bug#22154: 25.0.50; emacsclient -c "breaks" 256-color display in server

[Dan Nicolaescu <dann@gnu.org>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Dan Nicolaescu <dann@gnu.org>
>> Cc: Eric Hanchrow <eric.hanchrow@gmail.com>,  22154@debbugs.gnu.org
>> Gcc: nnml+archive:sent-mail-2015
>> Date: Mon, 14 Dec 2015 01:21:26 -0500
>> 
>> Using different number of colors on different ttys should work.
>> I just tried it briefly, and it works fine on my Fedora machine with
>> 24.5.
>> I don't have a very recent version compiled.
>> 
>> You can try it with
>> $ emacs -Q -f server-start&
>> Then from an xterm: emacsclient -t
>> And then from a different one: env TERM=vt100 emacsclient -t
>> 
>> The frame in the first xterm should display some colors, the one in the
>> second should be b&w...
>
> This simple use case indeed (almost) works.  (To have it work better,
> you need the patch I posted here.)  But in general, the current
> implementation doesn't support this, AFAICT, for 2 reasons:

What exactly is the problem that your patch fixes?
I don't remember all the details, but having multiple terminal frames
running on multiple kinds of terminals, with different color depths and
even background modes was heavily tested when the multi-tty work was
going on.  One of the usual tests was to have rxvt with both 8 and 256
colors and white on black and black on white (rxvt not xterm because
rxvt sets an environment variable with the default color and emacs can
decide if it's a light or dark background based on that).  It worked
fine.
Did something break meanwhile or you are dealing with some new thing
that was not dealt with back then? 

Thanks

        --Dan