gen_stub: Add return by reference flag

[Girgias]

Looks like this information is never set anywhere for internal functions/methods that return by reference.

EDIT: I'm not exactly sure that's the correct fix even if it looks like it, because I'm still running into some issues for Girgias#19

[kocsismate]

LGTM! A test in zend_test may be useful, but I'm also fine with the PR as-is.

[kocsismate]

I've just seen your edit: in case of doubt, a test is definitely useful.

Also, I've just found this:

https://github.com/php/php-src/blob/c2a9166ef09df59772bf9d4c42414c9daa64e426/Zend/zend_API.h#L126-L125 based on which it looks like the flag should be set via arginfo.

And later, the ZEND_ACC_RETURN_REFERENCE flag is applied here:

php-src/Zend/zend_API.c

Line 2917 in 1c30c5e

internal_function->fn_flags |= ZEND_ACC_RETURN_REFERENCE;

(I only found these code paths based on a very quick search, so please take it with a grain of salt ^^)

[kocsismate]

Further evidence I found: https://github.com/kocsismate/php-src/blob/c2a9166ef09df59772bf9d4c42414c9daa64e426/Zend/zend_API.h#L201 The returns_reference should be set properly when generating arginfo.

[Girgias]

Turns out the flag is already set, however I have no god-damn clue how one is mean to actually create a reference to some zval* that is usable for userland.

Even copying VM APIs seems to not do what I would expect it to do. So if anyone has any idea how to reliably implement this without using an INDIRECT zval I would love to hear the solution.

[morrisonlevi]

I'm not quite sure I understand your problem. I would mimic ZEND_RETURN_BY_REF:

	// retval_ptr is basically OP1
	if (Z_ISREF_P(retval_ptr)) {
		Z_ADDREF_P(retval_ptr);
	} else {
		ZVAL_MAKE_REF_EX(retval_ptr, 2);
	}
	ZVAL_REF(return_value, Z_REF_P(retval_ptr));

[Girgias]

I'm not quite sure I understand your problem. I would mimic ZEND_RETURN_BY_REF:

	// retval_ptr is basically OP1
	if (Z_ISREF_P(retval_ptr)) {
		Z_ADDREF_P(retval_ptr);
	} else {
		ZVAL_MAKE_REF_EX(retval_ptr, 2);
	}
	ZVAL_REF(return_value, Z_REF_P(retval_ptr));

This does not seem to work.

[nielsdos]

@Girgias This should fix it https://gist.github.com/nielsdos/f519a9c1b019a83871313cd6e6de29f7

[Girgias]

Turns out we already support this and my code was just wrong, because references are weird.