Adds TypeAlias annotation, where possible

mypy/binder.py

@@ -2,7 +2,7 @@
 from collections import defaultdict
 
 from typing import Dict, List, Set, Iterator, Union, Optional, Tuple, cast
-from typing_extensions import DefaultDict
+from typing_extensions import DefaultDict, TypeAlias as _TypeAlias
 
 from mypy.types import (
     Type, AnyType, PartialType, UnionType, TypeOfAny, NoneType, get_proper_type
@@ -16,7 +16,7 @@
 from mypy.nodes import IndexExpr, MemberExpr, AssignmentExpr, NameExpr
 
 
-BindableExpression = Union[IndexExpr, MemberExpr, AssignmentExpr, NameExpr]
+BindableExpression: _TypeAlias = Union[IndexExpr, MemberExpr, AssignmentExpr, NameExpr]
 
 
 class Frame:

mypy/build.py

@@ -23,7 +23,7 @@
 
 from typing import (AbstractSet, Any, Dict, Iterable, Iterator, List, Sequence,
                     Mapping, NamedTuple, Optional, Set, Tuple, TypeVar, Union, Callable, TextIO)
-from typing_extensions import ClassVar, Final, TYPE_CHECKING
+from typing_extensions import ClassVar, Final, TYPE_CHECKING, TypeAlias as _TypeAlias
 from mypy_extensions import TypedDict
 
 from mypy.nodes import MypyFile, ImportBase, Import, ImportFrom, ImportAll, SymbolTable
@@ -81,7 +81,7 @@
 }
 
 
-Graph = Dict[str, 'State']
+Graph: _TypeAlias = Dict[str, 'State']
 
 
 # TODO: Get rid of BuildResult.  We might as well return a BuildManager.

mypy/checker.py

@@ -8,7 +8,7 @@
     Any, Dict, Set, List, cast, Tuple, TypeVar, Union, Optional, NamedTuple, Iterator,
     Iterable, Sequence, Mapping, Generic, AbstractSet, Callable
 )
-from typing_extensions import Final
+from typing_extensions import Final, TypeAlias as _TypeAlias
 
 from mypy.backports import nullcontext
 from mypy.errors import Errors, report_internal_error
@@ -86,8 +86,8 @@
 
 DEFAULT_LAST_PASS: Final = 1  # Pass numbers start at 0
 
-DeferredNodeType = Union[FuncDef, LambdaExpr, OverloadedFuncDef, Decorator]
-FineGrainedDeferredNodeType = Union[FuncDef, MypyFile, OverloadedFuncDef]
+DeferredNodeType: _TypeAlias = Union[FuncDef, LambdaExpr, OverloadedFuncDef, Decorator]
+FineGrainedDeferredNodeType: _TypeAlias = Union[FuncDef, MypyFile, OverloadedFuncDef]
 
 # A node which is postponed to be processed during the next pass.
 # In normal mode one can defer functions and methods (also decorated and/or overloaded)
@@ -124,7 +124,7 @@
 # probably be better to have the dict keyed by the nodes' literal_hash
 # field instead.
 
-TypeMap = Optional[Dict[Expression, Type]]
+TypeMap: _TypeAlias = Optional[Dict[Expression, Type]]
 
 # An object that represents either a precise type or a type with an upper bound;
 # it is important for correct type inference with isinstance.

mypy/checkexpr.py

@@ -7,7 +7,7 @@
 from typing import (
     Any, cast, Dict, Set, List, Tuple, Callable, Union, Optional, Sequence, Iterator
 )
-from typing_extensions import ClassVar, Final, overload
+from typing_extensions import ClassVar, Final, overload, TypeAlias as _TypeAlias
 
 from mypy.errors import report_internal_error
 from mypy.typeanal import (
@@ -72,18 +72,21 @@
 
 # Type of callback user for checking individual function arguments. See
 # check_args() below for details.
-ArgChecker = Callable[[Type,
-                       Type,
-                       ArgKind,
-                       Type,
-                       int,
-                       int,
-                       CallableType,
-                       Optional[Type],
-                       Context,
-                       Context,
-                       MessageBuilder],
-                      None]
+ArgChecker: _TypeAlias = Callable[[
+        Type,
+        Type,
+        ArgKind,
+        Type,
+        int,
+        int,
+        CallableType,
+        Optional[Type],
+        Context,
+        Context,
+        MessageBuilder,
+    ],
+    None,
+]
 
 # Maximum nesting level for math union in overloads, setting this to large values
 # may cause performance issues. The reason is that although union math algorithm we use

mypy/checkstrformat.py

@@ -15,7 +15,7 @@
 from typing import (
     cast, List, Tuple, Dict, Callable, Union, Optional, Pattern, Match, Set
 )
-from typing_extensions import Final, TYPE_CHECKING
+from typing_extensions import Final, TYPE_CHECKING, TypeAlias as _TypeAlias
 
 from mypy.types import (
     Type, AnyType, TupleType, Instance, UnionType, TypeOfAny, get_proper_type, TypeVarType,
@@ -39,9 +39,9 @@
 from mypy.subtypes import is_subtype
 from mypy.parse import parse
 
-FormatStringExpr = Union[StrExpr, BytesExpr, UnicodeExpr]
-Checkers = Tuple[Callable[[Expression], None], Callable[[Type], bool]]
-MatchMap = Dict[Tuple[int, int], Match[str]]  # span -> match
+FormatStringExpr: _TypeAlias = Union[StrExpr, BytesExpr, UnicodeExpr]
+Checkers: _TypeAlias = Tuple[Callable[[Expression], None], Callable[[Type], bool]]
+MatchMap: _TypeAlias = Dict[Tuple[int, int], Match[str]]  # span -> match
 
 
 def compile_format_re() -> Pattern[str]:

mypy/config_parser.py

@@ -9,13 +9,15 @@
 import tomli
 from typing import (Any, Callable, Dict, List, Mapping, MutableMapping,  Optional, Sequence,
                     TextIO, Tuple, Union)
-from typing_extensions import Final
+from typing_extensions import Final, TypeAlias as _TypeAlias
 
 from mypy import defaults
 from mypy.options import Options, PER_MODULE_OPTIONS
 
-_CONFIG_VALUE_TYPES = Union[str, bool, int, float, Dict[str, str], List[str], Tuple[int, int]]
-_INI_PARSER_CALLABLE = Callable[[Any], _CONFIG_VALUE_TYPES]
+_CONFIG_VALUE_TYPES: _TypeAlias = Union[
+    str, bool, int, float, Dict[str, str], List[str], Tuple[int, int],
+]
+_INI_PARSER_CALLABLE: _TypeAlias = Callable[[Any], _CONFIG_VALUE_TYPES]
 
 
 def parse_version(v: str) -> Tuple[int, int]:

mypy/nodes.py

@@ -8,7 +8,7 @@
 from typing import (
     Any, TypeVar, List, Tuple, cast, Set, Dict, Union, Optional, Callable, Sequence, Iterator
 )
-from typing_extensions import DefaultDict, Final, TYPE_CHECKING
+from typing_extensions import DefaultDict, Final, TYPE_CHECKING, TypeAlias as _TypeAlias
 from mypy_extensions import trait
 
 import mypy.strconv
@@ -64,7 +64,7 @@ def get_column(self) -> int:
 
 T = TypeVar('T')
 
-JsonDict = Dict[str, Any]
+JsonDict: _TypeAlias = Dict[str, Any]
 
 
 # Symbol table node kinds
@@ -208,7 +208,7 @@ class FakeExpression(Expression):
 # TODO:
 # Lvalue = Union['NameExpr', 'MemberExpr', 'IndexExpr', 'SuperExpr', 'StarExpr'
 #                'TupleExpr']; see #1783.
-Lvalue = Expression
+Lvalue: _TypeAlias = Expression
 
 
 @trait
@@ -241,7 +241,7 @@ def deserialize(cls, data: JsonDict) -> 'SymbolNode':
 
 
 # Items: fullname, related symbol table node, surrounding type (if any)
-Definition = Tuple[str, 'SymbolTableNode', Optional['TypeInfo']]
+Definition: _TypeAlias = Tuple[str, 'SymbolTableNode', Optional['TypeInfo']]
 
 
 class MypyFile(SymbolNode):
@@ -514,7 +514,7 @@ def fullname(self) -> Bogus[str]:
         return self._fullname
 
 
-OverloadPart = Union['FuncDef', 'Decorator']
+OverloadPart: _TypeAlias = Union['FuncDef', 'Decorator']
 
 
 class OverloadedFuncDef(FuncBase, SymbolNode, Statement):

mypy/report.py

@@ -14,7 +14,7 @@
 
 import typing
 from typing import Any, Callable, Dict, List, Optional, Tuple, cast, Iterator
-from typing_extensions import Final
+from typing_extensions import Final, TypeAlias as _TypeAlias
 
 from mypy.nodes import MypyFile, Expression, FuncDef
 from mypy import stats
@@ -45,7 +45,10 @@
     ]
 )
 
-ReporterClasses = Dict[str, Tuple[Callable[['Reports', str], 'AbstractReporter'], bool]]
+ReporterClasses: _TypeAlias = Dict[
+    str,
+    Tuple[Callable[['Reports', str], 'AbstractReporter'], bool],
+]
 
 reporter_classes: Final[ReporterClasses] = {}
 

mypy/scope.py

@@ -5,12 +5,13 @@
 
 from contextlib import contextmanager
 from typing import List, Optional, Iterator, Tuple
+from typing_extensions import TypeAlias as _TypeAlias
 
 from mypy.backports import nullcontext
 from mypy.nodes import TypeInfo, FuncBase
 
 
-SavedScope = Tuple[str, Optional[TypeInfo], Optional[FuncBase]]
+SavedScope: _TypeAlias = Tuple[str, Optional[TypeInfo], Optional[FuncBase]]
 
 
 class Scope:

mypy/semanal.py

@@ -53,7 +53,7 @@
 from typing import (
     List, Dict, Set, Tuple, cast, TypeVar, Union, Optional, Callable, Iterator, Iterable
 )
-from typing_extensions import Final
+from typing_extensions import Final, TypeAlias as _TypeAlias
 
 from mypy.nodes import (
     MypyFile, TypeInfo, Node, AssignmentStmt, FuncDef, OverloadedFuncDef,
@@ -147,7 +147,7 @@
 
 
 # Used for tracking incomplete references
-Tag = int
+Tag: _TypeAlias = int
 
 
 class SemanticAnalyzer(NodeVisitor[None],

mypy/semanal_main.py

@@ -25,7 +25,7 @@
 """
 
 from typing import List, Tuple, Optional, Union, Callable
-from typing_extensions import TYPE_CHECKING, Final
+from typing_extensions import TYPE_CHECKING, Final, TypeAlias as _TypeAlias
 
 from mypy.backports import nullcontext
 from mypy.nodes import (
@@ -51,7 +51,7 @@
     from mypy.build import Graph, State
 
 
-Patches = List[Tuple[int, Callable[[], None]]]
+Patches: _TypeAlias = List[Tuple[int, Callable[[], None]]]
 
 
 # If we perform this many iterations, raise an exception since we are likely stuck.

mypy/subtypes.py

@@ -1,7 +1,7 @@
 from contextlib import contextmanager
 
 from typing import Any, List, Optional, Callable, Tuple, Iterator, Set, Union, cast, TypeVar
-from typing_extensions import Final
+from typing_extensions import Final, TypeAlias as _TypeAlias
 
 from mypy.types import (
     Type, AnyType, UnboundType, TypeVisitor, FormalArgument, NoneType,
@@ -30,7 +30,7 @@
 IS_CLASSVAR: Final = 2
 IS_CLASS_OR_STATIC: Final = 3
 
-TypeParameterChecker = Callable[[Type, Type, int], bool]
+TypeParameterChecker: _TypeAlias = Callable[[Type, Type, int], bool]
 
 
 def check_type_parameter(lefta: Type, righta: Type, variance: int) -> bool:

mypy/types.py

@@ -9,7 +9,7 @@
     Any, TypeVar, Dict, List, Tuple, cast, Set, Optional, Union, Iterable, NamedTuple,
     Sequence, Iterator
 )
-from typing_extensions import ClassVar, Final, TYPE_CHECKING, overload
+from typing_extensions import ClassVar, Final, TYPE_CHECKING, overload, TypeAlias as _TypeAlias
 
 import mypy.nodes
 from mypy import state
@@ -23,7 +23,7 @@
 
 T = TypeVar('T')
 
-JsonDict = Dict[str, Any]
+JsonDict: _TypeAlias = Dict[str, Any]
 
 # The set of all valid expressions that can currently be contained
 # inside of a Literal[...].
@@ -52,7 +52,7 @@
 # Note: Although "Literal[None]" is a valid type, we internally always convert
 # such a type directly into "None". So, "None" is not a valid parameter of
 # LiteralType and is omitted from this list.
-LiteralValue = Union[int, str, bool]
+LiteralValue: _TypeAlias = Union[int, str, bool]
 
 
 # If we only import type_visitor in the middle of the file, mypy

mypy/typestate.py

@@ -4,23 +4,23 @@
 """
 
 from typing import Dict, Set, Tuple, Optional, List
-from typing_extensions import ClassVar, Final
+from typing_extensions import ClassVar, Final, TypeAlias as _TypeAlias
 
 from mypy.nodes import TypeInfo
 from mypy.types import Instance, TypeAliasType, get_proper_type, Type
 from mypy.server.trigger import make_trigger
 from mypy import state
 
 # Represents that the 'left' instance is a subtype of the 'right' instance
-SubtypeRelationship = Tuple[Instance, Instance]
+SubtypeRelationship: _TypeAlias = Tuple[Instance, Instance]
 
 # A tuple encoding the specific conditions under which we performed the subtype check.
 # (e.g. did we want a proper subtype? A regular subtype while ignoring variance?)
-SubtypeKind = Tuple[bool, ...]
+SubtypeKind: _TypeAlias = Tuple[bool, ...]
 
 # A cache that keeps track of whether the given TypeInfo is a part of a particular
 # subtype relationship
-SubtypeCache = Dict[TypeInfo, Dict[SubtypeKind, Set[SubtypeRelationship]]]
+SubtypeCache: _TypeAlias = Dict[TypeInfo, Dict[SubtypeKind, Set[SubtypeRelationship]]]
 
 
 class TypeState: