2012年10月18日 · Copy elision is an optimization implemented by most compilers to prevent extra (potentially expensive) copies in certain situations. It makes returning by value or pass-by-value feasible in practice (restrictions apply).

2022年1月18日 · The hint is still correct though, since std::move on a temporary either doesn't have any effect at all (as here) or prevents elision if used in a context where copy elision would otherwise be allowed/mandatory, for example if this was the initializer of m_thread instead of an assignment to it.

2018年6月13日 · Pre C++ 17 A a3 = 0; will call copy constructor unless copy is elided. Pass -fno-elide-constructors flag from C++17, copy elision is guaranteed. So you will not see copy constructor getting called.

I want to know when copy/move elision applies (or is allowed to apply) to explicitly delete d copy/move constructors and to non- delete d copy/move constructors.

2015年7月3日 · Copy elision is important in c++ because of construction process and object semantics. In c you don't have this. A copy is just a dumb byte by byte copy, subject to usual variable management optimisation

2015年5月4日 · My question is about the compiler making unnecessary copies when returning structs in C. Do C compilers such as GCC use Return value optimization (RVO) optimization or is this a C++ only concept? Everything I have read about RVO and copy elision is in regards to C++. Let's consider an example.

2013年6月7日 · Suppose there's an std::array to be initialized. It's okay if using double braces: std::array<int, 2> x = {{0, 1}}; std::array<int, 2> x{{0, 1}}; It's also okay to use single braces in the good old aggregate initialization, as the brace elision will take care of the missing braces: std::array<int, 2> x = {0, 1}; However, is it okay to use list …

2010年4月5日 · Note that copy elision doesn't help with assignment, so the following will always result in a call to operator= if that operator prints anything: Foo f(1); f = getFoo(); Returning by value therefore can still result in "a copy", even if copy constructor elision is performed.

2018年1月4日 · Copy elision (before C++17) always requires the elided constructor to be actually accessible, so it cannot be the cause of your code working.

2016年10月9日 · For copy elision, you need to have the "copy" in the first place, i.e. your res vector has to be copy constructed from the return value. Otherwise you'll just have an assignment, which requires getting rid of whatever was in the vector and as such cannot be elided.