Improve with statement comment handling and expression breaking (#6621)

## Summary

The motivating code here was:

```python
with test as (
    # test
foo):
    pass
```

Which we were formatting as:

```python
with test as
# test
(foo):
    pass
```

`with` statements are oddly difficult. This PR makes a bunch of subtle
modifications and adds a more extensive test suite. For example, we now
only preserve parentheses if there's more than one `WithItem` _or_ a
trailing comma; before, we always preserved.

Our formatting is_not_ the same as Black, but here's a diff of our
formatted code vs. Black's for the `with.py` test suite. The primary
difference is that we tend to break parentheses when they contain
comments rather than move them to the end of the life (this is a
consistent difference that we make across the codebase):

```diff
diff --git a/crates/ruff_python_formatter/foo.py b/crates/ruff_python_formatter/foo.py
index 85e761080..31625c876 100644
--- a/crates/ruff_python_formatter/foo.py
+++ b/crates/ruff_python_formatter/foo.py
@@ -1,6 +1,4 @@
-with (
-    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
-), aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa:
+with aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa, aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa:
     ...
     # trailing
 
@@ -16,28 +14,33 @@ with (
     # trailing
 
 
-with a, b:  # a  # comma  # c  # colon
+with (
+    a,  # a  # comma
+    b,  # c
+):  # colon
     ...
 
 
 with (
-    a as  # a  # as
-    # own line
-    b,  # b  # comma
+    a as (  # a  # as
+        # own line
+        b
+    ),  # b  # comma
     c,  # c
 ):  # colon
     ...  # body
     # body trailing own
 
-with (
-    a as  # a  # as
+with a as (  # a  # as
     # own line
-    bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb  # b
-):
+    bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
+):  # b
     pass
 
 
-with (a,):  # magic trailing comma
+with (
+    a,
+):  # magic trailing comma
     ...
 
 
@@ -47,6 +50,7 @@ with a:  # should remove brackets
 with aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb as c:
     ...
 
+
 with (
     # leading comment
     a
@@ -74,8 +78,7 @@ with (
 with (
     a  # trailing same line comment
     # trailing own line comment
-    as b
-):
+) as b:
     ...
 
 with (
@@ -87,7 +90,9 @@ with (
 with (
     a
     # trailing own line comment
-) as b:  # trailing as same line comment  # trailing b same line comment
+) as (  # trailing as same line comment
+    b
+):  # trailing b same line comment
     ...
 
 with (
@@ -124,18 +129,24 @@ with (  # comment
     ...
 
 with (  # outer comment
-    CtxManager1() as example1,  # inner comment
+    (  # inner comment
+        CtxManager1()
+    ) as example1,
     CtxManager2() as example2,
     CtxManager3() as example3,
 ):
     ...
 
-with CtxManager() as example:  # outer comment
+with (  # outer comment
+    CtxManager()
+) as example:
     ...
 
 with (  # outer comment
     CtxManager()
-) as example, CtxManager2() as example2:  # inner comment
+) as example, (  # inner comment
+    CtxManager2()
+) as example2:
     ...
 
 with (  # outer comment
@@ -145,7 +156,9 @@ with (  # outer comment
     ...
 
 with (  # outer comment
-    (CtxManager1()),  # inner comment
+    (  # inner comment
+        CtxManager1()
+    ),
     CtxManager2(),
 ) as example:
     ...
@@ -179,7 +192,9 @@ with (
 ):
     pass
 
-with a as (b):  # foo
+with a as (  # foo
+    b
+):
     pass
 
 with f(
@@ -209,17 +224,13 @@ with f(
 ) as b, c as d:
     pass
 
-with (
-    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
-) as b:
+with aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb as b:
     pass
 
 with aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb as b:
     pass
 
-with (
-    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
-) as b, c as d:
+with aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb as b, c as d:
     pass
 
 with (
@@ -230,6 +241,8 @@ with (
     pass
 
 with (
-    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
-) as b, c as d:
+    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+    + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb as b,
+    c as d,
+):
     pass
```

Closes https://github.com/astral-sh/ruff/issues/6600.
## Test Plan

Before:

| project      | similarity index |
|--------------|------------------|
| cpython      | 0.75473          |
| django       | 0.99804          |
| transformers | 0.99618          |
| twine        | 0.99876          |
| typeshed     | 0.74292          |
| warehouse    | 0.99601          |
| zulip        | 0.99727          |

After:

| project      | similarity index |
|--------------|------------------|
| cpython      | 0.75473          |
| django       | 0.99804          |
| transformers | 0.99618          |
| twine        | 0.99876          |
| typeshed     | 0.74292          |
| warehouse    | 0.99601          |
| zulip        | 0.99727          |

`cargo test`

crates/ruff_python_formatter/src/statement/stmt_with.rs

@@ -4,13 +4,15 @@ use ruff_python_ast::{Ranged, StmtWith};
 use ruff_python_trivia::{SimpleTokenKind, SimpleTokenizer};
 use ruff_text_size::TextRange;
 
+use crate::builders::parenthesize_if_expands;
 use crate::comments::SourceComment;
 use crate::expression::parentheses::{
     in_parentheses_only_soft_line_break_or_space, optional_parentheses, parenthesized,
 };
+use crate::other::commas;
 use crate::prelude::*;
 use crate::statement::clause::{clause_header, ClauseHeader};
-use crate::FormatNodeRule;
+use crate::{FormatNodeRule, PyFormatOptions};
 
 #[derive(Default)]
 pub struct FormatStmtWith;
@@ -66,8 +68,8 @@ impl FormatNodeRule<StmtWith> for FormatStmtWith {
                             parenthesized("(", &joined, ")")
                                 .with_dangling_comments(parenthesized_comments)
                                 .fmt(f)?;
-                        } else if are_with_items_parenthesized(item, f.context())? {
-                            optional_parentheses(&format_with(|f| {
+                        } else if should_parenthesize(item, f.options(), f.context())? {
+                            parenthesize_if_expands(&format_with(|f| {
                                 let mut joiner =
                                     f.join_comma_separated(item.body.first().unwrap().start());
 
@@ -81,6 +83,16 @@ impl FormatNodeRule<StmtWith> for FormatStmtWith {
                                 joiner.finish()
                             }))
                             .fmt(f)?;
+                        } else if let [item] = item.items.as_slice() {
+                            // This is similar to `maybe_parenthesize_expression`, but we're not dealing with an
+                            // expression here, it's a `WithItem`.
+                            if comments.has_leading_comments(item)
+                                || comments.has_trailing_own_line_comments(item)
+                            {
+                                optional_parentheses(&item.format()).fmt(f)?;
+                            } else {
+                                item.format().fmt(f)?;
+                            }
                         } else {
                             f.join_with(format_args![text(","), space()])
                                 .entries(item.items.iter().formatted())
@@ -105,14 +117,50 @@ impl FormatNodeRule<StmtWith> for FormatStmtWith {
     }
 }
 
-fn are_with_items_parenthesized(with: &StmtWith, context: &PyFormatContext) -> FormatResult<bool> {
-    let first_with_item = with
-        .items
-        .first()
-        .ok_or(FormatError::syntax_error("Expected at least one with item"))?;
-    let before_first_with_item = TextRange::new(with.start(), first_with_item.start());
+/// Returns `true` if the `with` items should be parenthesized, if at least one item expands.
+///
+/// Black parenthesizes `with` items if there's more than one item and they're already
+/// parenthesized, _or_ there's a single item with a trailing comma.
+fn should_parenthesize(
+    with: &StmtWith,
+    options: &PyFormatOptions,
+    context: &PyFormatContext,
+) -> FormatResult<bool> {
+    if has_magic_trailing_comma(with, options, context) {
+        return Ok(true);
+    }
 
-    let mut tokenizer = SimpleTokenizer::new(context.source(), before_first_with_item)
+    if are_with_items_parenthesized(with, context)? {
+        return Ok(true);
+    }
+
+    Ok(false)
+}
+
+fn has_magic_trailing_comma(
+    with: &StmtWith,
+    options: &PyFormatOptions,
+    context: &PyFormatContext,
+) -> bool {
+    let Some(last_item) = with.items.last() else {
+        return false;
+    };
+
+    commas::has_magic_trailing_comma(
+        TextRange::new(last_item.end(), with.end()),
+        options,
+        context,
+    )
+}
+
+fn are_with_items_parenthesized(with: &StmtWith, context: &PyFormatContext) -> FormatResult<bool> {
+    let [first_item, _, ..] = with.items.as_slice() else {
+        return Ok(false);
+    };
+
+    let before_first_item = TextRange::new(with.start(), first_item.start());
+
+    let mut tokenizer = SimpleTokenizer::new(context.source(), before_first_item)
         .skip_trivia()
         .skip_while(|t| t.kind() == SimpleTokenKind::Async);