[Bug c++/51571] New: No named return value optimization while adding a dummy scope

[prasoonsaurav.nit at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51571

             Bug #: 51571
           Summary: No named return value optimization while adding a
                    dummy scope
    Classification: Unclassified
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: prasoonsaurav.nit@gmail.com


Simple code snippet

#include <iostream>
int global;
struct A
{
   A(){}
   A(const A&x){
       ++global;
   }
   ~A(){}
};
A foo()
{  
     A a;
     return a;  
}
int main()
{
   A x = foo();
   std::cout << global;
}
Output : 0

When the definition of foo is changed to

A foo()
{ 
  { 
     A a;
     return a;  
  }
}
I get 1 as the output i.e copy c-tor gets called once.

Compiler is not optimizing the call to the copy c-tor in this case.