I see a few cases of this code in src/backend/utils/adt/datetime.c:
else if ((fmask & DTK_DATE_M) != DTK_DATE_M)
Wouldn't this be clearer as:
else if (fmask & DTK_DATE_M)
-- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB
http://enterprisedb.com
+ It's impossible for everything to be true. +