Re: 'x-create-frame' succeeds, but 'x-open-connection' fails with same display argument

[Po Lu <luangruo@yahoo.com>]

Herman <mahlamytsike@gmail.com> writes:

> Hi !
>
> $ emacs --fg-daemon
> $ emacsclient --eval "(terminal-list)"
> (#<terminal 0 on initial_terminal>)
> $ emacsclient --eval "(get-device-terminal nil)"
> #<terminal 0 on initial_terminal>
> $ emacsclient --eval "(x-display-list)"
> nil
> $ emacsclient --eval "(x-create-frame \`((display . ,(getenv \"DISPLAY\"))))"
> #<frame *scratch* - GNU Emacs 0x55db73fd9c30>
> $ emacsclient --eval "(terminal-list)"
> (#<terminal 0 on initial_terminal> #<terminal 1 on :0.0>)
> $ emacsclient --eval "(get-device-terminal nil)"
> #<terminal 1 on :0.0>
> $ emacsclient --eval "(x-display-list)"
> (":0.0")
> $ emacsclient --eval "(kill-emacs)"
> $ emacs --fg-daemon
> $ emacsclient --eval "(x-open-connection (getenv \"DISPLAY\"))"
> nil
> ...
> Debugger entered--Lisp error: (error "Display :0.0 does not exist")
>   signal(error ("Display :0.0 does not exist"))
>   error("Display %s does not exist" ":0.0")
>   get-device-terminal(":0.0")
>   frames-on-display-list(":0.0")
>   font-setting-change-default-font(":0.0" nil)
>   dynamic-setting-handle-config-changed-event((config-changed-event font-render ":0.0"))
>   funcall-interactively(dynamic-setting-handle-config-changed-event (config-changed-event font-render ":0.0"))
>   call-interactively(dynamic-setting-handle-config-changed-event nil [(config-changed-event font-render ":0.0")])
>   command-execute(dynamic-setting-handle-config-changed-event nil [(config-changed-event font-render ":0.0")] t)
>
> Emacs 29.1.
>
> /--- 30.2 Multiple Terminals topic in Elisp manual says,
> 'x-open-connection' can be tested for communication with a given X
> display. What I have missed ?
>
> Thank you in advance for your help !

I think this is a bug in Emacs, since the display is opened but a font
configuration event arrives shortly after it does, and triggers some
form of bug where, as no frame on that display then exists,
get-device-terminal signals that the display in the configuration event
is nonexistent.