C++11-style [[unused]] attribute in gcc?

There is [[maybe_unused]] attribute in C++17. It’s implemented in GCC 7, see C++ Standards Support in GCC .

Example from P0212R1 proposal:

[[maybe_unused]] void f([[maybe_unused]] bool thing1,
                        [[maybe_unused]] bool thing2) {
    [[maybe_unused]] bool b = thing1 && thing2;
    assert(b);
}