Bug #12981: Date.parse raises an Argument error under a specific condition

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: 2.3.3p222 (2016-11-21 revision 56859) [x86_64-linux]
• Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN

[kenta-s (Kenta SHIRAI)]

Date.parse cannot accept incomplete strings whose delimiter is a hyphen like: "2016-12", although it can accept if a delimiter is a slash like: "2016/12"

I'm not really sure if this is a bug or an expected behavior, but a maintainer of rails/rails recommended me to report this to Ruby team when I issued a PR( https://github.com/rails/rails/pull/27181 ) to them. So I'd appreciate if this issue is looked into.

steps to reproduce:

require "date"
=> true

Date.parse("2016/12/01")
=> #<Date: 2016-12-01 ((2457724j,0s,0n),+0s,2299161j)>

Date.parse("2016-12-01")
=> #<Date: 2016-12-01 ((2457724j,0s,0n),+0s,2299161j)>

Date.parse("2016/12")
=> #<Date: 2016-12-01 ((2457724j,0s,0n),+0s,2299161j)>

Date.parse("2016-12")
ArgumentError: invalid date
	from (irb):3:in `parse'
	from (irb):3
	from /usr/local/bin/irb:11:in `<main>'

[kenta-s (Kenta SHIRAI)]

• Description updated (diff)

[alfiemax (Alfred Dominic)]

I see a similar inconsistency in the Date._parse method. Everything works fine as expected as long as the / delimiter is used.
I think it has something to do with _parse being able to parse strings with delimiter and one without it.

Date._parse("2016/12/01")
=> {:year=>2016, :mon=>12, :mday=>1}
Date._parse("2016-12-01")
=> {:year=>2016, :mon=>12, :mday=>1}
Date._parse("2016/12")
=> {:year=>2016, :mon=>12}
Date._parse("2016-12")
=> {:mon=>20, :mday=>16, :zone=>"-12", :offset=>-43200}

[jeremyevans0 (Jeremy Evans)]

• Is duplicate of Bug #12285: Date.iso8601 does not properly handle partial date strings added

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset git|75fb0a9afad1685cedee9c7665a7f30ec95068fc.

---

Allow mday in Date.iso8601 to be omitted

[Bug #12285]