I order to capture a warning for debugging, you could (locally with local ) change sigwarn

  DB<120> $SIG{__WARN__} = sub { print "<<<$_[0]>>>" }

  DB<121> warn "xxx" 
<<<xxx at (eval 58)[multi_perl5db.pl:644] line 2.
>>>

[download]

you can also run perlcode in a regex which checks $2 explicitly

edit

like in

  DB<133> $x =~ s/ (?{ print "\$2 undefined" unless $2 })/ /g
$2 undefined

[download]

And finally: please note that you are already using two eval levels with /ee (why?) so how to run check code should be obvious.

Cheers Rolf
(addicted to the Perl Programming Language and ☆☆☆☆ :)
Je suis Charlie!

In reply to Re: On error, how to show the regexp values? (tracing warnings) by LanX
in thread Tracing warnings: how to show the regexp values? by nikolay

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