Prefer breaking return-type over parameters

crates/ruff_python_formatter/src/other/parameters.rs

@@ -9,8 +9,9 @@ use crate::comments::{
     trailing_comments, SourceComment,
 };
 use crate::context::{NodeLevel, WithNodeLevel};
-use crate::expression::parentheses::empty_parenthesized;
+use crate::expression::parentheses::{empty_parenthesized, parenthesized};
 use crate::prelude::*;
+use crate::preview::is_empty_parameters_no_unnecessary_parentheses_around_return_value_enabled;
 
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Default)]
 pub enum ParametersParentheses {
@@ -249,30 +250,46 @@ impl FormatNodeRule<Parameters> for FormatParameters {
         } else if num_parameters == 1 && posonlyargs.is_empty() && kwonlyargs.is_empty() {
             // If we have a single argument, avoid the inner group, to ensure that we insert a
             // trailing comma if the outer group breaks.
-            let mut f = WithNodeLevel::new(NodeLevel::ParenthesizedExpression, f);
-            write!(
-                f,
-                [
-                    token("("),
-                    dangling_open_parenthesis_comments(parenthesis_dangling),
-                    soft_block_indent(&format_inner),
-                    token(")")
-                ]
-            )
+            if is_empty_parameters_no_unnecessary_parentheses_around_return_value_enabled(
+                f.context(),
+            ) {
+                parenthesized("(", &format_inner, ")")
+                    .with_dangling_comments(parenthesis_dangling)
+                    .fmt(f)
+            } else {
+                let mut f = WithNodeLevel::new(NodeLevel::ParenthesizedExpression, f);
+                write!(
+                    f,
+                    [
+                        token("("),
+                        dangling_open_parenthesis_comments(parenthesis_dangling),
+                        soft_block_indent(&format_inner),
+                        token(")")
+                    ]
+                )
+            }
         } else {
-            // Intentionally avoid `parenthesized`, which groups the entire formatted contents.
-            // We want parameters to be grouped alongside return types, one level up, so we
-            // format them "inline" here.
-            let mut f = WithNodeLevel::new(NodeLevel::ParenthesizedExpression, f);
-            write!(
-                f,
-                [
-                    token("("),
-                    dangling_open_parenthesis_comments(parenthesis_dangling),
-                    soft_block_indent(&group(&format_inner)),
-                    token(")")
-                ]
-            )
+            if is_empty_parameters_no_unnecessary_parentheses_around_return_value_enabled(
+                f.context(),
+            ) {
+                parenthesized("(", &group(&format_inner), ")")
+                    .with_dangling_comments(parenthesis_dangling)
+                    .fmt(f)
+            } else {
+                // Intentionally avoid `parenthesized`, which groups the entire formatted contents.
+                // We want parameters to be grouped alongside return types, one level up, so we
+                // format them "inline" here.
+                let mut f = WithNodeLevel::new(NodeLevel::ParenthesizedExpression, f);
+                write!(
+                    f,
+                    [
+                        token("("),
+                        dangling_open_parenthesis_comments(parenthesis_dangling),
+                        soft_block_indent(&group(&format_inner)),
+                        token(")")
+                    ]
+                )
+            }
         }
     }
 }

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

@@ -1,6 +1,7 @@
 ---
 source: crates/ruff_python_formatter/tests/fixtures.rs
 input_file: crates/ruff_python_formatter/resources/test/fixtures/black/cases/funcdef_return_type_trailing_comma.py
+snapshot_kind: text
 ---
 ## Input
 
@@ -155,31 +156,38 @@ def SimplePyFn(
 ```diff
 --- Black
 +++ Ruff
-@@ -36,7 +36,9 @@
+@@ -62,9 +62,9 @@
  
+ # long function definition, return type is longer
+ # this should maybe split on rhs?
+-def aaaaaaaaaaaaaaaaa(
+-    bbbbbbbbbbbbbbbbbb,
+-) -> list[Ccccccccccccccccccccccccccccccccccccccccccccccccccc, Dddddd]: ...
++def aaaaaaaaaaaaaaaaa(bbbbbbbbbbbbbbbbbb) -> list[
++    Ccccccccccccccccccccccccccccccccccccccccccccccccccc, Dddddd
++]: ...
  
- # magic trailing comma in return type, params
--def foo(a: A, b: B) -> list[
-+def foo(
-+    a: A, b: B
-+) -> list[
-     p,
-     q,
- ]:
-@@ -93,7 +95,11 @@
+ 
+ # long return type, no param list
+@@ -93,13 +93,13 @@
  
  
  # unskippable type hint (??)
 -def foo(a) -> list[aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa, aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa]:  # type: ignore
-+def foo(
-+    a,
-+) -> list[
++def foo(a) -> list[
 +    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa, aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
 +]:  # type: ignore
      pass
  
  
-@@ -112,7 +118,13 @@
+-def foo(
+-    a,
+-) -> list[
++def foo(a) -> list[
+     aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa, aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+ ]:  # abpedeifnore
+     pass
+@@ -112,7 +112,13 @@
  
  
  # don't lose any comments (no magic)
@@ -194,7 +202,7 @@ def SimplePyFn(
      ...  # 6
  
  
-@@ -120,12 +132,18 @@
+@@ -120,12 +126,18 @@
  def foo(  # 1
      a,  # 2
      b,
@@ -258,9 +266,7 @@ def a() -> tuple[
 
 
 # magic trailing comma in return type, params
-def foo(
-    a: A, b: B
-) -> list[
+def foo(a: A, b: B) -> list[
     p,
     q,
 ]:
@@ -286,9 +292,9 @@ def aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(
 
 # long function definition, return type is longer
 # this should maybe split on rhs?
-def aaaaaaaaaaaaaaaaa(
-    bbbbbbbbbbbbbbbbbb,
-) -> list[Ccccccccccccccccccccccccccccccccccccccccccccccccccc, Dddddd]: ...
+def aaaaaaaaaaaaaaaaa(bbbbbbbbbbbbbbbbbb) -> list[
+    Ccccccccccccccccccccccccccccccccccccccccccccccccccc, Dddddd
+]: ...
 
 
 # long return type, no param list
@@ -317,17 +323,13 @@ def thiiiiiiiiiiiiiiiiiis_iiiiiiiiiiiiiiiiiiiiiiiiiiiiiis_veeeeeeeeeeeeeeeeeeeee
 
 
 # unskippable type hint (??)
-def foo(
-    a,
-) -> list[
+def foo(a) -> list[
     aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa, aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
 ]:  # type: ignore
     pass
 
 
-def foo(
-    a,
-) -> list[
+def foo(a) -> list[
     aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa, aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
 ]:  # abpedeifnore
     pass

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

@@ -0,0 +1,73 @@
+---
+source: crates/ruff_python_formatter/tests/fixtures.rs
+input_file: crates/ruff_python_formatter/resources/test/fixtures/black/cases/typed_params_trailing_comma.py
+snapshot_kind: text
+---
+## Input
+
+```python
+def long_function_name_goes_here(
+    x: Callable[List[int]]
+) -> Union[List[int], float, str, bytes, Tuple[int]]:
+    pass
+
+
+def long_function_name_goes_here(
+    x: Callable[[str, Any], int]
+) -> Union[List[int], float, str, bytes, Tuple[int]]:
+    pass
+```
+
+## Black Differences
+
+```diff
+--- Black
++++ Ruff
+@@ -1,10 +1,10 @@
+-def long_function_name_goes_here(
+-    x: Callable[List[int]],
+-) -> Union[List[int], float, str, bytes, Tuple[int]]:
++def long_function_name_goes_here(x: Callable[List[int]]) -> Union[
++    List[int], float, str, bytes, Tuple[int]
++]:
+     pass
+ 
+ 
+-def long_function_name_goes_here(
+-    x: Callable[[str, Any], int],
+-) -> Union[List[int], float, str, bytes, Tuple[int]]:
++def long_function_name_goes_here(x: Callable[[str, Any], int]) -> Union[
++    List[int], float, str, bytes, Tuple[int]
++]:
+     pass
+```
+
+## Ruff Output
+
+```python
+def long_function_name_goes_here(x: Callable[List[int]]) -> Union[
+    List[int], float, str, bytes, Tuple[int]
+]:
+    pass
+
+
+def long_function_name_goes_here(x: Callable[[str, Any], int]) -> Union[
+    List[int], float, str, bytes, Tuple[int]
+]:
+    pass
+```
+
+## Black Output
+
+```python
+def long_function_name_goes_here(
+    x: Callable[List[int]],
+) -> Union[List[int], float, str, bytes, Tuple[int]]:
+    pass
+
+
+def long_function_name_goes_here(
+    x: Callable[[str, Any], int],
+) -> Union[List[int], float, str, bytes, Tuple[int]]:
+    pass
+```

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

@@ -1,6 +1,7 @@
 ---
 source: crates/ruff_python_formatter/tests/fixtures.rs
 input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/docstring_code_examples_dynamic_line_width.py
+snapshot_kind: text
 ---
 ## Input
 ```python
@@ -2831,6 +2832,19 @@ def length_rst_in_section():
 ```diff
 --- Stable
 +++ Preview
+@@ -676,9 +676,9 @@
+ 	...         def __init__(self, df: pl.DataFrame):
+ 	...                 self._df = df
+ 	...
+-	...         def by_first_letter_of_column_values(
+-	...                 self, col: str
+-	...         ) -> list[pl.DataFrame]:
++	...         def by_first_letter_of_column_values(self, col: str) -> list[
++	...                 pl.DataFrame
++	...         ]:
+ 	...                 return [
+ 	...                         self._df.filter(pl.col(col).str.starts_with(c))
+ 	...                         for c in sorted(
 @@ -700,9 +700,11 @@
 
  		Examples