Remove SyncUser::operator==()

It had incorrect semantics (users from different Apps which happened to have
the same id would compare equal), and simply isn't neccesary as there should
only ever be a single SyncUser instance per user and so pointer equality
suffices.

Author: tgoyne

CHANGELOG.md

@@ -17,6 +17,7 @@
 ### Breaking changes
 * SyncUser::provider_type() and realm_user_get_auth_provider() have been removed. Users don't have provider types; identities do.
 * SyncUser no longer has a `local_identity()`. `identity()` has been guaranteed to be unique per App ever since v10.
+* SyncUser no longer overrides operator==. Pointer equality should be used to compare sync users.
 
 ### Compatibility
 * Fileformat: Generates files with format v23. Reads and automatically upgrade from fileformat v5.

src/realm/object-store/c_api/types.hpp

@@ -661,7 +661,7 @@ struct realm_user : realm::c_api::WrapC, std::shared_ptr<realm::SyncUser> {
     bool equals(const WrapC& other) const noexcept final
     {
         if (auto ptr = dynamic_cast<const realm_user*>(&other)) {
-            return *get() == *(ptr->get());
+            return get() == ptr->get();
         }
         return false;
     }

src/realm/object-store/impl/realm_coordinator.cpp

@@ -183,7 +183,7 @@ void RealmCoordinator::set_config(const Realm::Config& config)
         if (config.sync_config) {
             auto old_user = m_config.sync_config->user;
             auto new_user = config.sync_config->user;
-            if (old_user && new_user && *old_user != *new_user) {
+            if (old_user != new_user) {
                 throw LogicError(
                     ErrorCodes::MismatchedConfig,
                     util::format("Realm at path '%1' already opened with different sync user.", config.path));

src/realm/object-store/sync/sync_user.hpp

@@ -284,17 +284,6 @@ class SyncUser : public std::enable_shared_from_this<SyncUser>, public Subscriba
         m_seconds_to_adjust_time_for_testing.store(seconds);
     }
 
-    /// Check the SyncUsers passed as argument have the same remote identity id.
-    friend bool operator==(const SyncUser& lhs, const SyncUser& rhs)
-    {
-        return lhs.identity() == rhs.identity();
-    }
-
-    friend bool operator!=(const SyncUser& lhs, const SyncUser& rhs)
-    {
-        return !(lhs == rhs);
-    }
-
 protected:
     friend class SyncManager;
     void detach_from_sync_manager() REQUIRES(!m_mutex);