For the more general question of operator precedence, you might want to check out the -p option of Deparse, which will add parentheses as needed to make the precedence clear.

Unfortunately it appears that my Deparse chokes on =~, but the principle is the same for something like +, and for

if(lc $foo + lc $bar) {print $foo} produces

if (lc(($foo + lc($bar)))) {
    print($foo);
}
-e syntax OK
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I'd like to be able to assign to an luser