bug#41372: 28.0.50; [PATCH] Wrong value of tab-bar-tab-name-ellipsis

[Juri Linkov]

> When I evaluate (char-displayable-p ?…) from current frame (under X) it
> evaluates to a valid font but, after I customized
> `tab-bar-tab-name-function` to equal `tab-bar-tab-name-truncated`, tab
> names are truncated using three dots characters.

Thanks for the patch.  One problem is that the patch hard-codes the ellipsis,
so that the user loses the ability to configure it.

A better way would be to leave defvar tab-bar-tab-name-ellipsis,
but by default set its value to nil.  So when it's non-nil,
then use its value, otherwise use "…"/"..." by default.

> -(defvar tab-bar-tab-name-ellipsis
> -  (if (char-displayable-p ?…) "…" "..."))
> -
>  (defun tab-bar-tab-name-truncated ()
>    "Generate tab name from the buffer of the selected window.
> -Truncate it to the length specified by `tab-bar-tab-name-truncated-max'.
> -Append ellipsis `tab-bar-tab-name-ellipsis' in this case."
> -  (let ((tab-name (buffer-name (window-buffer 
> (minibuffer-selected-window)))))
> +Truncate it to the length specified by `tab-bar-tab-name-truncated-max'."
> +  (let ((tab-name (buffer-name (window-buffer (minibuffer-selected-window))))
> +        (ellipsis (if (char-displayable-p ?…) "…" "...")))
>      (if (< (length tab-name) tab-bar-tab-name-truncated-max)
>          tab-name
>        (propertize (truncate-string-to-width
>                     tab-name tab-bar-tab-name-truncated-max nil nil
> -                   tab-bar-tab-name-ellipsis)
> +                   ellipsis)