Subject: bug#42045: 27.0.91; display-format-alist for X11 does not recognize DISPLAY with IPv6 literal

From: Valtteri Vuorikoski <[email-masked]>
Date: Thu, 3 Sep 2020 12:39:48 +0300

On 9/1/20 5:36 PM, Robert Pluim wrote:
>>>>>> On Thu, 25 Jun 2020 22:20:05 +0300, Valtteri Vuorikoski <[email-masked]> said:
> 
>      Valtteri> If the DISPLAY environment variable is to an IPv6 literal such as
>      Valtteri> [::1]:1, the regexp that x-win.el adds to the display-format-alist to
>      Valtteri> recognize X11 does not match, which results in breakage.
> 
>      Valtteri> x-win.el should probably add a second regexp to the alist, such as:
>      Valtteri> (add-to-list 'display-format-alist '("\\`\\[[^]]*\\]:[0-9]+\\(\\.[0-9]+\\)?\\'" . x))
> 
> That regexp won't work, since now youʼre requiring the '[' and ']' to
> be present.
> 
> "\\`\\[?[^]]*\\]?:[0-9]+\\(\\.[0-9]+\\)?\\'" would fix that, but since
> we donʼt really care what comes before the ':', so would
> 
> "\\`.*:[0-9]+\\(\\.[0-9]+\\)?\\'"

Yes, note "second regexp": the current regexp would remain and match 
other types of hostnames/addresses. But if no one cares about the format 
of the host part, your version is simpler.

  -Valtteri