parser.parse( ) also silently truncates fractional seconds beyond 6 digits (via _parsems int(f.ljust(6,"0")[:6])) #1546

Summary

dateutil.parser.parse truncates fractional-second digits beyond 6 in the generic parser path:

# dateutil/parser/_parser.py (_parsems)
return int(i), int(f.ljust(6, "0")[:6])

>>> from dateutil import parser
>>> parser.parse("2020-01-01 00:00:00.1234567").microsecond
123456      # correct rounding = 123457; the 7th digit is silently dropped

Same family as the isoparse report (#1545); this is the generic/most-used API (parser.parse), a distinct sink (_parsems). ISO-8601 permits arbitrary fraction precision; a silent wrong instant is returned with no error.

Suggested fix

Round to the nearest microsecond (Decimal / ROUND_HALF_EVEN) instead of truncating, and handle the carry when a rounded value reaches 1_000_000us. Alternatively reject >6 digits (matching datetime.fromisoformat). Happy to adjust to maintainer preference; caught by the exterminator sweep, four-gated.