pass by value and use std::move 

pass by value and use std::move 

parameter 'file_names' is passed by value and only copied once; consider moving it to avoid unnecessary copies 

pass by value and use std::move 

pass by value and use std::move 

initializer for member 'file_names_' is redundant 

pass by value and use std::move 

pass by value and use std::move 

pass by value and use std::move 

parameter 'file_names' is passed by value and only copied once; consider moving it to avoid unnecessary copies 

pass by value and use std::move 

pass by value and use std::move 

pass by value and use std::move 

parameter 'file_names' is passed by value and only copied once; consider moving it to avoid unnecessary copies 

function 'get_from_dir' should be marked [[nodiscard]] 

function 'get_to_dir' should be marked [[nodiscard]] 

function 'get_num_worker' should be marked [[nodiscard]] 

function 'get_file_names' should be marked [[nodiscard]] 

function 'has_file_set' should be marked [[nodiscard]] 

function 'is_gc_enabled' should be marked [[nodiscard]] 

function 'get_gc_snapshot' should be marked [[nodiscard]] 

pass by value and use std::move 

pass by value and use std::move 

the parameter 'options' is copied for each invocation but only used as a const reference; consider making it a const reference 

pass by value and use std::move