fix(query): transfer a leading boundary anchor across a zero-matched quantifier

`(P . Q* Y)` with zero `Q` dropped the leading `.`, so `Y` matched at any
position instead of being pinned to the parent's first named child. On a `?`/`*`
zero-skip, when the skipped step is the parent's first child and carries a
leading anchor, transfer that first-child requirement to the skip target.

crates/cli/src/tests/query_test.rs

@@ -1337,6 +1337,52 @@ function foo() {}
     });
 }
 
+#[test]
+fn test_query_matches_with_leading_anchor_before_zero_quantifier() {
+    allocations::record(|| {
+        let language = get_language("c");
+        let query = Query::new(
+            &language,
+            "(translation_unit . (comment)* (function_definition) @f)",
+        )
+        .unwrap();
+
+        // The leading `.` anchors the comment run to the parent's first child. When the
+        // run matches zero comments, that first-child requirement transfers to the
+        // function, so it matches only when it is itself the first child.
+        assert_query_matches(
+            &language,
+            &query,
+            "
+int main() {}
+",
+            &[(0, vec![("f", "int main() {}")])],
+        );
+
+        // The function is the second child, so with no leading comments it must not match.
+        assert_query_matches(
+            &language,
+            &query,
+            "
+int a;
+int main() {}
+",
+            &[],
+        );
+
+        // With a leading comment the run starts at the first child and the function follows.
+        assert_query_matches(
+            &language,
+            &query,
+            "
+// c
+int main() {}
+",
+            &[(0, vec![("f", "int main() {}")])],
+        );
+    });
+}
+
 #[test]
 fn test_query_matches_with_last_named_child() {
     allocations::record(|| {

lib/src/query.c

@@ -4478,13 +4478,26 @@ static inline bool ts_query_cursor__advance(
                   copy->seeking_immediate_match = true;
                 }
                 // Taking a `?`/`*` zero-skip means the quantified subpattern matched
-                // nothing, so an immediately-following anchor is vacuous for this copy,
-                // UNLESS the skipped step carried a leading anchor of its own. In that
-                // case the adjacency transfers through the empty run to the step we skip
-                // to, so `A . Q* . B` with zero `Q` still requires `A` and `B` to be
-                // immediate siblings.
-                if (child_step->alternative_is_skip && !child_step->is_immediate) {
-                  copy->skipped_quantifier = true;
+                // nothing. How an adjacent anchor behaves then depends on where it sat:
+                if (child_step->alternative_is_skip) {
+                  if (!child_step->is_immediate) {
+                    // No leading anchor on the skipped step, so an immediately-following
+                    // anchor on the skip target is vacuous (`Q* . B` with zero `Q` lets
+                    // `B` match anywhere).
+                    copy->skipped_quantifier = true;
+                  } else if (
+                    array_get(&self->query->steps, child_state->step_index - 1)->depth <
+                    child_step->depth
+                  ) {
+                    // The skipped step was the parent's first child pattern and carried a
+                    // leading *boundary* anchor (`(P . Q* Y)`). Transfer the first-child
+                    // requirement to the skip target so it survives the empty run: `Y`
+                    // must still be the parent's first named child.
+                    copy->seeking_immediate_match = true;
+                  }
+                  // Otherwise the skipped step carried a leading *between* anchor
+                  // (`A . Q* ...`): with zero `Q` that adjacency vanishes, while the skip
+                  // target's own anchor, if any, still applies (`A . Q* . B` stays adjacent).
                 }
               }
             }