Leaking water line at toilet !!

[Sean]

Can anyone tell me if the grey, I assume its polybutylene, water supply lines can be flared or do you have to buy them pre-made ? Supply line leaking at toilet and it is twisted and needs to be cut off and redone and I didn't know if it had to be totally replaced or how it got the flare. It's right at the connection so no way to splice it back together after cutting out the kink. Thanks