py                | 2 --
 mypy/checkexpr.py              | 2 +-
 mypy/checkstrformat.py         | 2 +-
 mypy/config_parser.py          | 6 ++++--
 mypy/errors.py                 | 2 +-
 mypy/exportjson.py             | 2 +-
 mypy/fastparse.py              | 6 ++----
 mypy/plugins/singledispatch.py | 2 +-
 mypy/scope.py                  | 1 -
 mypy/semanal_main.py           | 2 +-
 mypy/server/update.py          | 2 +-
 mypy/test/data.py              | 2 +-
 mypy/treetransform.py          | 2 +-
 mypy/types.py                  | 2 +-
 mypyc/build.py                 | 2 +-
 mypyc/codegen/emitmodule.py    | 2 +-
 mypyc/irbuild/ll_builder.py    | 2 +-
 mypyc/irbuild/specialize.py    | 2 +-
 mypyc/lower/registry.py        | 2 +-
 21 files changed, 23 insertions(+), 26 deletions(-)

diff --git a/mypy/binder.py b/mypy/binder.py
index 2f56143c7870..872b58c4bae0 100644
--- a/mypy/binder.py
+++ b/mypy/binder.py
@@ -3,7 +3,7 @@
 from collections import defaultdict
 from collections.abc import Iterator
 from contextlib import contextmanager
-from typing import NamedTuple, Optional, Union
+from typing import NamedTuple
 from typing_extensions import TypeAlias as _TypeAlias
 
 from mypy.erasetype import remove_instance_last_known_values
diff --git a/mypy/cache.py b/mypy/cache.py
index 92cf8609327b..c1b1aba8c0ca 100644
--- a/mypy/cache.py
+++ b/mypy/cache.py
@@ -48,7 +48,7 @@
 from __future__ import annotations
 
 from collections.abc import Sequence
-from typing import Any, Final, Union
+from typing import Any, Final
 from typing_extensions import TypeAlias as _TypeAlias
 
 from librt.internal import (
diff --git a/mypy/checker.py b/mypy/checker.py
index 762e8268bd28..21db62e79a6e 100644
--- a/mypy/checker.py
+++ b/mypy/checker.py
@@ -12,9 +12,7 @@
     Generic,
     Literal,
     NamedTuple,
-    Optional,
     TypeVar,
-    Union,
     cast,
     overload,
 )
diff --git a/mypy/checkexpr.py b/mypy/checkexpr.py
index 85bde81013cd..4e3be52ef60c 100644
--- a/mypy/checkexpr.py
+++ b/mypy/checkexpr.py
@@ -8,7 +8,7 @@
 from collections import defaultdict
 from collections.abc import Iterable, Iterator, Sequence
 from contextlib import contextmanager, nullcontext
-from typing import Callable, ClassVar, Final, Optional, cast, overload
+from typing import Callable, ClassVar, Final, cast, overload
 from typing_extensions import TypeAlias as _TypeAlias, assert_never
 
 import mypy.checker
diff --git a/mypy/checkstrformat.py b/mypy/checkstrformat.py
index 34cdc370d533..7c52ae9eec4d 100644
--- a/mypy/checkstrformat.py
+++ b/mypy/checkstrformat.py
@@ -14,7 +14,7 @@
 
 import re
 from re import Match, Pattern
-from typing import Callable, Final, Union, cast
+from typing import Callable, Final, cast
 from typing_extensions import TypeAlias as _TypeAlias
 
 import mypy.errorcodes as codes
diff --git a/mypy/config_parser.py b/mypy/config_parser.py
index 05daaafcfc5c..af697821757f 100644
--- a/mypy/config_parser.py
+++ b/mypy/config_parser.py
@@ -14,13 +14,15 @@
     import tomli as tomllib
 
 from collections.abc import Mapping, MutableMapping, Sequence
-from typing import Any, Callable, Final, TextIO, Union
+from typing import Any, Callable, Final, TextIO
 from typing_extensions import Never, TypeAlias
 
 from mypy import defaults
 from mypy.options import PER_MODULE_OPTIONS, Options
 
-_CONFIG_VALUE_TYPES: TypeAlias = str | bool | int | float | dict[str, str] | list[str] | tuple[int, int]
+_CONFIG_VALUE_TYPES: TypeAlias = (
+    str | bool | int | float | dict[str, str] | list[str] | tuple[int, int]
+)
 _INI_PARSER_CALLABLE: TypeAlias = Callable[[Any], _CONFIG_VALUE_TYPES]
 
 
diff --git a/mypy/errors.py b/mypy/errors.py
index 8bd5f4dbd447..e7325cbe2265 100644
--- a/mypy/errors.py
+++ b/mypy/errors.py
@@ -6,7 +6,7 @@
 from collections import defaultdict
 from collections.abc import Iterable, Iterator
 from itertools import chain
-from typing import Callable, Final, NoReturn, Optional, TextIO, TypeVar
+from typing import Callable, Final, NoReturn, TextIO, TypeVar
 from typing_extensions import Literal, Self, TypeAlias as _TypeAlias
 
 from mypy import errorcodes as codes
diff --git a/mypy/exportjson.py b/mypy/exportjson.py
index 0640f0a3eab6..3ee93ec0efcc 100644
--- a/mypy/exportjson.py
+++ b/mypy/exportjson.py
@@ -16,7 +16,7 @@
 import argparse
 import json
 import sys
-from typing import Any, Union
+from typing import Any
 from typing_extensions import TypeAlias as _TypeAlias
 
 from librt.internal import ReadBuffer
diff --git a/mypy/fastparse.py b/mypy/fastparse.py
index eb1cb8e2fbfa..19d7b5db21e2 100644
--- a/mypy/fastparse.py
+++ b/mypy/fastparse.py
@@ -4,7 +4,7 @@
 import sys
 import warnings
 from collections.abc import Sequence
-from typing import Any, Callable, Final, Literal, Optional, TypeVar, Union, cast, overload
+from typing import Any, Callable, Final, Literal, TypeVar, Union, cast, overload
 
 from mypy import defaults, errorcodes as codes, message_registry
 from mypy.errors import Errors
@@ -806,9 +806,7 @@ def _check_ifstmt_for_overloads(
         ):
             return None
 
-        overload_name = cast(
-            Decorator | FuncDef | OverloadedFuncDef, stmt.body[0].body[-1]
-        ).name
+        overload_name = cast(Decorator | FuncDef | OverloadedFuncDef, stmt.body[0].body[-1]).name
         if stmt.else_body is None:
             return overload_name
 
diff --git a/mypy/plugins/singledispatch.py b/mypy/plugins/singledispatch.py
index 4b4fb61db54c..a069fffbff20 100644
--- a/mypy/plugins/singledispatch.py
+++ b/mypy/plugins/singledispatch.py
@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 from collections.abc import Sequence
-from typing import NamedTuple, TypeVar, Union
+from typing import NamedTuple, TypeVar
 from typing_extensions import TypeAlias as _TypeAlias
 
 from mypy.messages import format_type
diff --git a/mypy/scope.py b/mypy/scope.py
index a95293648957..bc8b7457c9a0 100644
--- a/mypy/scope.py
+++ b/mypy/scope.py
@@ -7,7 +7,6 @@
 
 from collections.abc import Iterator
 from contextlib import contextmanager, nullcontext
-from typing import Optional
 from typing_extensions import TypeAlias as _TypeAlias
 
 from mypy.nodes import FuncBase, TypeInfo
diff --git a/mypy/semanal_main.py b/mypy/semanal_main.py
index 2d07c0a7a5de..a9f492443f94 100644
--- a/mypy/semanal_main.py
+++ b/mypy/semanal_main.py
@@ -29,7 +29,7 @@
 from collections.abc import Iterator
 from contextlib import nullcontext
 from itertools import groupby
-from typing import TYPE_CHECKING, Callable, Final, Optional, Union
+from typing import TYPE_CHECKING, Callable, Final
 from typing_extensions import TypeAlias as _TypeAlias
 
 import mypy.build
diff --git a/mypy/server/update.py b/mypy/server/update.py
index 7401201baf7d..16349a87546d 100644
--- a/mypy/server/update.py
+++ b/mypy/server/update.py
@@ -119,7 +119,7 @@
 import sys
 import time
 from collections.abc import Sequence
-from typing import Callable, Final, NamedTuple, Union
+from typing import Callable, Final, NamedTuple
 from typing_extensions import TypeAlias as _TypeAlias
 
 from mypy.build import (
diff --git a/mypy/test/data.py b/mypy/test/data.py
index c4993f128160..fc7be6ec2dd1 100644
--- a/mypy/test/data.py
+++ b/mypy/test/data.py
@@ -14,7 +14,7 @@
 from dataclasses import dataclass
 from pathlib import Path
 from re import Pattern
-from typing import Any, Final, NamedTuple, NoReturn, Union
+from typing import Any, Final, NamedTuple, NoReturn
 from typing_extensions import TypeAlias as _TypeAlias
 
 import pytest
diff --git a/mypy/treetransform.py b/mypy/treetransform.py
index 09187aeb5b94..1a76a50a2d94 100644
--- a/mypy/treetransform.py
+++ b/mypy/treetransform.py
@@ -6,7 +6,7 @@
 from __future__ import annotations
 
 from collections.abc import Iterable
-from typing import Optional, cast
+from typing import cast
 
 from mypy.nodes import (
     GDEF,
diff --git a/mypy/types.py b/mypy/types.py
index 389c9f41e50f..cdfc60a8e7df 100644
--- a/mypy/types.py
+++ b/mypy/types.py
@@ -5,7 +5,7 @@
 import sys
 from abc import abstractmethod
 from collections.abc import Iterable, Sequence
-from typing import TYPE_CHECKING, Any, ClassVar, Final, NewType, TypeVar, Union, cast, overload
+from typing import TYPE_CHECKING, Any, ClassVar, Final, NewType, TypeVar, cast, overload
 from typing_extensions import Self, TypeAlias as _TypeAlias, TypeGuard
 
 from librt.internal import (
diff --git a/mypyc/build.py b/mypyc/build.py
index 20da2e6a3aa2..e0aa91dc6afe 100644
--- a/mypyc/build.py
+++ b/mypyc/build.py
@@ -26,7 +26,7 @@
 import sys
 import time
 from collections.abc import Iterable
-from typing import TYPE_CHECKING, Any, NamedTuple, NoReturn, Union, cast
+from typing import TYPE_CHECKING, Any, NamedTuple, NoReturn, cast
 
 import mypyc.build_setup  # noqa: F401
 from mypy.build import BuildSource
diff --git a/mypyc/codegen/emitmodule.py b/mypyc/codegen/emitmodule.py
index 53fc3743d782..959ad3a6d73d 100644
--- a/mypyc/codegen/emitmodule.py
+++ b/mypyc/codegen/emitmodule.py
@@ -9,7 +9,7 @@
 import os
 import sys
 from collections.abc import Iterable
-from typing import Optional, TypeVar
+from typing import TypeVar
 
 from mypy.build import (
     BuildResult,
diff --git a/mypyc/irbuild/ll_builder.py b/mypyc/irbuild/ll_builder.py
index da5c8326dc42..bbc1d8e6b44a 100644
--- a/mypyc/irbuild/ll_builder.py
+++ b/mypyc/irbuild/ll_builder.py
@@ -8,7 +8,7 @@
 
 import sys
 from collections.abc import Sequence
-from typing import Callable, Final, Optional, cast
+from typing import Callable, Final, cast
 from typing_extensions import TypeGuard
 
 from mypy.argmap import map_actuals_to_formals
diff --git a/mypyc/irbuild/specialize.py b/mypyc/irbuild/specialize.py
index f1a838ddf1c8..ad2a591a0e7d 100644
--- a/mypyc/irbuild/specialize.py
+++ b/mypyc/irbuild/specialize.py
@@ -14,7 +14,7 @@
 
 from __future__ import annotations
 
-from typing import Callable, Final, Optional, cast
+from typing import Callable, Final, cast
 
 from mypy.nodes import (
     ARG_NAMED,
diff --git a/mypyc/lower/registry.py b/mypyc/lower/registry.py
index 8eb0501d5f3f..da1e7fd9537a 100644
--- a/mypyc/lower/registry.py
+++ b/mypyc/lower/registry.py
@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from typing import Callable, Final, Optional, TypeVar
+from typing import Callable, Final, TypeVar
 
 from mypyc.ir.ops import Value
 from mypyc.irbuild.ll_builder import LowLevelIRBuilder

From 92acd6ad5f5fac11cb59797b1a928eb98bc49898 Mon Sep 17 00:00:00 2001
From: Shantanu Jain <hauntsaninja@gmail.com>
Date: Fri, 28 Nov 2025 12:28:35 -0800
Subject: [PATCH 3/3] .

---
 mypy/checker.py | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/mypy/checker.py b/mypy/checker.py
index 21db62e79a6e..440d0175bc62 100644
--- a/mypy/checker.py
+++ b/mypy/checker.py
@@ -6,16 +6,7 @@
 from collections import defaultdict
 from collections.abc import Iterable, Iterator, Mapping, Sequence, Set as AbstractSet
 from contextlib import ExitStack, contextmanager
-from typing import (
-    Callable,
-    Final,
-    Generic,
-    Literal,
-    NamedTuple,
-    TypeVar,
-    cast,
-    overload,
-)
+from typing import Callable, Final, Generic, Literal, NamedTuple, TypeVar, cast, overload
 from typing_extensions import TypeAlias as _TypeAlias, TypeGuard
 
 import mypy.checkexpr