return value optimization
... that the return value optimization is one of the very few compiler optimizations that are allowed to change the observable behaviour of a C++ program?
... that the <b id="mwArA"><a class="mw-redirect" href="./Return_value_optimization" id="mwArE" rel="mw:WikiLink" title="Return value optimization">return value optimization</a></b> is one of the very few <a class="mw-redirect" href="./Compiler_optimization" id="mwArI" rel="mw:WikiLink" title="Compiler optimization">compiler optimizations</a> that are allowed to change the observable behaviour of a <a href="./C++" id="mwArM" rel="mw:WikiLink" title="C++">C++</a> program?