llr: Fix panic when two-way binding ListView viewport to a global

internal/compiler/generator/cpp.rs

@@ -2218,11 +2218,11 @@ fn generate_sub_component(
         ));
 
         let ensure_updated = if let Some(listview) = &repeated.listview {
-            let vp_y = access_local_member(&listview.viewport_y, &ctx);
-            let vp_h = access_local_member(&listview.viewport_height, &ctx);
-            let lv_h = access_local_member(&listview.listview_height, &ctx);
-            let vp_w = access_local_member(&listview.viewport_width, &ctx);
-            let lv_w = access_local_member(&listview.listview_width, &ctx);
+            let vp_y = access_member(&listview.viewport_y, &ctx).unwrap();
+            let vp_h = access_member(&listview.viewport_height, &ctx).unwrap();
+            let lv_h = access_member(&listview.listview_height, &ctx).unwrap();
+            let vp_w = access_member(&listview.viewport_width, &ctx).unwrap();
+            let lv_w = access_member(&listview.listview_width, &ctx).unwrap();
 
             format!(
                 "self->{repeater_id}.ensure_updated_listview(self, &{vp_w}, &{vp_h}, &{vp_y}, {lv_w}.get(), {lv_h}.get());"

internal/compiler/generator/rust.rs

@@ -974,11 +974,11 @@ fn generate_sub_component(
                 });
             });
             let ensure_updated = if let Some(listview) = &repeated.listview {
-                let vp_y = access_local_member(&listview.viewport_y, &ctx);
-                let vp_h = access_local_member(&listview.viewport_height, &ctx);
-                let lv_h = access_local_member(&listview.listview_height, &ctx);
-                let vp_w = access_local_member(&listview.viewport_width, &ctx);
-                let lv_w = access_local_member(&listview.listview_width, &ctx);
+                let vp_y = access_member(&listview.viewport_y, &ctx).unwrap();
+                let vp_h = access_member(&listview.viewport_height, &ctx).unwrap();
+                let lv_h = access_member(&listview.listview_height, &ctx).unwrap();
+                let vp_w = access_member(&listview.viewport_width, &ctx).unwrap();
+                let lv_w = access_member(&listview.listview_width, &ctx).unwrap();
 
                 quote! {
                     #inner_component_id::FIELD_OFFSETS.#repeater_id.apply_pin(_self).ensure_updated_listview(

internal/compiler/llr/item_tree.rs

@@ -268,13 +268,13 @@ pub struct Function {
 /// The property references might be either in the parent context, or in the
 /// repeated's component context
 pub struct ListViewInfo {
-    pub viewport_y: LocalMemberReference,
-    pub viewport_height: LocalMemberReference,
-    pub viewport_width: LocalMemberReference,
+    pub viewport_y: MemberReference,
+    pub viewport_height: MemberReference,
+    pub viewport_width: MemberReference,
     /// The ListView's inner visible height (not counting eventual scrollbar)
-    pub listview_height: LocalMemberReference,
+    pub listview_height: MemberReference,
     /// The ListView's inner visible width (not counting eventual scrollbar)
-    pub listview_width: LocalMemberReference,
+    pub listview_width: MemberReference,
 
     // In the repeated component context
     pub prop_y: MemberReference,

internal/compiler/llr/lower_to_item_tree.rs

@@ -783,11 +783,11 @@ fn lower_repeated_component(
     let listview = repeated.is_listview.as_ref().map(|lv| {
         let geom = component.root_element.borrow().geometry_props.clone().unwrap();
         ListViewInfo {
-            viewport_y: ctx.map_property_reference(&lv.viewport_y).local().clone(),
-            viewport_height: ctx.map_property_reference(&lv.viewport_height).local().clone(),
-            viewport_width: ctx.map_property_reference(&lv.viewport_width).local().clone(),
-            listview_height: ctx.map_property_reference(&lv.listview_height).local().clone(),
-            listview_width: ctx.map_property_reference(&lv.listview_width).local().clone(),
+            viewport_y: ctx.map_property_reference(&lv.viewport_y),
+            viewport_height: ctx.map_property_reference(&lv.viewport_height),
+            viewport_width: ctx.map_property_reference(&lv.viewport_width),
+            listview_height: ctx.map_property_reference(&lv.listview_height),
+            listview_width: ctx.map_property_reference(&lv.listview_width),
             prop_y: sc.mapping.map_property_reference(&geom.y, ctx.state),
             prop_height: sc.mapping.map_property_reference(&geom.height, ctx.state),
         }

internal/compiler/llr/optim_passes/count_property_use.rs

@@ -43,11 +43,11 @@ pub fn count_property_use(root: &CompilationUnit) {
         for (idx, r) in sc.repeated.iter_enumerated() {
             r.model.borrow().visit_property_references(ctx, &mut visit_property);
             if let Some(lv) = &r.listview {
-                visit_property(&lv.viewport_y.clone().into(), ctx);
-                visit_property(&lv.viewport_width.clone().into(), ctx);
-                visit_property(&lv.viewport_height.clone().into(), ctx);
-                visit_property(&lv.listview_width.clone().into(), ctx);
-                visit_property(&lv.listview_height.clone().into(), ctx);
+                visit_property(&lv.viewport_y, ctx);
+                visit_property(&lv.viewport_width, ctx);
+                visit_property(&lv.viewport_height, ctx);
+                visit_property(&lv.listview_width, ctx);
+                visit_property(&lv.listview_height, ctx);
 
                 let parent_ctx = ParentScope::new(ctx, Some(idx));
                 let rep_ctx = EvaluationContext::new_sub_component(

internal/compiler/llr/optim_passes/remove_unused.rs

@@ -333,11 +333,11 @@ mod visitor {
             }
 
             if let Some(listview) = listview {
-                visit_local_member_reference(&mut listview.viewport_y, &scope, state, visitor);
-                visit_local_member_reference(&mut listview.viewport_height, &scope, state, visitor);
-                visit_local_member_reference(&mut listview.viewport_width, &scope, state, visitor);
-                visit_local_member_reference(&mut listview.listview_width, &scope, state, visitor);
-                visit_local_member_reference(&mut listview.listview_height, &scope, state, visitor);
+                visit_member_reference(&mut listview.viewport_y, &scope, state, visitor);
+                visit_member_reference(&mut listview.viewport_height, &scope, state, visitor);
+                visit_member_reference(&mut listview.viewport_width, &scope, state, visitor);
+                visit_member_reference(&mut listview.listview_width, &scope, state, visitor);
+                visit_member_reference(&mut listview.listview_height, &scope, state, visitor);
 
                 visit_member_reference(&mut listview.prop_y, &inner_scope, state, visitor);
                 visit_member_reference(&mut listview.prop_height, &inner_scope, state, visitor);

tests/cases/issues/issue_11095_listview_twoway_global.slint

@@ -0,0 +1,61 @@
+// Copyright © SixtyFPS GmbH <info@slint.dev>
+// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-2.0 OR LicenseRef-Slint-Software-3.0
+
+// Test that two-way binding between a ListView's viewport-y and a global property
+// compiles and works correctly (issue #11095).
+
+import { ListView } from "std-widgets.slint";
+
+export global GlobalInfo {
+    in-out property <length> saved-viewport-y;
+}
+
+export component TestCase inherits Window {
+    width: 300px;
+    height: 200px;
+
+    in-out property <length> test-viewport-y <=> GlobalInfo.saved-viewport-y;
+
+    lv := ListView {
+        viewport-y <=> GlobalInfo.saved-viewport-y;
+        for i in [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]: Rectangle {
+            height: 100px;
+            background: mod(i, 2) == 0 ? blue : red;
+        }
+    }
+}
+
+/*
+```rust
+let instance = TestCase::new().unwrap();
+
+// Initially viewport-y should be 0
+assert_eq!(instance.get_test_viewport_y(), 0.);
+
+// Set the global property and verify it propagates to the ListView
+instance.set_test_viewport_y(-150.0);
+slint_testing::mock_elapsed_time(100);
+assert_eq!(instance.get_test_viewport_y(), -150.);
+```
+
+```cpp
+auto handle = TestCase::create();
+const TestCase &instance = *handle;
+
+// Initially viewport-y should be 0
+assert_eq(instance.get_test_viewport_y(), 0.);
+
+// Set the global property and verify it propagates to the ListView
+instance.set_test_viewport_y(-150.0);
+slint_testing::mock_elapsed_time(100);
+assert_eq(instance.get_test_viewport_y(), -150.);
+```
+
+```js
+var instance = new slint.TestCase();
+assert.equal(instance.test_viewport_y, 0.);
+instance.test_viewport_y = -150.0;
+slintlib.private_api.mock_elapsed_time(100);
+assert.equal(instance.test_viewport_y, -150.);
+```
+*/