C++: Using auto to declare classes as variables inside functions

Question

I'm trying to use auto for all local variables inside my functions.

Take the following code:

class obj 

{

  public:

  obj() {};

  obj( obj&& o ) = delete;

};



int main()

{

  obj test0;

  auto test1 = obj();



  return 0;

}

Compiling the code:

$ g++ --std=c++1z main.cpp

main.cpp: In function ‘int main()’:

main.cpp:13:20: error: use of deleted function ‘obj::obj(obj&&)’

   auto test1 = obj();

Notice that defining test0 is completely okay, but attempting to do the exact same type of declaration of test1 is a compiler error. Clearly is should be a compiler error, but in this case, does it mean obj can't be defined with auto? I'm running into this problem with QT objects I don't have control over.

Am I suck still using the C++98 format for declaring variables or is there another way to use auto?

Thanks!!!

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Answer 1

This is OK in C++17; guaranteed copy elision adjusts the rules so that a move constructor isn't even conceptually called, so it doesn't matter if it's deleted or inaccessible.

Before then, if you love auto so much, you can do

auto&& test1 = obj();

C++: Using auto to declare classes as variables inside functions

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