In this post, we are going to discuss a core language feature proposed by Corentin Jabot and Micheal Park in P2169R4. With the new standard we get a cool unnamed placeholder.

C++26: A Placeholder with No Name

by Sandor Dargo

From the article:

By convention, when we have a variable whose value we don’t want to use or care about, we often name it _. The problem is that with higher warning levels (-Wunused-variable), our compilation might fail because _ is unused.

int foo() {
return 42;
}

auto _ = foo();
/* error: unused variable '_' [-Werror,-Wunused-variable] */

To avoid this problem, we must mark it [[maybe_unused]].