From a1509dfc7c2b16f3762545fc802d49f5f03726e2 Mon Sep 17 00:00:00 2001
From: Dhruv Manilawala <dhruvmanila@gmail.com>
Date: Wed, 4 Oct 2023 13:25:01 +0530
Subject: [PATCH] Use correct start location for class/function clause header
 (#7802)

## Summary

This PR fixes the bug where the formatter would panic if a class/function with
decorators had a suppression comment.

The fix is to use to correct start location to find the `async`/`def`/`class`
keyword when decorators are present which is the end of the last
decorator.

## Test Plan

Add test cases for the fix and update the snapshots.
---
 .../test/fixtures/ruff/fmt_skip/decorators.py | 13 +++++++++
 .../src/statement/clause.rs                   | 12 +++++++--
 .../format@fmt_skip__decorators.py.snap       | 27 +++++++++++++++++++
 3 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/crates/ruff_python_formatter/resources/test/fixtures/ruff/fmt_skip/decorators.py b/crates/ruff_python_formatter/resources/test/fixtures/ruff/fmt_skip/decorators.py
index 98e3bedc6b94f..051eb28362a88 100644
--- a/crates/ruff_python_formatter/resources/test/fixtures/ruff/fmt_skip/decorators.py
+++ b/crates/ruff_python_formatter/resources/test/fixtures/ruff/fmt_skip/decorators.py
@@ -17,3 +17,16 @@ class Test:
 def test():
     pass
 
+
+# Regression test for https://github.com/astral-sh/ruff/issues/7735
+@decorator1
+@decorator2
+class Foo:  # fmt: skip
+    pass
+
+
+# Regression test for https://github.com/astral-sh/ruff/issues/7735
+@decorator1
+@decorator2
+def foo():  # fmt: skip
+    pass
diff --git a/crates/ruff_python_formatter/src/statement/clause.rs b/crates/ruff_python_formatter/src/statement/clause.rs
index 449b64e299644..b8138df503773 100644
--- a/crates/ruff_python_formatter/src/statement/clause.rs
+++ b/crates/ruff_python_formatter/src/statement/clause.rs
@@ -203,15 +203,23 @@ impl<'a> ClauseHeader<'a> {
     fn first_keyword_range(self, source: &str) -> FormatResult<TextRange> {
         match self {
             ClauseHeader::Class(header) => {
-                find_keyword(header.start(), SimpleTokenKind::Class, source)
+                let start_position = header
+                    .decorator_list
+                    .last()
+                    .map_or_else(|| header.start(), Ranged::end);
+                find_keyword(start_position, SimpleTokenKind::Class, source)
             }
             ClauseHeader::Function(header) => {
+                let start_position = header
+                    .decorator_list
+                    .last()
+                    .map_or_else(|| header.start(), Ranged::end);
                 let keyword = if header.is_async {
                     SimpleTokenKind::Async
                 } else {
                     SimpleTokenKind::Def
                 };
-                find_keyword(header.start(), keyword, source)
+                find_keyword(start_position, keyword, source)
             }
             ClauseHeader::If(header) => find_keyword(header.start(), SimpleTokenKind::If, source),
             ClauseHeader::ElifElse(ElifElseClause {
diff --git a/crates/ruff_python_formatter/tests/snapshots/format@fmt_skip__decorators.py.snap b/crates/ruff_python_formatter/tests/snapshots/format@fmt_skip__decorators.py.snap
index 330e73752d3f2..720890d63353e 100644
--- a/crates/ruff_python_formatter/tests/snapshots/format@fmt_skip__decorators.py.snap
+++ b/crates/ruff_python_formatter/tests/snapshots/format@fmt_skip__decorators.py.snap
@@ -23,6 +23,19 @@ class Test:
 def test():
     pass
 
+
+# Regression test for https://github.com/astral-sh/ruff/issues/7735
+@decorator1
+@decorator2
+class Foo:  # fmt: skip
+    pass
+
+
+# Regression test for https://github.com/astral-sh/ruff/issues/7735
+@decorator1
+@decorator2
+def foo():  # fmt: skip
+    pass
 ```
 
 ## Output
@@ -43,6 +56,20 @@ class Test:
 # leading class comment
 def test():
     pass
+
+
+# Regression test for https://github.com/astral-sh/ruff/issues/7735
+@decorator1
+@decorator2
+class Foo:  # fmt: skip
+    pass
+
+
+# Regression test for https://github.com/astral-sh/ruff/issues/7735
+@decorator1
+@decorator2
+def foo():  # fmt: skip
+    pass
 ```