Don't expand groups for trailing end-of-line comments

## Summary

The use of `|` as a union operator is not always safe, if a type
annotation is evaluated in a runtime context. For example, this code
errors at runtime:

```python
import httpretty
import requests_mock

item: type[requests_mock.Mocker | httpretty] = requests_mock.Mocker
```

However, it's fine in a `.pyi` file, with `__future__` annotations`, or
if the annotation is in a non-evaluated context, like:

```python
def func():
    item: type[requests_mock.Mocker | httpretty] = requests_mock.Mocker
```

This PR modifies the rule to avoid enforcing in those invalid,
runtime-evaluated contexts.

Closes https://github.com/astral-sh/ruff/issues/6455.

crates/ruff/resources/test/fixtures/flake8_pyi/PYI055.py

@@ -1,7 +1,6 @@
 import builtins
 from typing import Union
 
-
 w: builtins.type[int] | builtins.type[str] | builtins.type[complex]
 x: type[int] | type[str] | type[float]
 y: builtins.type[int] | type[str] | builtins.type[complex]
@@ -9,7 +8,9 @@ z: Union[type[float], type[complex]]
 z: Union[type[float, int], type[complex]]
 
 
-def func(arg: type[int] | str | type[float]) -> None: ...
+def func(arg: type[int] | str | type[float]) -> None:
+    ...
+
 
 # OK
 x: type[int, str, float]
@@ -17,4 +18,14 @@ y: builtins.type[int, str, complex]
 z: Union[float, complex]
 
 
-def func(arg: type[int, float] | str) -> None: ...
+def func(arg: type[int, float] | str) -> None:
+    ...
+
+
+# OK
+item: type[requests_mock.Mocker] | type[httpretty] = requests_mock.Mocker
+
+
+def func():
+    # PYI055
+    item: type[requests_mock.Mocker] | type[httpretty] = requests_mock.Mocker

crates/ruff/resources/test/fixtures/flake8_pyi/PYI055.pyi

@@ -1,14 +1,12 @@
 import builtins
 from typing import Union
 
-
 w: builtins.type[int] | builtins.type[str] | builtins.type[complex]
 x: type[int] | type[str] | type[float]
 y: builtins.type[int] | type[str] | builtins.type[complex]
 z: Union[type[float], type[complex]]
 z: Union[type[float, int], type[complex]]
 
-
 def func(arg: type[int] | str | type[float]) -> None: ...
 
 # OK
@@ -16,5 +14,11 @@ x: type[int, str, float]
 y: builtins.type[int, str, complex]
 z: Union[float, complex]
 
-
 def func(arg: type[int, float] | str) -> None: ...
+
+# OK
+item: type[requests_mock.Mocker] | type[httpretty] = requests_mock.Mocker
+
+def func():
+    # PYI055
+    item: type[requests_mock.Mocker] | type[httpretty] = requests_mock.Mocker

crates/ruff/resources/test/fixtures/pylint/logging_too_few_args.py

@@ -19,6 +19,10 @@ logging.error("Example log %s, %s", "foo", "bar", "baz", **kwargs)
 # do not handle keyword arguments
 logging.error("%(objects)d modifications: %(modifications)d errors: %(errors)d")
 
+logging.info(msg="Hello %s")
+
+logging.info(msg="Hello %s %s")
+
 import warning
 
 warning.warning("Hello %s %s", "World!")

crates/ruff/resources/test/fixtures/pylint/logging_too_many_args.py

@@ -15,6 +15,10 @@ logging.error("Example log %s, %s", "foo", "bar", "baz", **kwargs)
 # do not handle keyword arguments
 logging.error("%(objects)d modifications: %(modifications)d errors: %(errors)d", {"objects": 1, "modifications": 1, "errors": 1})
 
+logging.info(msg="Hello")
+
+logging.info(msg="Hello", something="else")
+
 import warning
 
 warning.warning("Hello %s", "World!", "again")

crates/ruff/src/rules/flake8_pyi/rules/unnecessary_type_union.rs

@@ -43,6 +43,11 @@ impl Violation for UnnecessaryTypeUnion {
 
 /// PYI055
 pub(crate) fn unnecessary_type_union<'a>(checker: &mut Checker, union: &'a Expr) {
+    // The `|` operator isn't always safe to allow to runtime-evaluated annotations.
+    if checker.semantic().execution_context().is_runtime() {
+        return;
+    }
+
     let mut type_exprs = Vec::new();
 
     // Check if `union` is a PEP604 union (e.g. `float | int`) or a `typing.Union[float, int]`

crates/ruff/src/rules/flake8_pyi/snapshots/ruff__rules__flake8_pyi__tests__PYI055_PYI055.py.snap

@@ -1,56 +1,12 @@
 ---
 source: crates/ruff/src/rules/flake8_pyi/mod.rs
 ---
-PYI055.py:5:4: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[int | str | complex]`.
-  |
-5 | w: builtins.type[int] | builtins.type[str] | builtins.type[complex]
-  |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI055
-6 | x: type[int] | type[str] | type[float]
-7 | y: builtins.type[int] | type[str] | builtins.type[complex]
-  |
-
-PYI055.py:6:4: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[int | str | float]`.
-  |
-5 | w: builtins.type[int] | builtins.type[str] | builtins.type[complex]
-6 | x: type[int] | type[str] | type[float]
-  |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI055
-7 | y: builtins.type[int] | type[str] | builtins.type[complex]
-8 | z: Union[type[float], type[complex]]
-  |
-
-PYI055.py:7:4: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[int | str | complex]`.
-  |
-5 | w: builtins.type[int] | builtins.type[str] | builtins.type[complex]
-6 | x: type[int] | type[str] | type[float]
-7 | y: builtins.type[int] | type[str] | builtins.type[complex]
-  |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI055
-8 | z: Union[type[float], type[complex]]
-9 | z: Union[type[float, int], type[complex]]
-  |
-
-PYI055.py:8:4: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[Union[float, complex]]`.
-  |
-6 | x: type[int] | type[str] | type[float]
-7 | y: builtins.type[int] | type[str] | builtins.type[complex]
-8 | z: Union[type[float], type[complex]]
-  |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI055
-9 | z: Union[type[float, int], type[complex]]
-  |
-
-PYI055.py:9:4: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[Union[float, int, complex]]`.
-  |
-7 | y: builtins.type[int] | type[str] | builtins.type[complex]
-8 | z: Union[type[float], type[complex]]
-9 | z: Union[type[float, int], type[complex]]
-  |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI055
-  |
-
-PYI055.py:12:15: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[int | float]`.
+PYI055.py:31:11: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[requests_mock.Mocker | httpretty]`.
    |
-12 | def func(arg: type[int] | str | type[float]) -> None: ...
-   |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI055
-13 | 
-14 | # OK
+29 | def func():
+30 |     # PYI055
+31 |     item: type[requests_mock.Mocker] | type[httpretty] = requests_mock.Mocker
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI055
    |
 
 

crates/ruff/src/rules/flake8_pyi/snapshots/ruff__rules__flake8_pyi__tests__PYI055_PYI055.pyi.snap

@@ -1,56 +1,79 @@
 ---
 source: crates/ruff/src/rules/flake8_pyi/mod.rs
 ---
-PYI055.pyi:5:4: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[int | str | complex]`.
+PYI055.pyi:4:4: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[int | str | complex]`.
   |
-5 | w: builtins.type[int] | builtins.type[str] | builtins.type[complex]
+2 | from typing import Union
+3 | 
+4 | w: builtins.type[int] | builtins.type[str] | builtins.type[complex]
   |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI055
-6 | x: type[int] | type[str] | type[float]
-7 | y: builtins.type[int] | type[str] | builtins.type[complex]
+5 | x: type[int] | type[str] | type[float]
+6 | y: builtins.type[int] | type[str] | builtins.type[complex]
   |
 
-PYI055.pyi:6:4: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[int | str | float]`.
+PYI055.pyi:5:4: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[int | str | float]`.
   |
-5 | w: builtins.type[int] | builtins.type[str] | builtins.type[complex]
-6 | x: type[int] | type[str] | type[float]
+4 | w: builtins.type[int] | builtins.type[str] | builtins.type[complex]
+5 | x: type[int] | type[str] | type[float]
   |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI055
-7 | y: builtins.type[int] | type[str] | builtins.type[complex]
-8 | z: Union[type[float], type[complex]]
+6 | y: builtins.type[int] | type[str] | builtins.type[complex]
+7 | z: Union[type[float], type[complex]]
   |
 
-PYI055.pyi:7:4: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[int | str | complex]`.
+PYI055.pyi:6:4: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[int | str | complex]`.
   |
-5 | w: builtins.type[int] | builtins.type[str] | builtins.type[complex]
-6 | x: type[int] | type[str] | type[float]
-7 | y: builtins.type[int] | type[str] | builtins.type[complex]
+4 | w: builtins.type[int] | builtins.type[str] | builtins.type[complex]
+5 | x: type[int] | type[str] | type[float]
+6 | y: builtins.type[int] | type[str] | builtins.type[complex]
   |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI055
-8 | z: Union[type[float], type[complex]]
-9 | z: Union[type[float, int], type[complex]]
+7 | z: Union[type[float], type[complex]]
+8 | z: Union[type[float, int], type[complex]]
   |
 
-PYI055.pyi:8:4: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[Union[float, complex]]`.
+PYI055.pyi:7:4: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[Union[float, complex]]`.
   |
-6 | x: type[int] | type[str] | type[float]
-7 | y: builtins.type[int] | type[str] | builtins.type[complex]
-8 | z: Union[type[float], type[complex]]
+5 | x: type[int] | type[str] | type[float]
+6 | y: builtins.type[int] | type[str] | builtins.type[complex]
+7 | z: Union[type[float], type[complex]]
   |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI055
-9 | z: Union[type[float, int], type[complex]]
+8 | z: Union[type[float, int], type[complex]]
   |
 
-PYI055.pyi:9:4: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[Union[float, int, complex]]`.
-  |
-7 | y: builtins.type[int] | type[str] | builtins.type[complex]
-8 | z: Union[type[float], type[complex]]
-9 | z: Union[type[float, int], type[complex]]
-  |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI055
-  |
-
-PYI055.pyi:12:15: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[int | float]`.
+PYI055.pyi:8:4: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[Union[float, int, complex]]`.
    |
-12 | def func(arg: type[int] | str | type[float]) -> None: ...
+ 6 | y: builtins.type[int] | type[str] | builtins.type[complex]
+ 7 | z: Union[type[float], type[complex]]
+ 8 | z: Union[type[float, int], type[complex]]
+   |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI055
+ 9 | 
+10 | def func(arg: type[int] | str | type[float]) -> None: ...
+   |
+
+PYI055.pyi:10:15: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[int | float]`.
+   |
+ 8 | z: Union[type[float, int], type[complex]]
+ 9 | 
+10 | def func(arg: type[int] | str | type[float]) -> None: ...
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI055
-13 | 
-14 | # OK
+11 | 
+12 | # OK
+   |
+
+PYI055.pyi:20:7: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[requests_mock.Mocker | httpretty]`.
+   |
+19 | # OK
+20 | item: type[requests_mock.Mocker] | type[httpretty] = requests_mock.Mocker
+   |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI055
+21 | 
+22 | def func():
+   |
+
+PYI055.pyi:24:11: PYI055 Multiple `type` members in a union. Combine them into one, e.g., `type[requests_mock.Mocker | httpretty]`.
+   |
+22 | def func():
+23 |     # PYI055
+24 |     item: type[requests_mock.Mocker] | type[httpretty] = requests_mock.Mocker
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI055
    |
 
 

crates/ruff/src/rules/pylint/rules/logging.rs

@@ -111,8 +111,8 @@ pub(crate) fn logging_call(checker: &mut Checker, call: &ast::ExprCall) {
     let Some(Expr::Constant(ast::ExprConstant {
         value: Constant::Str(value),
         ..
-    })) = call.arguments.find_argument("msg", 0)
-    else {
+    })) = call.arguments
+                .find_positional( 0) else {
         return;
     };
 

crates/ruff_python_ast/src/nodes.rs

@@ -2126,23 +2126,21 @@ impl Arguments {
         })
     }
 
+    /// Return the positional argument at the given index, or `None` if no such argument exists.
+    pub fn find_positional(&self, position: usize) -> Option<&Expr> {
+        self.args
+            .iter()
+            .take_while(|expr| !expr.is_starred_expr())
+            .nth(position)
+    }
+
     /// Return the argument with the given name or at the given position, or `None` if no such
     /// argument exists. Used to retrieve arguments that can be provided _either_ as keyword or
     /// positional arguments.
     pub fn find_argument(&self, name: &str, position: usize) -> Option<&Expr> {
-        self.keywords
-            .iter()
-            .find(|keyword| {
-                let Keyword { arg, .. } = keyword;
-                arg.as_ref().is_some_and(|arg| arg == name)
-            })
+        self.find_keyword(name)
             .map(|keyword| &keyword.value)
-            .or_else(|| {
-                self.args
-                    .iter()
-                    .take_while(|expr| !expr.is_starred_expr())
-                    .nth(position)
-            })
+            .or_else(|| self.find_positional(position))
     }
 }
 

crates/ruff_python_formatter/src/comments/format.rs

@@ -161,10 +161,11 @@ impl Format<PyFormatContext<'_>> for FormatTrailingComments<'_> {
             } else {
                 write!(
                     f,
-                    [
-                        line_suffix(&format_args![space(), space(), format_comment(trailing)]),
-                        expand_parent()
-                    ]
+                    [line_suffix(&format_args![
+                        space(),
+                        space(),
+                        format_comment(trailing)
+                    ])]
                 )?;
             }
 
@@ -210,13 +211,17 @@ impl Format<PyFormatContext<'_>> for FormatDanglingComments<'_> {
                 write!(f, [space(), space()])?;
             }
 
-            write!(
-                f,
-                [
-                    format_comment(comment),
-                    empty_lines(lines_after(comment.slice().end(), f.context().source()))
-                ]
-            )?;
+            if comment.line_position.is_end_of_line() {
+                write!(f, [format_comment(comment)])?;
+            } else {
+                write!(
+                    f,
+                    [
+                        format_comment(comment),
+                        empty_lines(lines_after(comment.slice().end(), f.context().source()))
+                    ]
+                )?;
+            }
 
             comment.mark_formatted();
 

crates/ruff_python_formatter/tests/snapshots/black_compatibility@py_310__pattern_matching_style.py.snap

@@ -65,7 +65,7 @@ match match(
 ```diff
 --- Black
 +++ Ruff
-@@ -1,35 +1,34 @@
+@@ -1,16 +1,11 @@
  match something:
 -    case b():
 +    case NOT_YET_IMPLEMENTED_Pattern:
@@ -85,29 +85,9 @@ match match(
 +    case NOT_YET_IMPLEMENTED_Pattern:
          pass
  
--match(arg)  # comment
-+match(
-+    arg  # comment
-+)
- 
- match()
- 
- match()
- 
--case(arg)  # comment
-+case(
-+    arg  # comment
-+)
- 
- case()
- 
- case()
- 
- 
--re.match(something)  # fast
-+re.match(
-+    something  # fast
-+)
+ match(arg)  # comment
+@@ -29,7 +24,5 @@
+ re.match(something)  # fast
  re.match()
  match match():
 -    case case(
@@ -130,26 +110,20 @@ match something:
     case NOT_YET_IMPLEMENTED_Pattern:
         pass
 
-match(
-    arg  # comment
-)
+match(arg)  # comment
 
 match()
 
 match()
 
-case(
-    arg  # comment
-)
+case(arg)  # comment
 
 case()
 
 case()
 
 
-re.match(
-    something  # fast
-)
+re.match(something)  # fast
 re.match()
 match match():
     case NOT_YET_IMPLEMENTED_Pattern:

crates/ruff_python_formatter/tests/snapshots/black_compatibility@simple_cases__comments2.py.snap

@@ -191,21 +191,7 @@ instruction()#comment with bad spacing
  )
  
  # Please keep __all__ alphabetized within each category.
-@@ -60,8 +60,12 @@
- # Comment before function.
- def inline_comments_in_brackets_ruin_everything():
-     if typedargslist:
--        parameters.children = [children[0], body, children[-1]]  # (1  # )1
-         parameters.children = [
-+            children[0],  # (1
-+            body,
-+            children[-1],  # )1
-+        ]
-+        parameters.children = [
-             children[0],
-             body,
-             children[-1],  # type: ignore
-@@ -72,7 +76,11 @@
+@@ -72,7 +72,11 @@
              body,
              parameters.children[-1],  # )2
          ]
@@ -218,41 +204,17 @@ instruction()#comment with bad spacing
      if (
          self._proc is not None
          # has the child process finished?
-@@ -115,7 +123,9 @@
+@@ -114,9 +118,7 @@
+         # yup
          arg3=True,
      )
-     lcomp = [
+-    lcomp = [
 -        element for element in collection if element is not None  # yup  # yup  # right
-+        element  # yup
-+        for element in collection  # yup
-+        if element is not None  # right
-     ]
+-    ]
++    lcomp = [element for element in collection if element is not None]  # yup  # yup  # right
      lcomp2 = [
          # hello
-@@ -143,7 +153,10 @@
-     # let's return
-     return Node(
-         syms.simple_stmt,
--        [Node(statement, result), Leaf(token.NEWLINE, "\n")],  # FIXME: \r\n?
-+        [
-+            Node(statement, result),
-+            Leaf(token.NEWLINE, "\n"),  # FIXME: \r\n?
-+        ],
-     )
- 
- 
-@@ -158,7 +171,10 @@
- 
- class Test:
-     def _init_host(self, parsed) -> None:
--        if parsed.hostname is None or not parsed.hostname.strip():  # type: ignore
-+        if (
-+            parsed.hostname is None  # type: ignore
-+            or not parsed.hostname.strip()
-+        ):
-             pass
- 
- 
+         element
 ```
 
 ## Ruff Output
@@ -320,11 +282,7 @@ else:
 # Comment before function.
 def inline_comments_in_brackets_ruin_everything():
     if typedargslist:
-        parameters.children = [
-            children[0],  # (1
-            body,
-            children[-1],  # )1
-        ]
+        parameters.children = [children[0], body, children[-1]]  # (1  # )1
         parameters.children = [
             children[0],
             body,
@@ -382,11 +340,7 @@ short
         # yup
         arg3=True,
     )
-    lcomp = [
-        element  # yup
-        for element in collection  # yup
-        if element is not None  # right
-    ]
+    lcomp = [element for element in collection if element is not None]  # yup  # yup  # right
     lcomp2 = [
         # hello
         element
@@ -413,10 +367,7 @@ short
     # let's return
     return Node(
         syms.simple_stmt,
-        [
-            Node(statement, result),
-            Leaf(token.NEWLINE, "\n"),  # FIXME: \r\n?
-        ],
+        [Node(statement, result), Leaf(token.NEWLINE, "\n")],  # FIXME: \r\n?
     )
 
 
@@ -431,10 +382,7 @@ CONFIG_FILES = (
 
 class Test:
     def _init_host(self, parsed) -> None:
-        if (
-            parsed.hostname is None  # type: ignore
-            or not parsed.hostname.strip()
-        ):
+        if parsed.hostname is None or not parsed.hostname.strip():  # type: ignore
             pass
 
 

crates/ruff_python_formatter/tests/snapshots/black_compatibility@simple_cases__fmtskip5.py.snap

@@ -21,26 +21,24 @@ else:
 ```diff
 --- Black
 +++ Ruff
-@@ -1,7 +1,7 @@
+@@ -1,9 +1,5 @@
  a, b, c = 3, 4, 5
- if (
-     a == 3
+-if (
+-    a == 3
 -    and b    != 9  # fmt: skip
-+    and b != 9  # fmt: skip
-     and c is not None
- ):
+-    and c is not None
+-):
++if a == 3 and b != 9 and c is not None:  # fmt: skip
      print("I'm good!")
+ else:
+     print("I'm bad")
 ```
 
 ## Ruff Output
 
 ```py
 a, b, c = 3, 4, 5
-if (
-    a == 3
-    and b != 9  # fmt: skip
-    and c is not None
-):
+if a == 3 and b != 9 and c is not None:  # fmt: skip
     print("I'm good!")
 else:
     print("I'm bad")

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

@@ -100,20 +100,7 @@ def foo() -> tuple[int, int, int,]:
 ```diff
 --- Black
 +++ Ruff
-@@ -26,7 +26,11 @@
-     return 2 * a
- 
- 
--def double(a: int) -> int:  # Hello
-+def double(
-+    a: int
-+) -> (
-+    int  # Hello
-+):
-     return 2 * a
- 
- 
-@@ -54,7 +58,9 @@
+@@ -54,7 +54,9 @@
      a: int,
      b: int,
      c: int,
@@ -157,11 +144,7 @@ def double(a: int) -> int:  # Hello
     return 2 * a
 
 
-def double(
-    a: int
-) -> (
-    int  # Hello
-):
+def double(a: int) -> int:  # Hello
     return 2 * a
 
 

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

@@ -255,11 +255,7 @@ c1 = (
 # Fits, either style
 d11 = x.e().e().e()  #
 d12 = x.e().e().e()  #
-d13 = (
-    x.e()  #
-    .e()
-    .e()
-)
+d13 = x.e().e().e()  #
 
 # Doesn't fit, default
 d2 = x.e().esadjkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkfsdddd()  #

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

@@ -506,12 +506,8 @@ x = (
     - (  #
     )
 )
-x = (
-    () - ()  #
-)
-x = (
-    () - ()  #
-)
+x = () - ()  #
+x = () - ()  #
 ```
 
 

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

@@ -195,11 +195,7 @@ result = (
 # TODO(konstin): Black has this special case for comment placement where everything stays in one line
 f("aaaaaaaa", "aaaaaaaa", "aaaaaaaa", "aaaaaaaa", "aaaaaaaa", "aaaaaaaa", "aaaaaaaa")
 
-f(
-    session,
-    b=1,
-    **dict(),  # oddly placed end-of-line comment
-)
+f(session, b=1, **dict())  # oddly placed end-of-line comment
 f(
     session,
     b=1,

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

@@ -138,10 +138,7 @@ a not in b
     == b
 )
 
-(
-    a  # comment
-    == b
-)
+(a == b)  # comment
 
 a < b > c == d
 

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

@@ -78,14 +78,9 @@ x={  # dangling end of line comment
 
 {**d}
 
-{
-    **a,  #  leading
-    **b,  # middle  # trailing
-}
+{**a, **b}  #  leading  # middle  # trailing
 
-{
-    **b  # middle with single item
-}
+{**b}  # middle with single item
 
 {
     # before

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

@@ -128,10 +128,7 @@ aaaaaaaaaaaaaaaaaaaaa = {
     ]
 }
 
-{
-    a: a  # a
-    for c in e  # for  # c  # in  # e
-}
+{a: a for c in e}  # a  # for  # c  # in  # e
 
 {
     # above a

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

@@ -158,9 +158,7 @@ lambda x: lambda y: lambda z: (
 # Trailing
 
 
-a = (
-    lambda: 1  # Dangling
-)
+a = lambda: 1  # Dangling
 
 # Regression test: lambda empty arguments ranges were too long, leading to unstable
 # formatting

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

@@ -92,10 +92,7 @@ aaaaaaaaaaaaaaaaaaaaa = [
     ]
 ]
 
-[
-    a  # a
-    for c in e  # for  # c  # in  # e
-]
+[a for c in e]  # a  # for  # c  # in  # e
 
 [
     # above a

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

@@ -72,10 +72,7 @@ selected_choices = {
     ]
 }
 
-{
-    a  # a
-    for c in e  # for  # c  # in  # e
-}
+{a for c in e}  # a  # for  # c  # in  # e
 
 {
     # above a

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

@@ -111,8 +111,7 @@ a1 = "a"[
 a2 = "a"[
     # a
     # b
-    :  # c
-    # d
+    :  # c# d
 ]
 
 # Check all places where comments can exist
@@ -151,9 +150,7 @@ c4 = "c"[
 ]
 
 # End of line comments
-d1 = "d"[  # comment
-    :
-]
+d1 = "d"[:]  # comment
 d2 = "d"[  # comment
     1:
 ]

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

@@ -635,9 +635,7 @@ def f(arg1=1, *, kwonlyarg1, kwonlyarg2=2):
 
 
 # Regression test for https://github.com/astral-sh/ruff/issues/5176#issuecomment-1598171989
-def foo(
-    b=3 + 2,  # comment
-):
+def foo(b=3 + 2):  # comment
     ...
 
 
@@ -1039,9 +1037,7 @@ def handleMatch(  # type: ignore[override] # https://github.com/python/mypy/issu
     ...
 
 
-def double(
-    a: int,  # Hello
-) -> int:
+def double(a: int) -> int:  # Hello
     return 2 * a
 
 

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

@@ -61,11 +61,7 @@ while some_condition(unformatted, args) and anotherCondition or aThirdCondition:
     print("Do something")
 
 
-while (
-    some_condition(unformatted, args)  # trailing some condition
-    and anotherCondition
-    or aThirdCondition  # trailing third condition
-):  # comment
+while some_condition(unformatted, args) and anotherCondition or aThirdCondition:  # trailing some condition  # trailing third condition  # comment
     print("Do something")
 ```
 

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

@@ -142,10 +142,7 @@ with (
     # trailing
 
 
-with (
-    a,  # a  # comma
-    b,  # c
-):  # colon
+with a, b:  # a  # comma  # c  # colon
     ...
 
 
@@ -218,11 +215,9 @@ with (
     ...
 
 with (
-    (
-        a
-        # trailing own line comment
-    ) as b  # trailing as same line comment  # trailing b same line comment
-):
+    a
+    # trailing own line comment
+) as b:  # trailing as same line comment  # trailing b same line comment
     ...
 
 with (

crates/ruff_python_literal/src/format.rs

@@ -188,14 +188,23 @@ impl FormatParse for FormatType {
 
 #[derive(Debug, PartialEq)]
 pub struct FormatSpec {
+    // Ex) `!s` in `'{!s}'`
     conversion: Option<FormatConversion>,
+    // Ex) `*` in `'{:*^30}'`
     fill: Option<char>,
+    // Ex) `<` in `'{:<30}'`
     align: Option<FormatAlign>,
+    // Ex) `+` in `'{:+f}'`
     sign: Option<FormatSign>,
+    // Ex) `#` in `'{:#x}'`
     alternate_form: bool,
+    // Ex) `30` in `'{:<30}'`
     width: Option<usize>,
+    // Ex) `,` in `'{:,}'`
     grouping_option: Option<FormatGrouping>,
+    // Ex) `2` in `'{:.2}'`
     precision: Option<usize>,
+    // Ex) `f` in `'{:+f}'`
     format_type: Option<FormatType>,
 }