Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> This would turn off the make failure when an old bison is called from
> the makefile?
Rephrase that as "this would give bison the right to fail of its own
accord, rather than our prejudging its ability to cope."
Given bison's on-again-off-again track record in recent releases,
I don't think it's wise to wire in a non-overridable assumption
that bison < X is broken and bison >= X is good. A hint that
bison < X might be broken is fine --- but let's not pretend that
configure is smarter than the user.
regards, tom lane