Make sure we replicate instructions unconditionally (#7523)

Eg. List::clear should replicate even though the list is already empty.
Obj::set should replicate even though old and new values are equal.

This has influence on OT. If you want to assign new values to an empty
list and does not replicate the clear instruction you could end up having
your values added to some content added by another client.

Author: jedelbo

src/realm/dictionary.cpp

@@ -433,16 +433,8 @@ void Dictionary::insert_collection(const PathElement& path_elem, CollectionType
     if (dict_or_list == CollectionType::Set) {
         throw IllegalOperation("Set nested in Dictionary is not supported");
     }
-
     check_level();
-    ensure_created();
-    Mixed new_val(0, dict_or_list);
-    auto old_val = try_get(path_elem.get_key());
-    if (!old_val || *old_val != new_val) {
-        m_values->ensure_keys();
-        auto [it, inserted] = insert(path_elem.get_key(), new_val);
-        set_key(*m_values, it.index());
-    }
+    insert(path_elem.get_key(), Mixed(0, dict_or_list));
 }
 
 DictionaryPtr Dictionary::get_dictionary(const PathElement& path_elem) const
@@ -549,6 +541,7 @@ std::pair<Dictionary::Iterator, bool> Dictionary::insert(Mixed key, Mixed value)
         throw StaleAccessor("Stale dictionary");
     }
 
+    bool set_nested_collection_key = value.is_type(type_Dictionary, type_List);
     bool old_entry = false;
     auto [ndx, actual_key] = find_impl(key);
     if (actual_key != key) {
@@ -577,16 +570,25 @@ std::pair<Dictionary::Iterator, bool> Dictionary::insert(Mixed key, Mixed value)
             repl->dictionary_insert(*this, ndx, key, value);
         }
     }
-
     bump_content_version();
 
     ObjLink old_link;
     if (old_entry) {
         Mixed old_value = m_values->get(ndx);
-        if (old_value.is_type(type_TypedLink)) {
-            old_link = old_value.get<ObjLink>();
+        if (!value.is_same_type(old_value) || value != old_value) {
+            if (old_value.is_type(type_TypedLink)) {
+                old_link = old_value.get<ObjLink>();
+            }
+            m_values->set(ndx, value);
         }
-        m_values->set(ndx, value);
+        else {
+            set_nested_collection_key = false;
+        }
+    }
+
+    if (set_nested_collection_key) {
+        m_values->ensure_keys();
+        set_key(*m_values, ndx);
     }
 
     if (new_link != old_link) {

src/realm/list.cpp

@@ -408,8 +408,12 @@ Mixed Lst<Mixed>::set(size_t ndx, Mixed value)
     if (Replication* repl = Base::get_replication()) {
         repl->list_set(*this, ndx, value);
     }
-    if (!(old.is_same_type(value) && old == value)) {
+    if (!value.is_same_type(old) || value != old) {
         do_set(ndx, value);
+        if (value.is_type(type_Dictionary, type_List)) {
+            m_tree->ensure_keys();
+            set_key(*m_tree, ndx);
+        }
         bump_content_version();
     }
     return old;
@@ -427,6 +431,10 @@ void Lst<Mixed>::insert(size_t ndx, Mixed value)
         repl->list_insert(*this, ndx, value, sz);
     }
     do_insert(ndx, value);
+    if (value.is_type(type_Dictionary, type_List)) {
+        m_tree->ensure_keys();
+        set_key(*m_tree, ndx);
+    }
     bump_content_version();
 }
 
@@ -529,37 +537,17 @@ void Lst<Mixed>::insert_collection(const PathElement& path_elem, CollectionType
     if (dict_or_list == CollectionType::Set) {
         throw IllegalOperation("Set nested in List<Mixed> is not supported");
     }
-
-    ensure_created();
     check_level();
-    m_tree->ensure_keys();
     insert(path_elem.get_ndx(), Mixed(0, dict_or_list));
-    set_key(*m_tree, path_elem.get_ndx());
-    bump_content_version();
 }
 
 void Lst<Mixed>::set_collection(const PathElement& path_elem, CollectionType dict_or_list)
 {
     if (dict_or_list == CollectionType::Set) {
         throw IllegalOperation("Set nested in List<Mixed> is not supported");
     }
-
-    auto ndx = path_elem.get_ndx();
-    // get will check for ndx out of bounds
-    Mixed old_val = do_get(ndx, "set_collection()");
-    Mixed new_val(0, dict_or_list);
-
     check_level();
-
-    if (old_val != new_val) {
-        m_tree->ensure_keys();
-        set(ndx, new_val);
-        int64_t key = m_tree->get_key(ndx);
-        if (key == 0) {
-            set_key(*m_tree, path_elem.get_ndx());
-        }
-        bump_content_version();
-    }
+    set(path_elem.get_ndx(), Mixed(0, dict_or_list));
 }
 
 DictionaryPtr Lst<Mixed>::get_dictionary(const PathElement& path_elem) const

src/realm/list.hpp

@@ -928,10 +928,11 @@ inline LnkLst Obj::get_linklist(StringData col_name) const
 template <class T>
 void Lst<T>::clear()
 {
-    if (size() > 0) {
-        if (Replication* repl = Base::get_replication()) {
-            repl->list_clear(*this);
-        }
+    auto sz = size();
+    if (Replication* repl = Base::get_replication()) {
+        repl->list_clear(*this);
+    }
+    if (sz > 0) {
         do_clear();
         bump_content_version();
     }