sub to_literal { "'$_[0]'" }

my $x;
for (...) {
    if (!$x) {
        $x = to_literal($_);
    } else {
        $x = join(', ', to_literal($_));
    }
}
my @a = eval $x;

##</code><code>##

sub to_literal { "'\Q$_[0]\E'" }     <---

my $x;
for (...) {
    if (!defined($x)) {              <---
        $x = to_literal($_);
    } else {
        $x = join(', ', to_literal($_));
    }
}
my @a = eval $x;

##</code><code>##

my @a;
for (...) {
    push @a, $_;
}