Will run. Which is weird

You're actually matching the string as you're using the balanced delimiters syntax of a regex match e.g

shell> perl -MO=Deparse -
sub m{
 local *_=\$_[0];
 s///;
}
 m("String");

sub m {
    local *_ = \$_[0];
    s///;
}
/"String"/;
- syntax OK
[download]

But if you change that sub name to replace then you get the expected error message

sub replace {
  local *_=\$_[0];
  s///;
}
replace("String");

Modification of a read-only value attempted at pmsopw_250834.pl line 3
+.
[download]

HTH

_________
broquaint