Fix panic when code in init callback of conditional/repeater re-trigg…

…ers repeater traversal

Don't call init() while mutably borrowing the repeater's inner.

Fixes #3214

internal/core/model.rs

@@ -896,27 +896,30 @@ impl<C: RepeatedItemTree + 'static> Repeater<C> {
  model: &ModelRc<C::Data>,
  count: usize,
  ) -> bool {
+ let mut indices_to_init = Vec::new();
  let mut inner = self.0.inner.borrow_mut();
  inner.instances.resize_with(count, || (RepeatedInstanceState::Dirty, None));
  let offset = inner.offset;
  let mut any_items_created = false;
  for (i, c) in inner.instances.iter_mut().enumerate() {
  if c.0 == RepeatedInstanceState::Dirty {
- let created = if c.1.is_none() {
+ if c.1.is_none() {
  any_items_created = true;
  c.1 = Some(init());
- true
- } else {
- false
+ indices_to_init.push(i);
  };
  c.1.as_ref().unwrap().update(i + offset, model.row_data(i + offset).unwrap());
- if created {
- c.1.as_ref().unwrap().init();
- }
  c.0 = RepeatedInstanceState::Clean;
  }
  }
  self.data().is_dirty.set(false);
+
+ drop(inner);
+ let inner = self.0.inner.borrow();
+ for item in indices_to_init.into_iter().filter_map(|index| inner.instances.get(index)) {
+ item.1.as_ref().unwrap().init();
+ }
+
  any_items_created
  }
 

tests/cases/models/init_recursion.slint

@@ -0,0 +1,36 @@
+// Copyright © SixtyFPS GmbH <[email protected]>
+// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-1.1 OR LicenseRef-Slint-commercial
+
+TestCase := Rectangle {
+ property <length> test-height: layout.preferred-height;
+ property <bool> test: self.test-height != 0;
+
+ layout := VerticalLayout {
+ if true: TextInput {
+ // Trigger a call into the layout
+ init => { debug(self.y); }
+ }
+ }
+}
+
+/*
+```cpp
+auto handle = TestCase::create();
+const TestCase &instance = *handle;
+
+assert(instance.get_test_height() != 0.);
+```
+
+
+```rust
+let instance = TestCase::new().unwrap();
+
+assert!(instance.get_test_height() != 0.);
+```
+
+```js
+var instance = new slint.TestCase();
+
+assert(instance.test_height != 0.);
+```
+*/