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

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## 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`
This commit is contained in:
Charlie Marsh
2023-08-17 23:30:38 -04:00
committed by GitHub
parent 26bba11be6
commit 1811312722
12 changed files with 472 additions and 98 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
crates/ruff_python_formatter/src/comments/format.rs
View File

@@ -247,12 +247,11 @@ pub(crate) struct FormatDanglingOpenParenthesisComments<'a> {
impl Format<PyFormatContext<'_>> for FormatDanglingOpenParenthesisComments<'_> {
fn fmt(&self, f: &mut Formatter<PyFormatContext>) -> FormatResult<()> {
let mut comments = self
for comment in self
.comments
.iter()
.filter(|comment| comment.is_unformatted());
if let Some(comment) = comments.next() {
.filter(|comment| comment.is_unformatted())
{
debug_assert!(
comment.line_position().is_end_of_line(),
"Expected dangling comment to be at the end of the line"
@@ -261,16 +260,11 @@ impl Format<PyFormatContext<'_>> for FormatDanglingOpenParenthesisComments<'_> {
write!(
f,
[
line_suffix(&format_args![space(), space(), format_comment(comment)]),
line_suffix(&format_args!(space(), space(), format_comment(comment))),
expand_parent()
]
)?;
comment.mark_formatted();
debug_assert!(
comments.next().is_none(),
"Expected at most one dangling comment"
);
}
Ok(())

5
crates/ruff_python_formatter/src/comments/placement.rs
View File

@@ -1130,9 +1130,8 @@ fn handle_with_item_comment<'a>(
if comment.end() < as_token.start() {
// If before the `as` keyword, then it must be a trailing comment of the context expression.
CommentPlacement::trailing(context_expr, comment)
}
// Trailing end of line comment coming after the `as` keyword`.
else if comment.line_position().is_end_of_line() {
} else if comment.line_position().is_end_of_line() {
// Trailing end of line comment coming after the `as` keyword`.
CommentPlacement::dangling(comment.enclosing_node(), comment)
} else {
CommentPlacement::leading(optional_vars, comment)