Fix FETCH_STATIC_PROP_W to prevent returning INDIRECT/UNDEF zval

[dstogov]

This behaviour repeats FETCH_OBJ_W behaviour introduced by the typed properties patch.

[dstogov]

Note this sets type of the property to NULL that is not valid and the next instruction must change it to valid ARRAY.

I'm not completely sure why @nikic decided non to return UNDEF for FETCH_OBJ_W.
It's not supported by optimizer and JIT, but this may be fixed.
May be there are some more fundamental problems.

For now I decided to fix this in a consistent with FETCH_OBJ_W way.

[nikic]

I'm not completely sure why @nikic decided non to return UNDEF for FETCH_OBJ_W.

Not sure I understand. Isn't this case handled by zend_handle_fetch_obj_flags with ZEND_FETCH_DIM_WRITE flag, in which case we keep the UNDEF until promotion? Setting it to null doesn't seem right.

[dstogov]

It's set to NULL at https://github.com/php/php-src/blob/master/Zend/zend_execute.c#L3230

[nikic]

I see, you're right. Unfortunately I don't remember why it is implemented in this way.

[dstogov]

I see, you're right. Unfortunately I don't remember why it is implemented in this way.

OK. I'll try another way, but I afraid it may be dangerous to commit this serious change into stable branch(es).

[dstogov]

@nikic please take a look at #11048 when you have time