And I guess the cop also can detect String#match and String#=~ if it is used as a condition.

It's very hard to tell if people are using the global variables stored by String#match, but perhaps can include a configuration option for this?

It's very hard to tell if people are using the global variables stored by String#match, but perhaps can include a configuration option for this?

Good point! I forgot the global variables.
Performance/RegexpMatch can be aware of the global variables, so the include cop will be able to support them also by using Performance/RegexpMatch code.

But I guess we can just omit supporting match and =~ from include cop.
RegexpMatch cop corrects match to match if it is possible, so the include cop can detect match + simple regexp usage after running RegexpMatch cop even if the include cop does not support match and =~ directly.

Agreed. Generally the use of the globals has been on the decline, so I guess we can also advise people not to do it. I guess the only thing the globals have for them is that they are more compact than the alternative.