[v4] Fix strptime era handling, add more era tests [BZ #24394]

[TAMUKI Shoichi]

Hello Rafal-san,

From: Rafal Luzynski <digitalfreak@lingonborough.com>
Subject: Re: [v4] Fix strptime era handling, add more era tests [BZ #24394]
Date: Fri, 29 Mar 2019 12:13:49 +0100 (CET)

> > [...] Regarding *_TW, Rafal-san
> > is preparing a patch.
> 
> That's true.  As always, my free time is limited so if anybody finds
> my work too slow and wants to take the task I'm always open to this.

OK.  I will help you as much as possible. :-)

> > In addition to ja_JP locale, I think it is necessary to check the
> > locale of other countries, in particular *_TW locale.
> 
> This sounds good but also we can add other locales later.
> 
> > What about the consideration of %EY, %_EY, and %-EY?
> 
> As far as I know these flags should be ignored and all potential
> input strings (no matter if they are zero-padded, space-padded
> or no padded at all) should be accepted by any of these format
> specifiers.  At least that was the rule when I was adding a support
> of "%OB"/"%Ob"/"%Oh": all format specifiers should accept all
> potentially possible forms of a month name.
> 
> Of course, we may add tests to verify if these flags are correctly
> ignored and all potential valid inputs are parsed correctly but
> I don't have a strong desire to implement this.

OK.

> > How does it behave if specifying a non-existent date, such as:
> > 
> > Heisei gan nen 01 gatsu 07 nichi
> > Showa   64 nen 01 gatsu 08 nichi
> > 
> > I think that these tests are also necessary.
> 
> I think we can't implement this without your help.

In the social life, the former can hardly occur, but the latter can
happen in reality.

Regards,
TAMUKI Shoichi