Oct 18, 2012 · This ensures that copy elision does not allow copying objects which are not normally copyable, e.g. because they have a private or deleted copy/move constructor. C++17: As of C++17, Copy Elision is guaranteed when an object is returned directly, and in this case, the copy or move constructor need not be accessible or present:

Dec 6, 2017 · Several things are going on here. funcElision is omitting the copy in its return because of Named Return Value Optimization (NRVO), a special rule for named return values when: "a function returns a class type by value, and the return statement's expression is the name of a non-volatile object with automatic storage duration, which isn't a function parameter, or a …

Jan 30, 2019 · Elision will not happen there, see @Barry's answer for details. In short, push_back does not support elision; it takes an rvalue reference or a const lvalue reference. You have an actual rvalue; calling std::move casts that rvalue into …

Jan 27, 2010 · If copy elision were not allowed, that line would require 3 invocations of the copy constructor and an associated call to a destructor. With copy elision being allowed, it can be reduced to 1 call of the copy constructor, the explicit one inside of BigCount::next() where newcounter is declared. If operator = had been declared and defined like this:

Aug 24, 2020 · When constructing std::tuple<int, INeedElision> from {i, {47}}, the selected constructor of std::tuple takes elements by lvalue-reference to const.

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.

Jan 4, 2018 · Copy elision (before C++17) always requires the elided constructor to be actually accessible, so it cannot be the cause of your code working. Note, however, that C++ (since C++11) has a rule (12.8/32) which boils down to the following: "when returning an object, then under certain circumstances, first try treating the object as an rvalue and ...

Dec 9, 2024 · When copy elision occurs, the implementation treats the source and target of the omitted copy/move(since ...

Jun 13, 2018 · That is evident if you declare the copy constructor explicit in above case (the compiler errors out). But I don't I see the output of copy constructor when it is not declared as explicit. I guess that is because of copy elision. Is there any way to disable copy elision or does the standard mandates it?

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.