fix(formatter): Handle leading comment after array elision (#20987)

Fixes #20962

crates/oxc_formatter/src/ast_nodes/iterator.rs

@@ -196,8 +196,8 @@ macro_rules! impl_ast_node_vec_for_option {
                             parent: self.parent,
                             allocator: self.allocator,
                             following_span_start: inner_iter
-                                .next()
-                                .and_then(|opt| opt.as_ref().map(|n| n.span().start))
+                                // Skip over `None` (elision) to find the next real element's span
+                                .find_map(|opt| opt.as_ref().map(|n| n.span().start))
                                 .unwrap_or(following),
                         }
                     }))
@@ -228,11 +228,25 @@ macro_rules! impl_ast_node_vec_for_option {
                 let following = self.following_span_start;
                 let get_span = self.get_following_span_start;
                 allocator
-                    .alloc(self.inner.next().map(|inner| AstNode {
-                        parent: self.parent,
-                        inner,
-                        allocator,
-                        following_span_start: self.inner.peek().map_or(following, |n| get_span(*n)),
+                    .alloc(self.inner.next().map(|inner| {
+                        AstNode {
+                            parent: self.parent,
+                            inner,
+                            allocator,
+                            following_span_start: match self.inner.peek().map(|n| get_span(n)) {
+                                Some(span) if span != 0 => span,
+                                // Skip over `None` (elision) to find the next real element's span
+                                Some(_) => self
+                                    .inner
+                                    .clone()
+                                    .find_map(|n| {
+                                        let span = get_span(n);
+                                        (span != 0).then_some(span)
+                                    })
+                                    .unwrap_or(following),
+                                None => following,
+                            },
+                        }
                     }))
                     .as_ref()
             }

crates/oxc_formatter/tests/fixtures/ts/array-elision/issue-20962.ts

@@ -0,0 +1,11 @@
+const foo = {
+  createNewConnection: ([
+  password,
+    ,
+    // @ts-expect-error THIS SHOULD STAY HERE
+      username,
+
+  ]) => {
+    void password; void username;
+  },
+}

crates/oxc_formatter/tests/fixtures/ts/array-elision/issue-20962.ts.snap

@@ -0,0 +1,48 @@
+---
+source: crates/oxc_formatter/tests/fixtures/mod.rs
+---
+==================== Input ====================
+const foo = {
+  createNewConnection: ([
+  password,
+    ,
+    // @ts-expect-error THIS SHOULD STAY HERE
+      username,
+
+  ]) => {
+    void password; void username;
+  },
+}
+
+==================== Output ====================
+------------------
+{ printWidth: 80 }
+------------------
+const foo = {
+  createNewConnection: ([
+    password,
+    ,
+    // @ts-expect-error THIS SHOULD STAY HERE
+    username,
+  ]) => {
+    void password;
+    void username;
+  },
+};
+
+-------------------
+{ printWidth: 100 }
+-------------------
+const foo = {
+  createNewConnection: ([
+    password,
+    ,
+    // @ts-expect-error THIS SHOULD STAY HERE
+    username,
+  ]) => {
+    void password;
+    void username;
+  },
+};
+
+===================== End =====================