bug#81637: Regression: Tree-sitter font-lock drops highlighting in indirect buffers

> Date: Sun, 16 Aug 2026 18:09:52 -0400
> From: James Cherti <[email protected]>
> 
> There is a regression in tree-sitter where syntax
> highlighting is completely lost when creating an indirect
> buffer (via clone-indirect-buffer or C-x 4 c) from a base
> buffer running a tree-sitter major mode.
> 
> This worked correctly in Emacs 29 but broke in the recent
> Emacs 31 and 32 changes.
> 
> To reproduce:
> 
> - Open a source file that uses a tree-sitter major mode.
> - Create an indirect buffer using
>    M-x clone-indirect-buffer (or 'C-x 4 c').
> - Observe that the syntax highlighting is entirely or
>    partially missing in the new indirect buffer.

Thanks.  Yuan, could you please look into this?