From de2073e42253c5b43a65b59b04b8bbc822605c6c Mon Sep 17 00:00:00 2001
From: Danny Yang <yangdanny@fb.com>
Date: Mon, 18 Nov 2024 16:13:36 -0500
Subject: [PATCH 1/7] replace Optional[T] and Union[T, None] with T | None

---
 src/fixit/api.py                              | 18 ++--
 src/fixit/cli.py                              | 10 +--
 src/fixit/config.py                           | 30 ++++---
 src/fixit/engine.py                           |  2 +-
 src/fixit/ftypes.py                           | 40 ++++-----
 src/fixit/lsp.py                              |  6 +-
 src/fixit/rule.py                             | 24 +++---
 src/fixit/rules/deprecated_abc_import.py      |  2 +-
 src/fixit/rules/no_namedtuple.py              |  2 +-
 src/fixit/rules/no_static_if_condition.py     |  2 +-
 ...py => replace_optional_type_annotation.py} | 82 +++++++++++--------
 src/fixit/rules/rewrite_to_comprehension.py   |  2 +-
 src/fixit/rules/use_fstring.py                |  4 +-
 src/fixit/tests/ftypes.py                     |  2 +-
 .../upgrade/deprecated_testcase_keywords.py   |  4 +-
 src/fixit/util.py                             |  2 +-
 16 files changed, 123 insertions(+), 109 deletions(-)
 rename src/fixit/rules/{replace_union_with_optional.py => replace_optional_type_annotation.py} (51%)

diff --git a/src/fixit/api.py b/src/fixit/api.py
index 32fb79b3..c125c94e 100644
--- a/src/fixit/api.py
+++ b/src/fixit/api.py
@@ -100,7 +100,7 @@ def fixit_bytes(
     *,
     config: Config,
     autofix: bool = False,
-    metrics_hook: Optional[MetricsHook] = None,
+    metrics_hook: MetricsHook | None = None,
 ) -> Generator[Result, bool, Optional[FileContent]]:
     """
     Lint raw bytes content representing a single path, using the given configuration.
@@ -154,8 +154,8 @@ def fixit_stdin(
     path: Path,
     *,
     autofix: bool = False,
-    options: Optional[Options] = None,
-    metrics_hook: Optional[MetricsHook] = None,
+    options: Options | None = None,
+    metrics_hook: MetricsHook | None = None,
 ) -> Generator[Result, bool, None]:
     """
     Wrapper around :func:`fixit_bytes` for formatting content from STDIN.
@@ -187,8 +187,8 @@ def fixit_file(
     path: Path,
     *,
     autofix: bool = False,
-    options: Optional[Options] = None,
-    metrics_hook: Optional[MetricsHook] = None,
+    options: Options | None = None,
+    metrics_hook: MetricsHook | None = None,
 ) -> Generator[Result, bool, None]:
     """
     Lint a single file on disk, detecting and generating appropriate configuration.
@@ -223,8 +223,8 @@ def _fixit_file_wrapper(
     path: Path,
     *,
     autofix: bool = False,
-    options: Optional[Options] = None,
-    metrics_hook: Optional[MetricsHook] = None,
+    options: Options | None = None,
+    metrics_hook: MetricsHook | None = None,
 ) -> List[Result]:
     """
     Wrapper because generators can't be pickled or used directly via multiprocessing
@@ -239,9 +239,9 @@ def fixit_paths(
     paths: Iterable[Path],
     *,
     autofix: bool = False,
-    options: Optional[Options] = None,
+    options: Options | None = None,
     parallel: bool = True,
-    metrics_hook: Optional[MetricsHook] = None,
+    metrics_hook: MetricsHook | None = None,
 ) -> Generator[Result, bool, None]:
     """
     Lint multiple files or directories, recursively expanding each path.
diff --git a/src/fixit/cli.py b/src/fixit/cli.py
index 84bd344a..02939870 100644
--- a/src/fixit/cli.py
+++ b/src/fixit/cli.py
@@ -89,11 +89,11 @@ def f(v: int) -> str:
 @click.option("--print-metrics", is_flag=True, help="Print metrics of this run")
 def main(
     ctx: click.Context,
-    debug: Optional[bool],
-    config_file: Optional[Path],
+    debug: bool | None,
+    config_file: Path | None,
     tags: str,
     rules: str,
-    output_format: Optional[OutputFormat],
+    output_format: OutputFormat | None,
     output_template: str,
     print_metrics: bool,
 ) -> None:
@@ -258,8 +258,8 @@ def fix(
 def lsp(
     ctx: click.Context,
     stdio: bool,
-    tcp: Optional[int],
-    ws: Optional[int],
+    tcp: int | None,
+    ws: int | None,
     debounce_interval: float,
 ) -> None:
     """
diff --git a/src/fixit/config.py b/src/fixit/config.py
index ededa89f..7be4c516 100644
--- a/src/fixit/config.py
+++ b/src/fixit/config.py
@@ -62,7 +62,7 @@
 
 
 class ConfigError(ValueError):
-    def __init__(self, msg: str, config: Optional[RawConfig] = None):
+    def __init__(self, msg: str, config: RawConfig | None = None):
         super().__init__(msg)
         self.config = config
 
@@ -203,7 +203,7 @@ def collect_rules(
     config: Config,
     *,
     # out-param to capture reasons when disabling rules for debugging
-    debug_reasons: Optional[Dict[Type[LintRule], str]] = None,
+    debug_reasons: Dict[Type[LintRule], str] | None = None,
 ) -> Collection[LintRule]:
     """
     Import and return rules specified by `enables` and `disables`.
@@ -272,7 +272,7 @@ def collect_rules(
     return materialized_rules
 
 
-def locate_configs(path: Path, root: Optional[Path] = None) -> List[Path]:
+def locate_configs(path: Path, root: Path | None = None) -> List[Path]:
     """
     Given a file path, locate all relevant config files in priority order.
 
@@ -335,7 +335,7 @@ def read_configs(paths: List[Path]) -> List[RawConfig]:
 
 
 def get_sequence(
-    config: RawConfig, key: str, *, data: Optional[Dict[str, Any]] = None
+    config: RawConfig, key: str, *, data: Dict[str, Any] | None = None
 ) -> Sequence[str]:
     value: Sequence[str]
     if data:
@@ -352,7 +352,7 @@ def get_sequence(
 
 
 def get_options(
-    config: RawConfig, key: str, *, data: Optional[Dict[str, Any]] = None
+    config: RawConfig, key: str, *, data: Dict[str, Any] | None = None
 ) -> RuleOptionsTable:
     if data:
         mapping = data.pop(key, {})
@@ -379,9 +379,7 @@ def get_options(
     return rule_configs
 
 
-def parse_rule(
-    rule: str, root: Path, config: Optional[RawConfig] = None
-) -> QualifiedRule:
+def parse_rule(rule: str, root: Path, config: RawConfig | None = None) -> QualifiedRule:
     """
     Given a raw rule string, parse and return a QualifiedRule object
     """
@@ -400,7 +398,7 @@ def parse_rule(
 
 
 def merge_configs(
-    path: Path, raw_configs: List[RawConfig], root: Optional[Path] = None
+    path: Path, raw_configs: List[RawConfig], root: Path | None = None
 ) -> Config:
     """
     Given multiple raw configs, merge them in priority order.
@@ -413,8 +411,8 @@ def merge_configs(
     enable_rules: Set[QualifiedRule] = {QualifiedRule("fixit.rules")}
     disable_rules: Set[QualifiedRule] = set()
     rule_options: RuleOptionsTable = {}
-    target_python_version: Optional[Version] = Version(platform.python_version())
-    target_formatter: Optional[str] = None
+    target_python_version: Version | None = Version(platform.python_version())
+    target_formatter: str | None = None
     output_format: OutputFormat = OutputFormat.fixit
     output_template: str = ""
 
@@ -423,9 +421,9 @@ def process_subpath(
         *,
         enable: Sequence[str] = (),
         disable: Sequence[str] = (),
-        options: Optional[RuleOptionsTable] = None,
+        options: RuleOptionsTable | None = None,
         python_version: Any = None,
-        formatter: Optional[str] = None,
+        formatter: str | None = None,
     ) -> None:
         nonlocal target_python_version
         nonlocal target_formatter
@@ -556,10 +554,10 @@ def process_subpath(
 
 
 def generate_config(
-    path: Optional[Path] = None,
-    root: Optional[Path] = None,
+    path: Path | None = None,
+    root: Path | None = None,
     *,
-    options: Optional[Options] = None,
+    options: Options | None = None,
 ) -> Config:
     """
     Given a file path, walk upwards looking for and applying cascading configs
diff --git a/src/fixit/engine.py b/src/fixit/engine.py
index 36ec39d6..ccc8578f 100644
--- a/src/fixit/engine.py
+++ b/src/fixit/engine.py
@@ -59,7 +59,7 @@ def collect_violations(
         self,
         rules: Collection[LintRule],
         config: Config,
-        metrics_hook: Optional[MetricsHook] = None,
+        metrics_hook: MetricsHook | None = None,
     ) -> Generator[LintViolation, None, int]:
         """Run multiple `LintRule`s and yield any lint violations.
 
diff --git a/src/fixit/ftypes.py b/src/fixit/ftypes.py
index 0205cc36..1238fa09 100644
--- a/src/fixit/ftypes.py
+++ b/src/fixit/ftypes.py
@@ -63,9 +63,9 @@ class OutputFormat(str, Enum):
 @dataclass(frozen=True)
 class Invalid:
     code: str
-    range: Optional[CodeRange] = None
-    expected_message: Optional[str] = None
-    expected_replacement: Optional[str] = None
+    range: CodeRange | None = None
+    expected_message: str | None = None
+    expected_replacement: str | None = None
 
 
 @dataclass(frozen=True)
@@ -105,8 +105,8 @@ class Valid:
 
 class QualifiedRuleRegexResult(TypedDict):
     module: str
-    name: Optional[str]
-    local: Optional[str]
+    name: str | None
+    local: str | None
 
 
 def is_sequence(value: Any) -> bool:
@@ -120,9 +120,9 @@ def is_collection(value: Any) -> bool:
 @dataclass(frozen=True)
 class QualifiedRule:
     module: str
-    name: Optional[str] = None
-    local: Optional[str] = None
-    root: Optional[Path] = field(default=None, hash=False, compare=False)
+    name: str | None = None
+    local: str | None = None
+    root: Path | None = field(default=None, hash=False, compare=False)
 
     def __str__(self) -> str:
         return self.module + (f":{self.name}" if self.name else "")
@@ -139,7 +139,7 @@ class Tags(Container[str]):
     exclude: Tuple[str, ...] = ()
 
     @staticmethod
-    def parse(value: Optional[str]) -> "Tags":
+    def parse(value: str | None) -> "Tags":
         if not value:
             return Tags()
 
@@ -185,11 +185,11 @@ class Options:
     Command-line options to affect runtime behavior
     """
 
-    debug: Optional[bool] = None
-    config_file: Optional[Path] = None
-    tags: Optional[Tags] = None
+    debug: bool | None = None
+    config_file: Path | None = None
+    tags: Tags | None = None
     rules: Sequence[QualifiedRule] = ()
-    output_format: Optional[OutputFormat] = None
+    output_format: OutputFormat | None = None
     output_template: str = ""
     print_metrics: bool = False
 
@@ -200,8 +200,8 @@ class LSPOptions:
     Command-line options to affect LSP runtime behavior
     """
 
-    tcp: Optional[int]
-    ws: Optional[int]
+    tcp: int | None
+    ws: int | None
     stdio: bool = True
     debounce_interval: float = 0.5
 
@@ -226,13 +226,13 @@ class Config:
     options: RuleOptionsTable = field(default_factory=dict)
 
     # filtering criteria
-    python_version: Optional[Version] = field(
+    python_version: Version | None = field(
         default_factory=lambda: Version(platform.python_version())
     )
     tags: Tags = field(default_factory=Tags)
 
     # post-run processing
-    formatter: Optional[str] = None
+    formatter: str | None = None
 
     # output formatting options
     output_format: OutputFormat = OutputFormat.fixit
@@ -263,7 +263,7 @@ class LintViolation:
     range: CodeRange
     message: str
     node: CSTNode
-    replacement: Optional[NodeReplacement[CSTNode]]
+    replacement: NodeReplacement[CSTNode] | None
     diff: str = ""
 
     @property
@@ -281,5 +281,5 @@ class Result:
     """
 
     path: Path
-    violation: Optional[LintViolation]
-    error: Optional[Tuple[Exception, str]] = None
+    violation: LintViolation | None
+    error: Tuple[Exception, str] | None = None
diff --git a/src/fixit/lsp.py b/src/fixit/lsp.py
index 00f34b7c..c735a853 100644
--- a/src/fixit/lsp.py
+++ b/src/fixit/lsp.py
@@ -65,7 +65,7 @@ def load_config(self, path: Path) -> Config:
 
     def diagnostic_generator(
         self, uri: str, autofix: bool = False
-    ) -> Optional[Generator[Result, bool, Optional[FileContent]]]:
+    ) -> Generator[Result, bool, Optional[FileContent]] | None:
         """
         LSP wrapper (provides document state from `pygls`) for `fixit_bytes`.
         """
@@ -125,7 +125,7 @@ def on_did_open(self, params: DidOpenTextDocumentParams) -> None:
     def on_did_change(self, params: DidChangeTextDocumentParams) -> None:
         self.validate(params.text_document.uri, params.text_document.version)
 
-    def format(self, params: DocumentFormattingParams) -> Optional[List[TextEdit]]:
+    def format(self, params: DocumentFormattingParams) -> List[TextEdit] | None:
         generator = self.diagnostic_generator(params.text_document.uri, autofix=True)
         if generator is None:
             return None
@@ -164,7 +164,7 @@ class Debouncer:
     def __init__(self, f: Callable[..., Any], interval: float) -> None:
         self.f = f
         self.interval = interval
-        self._timer: Optional[threading.Timer] = None
+        self._timer: threading.Timer | None = None
         self._lock = threading.Lock()
 
     def __call__(self, *args: Any, **kwargs: Any) -> None:
diff --git a/src/fixit/rule.py b/src/fixit/rule.py
index 954972b1..a3f8eb40 100644
--- a/src/fixit/rule.py
+++ b/src/fixit/rule.py
@@ -114,7 +114,7 @@ def __init_subclass__(cls) -> None:
     def __str__(self) -> str:
         return f"{self.__class__.__module__}:{self.__class__.__name__}"
 
-    _visit_hook: Optional[VisitHook] = None
+    _visit_hook: VisitHook | None = None
 
     def node_comments(self, node: CSTNode) -> Generator[str, None, None]:
         """
@@ -125,11 +125,9 @@ def node_comments(self, node: CSTNode) -> Generator[str, None, None]:
         while not isinstance(node, Module):
             # trailing_whitespace can either be a property of the node itself, or in
             # case of blocks, be part of the block's body element
-            tw: Optional[TrailingWhitespace] = getattr(
-                node, "trailing_whitespace", None
-            )
+            tw: TrailingWhitespace | None = getattr(node, "trailing_whitespace", None)
             if tw is None:
-                body: Optional[BaseSuite] = getattr(node, "body", None)
+                body: BaseSuite | None = getattr(node, "body", None)
                 if isinstance(body, SimpleStatementSuite):
                     tw = body.trailing_whitespace
                 elif isinstance(body, IndentedBlock):
@@ -138,20 +136,20 @@ def node_comments(self, node: CSTNode) -> Generator[str, None, None]:
             if tw and tw.comment:
                 yield tw.comment.value
 
-            comma: Optional[Comma] = getattr(node, "comma", None)
+            comma: Comma | None = getattr(node, "comma", None)
             if isinstance(comma, Comma):
                 tw = getattr(comma.whitespace_after, "first_line", None)
                 if tw and tw.comment:
                     yield tw.comment.value
 
-            rb: Optional[RightSquareBracket] = getattr(node, "rbracket", None)
+            rb: RightSquareBracket | None = getattr(node, "rbracket", None)
             if rb is not None:
                 tw = getattr(rb.whitespace_before, "first_line", None)
                 if tw and tw.comment:
                     yield tw.comment.value
 
-            el: Optional[Sequence[EmptyLine]] = None
-            lb: Optional[LeftSquareBracket] = getattr(node, "lbracket", None)
+            el: Sequence[EmptyLine] | None = None
+            lb: LeftSquareBracket | None = getattr(node, "lbracket", None)
             if lb is not None:
                 el = getattr(lb.whitespace_after, "empty_lines", None)
                 if el is not None:
@@ -165,7 +163,7 @@ def node_comments(self, node: CSTNode) -> Generator[str, None, None]:
                     if line.comment:
                         yield line.comment.value
 
-            ll: Optional[Sequence[EmptyLine]] = getattr(node, "leading_lines", None)
+            ll: Sequence[EmptyLine] | None = getattr(node, "leading_lines", None)
             if ll is not None:
                 for line in ll:
                     if line.comment:
@@ -219,10 +217,10 @@ def ignore_lint(self, node: CSTNode) -> bool:
     def report(
         self,
         node: CSTNode,
-        message: Optional[str] = None,
+        message: str | None = None,
         *,
-        position: Optional[Union[CodePosition, CodeRange]] = None,
-        replacement: Optional[NodeReplacement[CSTNode]] = None,
+        position: Union[CodePosition, CodeRange] | None = None,
+        replacement: NodeReplacement[CSTNode] | None = None,
     ) -> None:
         """
         Report a lint rule violation.
diff --git a/src/fixit/rules/deprecated_abc_import.py b/src/fixit/rules/deprecated_abc_import.py
index 03a3607c..adac9cc1 100644
--- a/src/fixit/rules/deprecated_abc_import.py
+++ b/src/fixit/rules/deprecated_abc_import.py
@@ -222,7 +222,7 @@ def visit_ImportFrom(self, node: cst.ImportFrom) -> None:
 
     def get_import_from(
         self, node: Union[cst.SimpleStatementLine, cst.BaseCompoundStatement]
-    ) -> Optional[cst.ImportFrom]:
+    ) -> cst.ImportFrom | None:
         """
         Iterate over a Statement Sequence and return a Statement if it is a
         `cst.ImportFrom` statement.
diff --git a/src/fixit/rules/no_namedtuple.py b/src/fixit/rules/no_namedtuple.py
index 95854566..d1fd190f 100644
--- a/src/fixit/rules/no_namedtuple.py
+++ b/src/fixit/rules/no_namedtuple.py
@@ -186,7 +186,7 @@ def partition_bases(
         self, original_bases: Sequence[cst.Arg]
     ) -> Tuple[Optional[cst.Arg], List[cst.Arg]]:
         # Returns a tuple of NamedTuple base object if it exists, and a list of non-NamedTuple bases
-        namedtuple_base: Optional[cst.Arg] = None
+        namedtuple_base: cst.Arg | None = None
         new_bases: List[cst.Arg] = []
         for base_class in original_bases:
             if QualifiedNameProvider.has_name(
diff --git a/src/fixit/rules/no_static_if_condition.py b/src/fixit/rules/no_static_if_condition.py
index dd7fba4c..4893bf33 100644
--- a/src/fixit/rules/no_static_if_condition.py
+++ b/src/fixit/rules/no_static_if_condition.py
@@ -115,7 +115,7 @@ async def some_func() -> none:
     ]
 
     @classmethod
-    def _extract_static_bool(cls, node: cst.BaseExpression) -> Optional[bool]:
+    def _extract_static_bool(cls, node: cst.BaseExpression) -> bool | None:
         if m.matches(node, m.Call()):
             # cannot reason about function calls
             return None
diff --git a/src/fixit/rules/replace_union_with_optional.py b/src/fixit/rules/replace_optional_type_annotation.py
similarity index 51%
rename from src/fixit/rules/replace_union_with_optional.py
rename to src/fixit/rules/replace_optional_type_annotation.py
index d7f2c1b7..f900dc69 100644
--- a/src/fixit/rules/replace_union_with_optional.py
+++ b/src/fixit/rules/replace_optional_type_annotation.py
@@ -9,27 +9,26 @@
 from fixit import Invalid, LintRule, Valid
 
 
-class ReplaceUnionWithOptional(LintRule):
+class ReplaceOptionalTypeAnnotation(LintRule):
     """
-    Enforces the use of ``Optional[T]`` over ``Union[T, None]`` and ``Union[None, T]``.
-    See https://docs.python.org/3/library/typing.html#typing.Optional to learn more about Optionals.
+    Enforces the use of ``T | None`` over ``Optional[T]`` and ``Union[T, None]`` and ``Union[None, T]``.
+    See https://docs.python.org/3/library/stdtypes.html#types-union.
     """
 
     MESSAGE: str = (
-        "`Optional[T]` is preferred over `Union[T, None]` or `Union[None, T]`. "
-        + "Learn more: https://docs.python.org/3/library/typing.html#typing.Optional"
+        "`T | None` is preferred over `Optional[T]` or `Union[T, None]` or `Union[None, T]`. "
+        + "Learn more: https://docs.python.org/3/library/stdtypes.html#types-union"
     )
-    METADATA_DEPENDENCIES = (cst.metadata.ScopeProvider,)
     VALID = [
         Valid(
             """
-            def func() -> Optional[str]:
+            def func() -> str | None:
                 pass
             """
         ),
         Valid(
             """
-            def func() -> Optional[Dict]:
+            def func() -> Dict | None:
                 pass
             """
         ),
@@ -43,43 +42,41 @@ def func() -> Union[str, int, None]:
     INVALID = [
         Invalid(
             """
-            def func() -> Union[str, None]:
+            def func() -> Optional[str]:
+                pass
+            """,
+            expected_replacement="""
+            def func() -> str | None:
                 pass
             """,
         ),
         Invalid(
             """
-            from typing import Optional
             def func() -> Union[Dict[str, int], None]:
                 pass
             """,
             expected_replacement="""
-            from typing import Optional
-            def func() -> Optional[Dict[str, int]]:
+            def func() -> Dict[str, int] | None:
                 pass
             """,
         ),
         Invalid(
             """
-            from typing import Optional
             def func() -> Union[str, None]:
                 pass
             """,
             expected_replacement="""
-            from typing import Optional
-            def func() -> Optional[str]:
+            def func() -> str | None:
                 pass
             """,
         ),
         Invalid(
             """
-            from typing import Optional
             def func() -> Union[Dict, None]:
                 pass
             """,
             expected_replacement="""
-            from typing import Optional
-            def func() -> Optional[Dict]:
+            def func() -> Dict | None:
                 pass
             """,
         ),
@@ -87,24 +84,34 @@ def func() -> Optional[Dict]:
 
     def leave_Annotation(self, original_node: cst.Annotation) -> None:
         if self.contains_union_with_none(original_node):
-            scope = self.get_metadata(cst.metadata.ScopeProvider, original_node, None)
             nones = 0
             indexes = []
             replacement = None
-            if scope is not None and "Optional" in scope:
-                for s in cst.ensure_type(original_node.annotation, cst.Subscript).slice:
-                    if m.matches(s, m.SubscriptElement(m.Index(m.Name("None")))):
-                        nones += 1
-                    else:
-                        indexes.append(s.slice)
-                if not (nones > 1) and len(indexes) == 1:
-                    replacement = original_node.with_changes(
-                        annotation=cst.Subscript(
-                            value=cst.Name("Optional"),
-                            slice=(cst.SubscriptElement(indexes[0]),),
-                        )
+            for s in cst.ensure_type(original_node.annotation, cst.Subscript).slice:
+                if m.matches(s, m.SubscriptElement(m.Index(m.Name("None")))):
+                    nones += 1
+                else:
+                    indexes.append(s.slice)
+            if not (nones > 1) and len(indexes) == 1:
+                inner_type = cst.ensure_type(indexes[0], cst.Index).value
+                replacement = original_node.with_changes(
+                    annotation=cst.BinaryOperation(
+                        operator=cst.BitOr(),
+                        left=inner_type,
+                        right=cst.Name("None"),
                     )
-                    # TODO(T57106602) refactor lint replacement once extract exists
+                )
+            self.report(original_node, replacement=replacement)
+        elif self.contains_optional(original_node):
+            subscript_element = cst.ensure_type(
+                original_node.annotation, cst.Subscript
+            ).slice[0]
+            inner_type = cst.ensure_type(subscript_element.slice, cst.Index).value
+            replacement = original_node.with_changes(
+                annotation=cst.BinaryOperation(
+                    operator=cst.BitOr(), left=inner_type, right=cst.Name("None")
+                )
+            )
             self.report(original_node, replacement=replacement)
 
     def contains_union_with_none(self, node: cst.Annotation) -> bool:
@@ -126,3 +133,14 @@ def contains_union_with_none(self, node: cst.Annotation) -> bool:
                 )
             ),
         )
+
+    def contains_optional(self, node: cst.Annotation) -> bool:
+        return m.matches(
+            node,
+            m.Annotation(
+                m.Subscript(
+                    value=m.Name("Optional"),
+                    slice=[m.SubscriptElement(m.Index())],
+                )
+            ),
+        )
diff --git a/src/fixit/rules/rewrite_to_comprehension.py b/src/fixit/rules/rewrite_to_comprehension.py
index 68e0953c..c3a5787b 100644
--- a/src/fixit/rules/rewrite_to_comprehension.py
+++ b/src/fixit/rules/rewrite_to_comprehension.py
@@ -114,7 +114,7 @@ def visit_Call(self, node: cst.Call) -> None:
                 exp = cst.ensure_type(node.args[0].value, cst.ListComp)
                 message_formatter = UNNECESSARY_LIST_COMPREHENSION
 
-            replacement: Optional[Union[cst.Call, cst.BaseComp]] = None
+            replacement: Union[cst.Call, cst.BaseComp] | None = None
             if call_name == "list":
                 replacement = node.deep_replace(
                     node, cst.ListComp(elt=exp.elt, for_in=exp.for_in)
diff --git a/src/fixit/rules/use_fstring.py b/src/fixit/rules/use_fstring.py
index b56ebcf5..605a1dc6 100644
--- a/src/fixit/rules/use_fstring.py
+++ b/src/fixit/rules/use_fstring.py
@@ -144,9 +144,9 @@ class UseFstring(LintRule):
         ),
     ]
 
-    _codegen: Optional[Callable[[cst.CSTNode], str]]
+    _codegen: Callable[[cst.CSTNode], str] | None
 
-    def visit_Module(self, node: cst.Module) -> Optional[bool]:
+    def visit_Module(self, node: cst.Module) -> bool | None:
         self._codegen = node.code_for_node
         return super().visit_Module(node)
 
diff --git a/src/fixit/tests/ftypes.py b/src/fixit/tests/ftypes.py
index 292aac01..5467c65a 100644
--- a/src/fixit/tests/ftypes.py
+++ b/src/fixit/tests/ftypes.py
@@ -106,7 +106,7 @@ def test_tags_parser(self) -> None:
 
     def test_tags_bool(self) -> None:
         Tags = ftypes.Tags
-        tags: Optional[str]
+        tags: str | None
 
         for tags in (
             "hello",
diff --git a/src/fixit/upgrade/deprecated_testcase_keywords.py b/src/fixit/upgrade/deprecated_testcase_keywords.py
index f38e4599..d82f7753 100755
--- a/src/fixit/upgrade/deprecated_testcase_keywords.py
+++ b/src/fixit/upgrade/deprecated_testcase_keywords.py
@@ -73,8 +73,8 @@ def visit_Call(self, node: Call) -> None:
                 self.convert_linecol_to_range(node)
 
     def convert_linecol_to_range(self, node: Call) -> None:
-        line: Optional[BaseExpression] = None
-        col: Optional[BaseExpression] = None
+        line: BaseExpression | None = None
+        col: BaseExpression | None = None
         index_to_remove = []
         for ind, arg in enumerate(node.args):
             if not arg.keyword:
diff --git a/src/fixit/util.py b/src/fixit/util.py
index 44ce518f..a13f6dce 100644
--- a/src/fixit/util.py
+++ b/src/fixit/util.py
@@ -36,7 +36,7 @@ class capture(Generic[Yield, Send, Return]):
 
     def __init__(self, generator: Generator[Yield, Send, Return]) -> None:
         self.generator = generator
-        self._send: Optional[Send] = None
+        self._send: Send | None = None
         self._result: Union[Return, object] = Sentinel
 
     def __iter__(self) -> Generator[Yield, Send, Return]:

From 3b82f4d5da1c9d4c7651701132f8e4b4822d2e10 Mon Sep 17 00:00:00 2001
From: Danny Yang <yangdanny@fb.com>
Date: Mon, 18 Nov 2024 16:27:54 -0500
Subject: [PATCH 2/7] update docs

---
 docs/guide/builtins.rst | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/docs/guide/builtins.rst b/docs/guide/builtins.rst
index 6f2b1484..b5bb342c 100644
--- a/docs/guide/builtins.rst
+++ b/docs/guide/builtins.rst
@@ -33,7 +33,7 @@ Built-in Rules
 - :class:`NoRedundantListComprehension`
 - :class:`NoStaticIfCondition`
 - :class:`NoStringTypeAnnotation`
-- :class:`ReplaceUnionWithOptional`
+- :class:`ReplaceOptionalTypeAnnotation`
 - :class:`RewriteToComprehension`
 - :class:`RewriteToLiteral`
 - :class:`SortedAttributes`
@@ -716,14 +716,14 @@ Built-in Rules
             async def foo() -> Class:
                 return await Class()
 
-.. class:: ReplaceUnionWithOptional
+.. class:: ReplaceOptionalTypeAnnotation
 
-    Enforces the use of ``Optional[T]`` over ``Union[T, None]`` and ``Union[None, T]``.
-    See https://docs.python.org/3/library/typing.html#typing.Optional to learn more about Optionals.
+    Enforces the use of ``T | None`` over ``Optional[T]`` and ``Union[T, None]`` and ``Union[None, T]``.
+    See https://docs.python.org/3/library/stdtypes.html#types-union.
 
     .. attribute:: MESSAGE
 
-        `Optional[T]` is preferred over `Union[T, None]` or `Union[None, T]`. Learn more: https://docs.python.org/3/library/typing.html#typing.Optional
+        `T | None` is preferred over `Optional[T]` or `Union[T, None]` or `Union[None, T]`. Learn more: https://docs.python.org/3/library/stdtypes.html#types-union
 
     .. attribute:: AUTOFIX
         :type: Yes
@@ -733,28 +733,31 @@ Built-in Rules
 
         .. code:: python
 
-            def func() -> Optional[str]:
+            def func() -> str | None:
                 pass
         .. code:: python
 
-            def func() -> Optional[Dict]:
+            def func() -> Dict | None:
                 pass
 
     .. attribute:: INVALID
 
         .. code:: python
 
-            def func() -> Union[str, None]:
+            def func() -> Optional[str]:
+                pass
+
+            # suggested fix
+            def func() -> str | None:
                 pass
+
         .. code:: python
 
-            from typing import Optional
             def func() -> Union[Dict[str, int], None]:
                 pass
 
             # suggested fix
-            from typing import Optional
-            def func() -> Optional[Dict[str, int]]:
+            def func() -> Dict[str, int] | None:
                 pass
 
 .. class:: RewriteToComprehension

From 7c84949d541dac1a9f1451262b8666401e154d74 Mon Sep 17 00:00:00 2001
From: Danny Yang <yangdanny@fb.com>
Date: Mon, 18 Nov 2024 16:29:47 -0500
Subject: [PATCH 3/7] restrict to 3.10

---
 src/fixit/rules/replace_optional_type_annotation.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/fixit/rules/replace_optional_type_annotation.py b/src/fixit/rules/replace_optional_type_annotation.py
index f900dc69..8f4a2fa9 100644
--- a/src/fixit/rules/replace_optional_type_annotation.py
+++ b/src/fixit/rules/replace_optional_type_annotation.py
@@ -15,6 +15,7 @@ class ReplaceOptionalTypeAnnotation(LintRule):
     See https://docs.python.org/3/library/stdtypes.html#types-union.
     """
 
+    PYTHON_VERSION = ">= 3.10"
     MESSAGE: str = (
         "`T | None` is preferred over `Optional[T]` or `Union[T, None]` or `Union[None, T]`. "
         + "Learn more: https://docs.python.org/3/library/stdtypes.html#types-union"

From b3e7ca8dff3a73065b48f695c27974d163cb9c78 Mon Sep 17 00:00:00 2001
From: Danny Yang <yangdanny@fb.com>
Date: Mon, 18 Nov 2024 16:40:51 -0500
Subject: [PATCH 4/7] revert lint fixes

---
 src/fixit/api.py                              | 18 ++++-----
 src/fixit/cli.py                              | 10 ++---
 src/fixit/config.py                           | 30 +++++++-------
 src/fixit/engine.py                           |  2 +-
 src/fixit/ftypes.py                           | 40 +++++++++----------
 src/fixit/lsp.py                              |  6 +--
 src/fixit/rule.py                             | 24 ++++++-----
 src/fixit/rules/deprecated_abc_import.py      |  6 +--
 src/fixit/rules/no_namedtuple.py              |  6 +--
 src/fixit/rules/no_static_if_condition.py     |  2 +-
 src/fixit/rules/rewrite_to_comprehension.py   |  2 +-
 src/fixit/rules/use_fstring.py                |  4 +-
 src/fixit/tests/ftypes.py                     |  2 +-
 .../upgrade/deprecated_testcase_keywords.py   |  8 ++--
 src/fixit/util.py                             |  2 +-
 15 files changed, 83 insertions(+), 79 deletions(-)

diff --git a/src/fixit/api.py b/src/fixit/api.py
index c125c94e..32fb79b3 100644
--- a/src/fixit/api.py
+++ b/src/fixit/api.py
@@ -100,7 +100,7 @@ def fixit_bytes(
     *,
     config: Config,
     autofix: bool = False,
-    metrics_hook: MetricsHook | None = None,
+    metrics_hook: Optional[MetricsHook] = None,
 ) -> Generator[Result, bool, Optional[FileContent]]:
     """
     Lint raw bytes content representing a single path, using the given configuration.
@@ -154,8 +154,8 @@ def fixit_stdin(
     path: Path,
     *,
     autofix: bool = False,
-    options: Options | None = None,
-    metrics_hook: MetricsHook | None = None,
+    options: Optional[Options] = None,
+    metrics_hook: Optional[MetricsHook] = None,
 ) -> Generator[Result, bool, None]:
     """
     Wrapper around :func:`fixit_bytes` for formatting content from STDIN.
@@ -187,8 +187,8 @@ def fixit_file(
     path: Path,
     *,
     autofix: bool = False,
-    options: Options | None = None,
-    metrics_hook: MetricsHook | None = None,
+    options: Optional[Options] = None,
+    metrics_hook: Optional[MetricsHook] = None,
 ) -> Generator[Result, bool, None]:
     """
     Lint a single file on disk, detecting and generating appropriate configuration.
@@ -223,8 +223,8 @@ def _fixit_file_wrapper(
     path: Path,
     *,
     autofix: bool = False,
-    options: Options | None = None,
-    metrics_hook: MetricsHook | None = None,
+    options: Optional[Options] = None,
+    metrics_hook: Optional[MetricsHook] = None,
 ) -> List[Result]:
     """
     Wrapper because generators can't be pickled or used directly via multiprocessing
@@ -239,9 +239,9 @@ def fixit_paths(
     paths: Iterable[Path],
     *,
     autofix: bool = False,
-    options: Options | None = None,
+    options: Optional[Options] = None,
     parallel: bool = True,
-    metrics_hook: MetricsHook | None = None,
+    metrics_hook: Optional[MetricsHook] = None,
 ) -> Generator[Result, bool, None]:
     """
     Lint multiple files or directories, recursively expanding each path.
diff --git a/src/fixit/cli.py b/src/fixit/cli.py
index 02939870..84bd344a 100644
--- a/src/fixit/cli.py
+++ b/src/fixit/cli.py
@@ -89,11 +89,11 @@ def f(v: int) -> str:
 @click.option("--print-metrics", is_flag=True, help="Print metrics of this run")
 def main(
     ctx: click.Context,
-    debug: bool | None,
-    config_file: Path | None,
+    debug: Optional[bool],
+    config_file: Optional[Path],
     tags: str,
     rules: str,
-    output_format: OutputFormat | None,
+    output_format: Optional[OutputFormat],
     output_template: str,
     print_metrics: bool,
 ) -> None:
@@ -258,8 +258,8 @@ def fix(
 def lsp(
     ctx: click.Context,
     stdio: bool,
-    tcp: int | None,
-    ws: int | None,
+    tcp: Optional[int],
+    ws: Optional[int],
     debounce_interval: float,
 ) -> None:
     """
diff --git a/src/fixit/config.py b/src/fixit/config.py
index 7be4c516..ededa89f 100644
--- a/src/fixit/config.py
+++ b/src/fixit/config.py
@@ -62,7 +62,7 @@
 
 
 class ConfigError(ValueError):
-    def __init__(self, msg: str, config: RawConfig | None = None):
+    def __init__(self, msg: str, config: Optional[RawConfig] = None):
         super().__init__(msg)
         self.config = config
 
@@ -203,7 +203,7 @@ def collect_rules(
     config: Config,
     *,
     # out-param to capture reasons when disabling rules for debugging
-    debug_reasons: Dict[Type[LintRule], str] | None = None,
+    debug_reasons: Optional[Dict[Type[LintRule], str]] = None,
 ) -> Collection[LintRule]:
     """
     Import and return rules specified by `enables` and `disables`.
@@ -272,7 +272,7 @@ def collect_rules(
     return materialized_rules
 
 
-def locate_configs(path: Path, root: Path | None = None) -> List[Path]:
+def locate_configs(path: Path, root: Optional[Path] = None) -> List[Path]:
     """
     Given a file path, locate all relevant config files in priority order.
 
@@ -335,7 +335,7 @@ def read_configs(paths: List[Path]) -> List[RawConfig]:
 
 
 def get_sequence(
-    config: RawConfig, key: str, *, data: Dict[str, Any] | None = None
+    config: RawConfig, key: str, *, data: Optional[Dict[str, Any]] = None
 ) -> Sequence[str]:
     value: Sequence[str]
     if data:
@@ -352,7 +352,7 @@ def get_sequence(
 
 
 def get_options(
-    config: RawConfig, key: str, *, data: Dict[str, Any] | None = None
+    config: RawConfig, key: str, *, data: Optional[Dict[str, Any]] = None
 ) -> RuleOptionsTable:
     if data:
         mapping = data.pop(key, {})
@@ -379,7 +379,9 @@ def get_options(
     return rule_configs
 
 
-def parse_rule(rule: str, root: Path, config: RawConfig | None = None) -> QualifiedRule:
+def parse_rule(
+    rule: str, root: Path, config: Optional[RawConfig] = None
+) -> QualifiedRule:
     """
     Given a raw rule string, parse and return a QualifiedRule object
     """
@@ -398,7 +400,7 @@ def parse_rule(rule: str, root: Path, config: RawConfig | None = None) -> Qualif
 
 
 def merge_configs(
-    path: Path, raw_configs: List[RawConfig], root: Path | None = None
+    path: Path, raw_configs: List[RawConfig], root: Optional[Path] = None
 ) -> Config:
     """
     Given multiple raw configs, merge them in priority order.
@@ -411,8 +413,8 @@ def merge_configs(
     enable_rules: Set[QualifiedRule] = {QualifiedRule("fixit.rules")}
     disable_rules: Set[QualifiedRule] = set()
     rule_options: RuleOptionsTable = {}
-    target_python_version: Version | None = Version(platform.python_version())
-    target_formatter: str | None = None
+    target_python_version: Optional[Version] = Version(platform.python_version())
+    target_formatter: Optional[str] = None
     output_format: OutputFormat = OutputFormat.fixit
     output_template: str = ""
 
@@ -421,9 +423,9 @@ def process_subpath(
         *,
         enable: Sequence[str] = (),
         disable: Sequence[str] = (),
-        options: RuleOptionsTable | None = None,
+        options: Optional[RuleOptionsTable] = None,
         python_version: Any = None,
-        formatter: str | None = None,
+        formatter: Optional[str] = None,
     ) -> None:
         nonlocal target_python_version
         nonlocal target_formatter
@@ -554,10 +556,10 @@ def process_subpath(
 
 
 def generate_config(
-    path: Path | None = None,
-    root: Path | None = None,
+    path: Optional[Path] = None,
+    root: Optional[Path] = None,
     *,
-    options: Options | None = None,
+    options: Optional[Options] = None,
 ) -> Config:
     """
     Given a file path, walk upwards looking for and applying cascading configs
diff --git a/src/fixit/engine.py b/src/fixit/engine.py
index ccc8578f..36ec39d6 100644
--- a/src/fixit/engine.py
+++ b/src/fixit/engine.py
@@ -59,7 +59,7 @@ def collect_violations(
         self,
         rules: Collection[LintRule],
         config: Config,
-        metrics_hook: MetricsHook | None = None,
+        metrics_hook: Optional[MetricsHook] = None,
     ) -> Generator[LintViolation, None, int]:
         """Run multiple `LintRule`s and yield any lint violations.
 
diff --git a/src/fixit/ftypes.py b/src/fixit/ftypes.py
index 1238fa09..0205cc36 100644
--- a/src/fixit/ftypes.py
+++ b/src/fixit/ftypes.py
@@ -63,9 +63,9 @@ class OutputFormat(str, Enum):
 @dataclass(frozen=True)
 class Invalid:
     code: str
-    range: CodeRange | None = None
-    expected_message: str | None = None
-    expected_replacement: str | None = None
+    range: Optional[CodeRange] = None
+    expected_message: Optional[str] = None
+    expected_replacement: Optional[str] = None
 
 
 @dataclass(frozen=True)
@@ -105,8 +105,8 @@ class Valid:
 
 class QualifiedRuleRegexResult(TypedDict):
     module: str
-    name: str | None
-    local: str | None
+    name: Optional[str]
+    local: Optional[str]
 
 
 def is_sequence(value: Any) -> bool:
@@ -120,9 +120,9 @@ def is_collection(value: Any) -> bool:
 @dataclass(frozen=True)
 class QualifiedRule:
     module: str
-    name: str | None = None
-    local: str | None = None
-    root: Path | None = field(default=None, hash=False, compare=False)
+    name: Optional[str] = None
+    local: Optional[str] = None
+    root: Optional[Path] = field(default=None, hash=False, compare=False)
 
     def __str__(self) -> str:
         return self.module + (f":{self.name}" if self.name else "")
@@ -139,7 +139,7 @@ class Tags(Container[str]):
     exclude: Tuple[str, ...] = ()
 
     @staticmethod
-    def parse(value: str | None) -> "Tags":
+    def parse(value: Optional[str]) -> "Tags":
         if not value:
             return Tags()
 
@@ -185,11 +185,11 @@ class Options:
     Command-line options to affect runtime behavior
     """
 
-    debug: bool | None = None
-    config_file: Path | None = None
-    tags: Tags | None = None
+    debug: Optional[bool] = None
+    config_file: Optional[Path] = None
+    tags: Optional[Tags] = None
     rules: Sequence[QualifiedRule] = ()
-    output_format: OutputFormat | None = None
+    output_format: Optional[OutputFormat] = None
     output_template: str = ""
     print_metrics: bool = False
 
@@ -200,8 +200,8 @@ class LSPOptions:
     Command-line options to affect LSP runtime behavior
     """
 
-    tcp: int | None
-    ws: int | None
+    tcp: Optional[int]
+    ws: Optional[int]
     stdio: bool = True
     debounce_interval: float = 0.5
 
@@ -226,13 +226,13 @@ class Config:
     options: RuleOptionsTable = field(default_factory=dict)
 
     # filtering criteria
-    python_version: Version | None = field(
+    python_version: Optional[Version] = field(
         default_factory=lambda: Version(platform.python_version())
     )
     tags: Tags = field(default_factory=Tags)
 
     # post-run processing
-    formatter: str | None = None
+    formatter: Optional[str] = None
 
     # output formatting options
     output_format: OutputFormat = OutputFormat.fixit
@@ -263,7 +263,7 @@ class LintViolation:
     range: CodeRange
     message: str
     node: CSTNode
-    replacement: NodeReplacement[CSTNode] | None
+    replacement: Optional[NodeReplacement[CSTNode]]
     diff: str = ""
 
     @property
@@ -281,5 +281,5 @@ class Result:
     """
 
     path: Path
-    violation: LintViolation | None
-    error: Tuple[Exception, str] | None = None
+    violation: Optional[LintViolation]
+    error: Optional[Tuple[Exception, str]] = None
diff --git a/src/fixit/lsp.py b/src/fixit/lsp.py
index c735a853..00f34b7c 100644
--- a/src/fixit/lsp.py
+++ b/src/fixit/lsp.py
@@ -65,7 +65,7 @@ def load_config(self, path: Path) -> Config:
 
     def diagnostic_generator(
         self, uri: str, autofix: bool = False
-    ) -> Generator[Result, bool, Optional[FileContent]] | None:
+    ) -> Optional[Generator[Result, bool, Optional[FileContent]]]:
         """
         LSP wrapper (provides document state from `pygls`) for `fixit_bytes`.
         """
@@ -125,7 +125,7 @@ def on_did_open(self, params: DidOpenTextDocumentParams) -> None:
     def on_did_change(self, params: DidChangeTextDocumentParams) -> None:
         self.validate(params.text_document.uri, params.text_document.version)
 
-    def format(self, params: DocumentFormattingParams) -> List[TextEdit] | None:
+    def format(self, params: DocumentFormattingParams) -> Optional[List[TextEdit]]:
         generator = self.diagnostic_generator(params.text_document.uri, autofix=True)
         if generator is None:
             return None
@@ -164,7 +164,7 @@ class Debouncer:
     def __init__(self, f: Callable[..., Any], interval: float) -> None:
         self.f = f
         self.interval = interval
-        self._timer: threading.Timer | None = None
+        self._timer: Optional[threading.Timer] = None
         self._lock = threading.Lock()
 
     def __call__(self, *args: Any, **kwargs: Any) -> None:
diff --git a/src/fixit/rule.py b/src/fixit/rule.py
index a3f8eb40..954972b1 100644
--- a/src/fixit/rule.py
+++ b/src/fixit/rule.py
@@ -114,7 +114,7 @@ def __init_subclass__(cls) -> None:
     def __str__(self) -> str:
         return f"{self.__class__.__module__}:{self.__class__.__name__}"
 
-    _visit_hook: VisitHook | None = None
+    _visit_hook: Optional[VisitHook] = None
 
     def node_comments(self, node: CSTNode) -> Generator[str, None, None]:
         """
@@ -125,9 +125,11 @@ def node_comments(self, node: CSTNode) -> Generator[str, None, None]:
         while not isinstance(node, Module):
             # trailing_whitespace can either be a property of the node itself, or in
             # case of blocks, be part of the block's body element
-            tw: TrailingWhitespace | None = getattr(node, "trailing_whitespace", None)
+            tw: Optional[TrailingWhitespace] = getattr(
+                node, "trailing_whitespace", None
+            )
             if tw is None:
-                body: BaseSuite | None = getattr(node, "body", None)
+                body: Optional[BaseSuite] = getattr(node, "body", None)
                 if isinstance(body, SimpleStatementSuite):
                     tw = body.trailing_whitespace
                 elif isinstance(body, IndentedBlock):
@@ -136,20 +138,20 @@ def node_comments(self, node: CSTNode) -> Generator[str, None, None]:
             if tw and tw.comment:
                 yield tw.comment.value
 
-            comma: Comma | None = getattr(node, "comma", None)
+            comma: Optional[Comma] = getattr(node, "comma", None)
             if isinstance(comma, Comma):
                 tw = getattr(comma.whitespace_after, "first_line", None)
                 if tw and tw.comment:
                     yield tw.comment.value
 
-            rb: RightSquareBracket | None = getattr(node, "rbracket", None)
+            rb: Optional[RightSquareBracket] = getattr(node, "rbracket", None)
             if rb is not None:
                 tw = getattr(rb.whitespace_before, "first_line", None)
                 if tw and tw.comment:
                     yield tw.comment.value
 
-            el: Sequence[EmptyLine] | None = None
-            lb: LeftSquareBracket | None = getattr(node, "lbracket", None)
+            el: Optional[Sequence[EmptyLine]] = None
+            lb: Optional[LeftSquareBracket] = getattr(node, "lbracket", None)
             if lb is not None:
                 el = getattr(lb.whitespace_after, "empty_lines", None)
                 if el is not None:
@@ -163,7 +165,7 @@ def node_comments(self, node: CSTNode) -> Generator[str, None, None]:
                     if line.comment:
                         yield line.comment.value
 
-            ll: Sequence[EmptyLine] | None = getattr(node, "leading_lines", None)
+            ll: Optional[Sequence[EmptyLine]] = getattr(node, "leading_lines", None)
             if ll is not None:
                 for line in ll:
                     if line.comment:
@@ -217,10 +219,10 @@ def ignore_lint(self, node: CSTNode) -> bool:
     def report(
         self,
         node: CSTNode,
-        message: str | None = None,
+        message: Optional[str] = None,
         *,
-        position: Union[CodePosition, CodeRange] | None = None,
-        replacement: NodeReplacement[CSTNode] | None = None,
+        position: Optional[Union[CodePosition, CodeRange]] = None,
+        replacement: Optional[NodeReplacement[CSTNode]] = None,
     ) -> None:
         """
         Report a lint rule violation.
diff --git a/src/fixit/rules/deprecated_abc_import.py b/src/fixit/rules/deprecated_abc_import.py
index adac9cc1..e9917cab 100644
--- a/src/fixit/rules/deprecated_abc_import.py
+++ b/src/fixit/rules/deprecated_abc_import.py
@@ -8,10 +8,10 @@
 import libcst as cst
 import libcst.matchers as m
 
-from libcst.metadata import ParentNodeProvider
-
 from fixit import Invalid, LintRule, Valid
 
+from libcst.metadata import ParentNodeProvider
+
 
 # The ABCs that have been moved to `collections.abc`
 ABCS = frozenset(
@@ -222,7 +222,7 @@ def visit_ImportFrom(self, node: cst.ImportFrom) -> None:
 
     def get_import_from(
         self, node: Union[cst.SimpleStatementLine, cst.BaseCompoundStatement]
-    ) -> cst.ImportFrom | None:
+    ) -> Optional[cst.ImportFrom]:
         """
         Iterate over a Statement Sequence and return a Statement if it is a
         `cst.ImportFrom` statement.
diff --git a/src/fixit/rules/no_namedtuple.py b/src/fixit/rules/no_namedtuple.py
index d1fd190f..cae8d0cd 100644
--- a/src/fixit/rules/no_namedtuple.py
+++ b/src/fixit/rules/no_namedtuple.py
@@ -6,10 +6,10 @@
 from typing import List, Optional, Sequence, Tuple
 
 import libcst as cst
-from libcst import ensure_type, MaybeSentinel, parse_expression
-from libcst.metadata import QualifiedName, QualifiedNameProvider, QualifiedNameSource
 
 from fixit import Invalid, LintRule, Valid
+from libcst import ensure_type, MaybeSentinel, parse_expression
+from libcst.metadata import QualifiedName, QualifiedNameProvider, QualifiedNameSource
 
 
 class NoNamedTuple(LintRule):
@@ -186,7 +186,7 @@ def partition_bases(
         self, original_bases: Sequence[cst.Arg]
     ) -> Tuple[Optional[cst.Arg], List[cst.Arg]]:
         # Returns a tuple of NamedTuple base object if it exists, and a list of non-NamedTuple bases
-        namedtuple_base: cst.Arg | None = None
+        namedtuple_base: Optional[cst.Arg] = None
         new_bases: List[cst.Arg] = []
         for base_class in original_bases:
             if QualifiedNameProvider.has_name(
diff --git a/src/fixit/rules/no_static_if_condition.py b/src/fixit/rules/no_static_if_condition.py
index 4893bf33..dd7fba4c 100644
--- a/src/fixit/rules/no_static_if_condition.py
+++ b/src/fixit/rules/no_static_if_condition.py
@@ -115,7 +115,7 @@ async def some_func() -> none:
     ]
 
     @classmethod
-    def _extract_static_bool(cls, node: cst.BaseExpression) -> bool | None:
+    def _extract_static_bool(cls, node: cst.BaseExpression) -> Optional[bool]:
         if m.matches(node, m.Call()):
             # cannot reason about function calls
             return None
diff --git a/src/fixit/rules/rewrite_to_comprehension.py b/src/fixit/rules/rewrite_to_comprehension.py
index c3a5787b..68e0953c 100644
--- a/src/fixit/rules/rewrite_to_comprehension.py
+++ b/src/fixit/rules/rewrite_to_comprehension.py
@@ -114,7 +114,7 @@ def visit_Call(self, node: cst.Call) -> None:
                 exp = cst.ensure_type(node.args[0].value, cst.ListComp)
                 message_formatter = UNNECESSARY_LIST_COMPREHENSION
 
-            replacement: Union[cst.Call, cst.BaseComp] | None = None
+            replacement: Optional[Union[cst.Call, cst.BaseComp]] = None
             if call_name == "list":
                 replacement = node.deep_replace(
                     node, cst.ListComp(elt=exp.elt, for_in=exp.for_in)
diff --git a/src/fixit/rules/use_fstring.py b/src/fixit/rules/use_fstring.py
index 605a1dc6..b56ebcf5 100644
--- a/src/fixit/rules/use_fstring.py
+++ b/src/fixit/rules/use_fstring.py
@@ -144,9 +144,9 @@ class UseFstring(LintRule):
         ),
     ]
 
-    _codegen: Callable[[cst.CSTNode], str] | None
+    _codegen: Optional[Callable[[cst.CSTNode], str]]
 
-    def visit_Module(self, node: cst.Module) -> bool | None:
+    def visit_Module(self, node: cst.Module) -> Optional[bool]:
         self._codegen = node.code_for_node
         return super().visit_Module(node)
 
diff --git a/src/fixit/tests/ftypes.py b/src/fixit/tests/ftypes.py
index 5467c65a..292aac01 100644
--- a/src/fixit/tests/ftypes.py
+++ b/src/fixit/tests/ftypes.py
@@ -106,7 +106,7 @@ def test_tags_parser(self) -> None:
 
     def test_tags_bool(self) -> None:
         Tags = ftypes.Tags
-        tags: str | None
+        tags: Optional[str]
 
         for tags in (
             "hello",
diff --git a/src/fixit/upgrade/deprecated_testcase_keywords.py b/src/fixit/upgrade/deprecated_testcase_keywords.py
index d82f7753..863f3a03 100755
--- a/src/fixit/upgrade/deprecated_testcase_keywords.py
+++ b/src/fixit/upgrade/deprecated_testcase_keywords.py
@@ -6,6 +6,8 @@
 
 from typing import Optional
 
+from fixit import Invalid, LintRule, Valid
+
 from libcst import (
     Arg,
     BaseExpression,
@@ -17,8 +19,6 @@
 )
 from libcst.metadata import QualifiedNameProvider
 
-from fixit import Invalid, LintRule, Valid
-
 
 class FixitDeprecatedTestCaseKeywords(LintRule):
     """
@@ -73,8 +73,8 @@ def visit_Call(self, node: Call) -> None:
                 self.convert_linecol_to_range(node)
 
     def convert_linecol_to_range(self, node: Call) -> None:
-        line: BaseExpression | None = None
-        col: BaseExpression | None = None
+        line: Optional[BaseExpression] = None
+        col: Optional[BaseExpression] = None
         index_to_remove = []
         for ind, arg in enumerate(node.args):
             if not arg.keyword:
diff --git a/src/fixit/util.py b/src/fixit/util.py
index a13f6dce..44ce518f 100644
--- a/src/fixit/util.py
+++ b/src/fixit/util.py
@@ -36,7 +36,7 @@ class capture(Generic[Yield, Send, Return]):
 
     def __init__(self, generator: Generator[Yield, Send, Return]) -> None:
         self.generator = generator
-        self._send: Send | None = None
+        self._send: Optional[Send] = None
         self._result: Union[Return, object] = Sentinel
 
     def __iter__(self) -> Generator[Yield, Send, Return]:

From 9536d24ef1e0884851a3496fb61e0ab9a6486b9d Mon Sep 17 00:00:00 2001
From: Danny Yang <yangdanny@fb.com>
Date: Tue, 19 Nov 2024 10:25:29 -0500
Subject: [PATCH 5/7] change fixit config to 3.8

---
 docs/guide/builtins.rst                           | 2 ++
 pyproject.toml                                    | 2 +-
 src/fixit/rules/deprecated_abc_import.py          | 4 ++--
 src/fixit/rules/no_namedtuple.py                  | 4 ++--
 src/fixit/upgrade/deprecated_testcase_keywords.py | 4 ++--
 5 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/docs/guide/builtins.rst b/docs/guide/builtins.rst
index b5bb342c..c588187d 100644
--- a/docs/guide/builtins.rst
+++ b/docs/guide/builtins.rst
@@ -728,6 +728,8 @@ Built-in Rules
     .. attribute:: AUTOFIX
         :type: Yes
 
+    .. attribute:: PYTHON_VERSION
+        :type: '>= 3.10'
 
     .. attribute:: VALID
 
diff --git a/pyproject.toml b/pyproject.toml
index 5eb0080c..f3689299 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -78,7 +78,7 @@ target-version = ["py38"]
 
 [tool.fixit]
 enable = ["fixit.rules"]
-python-version = "3.10"
+python-version = "3.8"
 formatter = "ufmt"
 
 [[tool.fixit.overrides]]
diff --git a/src/fixit/rules/deprecated_abc_import.py b/src/fixit/rules/deprecated_abc_import.py
index e9917cab..03a3607c 100644
--- a/src/fixit/rules/deprecated_abc_import.py
+++ b/src/fixit/rules/deprecated_abc_import.py
@@ -8,10 +8,10 @@
 import libcst as cst
 import libcst.matchers as m
 
-from fixit import Invalid, LintRule, Valid
-
 from libcst.metadata import ParentNodeProvider
 
+from fixit import Invalid, LintRule, Valid
+
 
 # The ABCs that have been moved to `collections.abc`
 ABCS = frozenset(
diff --git a/src/fixit/rules/no_namedtuple.py b/src/fixit/rules/no_namedtuple.py
index cae8d0cd..95854566 100644
--- a/src/fixit/rules/no_namedtuple.py
+++ b/src/fixit/rules/no_namedtuple.py
@@ -6,11 +6,11 @@
 from typing import List, Optional, Sequence, Tuple
 
 import libcst as cst
-
-from fixit import Invalid, LintRule, Valid
 from libcst import ensure_type, MaybeSentinel, parse_expression
 from libcst.metadata import QualifiedName, QualifiedNameProvider, QualifiedNameSource
 
+from fixit import Invalid, LintRule, Valid
+
 
 class NoNamedTuple(LintRule):
     """
diff --git a/src/fixit/upgrade/deprecated_testcase_keywords.py b/src/fixit/upgrade/deprecated_testcase_keywords.py
index 863f3a03..f38e4599 100755
--- a/src/fixit/upgrade/deprecated_testcase_keywords.py
+++ b/src/fixit/upgrade/deprecated_testcase_keywords.py
@@ -6,8 +6,6 @@
 
 from typing import Optional
 
-from fixit import Invalid, LintRule, Valid
-
 from libcst import (
     Arg,
     BaseExpression,
@@ -19,6 +17,8 @@
 )
 from libcst.metadata import QualifiedNameProvider
 
+from fixit import Invalid, LintRule, Valid
+
 
 class FixitDeprecatedTestCaseKeywords(LintRule):
     """

From 8de94535df9079f9cef335d0f519d9096d2da28a Mon Sep 17 00:00:00 2001
From: Danny Yang <yangdanny97@users.noreply.github.com>
Date: Wed, 5 Nov 2025 00:43:42 -0500
Subject: [PATCH 6/7] Update
 src/fixit/rules/replace_optional_type_annotation.py

Co-authored-by: Bowie Chen <543091+bowiechen@users.noreply.github.com>
---
 src/fixit/rules/replace_optional_type_annotation.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/fixit/rules/replace_optional_type_annotation.py b/src/fixit/rules/replace_optional_type_annotation.py
index 8f4a2fa9..248ecccc 100644
--- a/src/fixit/rules/replace_optional_type_annotation.py
+++ b/src/fixit/rules/replace_optional_type_annotation.py
@@ -93,7 +93,7 @@ def leave_Annotation(self, original_node: cst.Annotation) -> None:
                     nones += 1
                 else:
                     indexes.append(s.slice)
-            if not (nones > 1) and len(indexes) == 1:
+            if nones <= 1 and len(indexes) == 1:
                 inner_type = cst.ensure_type(indexes[0], cst.Index).value
                 replacement = original_node.with_changes(
                     annotation=cst.BinaryOperation(

From f8225e0d07a6cb31646f8bfca03a94a71c3aa829 Mon Sep 17 00:00:00 2001
From: Danny Yang <yangdanny97@users.noreply.github.com>
Date: Wed, 5 Nov 2025 00:44:01 -0500
Subject: [PATCH 7/7] Update pyproject.toml

Co-authored-by: Bowie Chen <543091+bowiechen@users.noreply.github.com>
---
 pyproject.toml | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/pyproject.toml b/pyproject.toml
index f3689299..53850f81 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -79,7 +79,12 @@ target-version = ["py38"]
 [tool.fixit]
 enable = ["fixit.rules"]
 python-version = "3.8"
-formatter = "ufmt"
+[tool.black]
+target-version = ["py310"]
+
+[tool.fixit]
+enable = ["fixit.rules"]
+python-version = "3.10"
 
 [[tool.fixit.overrides]]
 path = "examples"