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  • Why does std::move prevent RVO (return value optimization)?
    Hence in a return statement copy elision can only occur, if the expression is the name of a local variable If you write std::move(var), then it is not the name of a variable anymore Therefore the compiler cannot elide the move, if it should conform to the standard
  • C++ 函数返回局部变量的std::move ()问题？ - 知乎
    这时候用move就合情合理。 那到底什么时候应该move，什么时候应该依靠copy elision呢？ 通常主流的编译器都会100% copy elision以下两种情况： 1 URVO（Unnamed Return Value Optimization)：函数的所有执行路径都返回 同一个类型的匿名变量，比如
  • How to avoid the pessimizing-move warning of NRVO?
    I know if I change return std::move(s); to return s;, the warning will be avoided However, according to the C++ standard, NRVO, say in this case, is not guaranteed If I write return s;, I feel uncertain whether NRVO will be executed How to ease the feel of uncertainty?
  • What are copy elision and return value optimization?
    Common forms of copy elision For a technical overview - skip to this answer For a less technical view introduction - skip to this answer (Named) Return value optimization is a common form of copy elision It refers to the situation where an object returned by value from a method has its copy elided The example set forth in the standard illustrates named return value optimization, since
  • Return value optimization or move in C++11 - Stack Overflow
    Since C++ 17, copy elision is mandatory for return statement prvalue object initialisers and variable prvalue object initialisers, therefore the option now only disables copy elision in the remaining cases
  • Why copy elision not working with std::move? - Stack Overflow
    Copy elision for can only occur in a few specific situations, the most common of which is the copying of a temporary (the others are returning locals, and throwing catching exceptions) There is no temporary being produced by your code, so no copy is elided The copy constructor is being called because foo does not have a move constructor (move constructors are not implicitly generated for
  • Using std::move () when returning a value from a function to avoid to copy
    No Whenever a local variable in a return statement is eligible for copy elision, it binds to an rvalue re­fe­rence, and thus return t; is identical to return std::move(t); in your example with respect to which constructors are eligible Note however that return std::move(t); prevents the compiler from exercising copy elision, while return t; does not, and thus the latter is the preferred
  • c++ - std::move versus copy elision - Stack Overflow
    Since this is assignment I don't think it's possible for copy elision to take place, but as eerorika points out your std::move is redundant because you're casting an rvalue into an rvalue, so the clang warning is still pertinent


















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