bug#41957: 27.0.91; overlay-put freeze with auto-composition-mode ligatures

[Eli Zaretskii]

> From: "James N. V. Cash" <james.nvc@gmail.com>
> Date: Fri, 19 Jun 2020 17:05:30 -0400
> 
> It seems that when putting the after-string property to an overlay, if
> auto-composition-mode is enabled and the string contains a ligature,
> Emacs freezes in overlay-put.
> 
> The below code freezes when starting with emacs -Q:
> 
> 
>     (auto-composition-mode)
>     (set-char-table-range composition-function-table ?= `(["=>" 0 
> compose-gstring-for-graphic]))
>     (let ((o (make-overlay (point-min) (+ (point-min) 3) (current-buffer))))
>       (overlay-put o 'after-string "=>"))

Thanks, this is a known bug that is already fixed on the master
branch, and will be available in Emacs 28.