[Bug libstdc++/52745] New: GCC4.7 vector uses copy instead of move constructor
J.W.Rogers+gcc at gmail dot com
gcc-bugzilla@gcc.gnu.org
Tue Mar 27 23:06:00 GMT 2012
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52745
Bug #: 52745
Summary: GCC4.7 vector uses copy instead of move constructor
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: J.W.Rogers+gcc@gmail.com
Using GCC 4.7.0, vector seems to prefer copy rather than move when resizing.
The following program produces different (and I think incorrect) results under
GCC 4.7.0 vs GCC 4.6.1
#include <iostream>
#include <vector>
struct Stuff
{
Stuff( ) { }
Stuff( Stuff&& o ) { std::cout << "Move" << std::endl; }
Stuff( const Stuff& o ) { std::cout << "Copy" << std::endl; }
};
int main( const int argc, const char** argv )
{
std::vector< Stuff > stuff;
std::cout << "1" << std::endl;
stuff.push_back( Stuff() );
std::cout << "2" << std::endl;
stuff.push_back( Stuff() );
std::cout << "3" << std::endl;
stuff.push_back( Stuff() );
}
Here is the output under GCC 4.6.1
jonathan@grindserv:~$ g++-4.6.1 -std=c++0x test.cpp
jonathan@grindserv:~$ ./a.out
1
Move
2
Move
Move
3
Move
Move
Move
Here is the output under GCC 4.7.0
jonathan@grindserv:~$ g++-4.7.0 -std=c++0x test.cpp
jonathan@grindserv:~$ ./a.out
1
Move
2
Move
Copy
3
Move
Copy
Copy
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