break/continue loop/while/until/for/do refer to anonymous containing iteration

[edemaine]

As mentioned in Discord, this seems in line with continue switch and fairly intuitive.

It is technically a breaking change, but these seem like unlikely constructions:

• old break loop (infinitely many breaks) is equivalent to break
• old break while cond() is equivalent to break if cond() (and is now a parse error)
• old break until cond() is equivalent to break unless cond() (and is now a parse error)

[STRd6]

Nice, looks good!

For the compatibility of previous break while cond() is closer to equivalent to cond() since it checks the cond and breaks from inside the wile, it wouldn't affect outside.

I don't think we need to worry about it since probably no one used it unless by accident.