$rv is clearly undefined. An undefined value is represented by an empty string when printed (whether it is in an interpolated string or not).

#!/usr/bin/perl
use strict;
my $rv = 42 for (1);
print "rv unquoted: '", $rv, "'\n";
print "rv quoted: '$rv'\n";

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In reply to Re^2: my Scope Pop Quiz by Mr. Muskrat
in thread my Scope Pop Quiz by saintmike

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