I put it at level 3 following the conventions in other treesit modes

I checked: python-ts-mode, ruby-ts-mode, rust-ts-mode all put builtins at level 3.

But, I haven't done a full census of the ts modes so there might be variability.

On Sat, Apr 13, 2024 at 12:23 AM Eli Zaretskii <eliz@gnu.org> wrote:

> From: Noah Peart <noah.v.peart@gmail.com>
> Date: Fri, 12 Apr 2024 22:47:37 -0700
>
> This patch adds a new `builtin` feature to
> `treesit-font-lock-feature-list` in `go-ts-mode` and a corresponding
> rule to `go-ts-mode--font-lock-settings` to highlight Go's built-in functions.

Thanks.

I will ask here as well: at what level of font-lock will this be
fontified? I think it should be fontified only on level 4.