Re: [Emacs-trunk-diffs] Changes to emacs/src/sysdep.c

[Richard Stallman <rms@gnu.org>]

    I don't quite understand why it is assumed that everything run by
    a post-command-hook or a timer is a critical code not allowed to be
    interrupted with C-g?

When code runs asynchronously, the user could interrupt it without
knowing he's interrupting anything.  That gives a lot of potential
for confusion.

      One of the timers where such assumption has
    a negative effect is the isearch lazy highlighting timer which often
    enters into a very deep loop (several minutes and more) trying to
    fontify regexps with nested repetition constructs, and which is not
    interruptible with C-g.

If that loop has the potential to run along time, it should check for
arrival of input, and stop when input arrives.

We were just recently talking about how to implement a construct to
interrupt some code if input arrives.  I suggested code to implement
it; then someone reported a problem in it, but I think I found a fix
for that.  Would use of that code solve this problem?

    Is it a bug that regex.c can't detect long or infinite loops?

It would be nice if it could do so, but I hesitate to say this is a
bug, because that might be tantamount to demanding the impossible.

However, maybe it isn't impossible.  Do you think it is doable?  Would
you like to try?