Remove parentheses around some walrus operators (#6173)

## Summary

Closes #5781

## Test Plan

Added cases to
`crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/named_expr.py`
one-by-one and adjusted the condition as needed.

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/named_expr.py

@@ -11,3 +11,28 @@
 y0 = (y1 := f(x))
 
 f(x:=y, z=True)
+
+assert (x := 1)
+
+
+def f():
+    return (x := 1)
+
+
+for x in (y := [1, 2, 3]):
+    pass
+
+async for x in (y := [1, 2, 3]):
+    pass
+
+del (x := 1)
+
+try:
+    pass
+except (e := Exception):
+    if x := 1:
+        pass
+
+(x := 1)
+
+(x := 1) + (y := 2)

crates/ruff_python_formatter/src/expression/expr_named_expr.rs

@@ -32,11 +32,25 @@ impl FormatNodeRule<ExprNamedExpr> for FormatExprNamedExpr {
 impl NeedsParentheses for ExprNamedExpr {
     fn needs_parentheses(
         &self,
-        _parent: AnyNodeRef,
+        parent: AnyNodeRef,
         _context: &PyFormatContext,
     ) -> OptionalParentheses {
         // Unlike tuples, named expression parentheses are not part of the range even when
         // mandatory. See [PEP 572](https://peps.python.org/pep-0572/) for details.
-        OptionalParentheses::Always
+        if parent.is_stmt_ann_assign()
+            || parent.is_stmt_assign()
+            || parent.is_stmt_aug_assign()
+            || parent.is_stmt_assert()
+            || parent.is_stmt_return()
+            || parent.is_except_handler_except_handler()
+            || parent.is_with_item()
+            || parent.is_stmt_delete()
+            || parent.is_stmt_for()
+            || parent.is_stmt_async_for()
+        {
+            OptionalParentheses::Always
+        } else {
+            OptionalParentheses::Never
+        }
     }
 }

crates/ruff_python_formatter/tests/snapshots/black_compatibility@py_39__python39.py.snap

@@ -32,19 +32,6 @@ def f():
  @relaxed_decorator[0]
  def f():
      ...
-@@ -13,8 +12,10 @@
-     ...
- 
- 
--@extremely_long_variable_name_that_doesnt_fit := complex.expression(
--    with_long="arguments_value_that_wont_fit_at_the_end_of_the_line"
-+@(
-+    extremely_long_variable_name_that_doesnt_fit := complex.expression(
-+        with_long="arguments_value_that_wont_fit_at_the_end_of_the_line"
-+    )
- )
- def f():
-     ...
 ```
 
 ## Ruff Output
@@ -64,10 +51,8 @@ def f():
     ...
 
 
-@(
-    extremely_long_variable_name_that_doesnt_fit := complex.expression(
-        with_long="arguments_value_that_wont_fit_at_the_end_of_the_line"
-    )
+@extremely_long_variable_name_that_doesnt_fit := complex.expression(
+    with_long="arguments_value_that_wont_fit_at_the_end_of_the_line"
 )
 def f():
     ...

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

@@ -17,6 +17,31 @@ if (
 y0 = (y1 := f(x))
 
 f(x:=y, z=True)
+
+assert (x := 1)
+
+
+def f():
+    return (x := 1)
+
+
+for x in (y := [1, 2, 3]):
+    pass
+
+async for x in (y := [1, 2, 3]):
+    pass
+
+del (x := 1)
+
+try:
+    pass
+except (e := Exception):
+    if x := 1:
+        pass
+
+(x := 1)
+
+(x := 1) + (y := 2)
 ```
 
 ## Output
@@ -32,6 +57,31 @@ if (
 y0 = (y1 := f(x))
 
 f(x := y, z=True)
+
+assert (x := 1)
+
+
+def f():
+    return (x := 1)
+
+
+for x in (y := [1, 2, 3]):
+    pass
+
+async for x in (y := [1, 2, 3]):
+    pass
+
+del (x := 1)
+
+try:
+    pass
+except (e := Exception):
+    if x := 1:
+        pass
+
+(x := 1)
+
+(x := 1) + (y := 2)
 ```