Oct 18, 2012 · 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).

Jan 18, 2022 · 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.

Mar 16, 2023 · Moving a temporary object prevents copy elision (fix available)clang(-Wpessimizing-move) I am using clang-14 and vscode, vscode's quick fix let me delete std::move, but why?

Jun 2, 2017 · Copy elision was permitted to happen under a number of circumstances. However, even if it was permitted, the code still had to be able to work as if the copy were not elided. Namely, there had to be an accessible copy and/or move constructor. Guaranteed copy elision redefines a number of C++ concepts, such that certain circumstances where copies/moves …

Dec 6, 2017 · CPP Refs states: — when a temporary class object that has not been bound to a reference (12.2) would be copied/moved to a class object with the same cv-unqualified type, the copy/move operation ...

May 15, 2019 · So copy elision or not the example code is correct because std::unique_ptr has a move constructor and I am passing in an rvalue. This other answer is pretty comprehensive.

Aug 8, 2017 · @Zereges When copy/move elision is allowed, it is allowed even if the compilers have side effects (in the formal sense defined by the standard).

Copy elision (the mechanism behind RVO) is permitted only under certain, strict conditions. Writing std::move prevents those conditions from being met.

Nov 23, 2015 · Copy elision is the only allowed form of optimization that can change the observable side-effects. Consequently, due to the fact that some compilers do not perform copy elision in every situation where it is allowed (e.g., in debug mode), programs that rely on the side-effects of copy/move constructors and destructors are not portable.

Aug 24, 2020 · you only get copy elision if you return the object itself : std::vector<int> fn1() { return std::vector<int>{}; // guaranteed copy elision } std::vector<int> fn2() { std::vector<int> vec; return vec; // a good compiler will manage to elide the copy/move here } in your case you are returning tuple so the tuple itself maybe copy elided but not the arguments passed to the …