Bug #12297: Ruby stdlib date can parse non-existent date with year 0

• Status: Rejected
• Priority: Normal
• Assignee: -
• Target version: -
• Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN

[globi (t b)]

Ruby date lib can parse date with year 0
$ pry [1] pry(main)> shitdate=Date.strptime('0000-01-07','%Y-%m-%d') => #<Date: 0000-01-07 ((1721064j,0s,0n),+0s,2299161j)> [2] pry(main)> shitdate.year => 0 [3] pry(main)>

There is no year 0 in gregorian and julian calendar between 1 BC and 1 AD
It should raise ArgumentError like it do when month/day number is 0.

[noahgibbs (Noah Gibbs)]

• File no_year_0.patch no_year_0.patch added

Ruby has a lot of different time-parsing and date-parsing code. But for Date's strptime specifically, this is an easy fix. Patch is attached.

[noahgibbs (Noah Gibbs)]

Ah! It would be hard to "fix" Ruby's stdlib to not allow dates to have a 0 year in general, because of code like the Date test that can use a Date as a delta. That is:

class DateSub < Date; end

d2 = d - 1
assert_instance_of(DateSub, d2)

Things like DateSub can clearly have a 0 year, because that implies that the difference in years is 0, not that it's the year 0.

I think it still makes sense to fix strptime with the fix above. But I don't think Date or DateTime should disallow the year 0 in general.

[matz (Yukihiro Matsumoto)]

According to [ruby-dev:10241] (Japanese), it's intentional.
In Gregorian calendar, the year 0 does not exist, but in astronomical year numbering, the year 0 does exist.

https://en.wikipedia.org/wiki/0_(year)

Matz.

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Rejected