I wrote:
> Hmmm ... looking at PGTYPESnumeric_from_asc, it seems like the current
> behavior is different from what was described in that old thread; the only
> case where a digit buffer wouldn't be created is a NaN. But maybe a crash
> could occur for NaN. Perhaps we should use "if (num->sign !=
> NUMERIC_NAN)" as a guard?
After sleeping on it, it seems like the right thing to check for is
whether num->buf is NULL, which describes precisely the situation
where we should not try to make a copy of the digit buffer (and the
initial struct memcpy has made a valid copy of the null pointers).
So I fixed it like that.
regards, tom lane