Re: Timezone change in US

[Eli Zaretskii]

> From: Chris McMahan <first_initiallastname@one.dot.net>
> Date: Thu, 15 Mar 2007 18:37:44 +0400
> 
> I use cygwin to launch emacs so I can manipulate my environment
> settings and such within the tcsh shell, rather than my windows
> environment. This minimizes the potential collisions in application
> names and paths between my unix programs and my windows programs (some
> of which use unix program names for basic management).

I'm not sure I understand the potential problems.  Can you give an
example of how starting Emacs from a Windows icon could cause trouble?

> I've been using this system for roughly 12 years now, and have had no
> real problems.

I don't doubt the fact, I'm just saying that you were lucky.  Cygwin
and native Windows programs are incompatible, so much so that I don't
see any reason to try to figure out what went wrong in this specific
case.

> As far as the TZ environment variable inside emacs, it is showing as
>   TZ=EST5EDT4,M3.2.0/2,M11.1.0/2 
> Which is correct for the new time zone rules.

But we've already established that the Windows native versions of time
functions don't grok this syntax of TZ.  I posted here a URL where the
Microsoft documentation clearly shows that.  So I think it's no
mystery anymore that the above value of TZ does not do what you
expect: the runtime functions used by Emacs simply don't support such
values of TZ.

> There is something in
> the emacs program itself that still assuming I'm in EST

That something is the code that interprets the value of TZ: it cannot
parse the `M3.2.0/2,M11.1.0/2' part, so it doesn't switch to EDT4.

> even though
> the TCSH shell and MS Windows (XP) put me in EDT.

Your tcsh is a Cygwin program, so it uses the Cygwin implementation of
the time routines, which do grok this syntax of TZ.