Mark RET501 fix unsafe if comments are inside (astral-sh#18780)

Co-authored-by: Charlie Marsh <[email protected]>

Author: njhearp

crates/ruff_linter/resources/test/fixtures/flake8_return/RET501.py

@@ -49,3 +49,13 @@ def prop3(self) -> None:
     def prop4(self) -> None:
         print("I've run out of things to say")
         return None
+
+
+# https://github.com/astral-sh/ruff/issues/18774
+class _:
+    def foo(bar):
+        if not bar:
+            return
+        return (
+            None # comment
+        )

crates/ruff_linter/src/rules/flake8_return/rules/function.rs

@@ -1,5 +1,6 @@
 use anyhow::Result;
 
+use ruff_diagnostics::Applicability;
 use ruff_macros::{ViolationMetadata, derive_message_formats};
 use ruff_python_ast::helpers::{is_const_false, is_const_true};
 use ruff_python_ast::stmt_if::elif_else_range;
@@ -50,6 +51,11 @@ use super::super::visitor::{ReturnVisitor, Stack};
 ///         return
 ///     return
 /// ```
+///
+/// ## Fix Safety
+/// This rule's fix is marked as unsafe for cases in which comments would be
+/// dropped from the `return` statement.
+///
 #[derive(ViolationMetadata)]
 pub(crate) struct UnnecessaryReturnNone;
 
@@ -381,10 +387,15 @@ fn unnecessary_return_none(checker: &Checker, decorator_list: &[Decorator], stac
         }
 
         let mut diagnostic = checker.report_diagnostic(UnnecessaryReturnNone, stmt.range());
-        diagnostic.set_fix(Fix::safe_edit(Edit::range_replacement(
-            "return".to_string(),
-            stmt.range(),
-        )));
+        let edit = Edit::range_replacement("return".to_string(), stmt.range());
+        diagnostic.set_fix(Fix::applicable_edit(
+            edit,
+            if checker.comment_ranges().intersects(stmt.range()) {
+                Applicability::Unsafe
+            } else {
+                Applicability::Safe
+            },
+        ));
     }
 }
 

crates/ruff_linter/src/rules/flake8_return/snapshots/ruff_linter__rules__flake8_return__tests__RET501_RET501.py.snap

@@ -40,3 +40,23 @@ RET501.py:14:9: RET501 [*] Do not explicitly `return None` in function if it is
 15 15 | 
 16 16 |     @property
 17 17 |     def prop(self) -> None:
+
+RET501.py:59:9: RET501 [*] Do not explicitly `return None` in function if it is the only possible return value
+   |
+57 |           if not bar:
+58 |               return
+59 | /         return (
+60 | |             None # comment
+61 | |         )
+   | |_________^ RET501
+   |
+   = help: Remove explicit `return None`
+
+ℹ Unsafe fix
+56 56 |     def foo(bar):
+57 57 |         if not bar:
+58 58 |             return
+59    |-        return (
+60    |-            None # comment
+61    |-        )
+   59 |+        return