&&

[Wu zhen hai]

#include <iostream>

int main()
{
	int x = 1;
	int&& x1 = static_cast<int&&>(x);
	int&& x2 = x1;
}

//why a compilation errror?

[gedamial]

x, x1 and x2 are all l-values since they have a name and are addressable in memory

[cire]

The more usual way to write that would be (with the error corrected):

#include <utility>

int main()
{
	int x = 1;
	int&& x1 = std::move(x);
	int&& x2 = std::move(x1);
}

Btw, when posting about compilation errors, provide the text of the error.

[Wu zhen hai]

@gedanial, Thanks!
@cire, it is equal to:

#include <utility>

int main()
{
	int x = 1;
	int&& x1 = static_cast<int&&>(x);
	int&& x2 = static_cast<int&&>(x1);
}