M12: report rows cut from repeats in positioned containers

A repeating subform drawn inside a positioned container (a tb, lr-tb or
rl-tb subform placed on a positioned page) was cut at its occur max or
MAX_INSTANCES like a flowed one, but the rows past the cut were dropped
without the layout warning that flowed subforms and tables give. Both
drawing paths now call warn_truncated, so the README, the MAX_INSTANCES
doc and the form.xfa-data note are true for these layouts too
(XFA 3.3, "The occur element", p. 786).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0175FWj4xFhMhSH3UpMU8DSC

crates/xfa/src/layout/draw.rs

@@ -97,8 +97,11 @@ impl Layouter<'_> {
                             }
                             let (w, h) = self.size_of(k, inner.w, &ctx, depth + 1);
                             // A repeating subform here (a table in an area of a positioned page,
-                            // say) gets its instances, as in a flowed one, one under another.
-                            for instance in 0..self.instances(k, &ctx.som) {
+                            // say) gets its instances, as in a flowed one, one under another,
+                            // and the rows past them are reported as there.
+                            let instances = self.instances(k, &ctx.som);
+                            self.warn_truncated(k, &ctx.som, instances);
+                            for instance in 0..instances {
                                 self.draw_node(k, Rect::new(inner.x, y, w, h), &ctx, depth + 1, sibs.at(i) + instance)?;
                                 y += h;
                             }
@@ -106,7 +109,11 @@ impl Layouter<'_> {
                     }
                     Layout::LrTb | Layout::RlTb => {
                         // A repeating subform here (rows of fields under a heading) gets its
-                        // instances, as in the other layouts.
+                        // instances, as in the other layouts, and the rows past them are reported.
+                        for k in s.children.iter().filter(|k| k.common().presence.occupies()) {
+                            let instances = self.instances(k, &ctx.som);
+                            self.warn_truncated(k, &ctx.som, instances);
+                        }
                         let (placed, _) = self.pack_instances(&s.children, inner.w, &ctx, depth, &ctx.som);
                         for (i, instance, r) in placed {
                             if let Some(k) = s.children.get(i) {

crates/xfa/src/layout/flow.rs

@@ -295,7 +295,7 @@ impl Layouter<'_> {
     /// The data holds more instances of `node` than `laid_out`: say so, since calculations
     /// then see only those, and say why. (The template's own counts can't ask for more: the
     /// parser reads `initial` and `max` up to [`MAX_INSTANCES`].)
-    fn warn_truncated(&mut self, node: &Node, parent_som: &str, laid_out: usize) {
+    pub(super) fn warn_truncated(&mut self, node: &Node, parent_som: &str, laid_out: usize) {
         let Node::Subform(sf) = node else { return };
         let from_data = match (&sf.common.name, self.data) {
             (Some(name), Some(d)) if sf.occur.max != Some(1) => d.count(&data_path(self.tpl, parent_som), name),

crates/xfa/src/repeat_tests.rs

@@ -100,3 +100,21 @@ fn an_initial_count_lays_out_whole_up_to_the_limit() {
     assert_eq!(crate::layout::instance_count(&unbounded, 0), MAX_INSTANCES);
     assert_eq!(crate::layout::instance_count(&unbounded, usize::MAX), MAX_INSTANCES);
 }
+
+#[test]
+fn rows_cut_in_a_positioned_container_are_reported_too() {
+    // The list sits in a positioned subform, so it is drawn rather than flowed: its `tb`,
+    // `lr-tb` and `rl-tb` repeats are cut at the same bounds and must say so as a flowed one does.
+    for layout in ["tb", "lr-tb", "rl-tb"] {
+        let xml = rows_form("5", 60, false)
+            .replace(r#"<subform name="form" layout="tb">"#, r#"<subform name="form" layout="tb"><subform name="page" w="540pt" h="720pt">"#)
+            .replace("</subform></template>", "</subform></subform></template>")
+            .replace(r#"<subform name="list" layout="tb">"#, &format!(r#"<subform name="list" x="0pt" y="0pt" w="540pt" layout="{layout}">"#))
+            .replace("<xfa:data><form><list>", "<xfa:data><form><page><list>")
+            .replace("</list></form></xfa:data>", "</list></page></form></xfa:data>");
+        let form = layout_xml(&xml).unwrap();
+        assert_eq!(values(&form), expected(5), "{layout}");
+        let w = cut_warning(&form).unwrap_or_else(|| panic!("{layout}: the rows past occur max are reported: {:?}", form.warnings));
+        assert!(w.contains("holds 60 rows") && w.contains("first 5"), "{layout}: {w}");
+    }
+}