C++ Question
C++: Using auto to declare classes as variables inside functions
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!!!
Answer Source
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();