How to enforce copy elision, why it won’t work with deleted copy constructor?

by

Until C++17 copy elision is an optimization the compiler is not required to do, so classes must be copyable since the compiler might want to copy (even if it actually does not). In C++17 copy elision will be guaranteed in many cases and then classes won’t need copy ctors.

See also:

http://en.cppreference.com/w/cpp/language/copy_elision

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0135r0.html

https://herbsutter.com/2016/06/30/trip-report-summer-iso-c-standards-meeting-oulu/
(the bit about “Guaranteed copy elision”)

You could perhaps use the old trick of declaring the copy constructor in your class but not actually implement it? That should please the compiler as long as it does not actually invoke the copy ctor. I didn’t test that, but I believe it should work for your case until C++17 arrives.

More Related Contents:

  1. what is the concept of evaluation of expression z = (y = 30) + (y = 10) + (y = 20); [closed]
  2. C++ 11: conversion const int* to int* using unordered_set::push
  3. What are copy elision and return value optimization?
  4. Is cout synchronized/thread-safe?
  5. Is local static variable initialization thread-safe in C++11? [duplicate]
  6. Do rvalue references to const have any use?
  7. How to succinctly, portably, and thoroughly seed the mt19937 PRNG?
  8. Does constexpr imply inline?
  9. C++11: The range-based for statement: “range-init” lifetime?
  10. Do rvalue references allow dangling references?
  11. What does this variadic template code do?
  12. Get base class for a type in class hierarchy
  13. Garbage Collection in C++ — why?
  14. std::unique_ptr, deleters and the Win32 API
  15. Difference between std::system_clock and std::steady_clock?
  16. C++ Modules – why were they removed from C++0x? Will they be back later on?
  17. Which headers in the C++ standard library are guaranteed to include another header?
  18. Default template argument when using std::enable_if as templ. param.: why OK with two template functions that differ only in the enable_if parameter?
  19. How can an incomplete type be used as a template parameter to vector here?
  20. How can I use C++ 11 features in Clang?
  21. The new keyword “auto”; When should it be used to declare a variable type? [duplicate]
  22. When Does Move Constructor get called?
  23. Questions about Hinnant’s stack allocator
  24. Equivalent of “using namespace X” for scoped enumerations?
  25. The implementation of random_device in VS2010?
  26. Idiomatic Way to declare C++ Immutable Classes
  27. Why is reinterpret_cast not constexpr?
  28. const auto std::initializer_list difference between Clang and GCC
  29. Workaround for error C2536: cannot specify explicit initializer for arrays in Visual Studio 2013
  30. Is it possible to write an agile Pimpl in c++?

Leave a Comment