Fix unstable with-items formatting

crates/ruff_python_formatter/resources/test/fixtures/ruff/statement/with.py

@@ -304,6 +304,17 @@
     with anyio.CancelScope(shield=True) if get_running_loop() else contextlib.nullcontext():
         pass
 
+if True:
+    with anyio.CancelScope(shield=True) if get_running_loop() else contextlib.nullcontext() as c:
+        pass
 
 with Child(aaaaaaaaa, bbbbbbbbbbbbbbb, cccccc), Document(aaaaa, bbbbbbbbbb, ddddddddddddd):
     pass
+
+# Regression test for https://github.com/astral-sh/ruff/issues/10267
+with (
+    open(
+        "/etc/hosts"  # This is an incredibly long comment that has been replaced for sanitization
+    )
+):
+    pass

crates/ruff_python_formatter/resources/test/fixtures/ruff/statement/with_39.py

@@ -85,4 +85,8 @@
 with (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb as c):
     pass
 
-
+with (  # outer comment
+    CtxManager1(),
+    CtxManager2(),
+):
+    pass

crates/ruff_python_formatter/src/other/with_item.rs

@@ -22,6 +22,23 @@ pub enum WithItemLayout {
     /// This layout is used independent of the target version.
     SingleParenthesizedContextManager,
 
+    /// A with item that is the `with`s only context manager and it has no `target`.
+    ///
+    /// ```python
+    /// with a + b:
+    ///     ...
+    /// ```
+    ///
+    /// In this case, use [`maybe_parenthesize_expression`] to get the same formatting as when
+    /// formatting any other statement with a clause header.
+    ///
+    /// This layout is only used for Python 3.9+.
+    ///
+    /// Be careful that [`Self::SingleParenthesizedContextManager`] and this layout are compatible because
+    /// removing optional parentheses or adding parentheses will make the formatter pick the opposite layout
+    /// the second time the file gets formatted.
+    SingleWithoutTarget,
+
     /// This layout is used when the target python version doesn't support parenthesized context managers and
     /// it's either a single, unparenthesized with item or multiple items.
     ///
@@ -106,7 +123,8 @@ impl FormatNodeRule<WithItem> for FormatWithItem {
                 }
             }
 
-            WithItemLayout::SingleParenthesizedContextManager => {
+            WithItemLayout::SingleParenthesizedContextManager
+            | WithItemLayout::SingleWithoutTarget => {
                 write!(
                     f,
                     [maybe_parenthesize_expression(

crates/ruff_python_formatter/src/statement/stmt_with.rs

@@ -73,6 +73,11 @@ impl FormatNodeRule<StmtWith> for FormatStmtWith {
                                 optional_parentheses(&single.format()).fmt(f)
                             }
 
+                            WithItemsLayout::SingleWithoutTarget(single) => single
+                                .format()
+                                .with_options(WithItemLayout::SingleWithoutTarget)
+                                .fmt(f),
+
                             WithItemsLayout::SingleParenthesizedContextManager(single) => single
                                 .format()
                                 .with_options(WithItemLayout::SingleParenthesizedContextManager)
@@ -150,15 +155,35 @@ enum WithItemsLayout<'a> {
     ///
     /// In this case, prefer keeping the parentheses around the context expression instead of parenthesizing the entire
     /// with item.
+    ///
+    /// Ensure that this layout is compatible with [`Self::SingleWithoutTarget`] because removing the parentheses
+    /// results in the formatter taking that layout when formatting the file again
     SingleParenthesizedContextManager(&'a WithItem),
 
+    /// The with statement's only item has no target.
+    ///
+    /// ```python
+    /// with a + b:
+    ///     ...
+    /// ```
+    ///
+    /// In this case, use [`maybe_parenthesize_expression`] to format the context expression
+    /// to get the exact same formatting as when formatting an expression in any other clause header.
+    ///
+    /// Only used for Python 3.9+
+    ///
+    /// Be careful that [`Self::SingleParenthesizedContextManager`] and this layout are compatible because
+    /// adding parentheses around a [`WithItem`] will result in the context expression being parenthesized in
+    /// the next formatting pass.
+    SingleWithoutTarget(&'a WithItem),
+
     /// It's a single with item with a target. Use the optional parentheses layout (see [`optional_parentheses`])
     /// to mimic the `maybe_parenthesize_expression` behavior.
     ///
     /// ```python
     /// with (
-    ///     a + b
-    /// ) as b:
+    ///     a + b as b
+    /// ):
     ///     ...
     /// ```
     ///
@@ -275,7 +300,9 @@ impl<'a> WithItemsLayout<'a> {
 
         Ok(match with.items.as_slice() {
             [single] => {
-                if can_omit_optional_parentheses(&single.context_expr, context) {
+                if single.optional_vars.is_none() {
+                    Self::SingleWithoutTarget(single)
+                } else if can_omit_optional_parentheses(&single.context_expr, context) {
                     Self::SingleWithTarget(single)
                 } else {
                     Self::ParenthesizeIfExpands

crates/ruff_python_formatter/tests/snapshots/format@statement__with.py.snap

@@ -310,9 +310,20 @@ if True:
     with anyio.CancelScope(shield=True) if get_running_loop() else contextlib.nullcontext():
         pass
 
+if True:
+    with anyio.CancelScope(shield=True) if get_running_loop() else contextlib.nullcontext() as c:
+        pass
 
 with Child(aaaaaaaaa, bbbbbbbbbbbbbbb, cccccc), Document(aaaaa, bbbbbbbbbb, ddddddddddddd):
     pass
+
+# Regression test for https://github.com/astral-sh/ruff/issues/10267
+with (
+    open(
+        "/etc/hosts"  # This is an incredibly long comment that has been replaced for sanitization
+    )
+):
+    pass
 ```
 
 ## Outputs
@@ -661,11 +672,22 @@ if True:
     ) if get_running_loop() else contextlib.nullcontext():
         pass
 
+if True:
+    with anyio.CancelScope(
+        shield=True
+    ) if get_running_loop() else contextlib.nullcontext() as c:
+        pass
 
 with Child(aaaaaaaaa, bbbbbbbbbbbbbbb, cccccc), Document(
     aaaaa, bbbbbbbbbb, ddddddddddddd
 ):
     pass
+
+# Regression test for https://github.com/astral-sh/ruff/issues/10267
+with open(
+    "/etc/hosts"  # This is an incredibly long comment that has been replaced for sanitization
+):
+    pass
 ```
 
 
@@ -1052,13 +1074,23 @@ if True:
     ):
         pass
 
+if True:
+    with (
+        anyio.CancelScope(shield=True)
+        if get_running_loop()
+        else contextlib.nullcontext() as c
+    ):
+        pass
 
 with (
     Child(aaaaaaaaa, bbbbbbbbbbbbbbb, cccccc),
     Document(aaaaa, bbbbbbbbbb, ddddddddddddd),
 ):
     pass
-```
-
-
 
+# Regression test for https://github.com/astral-sh/ruff/issues/10267
+with open(
+    "/etc/hosts"  # This is an incredibly long comment that has been replaced for sanitization
+):
+    pass
+```

crates/ruff_python_formatter/tests/snapshots/format@statement__with_39.py.snap

@@ -91,7 +91,11 @@ if True:
 with (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb as c):
     pass
 
-
+with (  # outer comment
+    CtxManager1(),
+    CtxManager2(),
+):
+    pass
 ```
 
 ## Outputs
@@ -217,7 +221,10 @@ with (
     aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb as c
 ):
     pass
-```
-
-
 
+with (  # outer comment
+    CtxManager1(),
+    CtxManager2(),
+):
+    pass
+```