Merge branch 'brent/fix-kwargs' into brent/indent-lambda-params

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/lambda.py

@@ -725,3 +725,25 @@ transform = lambda left, right: ibis.timestamp("2017-04-01").cast(dt.date).betwe
     x:
     x
 )
+
+(
+    lambda
+    # comment
+    *x,
+    **y: x
+)
+
+(
+    lambda
+    * # comment 2
+    x,
+    **y:
+    x
+)
+
+(
+    lambda
+    ** # comment 1
+    x:
+    x
+)

crates/ruff_python_formatter/src/other/parameters.rs

@@ -241,6 +241,32 @@ impl FormatNodeRule<Parameters> for FormatParameters {
         let num_parameters = item.len();
 
         if self.parentheses == ParametersParentheses::Never {
+            // In a lambda, format any leading comments on the first parameter outside of the
+            // parameters group so that the parameters don't break. For example, format this input:
+            //
+            // ```py
+            // (
+            //     lambda
+            //     * # this becomes a leading comment on *x
+            //     x, **y:
+            //     x
+            // )
+            // ```
+            //
+            // as:
+            //
+            // ```py
+            // (
+            //     lambda
+            //     # this becomes a leading comment on *x
+            //     *x, **y: x
+            // )
+            // ```
+            if let Some(first) = item.iter().next()
+                && comments.has_leading(first.as_parameter())
+            {
+                leading_node_comments(first.as_parameter()).fmt(f)?;
+            }
             write!(f, [group(&format_inner), dangling_comments(dangling)])
         } else if num_parameters == 0 {
             let mut f = WithNodeLevel::new(NodeLevel::ParenthesizedExpression, f);

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

@@ -731,6 +731,28 @@ transform = lambda left, right: ibis.timestamp("2017-04-01").cast(dt.date).betwe
     x:
     x
 )
+
+(
+    lambda
+    # comment
+    *x,
+    **y: x
+)
+
+(
+    lambda
+    * # comment 2
+    x,
+    **y:
+    x
+)
+
+(
+    lambda
+    ** # comment 1
+    x:
+    x
+)
 ```
 
 ## Output
@@ -1495,6 +1517,24 @@ transform = (
     y, *x:  # comment 2
     x
 )
+
+(
+    lambda
+    # comment
+    *x, **y: x
+)
+
+(
+    lambda
+    # comment 2
+    *x, **y: x
+)
+
+(
+    lambda
+    # comment 1
+    **x: x
+)
 ```