Re: next-error-last-buffer

[Richard Stallman]

    Maybe if there's more than one next-error capable buffers that are
    linked together (e.g. occur on a diff) then C-u next-error should
    advance through the "underlying" next-error buffer (the diff) while
    next-error should advance through the "overlay" next-error buffer
    (the occur).

That is a bad solution because it requires people to remember
yet another feature.  The other solution is better, because
it is more likely that the intended thing will happen
as a result of use of the other existing features.