Re: OR_AND semantics (was: GNU property saga)

[Cary Coutant <ccoutant at gmail dot com>]

> > Now the above language would include FEATURE_X in the output, but bit 4
> > would be reliable (set a.bit4 && b.bit4) while bit 5 would be unreliable
> > (it is zero, even if it is one in a.o and _would_ be one in b.o had we
> > used a newer producer).
>
> We can't add a bit to FEATURE_X in such a way that  FEATURE_X generated
> by older producers become invalid.   We must add the bit to FEATURE_Y which is
> unsupported to all prior producers.  Am I missing something obvious?

Yes, I think so. This is the point Michael (and I) were making. By
using KNOWN bits, you can add new feature bits without having to start
a whole new word of bits.

-cary