Use more Final and TypeAlias types

misc/analyze_cache.py

@@ -5,10 +5,11 @@
 import os.path
 from collections import Counter
 from typing import Any, Dict, Iterable, List, Optional
+from typing_extensions import Final, TypeAlias as _TypeAlias
 
-ROOT = ".mypy_cache/3.5"
+ROOT: Final = ".mypy_cache/3.5"
 
-JsonDict = Dict[str, Any]
+JsonDict: _TypeAlias = Dict[str, Any]
 
 
 class CacheData:

misc/incremental_checker.py

@@ -43,13 +43,14 @@
 import time
 from argparse import ArgumentParser, Namespace, RawDescriptionHelpFormatter
 from typing import Any, Dict, List, Optional, Tuple
+from typing_extensions import TypeAlias as _TypeAlias
 
-CACHE_PATH = ".incremental_checker_cache.json"
-MYPY_REPO_URL = "https://github.com/python/mypy.git"
-MYPY_TARGET_FILE = "mypy"
-DAEMON_CMD = ["python3", "-m", "mypy.dmypy"]
+CACHE_PATH: Final = ".incremental_checker_cache.json"
+MYPY_REPO_URL: Final = "https://github.com/python/mypy.git"
+MYPY_TARGET_FILE: Final = "mypy"
+DAEMON_CMD: Final = ["python3", "-m", "mypy.dmypy"]
 
-JsonDict = Dict[str, Any]
+JsonDict: _TypeAlias = Dict[str, Any]
 
 
 def print_offset(text: str, indent_length: int = 4) -> None:

mypy/dmypy_server.py

@@ -16,7 +16,7 @@
 import traceback
 from contextlib import redirect_stderr, redirect_stdout
 from typing import AbstractSet, Any, Callable, Dict, List, Optional, Sequence, Set, Tuple
-from typing_extensions import Final
+from typing_extensions import Final, TypeAlias as _TypeAlias
 
 import mypy.build
 import mypy.errors
@@ -161,9 +161,9 @@ def ignore_suppressed_imports(module: str) -> bool:
     return module.startswith("encodings.")
 
 
-ModulePathPair = Tuple[str, str]
-ModulePathPairs = List[ModulePathPair]
-ChangesAndRemovals = Tuple[ModulePathPairs, ModulePathPairs]
+ModulePathPair: _TypeAlias = Tuple[str, str]
+ModulePathPairs: _TypeAlias = List[ModulePathPair]
+ChangesAndRemovals: _TypeAlias = Tuple[ModulePathPairs, ModulePathPairs]
 
 
 class Server:

mypy/errors.py

@@ -3,7 +3,7 @@
 import traceback
 from collections import defaultdict
 from typing import Callable, Dict, List, NoReturn, Optional, Set, TextIO, Tuple, TypeVar, Union
-from typing_extensions import Final, Literal
+from typing_extensions import Final, Literal, TypeAlias as _TypeAlias
 
 from mypy import errorcodes as codes
 from mypy.errorcodes import IMPORT, ErrorCode
@@ -123,7 +123,9 @@ def __init__(
 
 # Type used internally to represent errors:
 #   (path, line, column, end_line, end_column, severity, message, allow_dups, code)
-ErrorTuple = Tuple[Optional[str], int, int, int, int, str, str, bool, Optional[ErrorCode]]
+ErrorTuple: _TypeAlias = Tuple[
+    Optional[str], int, int, int, int, str, str, bool, Optional[ErrorCode]
+]
 
 
 class ErrorWatcher:

mypy/literals.py

@@ -1,5 +1,5 @@
 from typing import Any, Iterable, Optional, Tuple, Union
-from typing_extensions import Final
+from typing_extensions import Final, TypeAlias as _TypeAlias
 
 from mypy.nodes import (
     LITERAL_NO,
@@ -123,7 +123,7 @@ def literal(e: Expression) -> int:
     return LITERAL_NO
 
 
-Key = Tuple[Any, ...]
+Key: _TypeAlias = Tuple[Any, ...]
 
 
 def subkeys(key: Key) -> Iterable[Key]:

mypy/plugins/singledispatch.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 from typing import List, NamedTuple, Optional, Sequence, TypeVar, Union
-from typing_extensions import Final
+from typing_extensions import Final, TypeAlias as _TypeAlias
 
 from mypy.messages import format_type
 from mypy.nodes import ARG_POS, Argument, Block, ClassDef, Context, SymbolTable, TypeInfo, Var
@@ -76,7 +76,7 @@ def make_fake_register_class_instance(
     return Instance(info, type_args)
 
 
-PluginContext = Union[FunctionContext, MethodContext]
+PluginContext: _TypeAlias = Union[FunctionContext, MethodContext]
 
 
 def fail(ctx: PluginContext, msg: str, context: Optional[Context]) -> None:

mypy/semanal_main.py

@@ -294,7 +294,9 @@ def process_top_level_function(
     analyzer.saved_locals.clear()
 
 
-TargetInfo = Tuple[str, Union[MypyFile, FuncDef, OverloadedFuncDef, Decorator], Optional[TypeInfo]]
+TargetInfo: _TypeAlias = Tuple[
+    str, Union[MypyFile, FuncDef, OverloadedFuncDef, Decorator], Optional[TypeInfo]
+]
 
 
 def get_all_leaf_targets(file: MypyFile) -> List[TargetInfo]:

mypy/server/astdiff.py

@@ -53,6 +53,7 @@ class level -- these are handled at attribute level (say, 'mod.Cls.method'
 from __future__ import annotations
 
 from typing import Dict, Optional, Sequence, Set, Tuple, Union
+from typing_extensions import TypeAlias as _TypeAlias
 
 from mypy.nodes import (
     UNBOUND_IMPORTED,
@@ -103,7 +104,7 @@ class level -- these are handled at attribute level (say, 'mod.Cls.method'
 # snapshots are immutable).
 #
 # For example, the snapshot of the 'int' type is ('Instance', 'builtins.int', ()).
-SnapshotItem = Tuple[object, ...]
+SnapshotItem: _TypeAlias = Tuple[object, ...]
 
 
 def compare_symbol_table_snapshots(

mypy/server/aststrip.py

@@ -35,6 +35,7 @@
 
 from contextlib import contextmanager, nullcontext
 from typing import Dict, Iterator, Optional, Tuple, Union
+from typing_extensions import TypeAlias as _TypeAlias
 
 from mypy.nodes import (
     CLASSDEF_NO_INFO,
@@ -66,7 +67,7 @@
 from mypy.types import CallableType
 from mypy.typestate import TypeState
 
-SavedAttributes = Dict[Tuple[ClassDef, str], SymbolTableNode]
+SavedAttributes: _TypeAlias = Dict[Tuple[ClassDef, str], SymbolTableNode]
 
 
 def strip_target(

mypy/server/update.py

@@ -118,7 +118,7 @@
 import sys
 import time
 from typing import Callable, Dict, List, NamedTuple, Optional, Sequence, Set, Tuple, Union
-from typing_extensions import Final
+from typing_extensions import Final, TypeAlias as _TypeAlias
 
 from mypy.build import (
     DEBUG_FINE_GRAINED,
@@ -540,7 +540,7 @@ class BlockedUpdate(NamedTuple):
     messages: List[str]
 
 
-UpdateResult = Union[NormalUpdate, BlockedUpdate]
+UpdateResult: _TypeAlias = Union[NormalUpdate, BlockedUpdate]
 
 
 def update_module_isolated(

mypy/stubdoc.py

@@ -17,10 +17,10 @@
     Sequence,
     Tuple,
 )
-from typing_extensions import Final
+from typing_extensions import Final, TypeAlias as _TypeAlias
 
 # Type alias for signatures strings in format ('func_name', '(arg, opt_arg=False)').
-Sig = Tuple[str, str]
+Sig: _TypeAlias = Tuple[str, str]
 
 
 _TYPE_RE: Final = re.compile(r"^[a-zA-Z_][\w\[\], ]*(\.[a-zA-Z_][\w\[\], ]*)*$")

mypy/stubtest.py

@@ -1179,7 +1179,7 @@ def verify_typealias(
 # ====================
 
 
-IGNORED_MODULE_DUNDERS = frozenset(
+IGNORED_MODULE_DUNDERS: typing_extensions.Final = frozenset(
     {
         "__file__",
         "__doc__",
@@ -1199,7 +1199,7 @@ def verify_typealias(
     }
 )
 
-IGNORABLE_CLASS_DUNDERS = frozenset(
+IGNORABLE_CLASS_DUNDERS: typing_extensions.Final = frozenset(
     {
         # Special attributes
         "__dict__",

mypy/test/data.py

@@ -11,7 +11,7 @@
 import tempfile
 from abc import abstractmethod
 from typing import Any, Dict, Iterator, List, NamedTuple, Optional, Pattern, Set, Tuple, Union
-from typing_extensions import Final
+from typing_extensions import Final, TypeAlias as _TypeAlias
 
 import pytest
 
@@ -38,7 +38,7 @@ class DeleteFile(NamedTuple):
     path: str
 
 
-FileOperation = Union[UpdateFile, DeleteFile]
+FileOperation: _TypeAlias = Union[UpdateFile, DeleteFile]
 
 
 def parse_test_case(case: "DataDrivenTestCase") -> None: