Needs Feedback - Yield without value in reference generator function does not create notice

Le 26 nov. 2024 à 01:49, aggelos bellos aggelosbellos7@gmail.com a écrit :

In this issue #16761 https://github.com/php/php-src/issues/16761 it was verified that in the above code it should throw a notice for both yields:

<?php
error_reporting(E_ALL);
function &y()
{
  yield null; // warning
  yield; // no warning, agreed to be a bug
}
foreach (y() as &$y);

I have created this PR https://github.com/php/php-src/pull/16882 which adds the "missing" notice but we aren't sure on
how to continue on this.
There are 2 main questions:
Should we continue with adding the missing notice and merge it also in master?
Should we deprecate / remove the usage of yield without value in reference generator functions?

A notice would be consistent with what happens with: function &f() { return; }; f();. But don’t add new notices in patch releases, otherwise you may break without warning a non-trivial amount of code that conflates notices with fatal errors. The bug is not serious enough to warrant such a risk.

Whether it should be deprecated, is a separate question. You should also consider what to do with: function &g() { yield null; }, function &g() { if (false) yield; }, function &f() { return; }, etc.

In my opinion, whether it should be deprecated is not a separate
question, but the one we should answer first. If we're not going to
deprecate/remove the auto-conversion to a reference, we may as well drop
the notice altogether, instead of adding a further notice.

Christoph