Re: BUG #19771: to_char(): NUL byte in result for formats with a trailing decimal point (regression from ec352b37d)

Gowtham Reddy <gowthamdoma18(at)gmail(dot)com> writes:
> Please find attached a proposed patch for BUG #NNNNN.
> It stops NUM_numpart_to_char() from emitting the number string's
> terminating '\0' as a digit, and adds a regression test to numeric.sql
> (the test fails without the fix). make check passes (239/239) on
> master 45fc51fcbf45.
> Tom, CCing you since this became visible with ec352b37d.

That's definitely a bug, but on what basis do you say that it
wasn't visible before ec352b37d? AFAICT it's ancient.
I get this as far back as 9.2, for instance:

regression=# select to_char(7, 'FM99.SG') AS d;
d
---
7
(1 row)

Normally I'd think we should back-patch, but it's possible that
people didn't realize this behavior was unintended --- else we'd
have heard bug reports sooner. (It's not instantly obvious that
we should drop the decimal point but not the sign, I think.)
So I'm inclined to leave the stable branches alone. Maybe there's
still room to squeeze the fix into v19, though.

regards, tom lane