by Perl. This combination appears in an interpolated variable or a
C<'>-delimited regular expression.
+=item /%s/ should probably be written as "%s"
+
+(W) You have used a pattern where Perl expected to find a string,
+like in the first argument to C<join>. Perl will treat the true
+or false result of matching the pattern against $_ as the string,
+which is probably not what you had in mind.
+
=item %s (...) interpreted as function
(W) You've run afoul of the rule that says that any list operator followed