A couple of problems with new packages

[Stephen J. Turnbull]

Vin Shelton writes:

 > We try not to do that.  At the moment, it's not possible to build the
 > packages with the 21.4 compiler, so it's pretty important that we be
 > able to build the packages with 21.5 and load them into 21.4.

If that's so, then we need to fix the packages pronto.  It's been
policy for quite a while that distributed packages be built with 21.4.

Note that it's not just bytecodes; it's also internal functions and
things like that which might end up in macros, either different
functions or with a different signature.  It's also theoretically
possible that a 21.4 macro might turn into a 21.5 function, though
that should be extremely unusual.

I think asking that 21.5-compiled files be usable with 21.4 is asking
too much.