fix: leading comma panic

Author: benfdking

crates/lib/src/rules/layout/lt08.rs

@@ -157,7 +157,9 @@ SELECT a FROM plop
                         }
                     }
                 } else if comma_style == "leading" {
-                    fix_point = forward_slice[comma_seg_idx].clone().into();
+                    if comma_seg_idx < forward_slice.len() {
+                        fix_point = forward_slice[comma_seg_idx].clone().into();
+                    }
                 } else {
                     let mut offset = 1;
 
@@ -186,16 +188,22 @@ SELECT a FROM plop
                 1
             };
 
-            let fixes = vec![LintFix {
-                edit_type: fix_type,
-                anchor: fix_point.unwrap(),
-                edit: std::iter::repeat_n(
-                    SegmentBuilder::newline(context.tables.next_id(), "\n"),
-                    num_newlines,
-                )
-                .collect_vec(),
-                source: Vec::new(),
-            }];
+            // Only create fixes if we have a valid fix point
+            let fixes = if let Some(anchor) = fix_point {
+                vec![LintFix {
+                    edit_type: fix_type,
+                    anchor,
+                    edit: std::iter::repeat_n(
+                        SegmentBuilder::newline(context.tables.next_id(), "\n"),
+                        num_newlines,
+                    )
+                    .collect_vec(),
+                    source: Vec::new(),
+                }]
+            } else {
+                // Skip generating a fix if we don't have a valid anchor point
+                Vec::new()
+            };
 
             error_buffer.push(LintResult::new(
                 forward_slice[seg_idx].clone().into(),

crates/lib/test/fixtures/rules/std_rule_cases/LT08.yml

@@ -205,6 +205,18 @@ test_pass_column_name_definition_multiple:
         cte_2.var
     FROM cte_1, cte_2;
 
+test_pass_edge_case_leading_comma:
+  # Regression test for panic with leading comma CTE
+  pass_str: |
+    with x as (
+      select 1 as a
+    )
+    
+    , b as ( select 2 as e)
+    
+    select * 
+    from x, b;
+
 test_fail_column_name_definition_newline:
   fail_str: |
     WITH