How to resolve “must be an instance of string, string given” prior to PHP 7?

Question

Here is my code:

function phpwtf(string $s) {
    echo \"$s\\n\";
}
phpwtf(\"Type hinting is da bomb\");

Which results in this error:

Answer 1

As of PHP 7.0 type declarations allow scalar types, so these types are now available: self, array, callable, bool, float, int, string. The first three were available in PHP 5, but the last four are new in PHP 7. If you use anything else (e.g. integer or boolean) that will be interpreted as a class name.

See the PHP manual for more information.