The BtreeInterfaceImpl::getBulkBuilder method passes a BtreeLogic<OnDiskFormat>::Builder object (new'ed in BtreeLogic<OnDiskFormat>::newBuilder) to the constructor of a BtreeBuilderInterfaceImpl<OnDiskFormat> object, which appears to take ownership of the Builder object. However, the destructor of the BtreeBuilderInterfaceImpl object does not delete the BtreeLogic<OnDiskFormat>::Builder object, and no other references exist.