foo.php

<?php

// Proposal: Support `::function` syntax for sake of readability, static
// analysis, and consistency with `::class` syntax.

// For example, instead of:
call_user_func('printf', "hello\n");

// favor:
call_user_func(printf::function, "hello\n");

// Cases which some may find helpful/explicit, others may find confusing:
class X {
    const F = printf::function;
    static function sf($x) { return printf($x); }
    function f($x)         { return printf($x); }
    static function ff()   { return self::F; }
};
$x = new X();
call_user_func('printf'::function, "A\n");
call_user_func([$x, 'f']::function, "B\n");
call_user_func('X::sf'::function, "C\n");
call_user_func(X::F::function, "D\n");
call_user_func((fn ($x) => printf($x))::function, "E\n");
call_user_func((fn () => 'printf')()::function, "F\n");

// Needless case:
var_dump(printf::function::function::function);

// The proof-of-concept patch breaks in the case below. I think it may require
// altering ZEND_FETCH_CLASS_NAME, or emitting a new opcode, or reserving
// the field name `function` as we do with `class`.
class Y {
    const function = 'Z';
}
var_dump(Y::function); // should be "Z", but is "Y"