test: add unexpected allowed expression position showcase

[xepozz]

Hi!

I'm playing with PHP's internals and see how throw can be used within any other expr variations.

Realtime example: https://3v4l.org/WkOUr

So, quite interesting. Is it expected behavior?

try {
    (function () {
        return "string" + throw null ?? throw new Exception('return throw null ?? throw new Exception();');
    })();
} catch (Exception $e) {
    var_dump($e->getMessage());
}

try {
    (function () {
        return "string1" . 5 . "ok" / throw throw throw throw new Exception("cool");
    })();
} catch (Exception $e) {
    var_dump($e->getMessage());
}

The result is successful:

string(43) "return throw null ?? throw new Exception();"
string(4) "cool"

[iluuu1994]

@xepozz Yes, this is expected behavior. You only get an Error exception when the throw is actually executed. https://3v4l.org/fkSnW

[xepozz]

@iluuu1994 Yeap, I understand how it works.

I don't like that throw can be used as this: https://3v4l.org/RqqZK

Looks like we have one more way to do same thing:

• throw
• return + throw
• return + throw + throw + throw ...

As well as the rest operations with the throw operation: https://3v4l.org/j7tO4

[iluuu1994]

@xepozz throw is an expression since https://wiki.php.net/rfc/throw_expression, and it also accepts arbitrary expressions as its exception argument, so naturally you can combine it in non-sensical ways.

[xepozz]

Actually, it does not make such constructions less weird.

Anyway, would you accept the test case? Is there something left from my side?

[iluuu1994]

Anyway, would you accept the test case? Is there something left from my side?

Sure, expanding the tests is useful, as long as they test something that hasn't been tested before. It's not completely clear to me from the PR what that is.

return "string" + throw null ?? throw new Exception('return throw null ?? throw new Exception();');

What is this test showing? That the throw may occur after +, or the throw (null ?? throw) precedence?

return "string1" . 5 . "ok" / throw throw throw throw new Exception("cool");

Similarly, what is this showing? That throw throw may be used? Then why do we need 4 of them? 🙂