Bug #69419 [Com]: Returning compatible sub generator produces a warning

Edit report at https://bugs.php.net/bug.php?id=69419&edit=1 ID: 69419 Comment by: nikic@php.net Reported by: elliotlevin at hotmail dot com Summary: Returning compatible sub generator produces a warning Status: Closed Type: Bug Package: Scripting Engine problem PHP Version: master-Git-2015-04-10 (Git) Assigned To: nikic Block user comment: N Private report: N New Comment: I've split the inheritance issue into another bug: https://bugs.php.net/bug.php?id=69447. Previous Comments: ------------------------------------------------------------------------ [2015-04-14 14:39:28] nikic@php.net Automatic comment on behalf of nikic Revision: http://git.php.net/?p=php-src.git;a=commit;h=95650d0942c99db8c247797d2ce708a586298ae9 Log: Fixed bug #69419 ------------------------------------------------------------------------ [2015-04-10 16:07:58] nikic@php.net Another interesting case I didn't consider before is this: <?php class A { public function &gen() { yield; } } class B extends A { public function gen() { yield; } } ?> Currently this throws the usual LSP strict standards notice, because by-reference returns are covariant. Intuitively this seem correct to me as well, as you can iterate a by-ref generator by-val, but can't iterate a by-val generator by-ref. ------------------------------------------------------------------------ [2015-04-10 15:33:38] nikic@php.net The behavior in PHP 7 is correct, I'll fix it to throw a strict standards notice in 5.x as well. ------------------------------------------------------------------------ [2015-04-10 13:02:37] elliotlevin at hotmail dot com Description: ------------ When generators were implemented, a generator function could return another generator even if it was a return by reference generator. In PHP7 this now produces a warning because it is not a variable. See http://3v4l.org/sFR11#vphp7@20141101 Test script: --------------- <?php function & genRefInner() { $var = 1; yield $var; } function & genRefOuter() { return genRefInner(); } foreach(genRefOuter() as $i) { var_dump($i); } ?> Expected result: ---------------- int(1) Actual result: -------------- Notice: Only variable references should be returned by reference in /in/sFR11 on line 9 int(1) ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=69419&edit=1