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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. struct CtorDefParam {
  5. 	CtorDefParam() {
  6. 		cout << __FUNCTION__ << " - def.ctor! " << std::hex << static_cast<void*>(this) << endl;
  7. 	}
  8.  
  9. 	CtorDefParam(CtorDefParam const&
  10. 		, int dummy=0
  11. 	) {
  12. 		cout << __FUNCTION__ << " - cpy.ctor! " << std::hex << static_cast<void*>(this) << endl;
  13. 	}
  14. };
  15.  
  16. CtorDefParam NRVO() {
  17. 	CtorDefParam obj;
  18. 	return obj;
  19. }
  20.  
  21. CtorDefParam RVO() {
  22. 	return CtorDefParam();
  23. }
  24.  
  25. int main()
  26. {
  27. 	cout << "# Init Object (should elide):\n";
  28. 	auto obj1 = CtorDefParam(); // copied once!
  29. 	cout << "# Init obj from function return value (should elide via NRVO):\n";
  30. 	auto obj2 = NRVO(); // copied twice!!!
  31. 	cout << "# Init obj from function return value (should elide via RVO):\n";
  32. 	auto obj3 = RVO(); // copied twice!!!
  33. 	return 0;
  34. }
  35.  
  36.  
Success #stdin #stdout 0s 3296KB
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Standard input is empty
stdout
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# Init Object (should elide):
CtorDefParam - def.ctor! 0xbff3256d
# Init obj from function return value (should elide via NRVO):
CtorDefParam - def.ctor! 0xbff3256e
# Init obj from function return value (should elide via RVO):
CtorDefParam - def.ctor! 0xbff3256f
https://ideone.com/9XcO6w
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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