Fix assertion failed: lhs_lookup.is_local_to_component

Fixes #6632

Author: ogoffart

internal/compiler/passes/resolving.rs

@@ -1591,10 +1591,12 @@ fn resolve_two_way_bindings(
                                 .or_default()
                                 .is_linked = true;
 
-                            if lhs_lookup.property_visibility == PropertyVisibility::Private
-                                && !lhs_lookup.is_local_to_component
+                            if matches!(
+                                lhs_lookup.property_visibility,
+                                PropertyVisibility::Private | PropertyVisibility::Output
+                            ) && !lhs_lookup.is_local_to_component
                             {
-                                // Assignment to private property should have been reported earlier
+                                // invalid property assignment should have been reported earlier
                                 assert!(diag.has_errors());
                                 continue;
                             }

internal/compiler/tests/syntax/fuzzing/6632.slint

@@ -0,0 +1,9 @@
+// Copyright © SixtyFPS GmbH <[email protected]>
+// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-2.0 OR LicenseRef-Slint-Software-3.0
+
+export component S{
+    t:=TextInput{
+        has-focus<=>t.has-focus;
+//      ^error{Cannot assign to output property 'has-focus'}
+    }
+}

internal/compiler/tests/syntax/new_syntax/two_way_input_output.slint

@@ -336,9 +336,31 @@ export component C13 {
 //           ^error{Cannot assign to private property 'internal'}
     Button { internal <=> self.checked; }
 //           ^error{Cannot assign to private property 'internal'}
+
+    Button { pressed <=> self.pressed; }
+//           ^error{Cannot assign to output property 'pressed'}
+    Button { pressed <=> self.checked; }
+//           ^error{Cannot assign to output property 'pressed'}
+    Button { pressed <=> self.enabled; }
+//           ^error{Cannot assign to output property 'pressed'}
+    Button { pressed <=> self.accessible-checked; }
+//           ^error{Cannot assign to output property 'pressed'}
+    Button { pressed <=> self.internal; }
+//           ^error{Cannot assign to output property 'pressed'}
+//                            ^^error{The property 'internal' is private. Annotate it with}
+    Button { pressed <=> out; }
+//           ^error{Cannot assign to output property 'pressed'}
+    Button { pressed <=> in; }
+//           ^error{Cannot assign to output property 'pressed'}
+    Button { pressed <=> inout; }
+//           ^error{Cannot assign to output property 'pressed'}
+    Button { pressed <=> priv; }
+//           ^error{Cannot assign to output property 'pressed'}
+
 }
 
 export Legacy1 := Rectangle {
+//             ^warning{':=' to declare a component is deprecated}
     b1:= Button {}
     in property in1 <=> b1.pressed;
 //                  ^warning{Link to a output property is deprecated}