Allow # fmt: skip with interspersed same-line comments (#9395)

## Summary

This is similar to https://github.com/astral-sh/ruff/pull/8876, but more
limited in scope:

1. It only applies to `# fmt: skip` (like Black). Like `# isort: on`, `#
fmt: on` needs to be on its own line (still).
2. It only delimits on `#`, so you can do `# fmt: skip # noqa`, but not
`# fmt: skip - some other content` or `# fmt: skip; noqa`.

If we want to support the `;`-delimited version, we should revisit
later, since we don't support that in the linter (so `# fmt: skip; noqa`
wouldn't register a `noqa`).

Closes https://github.com/astral-sh/ruff/issues/8892.

crates/ruff_python_formatter/resources/test/fixtures/ruff/fmt_skip/reason.py

@@ -0,0 +1,9 @@
+# Supported
+x =    1  # fmt: skip
+x =    1  # fmt: skip # reason
+x =    1  # reason # fmt: skip
+
+# Unsupported
+x =    1  # fmt: skip reason
+x =    1  # fmt: skip - reason
+x =    1  # fmt: skip; noqa

crates/ruff_python_formatter/src/comments/mod.rs

@@ -171,24 +171,37 @@ impl SourceComment {
 
     pub(crate) fn suppression_kind(&self, source: &str) -> Option<SuppressionKind> {
         let text = self.slice.text(SourceCode::new(source));
-        let trimmed = text.strip_prefix('#').unwrap_or(text).trim_whitespace();
 
+        // Match against `# fmt: on`, `# fmt: off`, `# yapf: disable`, and `# yapf: enable`, which
+        // must be on their own lines.
+        let trimmed = text.strip_prefix('#').unwrap_or(text).trim_whitespace();
         if let Some(command) = trimmed.strip_prefix("fmt:") {
             match command.trim_whitespace_start() {
-                "off" => Some(SuppressionKind::Off),
-                "on" => Some(SuppressionKind::On),
-                "skip" => Some(SuppressionKind::Skip),
-                _ => None,
+                "off" => return Some(SuppressionKind::Off),
+                "on" => return Some(SuppressionKind::On),
+                "skip" => return Some(SuppressionKind::Skip),
+                _ => {}
             }
         } else if let Some(command) = trimmed.strip_prefix("yapf:") {
             match command.trim_whitespace_start() {
-                "disable" => Some(SuppressionKind::Off),
-                "enable" => Some(SuppressionKind::On),
-                _ => None,
+                "disable" => return Some(SuppressionKind::Off),
+                "enable" => return Some(SuppressionKind::On),
+                _ => {}
             }
-        } else {
-            None
         }
+
+        // Search for `# fmt: skip` comments, which can be interspersed with other comments (e.g.,
+        // `# fmt: skip # noqa: E501`).
+        for segment in text.split('#') {
+            let trimmed = segment.trim_whitespace();
+            if let Some(command) = trimmed.strip_prefix("fmt:") {
+                if command.trim_whitespace_start() == "skip" {
+                    return Some(SuppressionKind::Skip);
+                }
+            }
+        }
+
+        None
     }
 
     /// Returns true if this comment is a `fmt: off` or `yapf: disable` own line suppression comment.

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

@@ -21,8 +21,7 @@ skip_will_not_work2 =  "a" +  "b"  # some text; fmt:skip happens to be part of i
 --- Black
 +++ Ruff
 @@ -1,8 +1,8 @@
--foo =  123  # fmt: skip # noqa: E501 # pylint
-+foo = 123  # fmt: skip # noqa: E501 # pylint
+ foo =  123  # fmt: skip # noqa: E501 # pylint
  bar = (
 -    123   ,
 -    (        1      +           5      )  # pylint # fmt:skip
@@ -38,7 +37,7 @@ skip_will_not_work2 =  "a" +  "b"  # some text; fmt:skip happens to be part of i
 ## Ruff Output
 
 ```python
-foo = 123  # fmt: skip # noqa: E501 # pylint
+foo =  123  # fmt: skip # noqa: E501 # pylint
 bar = (
     123,
     (1 + 5),  # pylint # fmt:skip

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

@@ -0,0 +1,32 @@
+---
+source: crates/ruff_python_formatter/tests/fixtures.rs
+input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/fmt_skip/reason.py
+---
+## Input
+```python
+# Supported
+x =    1  # fmt: skip
+x =    1  # fmt: skip # reason
+x =    1  # reason # fmt: skip
+
+# Unsupported
+x =    1  # fmt: skip reason
+x =    1  # fmt: skip - reason
+x =    1  # fmt: skip; noqa
+```
+
+## Output
+```python
+# Supported
+x =    1  # fmt: skip
+x =    1  # fmt: skip # reason
+x =    1  # reason # fmt: skip
+
+# Unsupported
+x = 1  # fmt: skip reason
+x = 1  # fmt: skip - reason
+x = 1  # fmt: skip; noqa
+```
+
+
+