issue #21044: mortalization of undef return

Porters,

This email is about a release blocker, #21044 <https://github.com/Perl/perl5/issues/21044>.

snowdrop:~$ perl5.36.0 -e '$_->{x} for sub { undef }->()'
snowdrop:~$ echo $?
0

Great.  But:

snowdrop:~$ perl5.37.10 -e '$_->{x} for sub { undef }->()'
Modification of a read-only value attempted at -e line 1.

This affects code on the CPAN, and it doesn't seem like an extremely unusual thing to expect out in the world.  Richard L. suggested we revert #20800 <https://github.com/Perl/perl5/pull/20800>.  Any objections or better ideas?

-- 
rjbs

• issue #21044: mortalization of undef return by Ricardo Signes
• Re: issue #21044: mortalization of undef return by Tony Cook
• Re: issue #21044: mortalization of undef return by Ricardo Signes