From a8486ca23915be41174dfd22b0d251d324483daa Mon Sep 17 00:00:00 2001
From: Will Lillis <will.lillis24@gmail.com>
Date: Mon, 29 Jun 2026 01:49:15 -0400
Subject: [PATCH] fix(query): apply a trailing anchor when its optional node is
 skipped

A trailing `.` after an optional node, e.g. `(p (a)+ @a . (b)? @b .)`, sets
`is_last_child` on the `(b)?` step. When `(b)?` matched zero, the zero-skip
jumped past that step to completion, so the last-child requirement was never
enforced.

When a zero-skip would bypass a step carrying `is_last_child`, require that
the last matched node really is the last named child. Gated on the
`alternative_is_skip` edge marker.
---
 crates/cli/src/tests/query_test.rs | 39 ++++++++++++++++++++++++++++++
 lib/src/query.c                    | 11 +++++++++
 2 files changed, 50 insertions(+)

diff --git a/crates/cli/src/tests/query_test.rs b/crates/cli/src/tests/query_test.rs
index 1baf1e471..abba409da 100644
--- a/crates/cli/src/tests/query_test.rs
+++ b/crates/cli/src/tests/query_test.rs
@@ -1258,6 +1258,45 @@ function foo() {}
     });
 }
 
+#[test]
+fn test_query_matches_with_last_child_anchor_after_optional() {
+    allocations::record(|| {
+        let language = get_language("c");
+        let query = Query::new(
+            &language,
+            "(preproc_if (preproc_def)+ @def . (preproc_else)? @else .)",
+        )
+        .unwrap();
+
+        // The optional `(preproc_else)?` is absent, so the trailing anchor's
+        // last-child requirement transfers to the last `preproc_def`. A trailing
+        // comment means the def is not the last child, so nothing matches.
+        assert_query_matches(
+            &language,
+            &query,
+            "
+#if X
+#define A
+// c
+#endif
+",
+            &[],
+        );
+
+        // With the def as the last child, the (else-less) match is allowed.
+        assert_query_matches(
+            &language,
+            &query,
+            "
+#if X
+#define A
+#endif
+",
+            &[(0, vec![("def", "#define A\n")])],
+        );
+    });
+}
+
 #[test]
 fn test_query_matches_with_last_named_child() {
     allocations::record(|| {
diff --git a/lib/src/query.c b/lib/src/query.c
index 23db6ca64..c47101dd9 100644
--- a/lib/src/query.c
+++ b/lib/src/query.c
@@ -4450,6 +4450,17 @@ static inline bool ts_query_cursor__advance(
                 k--;
               }
 
+              // A `?`/`*` zero-skip past a step that carries a trailing last-child
+              // anchor transfers that requirement to the last matched node. The
+              // skip is only valid if that node really is the last named child.
+              if (
+                child_step->alternative_is_skip &&
+                child_step->is_last_child &&
+                has_later_named_siblings
+              ) {
+                continue;
+              }
+
               QueryState *copy = ts_query_cursor__copy_state(self, &child_state);
               if (copy) {
                 LOG(