Error in from_char() for field 'D'?

Hey hackers,

I was doing some work in backend/utils/adt/formatting.c, and found the
following:

case DCH_D:
INVALID_FOR_INTERVAL;
if (is_to_char)
{
sprintf(inout, "%d", tm->tm_wday + 1);
if (S_THth(suf))
str_numth(p_inout, inout, S_TH_TYPE(suf));
return strlen(p_inout);
}
else
{
sscanf(inout, "%1d", &tmfc->d);
return strspace_len(inout) + 1 + SKIP_THth(suf);
}

The tm_wday field is internally stored as an integer 0 - 6, with 0
being Sunday. The 'D' formatting field, as per the documentation,
gives 1 - 7 with 1 being Sunday. So to convert tm_wday to 'D' in
to_char(), you add one. This works as expected.

However, in from_char(), the reverse is not true. Looking at the code
snippet above, the digit is scanned straight into tmfc->d unaltered
(this value is later copied directly to tm->tm_wday circa line 3394).

Unless I'm missing something, when converting to text, 'D' yields 1-7,
but when converting back from text, 'D' expects 0-6.

It's not a major problem, since there's not really a use-case for
specifying dates for conversion with the 'D' field, but this behaviour
appears to be incorrect, or at the very least, incorrectly documented.

The fix should be trivial; subtract one from tmfc->d after the call to sscanf()

Regards,
BJ