.github/workflows/main.yml

@@ -10,10 +10,10 @@ jobs:
   main-windows:
     uses: asottile/workflows/.github/workflows/tox.yml@v1.6.0
     with:
-      env: '["py38"]'
+      env: '["py39"]'
       os: windows-latest
   main-linux:
     uses: asottile/workflows/.github/workflows/tox.yml@v1.6.0
     with:
-      env: '["py38", "py39", "py310", "py311", "py312"]'
+      env: '["py39", "py310", "py311", "py312"]'
       os: ubuntu-latest

.pre-commit-config.yaml

@@ -23,19 +23,19 @@ repos:
     hooks:
     -   id: add-trailing-comma
 -   repo: https://github.com/asottile/pyupgrade
-    rev: v3.16.0
+    rev: v3.17.0
     hooks:
     -   id: pyupgrade
         args: [--py38-plus]
 -   repo: https://github.com/hhatto/autopep8
-    rev: v2.2.0
+    rev: v2.3.1
     hooks:
     -   id: autopep8
 -   repo: https://github.com/PyCQA/flake8
-    rev: 7.0.0
+    rev: 7.1.0
     hooks:
     -   id: flake8
 -   repo: https://github.com/pre-commit/mirrors-mypy
-    rev: v1.10.0
+    rev: v1.11.0
     hooks:
     -   id: mypy

README.md

@@ -21,7 +21,7 @@ Sample `.pre-commit-config.yaml`:
 
 ```yaml
 -   repo: https://github.com/asottile/pyupgrade
-    rev: v3.16.0
+    rev: v3.17.0
     hooks:
     -   id: pyupgrade
 ```
@@ -754,6 +754,24 @@ Availability:
      ...
 ```
 
+### pep 696 TypeVar defaults
+
+Availability:
+- File imports `from __future__ import annotations`
+    - Unless `--keep-runtime-typing` is passed on the commandline.
+- `--py313-plus` is passed on the commandline.
+
+```diff
+-def f() -> Generator[int, None, None]:
++def f() -> Generator[int]:
+     yield 1
+```
+
+```diff
+-async def f() -> AsyncGenerator[int, None]:
++async def f() -> AsyncGenerator[int]:
+     yield 1
+```
 
 ### remove quoted annotations
 

pyupgrade/_data.py

@@ -40,6 +40,7 @@ class State(NamedTuple):
     '__future__',
     'asyncio',
     'collections',
+    'collections.abc',
     'functools',
     'mmap',
     'os',
@@ -53,7 +54,8 @@ class State(NamedTuple):
     'typing_extensions',
 ))
 
-FUNCS = collections.defaultdict(list)
+FUNCS: ASTCallbackMapping  # python/mypy#17566
+FUNCS = collections.defaultdict(list)  # type: ignore[assignment]
 
 
 def register(tp: type[AST_T]) -> Callable[[ASTFunc[AST_T]], ASTFunc[AST_T]]:

pyupgrade/_plugins/legacy.py

@@ -91,7 +91,7 @@ def __init__(self) -> None:
         self.yield_offsets: set[Offset] = set()
 
     @contextlib.contextmanager
-    def _scope(self, node: ast.AST) -> Generator[None, None, None]:
+    def _scope(self, node: ast.AST) -> Generator[None]:
         self._scopes.append(Scope(node))
         try:
             yield

pyupgrade/_plugins/percent_format.py

@@ -46,7 +46,7 @@ def _must_match(regex: Pattern[str], string: str, pos: int) -> Match[str]:
 
 
 def _parse_percent_format(s: str) -> tuple[PercentFormat, ...]:
-    def _parse_inner() -> Generator[PercentFormat, None, None]:
+    def _parse_inner() -> Generator[PercentFormat]:
         string_start = 0
         string_end = 0
         in_fmt = False

pyupgrade/_plugins/typing_classes.py

@@ -2,7 +2,6 @@
 
 import ast
 import functools
-import sys
 from typing import Iterable
 
 from tokenize_rt import Offset
@@ -24,19 +23,13 @@ def _unparse(node: ast.expr) -> str:
     elif isinstance(node, ast.Attribute):
         return ''.join((_unparse(node.value), '.', node.attr))
     elif isinstance(node, ast.Subscript):
-        if sys.version_info >= (3, 9):  # pragma: >=3.9 cover
-            node_slice: ast.expr = node.slice
-        elif isinstance(node.slice, ast.Index):  # pragma: <3.9 cover
-            node_slice = node.slice.value
-        else:
-            raise AssertionError(f'expected Slice: {ast.dump(node)}')
-        if isinstance(node_slice, ast.Tuple):
-            if len(node_slice.elts) == 1:
-                slice_s = f'{_unparse(node_slice.elts[0])},'
+        if isinstance(node.slice, ast.Tuple):
+            if len(node.slice.elts) == 1:
+                slice_s = f'{_unparse(node.slice.elts[0])},'
             else:
-                slice_s = ', '.join(_unparse(elt) for elt in node_slice.elts)
+                slice_s = ', '.join(_unparse(elt) for elt in node.slice.elts)
         else:
-            slice_s = _unparse(node_slice)
+            slice_s = _unparse(node.slice)
         return f'{_unparse(node.value)}[{slice_s}]'
     elif (
             isinstance(node, ast.Constant) and

pyupgrade/_plugins/typing_pep563.py

@@ -90,15 +90,8 @@ def _process_call(node: ast.Call) -> Iterable[ast.AST]:
 def _process_subscript(node: ast.Subscript) -> Iterable[ast.AST]:
     name = _get_name(node.value)
     if name == 'Annotated':
-        if sys.version_info >= (3, 9):  # pragma: >=3.9 cover
-            node_slice = node.slice
-        elif isinstance(node.slice, ast.Index):  # pragma: <3.9 cover
-            node_slice: ast.AST = node.slice.value
-        else:  # pragma: <3.9 cover
-            node_slice = node.slice
-
-        if isinstance(node_slice, ast.Tuple) and node_slice.elts:
-            yield node_slice.elts[0]
+        if isinstance(node.slice, ast.Tuple) and node.slice.elts:
+            yield node.slice.elts[0]
     elif name != 'Literal':
         yield node.slice
 

pyupgrade/_plugins/typing_pep604.py

@@ -153,14 +153,7 @@ def visit_Subscript(
 
     # don't rewrite forward annotations (unless we know they will be dequoted)
     if 'annotations' not in state.from_imports['__future__']:
-        if (
-                (sys.version_info >= (3, 9) and _any_arg_is_str(node.slice)) or
-                (
-                    sys.version_info < (3, 9) and
-                    isinstance(node.slice, ast.Index) and
-                    _any_arg_is_str(node.slice.value)
-                )
-        ):
+        if _any_arg_is_str(node.slice):
             return
 
     if is_name_attr(
@@ -171,19 +164,12 @@ def visit_Subscript(
     ):
         yield ast_to_offset(node), _fix_optional
     elif is_name_attr(node.value, state.from_imports, ('typing',), ('Union',)):
-        if sys.version_info >= (3, 9):  # pragma: >=3.9 cover
-            node_slice = node.slice
-        elif isinstance(node.slice, ast.Index):  # pragma: <3.9 cover
-            node_slice: ast.AST = node.slice.value
-        else:  # pragma: <3.9 cover
-            node_slice = node.slice  # unexpected slice type
-
-        if isinstance(node_slice, ast.Slice):  # not a valid annotation
+        if isinstance(node.slice, ast.Slice):  # not a valid annotation
             return
 
-        if isinstance(node_slice, ast.Tuple):
-            if node_slice.elts:
-                arg_count = len(node_slice.elts)
+        if isinstance(node.slice, ast.Tuple):
+            if node.slice.elts:
+                arg_count = len(node.slice.elts)
             else:
                 return  # empty Union
         else:

pyupgrade/_plugins/typing_pep646_unpack.py

@@ -35,7 +35,7 @@ def visit_Subscript(
         return
 
     if is_name_attr(node.value, state.from_imports, ('typing',), ('Unpack',)):
-        if isinstance(parent, (ast.Subscript, ast.Index)):
+        if isinstance(parent, ast.Subscript):
             yield ast_to_offset(node.value), _replace_unpack_with_star
 
 

pyupgrade/_plugins/typing_pep696_typevar_defaults.py

@@ -0,0 +1,72 @@
+from __future__ import annotations
+
+import ast
+from typing import Iterable
+
+from tokenize_rt import Offset
+from tokenize_rt import Token
+
+from pyupgrade._ast_helpers import ast_to_offset
+from pyupgrade._ast_helpers import is_name_attr
+from pyupgrade._data import register
+from pyupgrade._data import State
+from pyupgrade._data import TokenFunc
+from pyupgrade._token_helpers import find_op
+from pyupgrade._token_helpers import parse_call_args
+
+
+def _fix_typevar_default(i: int, tokens: list[Token]) -> None:
+    j = find_op(tokens, i, '[')
+    args, end = parse_call_args(tokens, j)
+    # remove the trailing `None` arguments
+    del tokens[args[0][1]:args[-1][1]]
+
+
+def _should_rewrite(state: State) -> bool:
+    return (
+        state.settings.min_version >= (3, 13) or (
+            not state.settings.keep_runtime_typing and
+            state.in_annotation and
+            'annotations' in state.from_imports['__future__']
+        )
+    )
+
+
+def _is_none(node: ast.AST) -> bool:
+    return isinstance(node, ast.Constant) and node.value is None
+
+
+@register(ast.Subscript)
+def visit_Subscript(
+        state: State,
+        node: ast.Subscript,
+        parent: ast.AST,
+) -> Iterable[tuple[Offset, TokenFunc]]:
+    if not _should_rewrite(state):
+        return
+
+    if (
+            is_name_attr(
+                node.value,
+                state.from_imports,
+                ('collections.abc', 'typing', 'typing_extensions'),
+                ('Generator',),
+            ) and
+            isinstance(node.slice, ast.Tuple) and
+            len(node.slice.elts) == 3 and
+            _is_none(node.slice.elts[1]) and
+            _is_none(node.slice.elts[2])
+    ):
+        yield ast_to_offset(node), _fix_typevar_default
+    elif (
+            is_name_attr(
+                node.value,
+                state.from_imports,
+                ('collections.abc', 'typing', 'typing_extensions'),
+                ('AsyncGenerator',),
+            ) and
+            isinstance(node.slice, ast.Tuple) and
+            len(node.slice.elts) == 2 and
+            _is_none(node.slice.elts[1])
+    ):
+        yield ast_to_offset(node), _fix_typevar_default

setup.cfg

@@ -1,6 +1,6 @@
 [metadata]
 name = pyupgrade
-version = 3.16.0
+version = 3.17.0
 description = A tool to automatically upgrade syntax for newer versions.
 long_description = file: README.md
 long_description_content_type = text/markdown
@@ -20,7 +20,7 @@ classifiers =
 packages = find:
 install_requires =
     tokenize-rt>=5.2.0
-python_requires = >=3.8.1
+python_requires = >=3.9
 
 [options.packages.find]
 exclude =