R (development) changes in arith, logic, relop with (0-extent) arrays

    > But isn't the intent to make it an error later?  So I assume we're
    > debating making it an error, not just a warning.  

Yes, that's correct.
But if we have a longish deprecation period (i.e. where there's
only a warning) all important code should have been adapted
before it turns to an error 

That might be true for continuously-used code.  But for old scripts
for analysing some dataset that someone decides to run again five
years from now, they will be reduced to trying to guess which version
of R they ran under originally, or if they now want to use newer
features, to doing a binary search for the most recent version of R
for which they still work, or of course going through the script
trying to find the problem.

This wouldn't be a disaster, but I'm not seeing the magnitude of
benefit that would justify imposing this burden on users.  A language
specification shouldn't really be changing all the time for no
particular reason.

   Radford Neal