Re: buffer-swap-text

[Richard M. Stallman]

    I don't see any benefit to hardcode this in buffer-swap-text.
    We may very well rename buffer-swap-text to buffer-swap-text-internal
    and introduce a new buffer-swap-text which can perform such things
    (probably using write-region-annotation-function), as well as swap
    variables like buffer-file-coding-system.

That would be ok, I suppose, but one advantage of doing it in C
is that there is no chance anything can cause it to swap
the text without swapping the rest.