cperl-bad-style-regexp

cperl-bad-style-regexp is a variable defined in `cperl-mode.el'.
Its value is

"[^-\n <>=+!.&|(*/'`\"#^][-=+<>!|&^]\\|[-<>=+^&|]+[^- \n=+<>~]"


Documentation:
Finds places such that insertion of a whitespace may help a lot.