Resolve deferred size comparisons before allocating span slots

tests/scenario/mod.rs

@@ -213,7 +213,7 @@ fn resize_one(warm: &mut Harness, tree: &Tree, idx: usize, rng: &mut Rng) -> Siz
     };
     warm.rsc
         .widgets_mut()
-        .set_size_rules(tree.sized[idx], lens.x, lens.y);
+        .set_size_rules(tree.sized[idx], lens.x.clone(), lens.y.clone());
     lens
 }
 
@@ -362,6 +362,7 @@ fn describe(id: WidgetId, h: &Harness) -> String {
     let rule = |r: SizeRule| match r {
         SizeRule::Free => "-".into(),
         SizeRule::Exact(len) => format!("{len}"),
+        SizeRule::Request(request) => format!("{request:?}"),
         SizeRule::Min(min) => format!(">{}", LayoutLen::from(min)),
         SizeRule::Max(max) => format!("<{}", LayoutLen::from(max)),
         SizeRule::Clamp { min, max } => {
@@ -383,7 +384,7 @@ fn describe(id: WidgetId, h: &Harness) -> String {
     // A rule and an alignment are properties of whatever carries them, so
     // they print with that widget rather than as widgets of their own.
     let mut out = describe_widget(id, h);
-    if (rules.x, rules.y) != (SizeRule::Free, SizeRule::Free) {
+    if rules != SizeRules::default() {
         out += &format!("[x:{},y:{}]", rule(rules.x), rule(rules.y));
     }
     if align != RegionAlign::default() {