Avoid extra parentheses for long match patterns with as captures (#21176)

Summary
--

This PR fixes #17796 by taking the approach mentioned in
https://github.com/astral-sh/ruff/issues/17796#issuecomment-2847943862
of simply recursing into the `MatchAs` patterns when checking if we need
parentheses. This allows us to reuse the parentheses in the inner
pattern before also breaking the `MatchAs` pattern itself:

```diff
 match class_pattern:
     case Class(xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx) as capture:
         pass
-    case (
-        Class(xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx) as capture
-    ):
+    case Class(
+        xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+    ) as capture:
         pass
-    case (
-        Class(
-            xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
-        ) as capture
-    ):
+    case Class(
+        xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+    ) as capture:
         pass
     case (
         Class(
@@ -685,13 +683,11 @@
 match sequence_pattern_brackets:
     case [xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx] as capture:
         pass
-    case (
-        [xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx] as capture
-    ):
+    case [
+        xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+    ] as capture:
         pass
-    case (
-        [
-            xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
-        ] as capture
-    ):
+    case [
+        xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+    ] as capture:
         pass
```

I haven't really resolved the question of whether or not it's okay
always to recurse, but I'm hoping the ecosystem check on this PR might
shed some light on that.

Test Plan
--

New tests based on the issue and then reviewing the ecosystem check here

crates/ruff_python_formatter/src/pattern/mod.rs

@@ -1,5 +1,5 @@
 use ruff_formatter::{FormatOwnedWithRule, FormatRefWithRule, FormatRule, FormatRuleWithOptions};
-use ruff_python_ast::{AnyNodeRef, Expr};
+use ruff_python_ast::{AnyNodeRef, Expr, PatternMatchAs};
 use ruff_python_ast::{MatchCase, Pattern};
 use ruff_python_trivia::CommentRanges;
 use ruff_python_trivia::{
@@ -14,6 +14,7 @@ use crate::expression::parentheses::{
     NeedsParentheses, OptionalParentheses, Parentheses, optional_parentheses, parenthesized,
 };
 use crate::prelude::*;
+use crate::preview::is_avoid_parens_for_long_as_captures_enabled;
 
 pub(crate) mod pattern_arguments;
 pub(crate) mod pattern_keyword;
@@ -242,8 +243,14 @@ pub(crate) fn can_pattern_omit_optional_parentheses(
                 Pattern::MatchValue(_)
                 | Pattern::MatchSingleton(_)
                 | Pattern::MatchStar(_)
-                | Pattern::MatchAs(_)
                 | Pattern::MatchOr(_) => false,
+                Pattern::MatchAs(PatternMatchAs { pattern, .. }) => match pattern {
+                    Some(pattern) => {
+                        is_avoid_parens_for_long_as_captures_enabled(context)
+                            && has_parentheses_and_is_non_empty(pattern, context)
+                    }
+                    None => false,
+                },
                 Pattern::MatchSequence(sequence) => {
                     !sequence.patterns.is_empty() || context.comments().has_dangling(pattern)
                 }
@@ -318,7 +325,14 @@ impl<'a> CanOmitOptionalParenthesesVisitor<'a> {
                 // The pattern doesn't start with a parentheses pattern, but with the class's identifier.
                 self.first.set_if_none(First::Token);
             }
-            Pattern::MatchStar(_) | Pattern::MatchSingleton(_) | Pattern::MatchAs(_) => {}
+            Pattern::MatchAs(PatternMatchAs { pattern, .. }) => {
+                if let Some(pattern) = pattern
+                    && is_avoid_parens_for_long_as_captures_enabled(context)
+                {
+                    self.visit_sub_pattern(pattern, context);
+                }
+            }
+            Pattern::MatchStar(_) | Pattern::MatchSingleton(_) => {}
             Pattern::MatchOr(or_pattern) => {
                 self.update_max_precedence(
                     OperatorPrecedence::Or,

crates/ruff_python_formatter/src/preview.rs

@@ -43,3 +43,12 @@ pub(crate) const fn is_remove_parens_around_except_types_enabled(
 pub(crate) const fn is_allow_newline_after_block_open_enabled(context: &PyFormatContext) -> bool {
     context.is_preview()
 }
+
+/// Returns `true` if the
+/// [`avoid_parens_for_long_as_captures`](https://github.com/astral-sh/ruff/pull/21176) preview
+/// style is enabled.
+pub(crate) const fn is_avoid_parens_for_long_as_captures_enabled(
+    context: &PyFormatContext,
+) -> bool {
+    context.is_preview()
+}