Express `Results`' asignment operators in terms of their equivalent

constructors.

This avoids having to repeat the move constructor's logic in the move
assignment operator, and allows the copy assignment operator to compile
despite `TableViewBase`'s missing copy assignment implementation. the
copy assignment implementation can be defaulted once `TableViewBase` is
fixed.

src/results.cpp

@@ -88,30 +88,16 @@ Results::Results(SharedRealm r, const ObjectSchema& o, TableView tv, SortOrder s
 
 Results::Results(const Results& other) = default;
 
-#if 0
-// FIXME: TableViewBase::operator= is missing from the core static library.
+// Cannot be defaulted as TableViewBase::operator= is missing from the core static library.
+// Delegate to the copy constructor and move-assignment operators instead.
 Results& Results::operator=(const Results& other)
 {
-    if (this == &other) {
-        return *this;
+    if (this != &other) {
+        *this = Results(other);
     }
 
-    m_realm = other.m_realm;
-    m_object_schema = other.m_object_schema;
-    m_query = other.m_query;
-    m_table_view = other.m_table_view;
-    m_link_view = other.m_link_view;
-    m_table = other.m_table;
-    m_sort = other.m_sort;
-    m_live = other.m_live;
-    m_notifier.reset();
-    m_mode = other.m_mode;
-    m_has_used_table_view = false;
-    m_wants_background_updates = true;
-
     return *this;
 }
-#endif
 
 Results::Results(Results&& other)
 : m_realm(std::move(other.m_realm))
@@ -134,23 +120,8 @@ Results::Results(Results&& other)
 
 Results& Results::operator=(Results&& other)
 {
-    m_realm = std::move(other.m_realm);
-    m_object_schema = std::move(other.m_object_schema);
-    m_query = std::move(other.m_query);
-    m_table_view = std::move(other.m_table_view);
-    m_link_view = std::move(other.m_link_view);
-    m_table = other.m_table;
-    m_sort = std::move(other.m_sort);
-    m_live = other.m_live;
-    m_notifier = std::move(other.m_notifier);
-    m_mode = other.m_mode;
-    m_has_used_table_view = other.m_has_used_table_view;
-    m_wants_background_updates = other.m_wants_background_updates;
-
-    if (m_notifier) {
-        m_notifier->target_results_moved(other, *this);
-    }
-
+    this->~Results();
+    new (this) Results(std::move(other));
     return *this;
 }