c++ - Can compiler optimize return value from copy to a reference? -

if write code way:

shared_ptr<foo> bar::getfoo() {     return m_foo; }  void somewhereelse() {     shared_ptr<foo> foo = mybar.getfoo();     //do stuff foo } 

can compiler somehow optimize code changed that:

void somewhereelse() {     const shared_ptr<foo> &foo = mybar.getfoo__by_ref_somehow();     //do stuff foo } 

i'm asking because problem in case of concurrent execution.

i understand rvo can applied , remove copy, compiler eliminate copy @ all?

no. asked value, get value. copy elision eliding unnecessary copies. wanted value; function returns value. you're going @ least 1 copy. you're wanting form of code transformation, turning value reference.

you create function getfoo__by_ref_somehow, returns const& value stored in class. different function create, not compiler allowed create you.