Add a warning when a copy value is used in a higher scope than it was created in (#2771)

packages/signals/docs/hoist/fixed_list.rs

@@ -0,0 +1,32 @@
+#[component]
+fn Counters() -> Element {
+    let mut counts = use_signal(Vec::new);
+
+    rsx! {
+        button { onclick: move |_| counts.write().push(0), "Add child" }
+        button {
+            onclick: move |_| {
+                counts.write().pop();
+            },
+            "Remove child"
+        }
+        "{counts:?}"
+        // Instead of passing up a signal, we can just write to the signal that lives in the parent
+        for index in 0..counts.len() {
+            Counter {
+                index,
+                counts
+            }
+        }
+    }
+}
+
+#[component]
+fn Counter(index: usize, mut counts: Signal<Vec<i32>>) -> Element {
+    rsx! {
+        button {
+            onclick: move |_| counts.write()[index] += 1,
+            "{counts.read()[index]}"
+        }
+    }
+}