bug#72388: 31.0.50; Use tree-sitter-cuda grammar but with tree-sitter-cpp's font-lock/indentation rules

[Yuan Fu]

Hey Ergus, sorry for the delay.

> On Aug 12, 2024, at 4:10 PM, Ergus via Bug reports for GNU Emacs, the Swiss 
> army knife of text editors <bug-gnu-emacs@gnu.org> wrote:
> 
> Hi Yuan:
> 
> I am just trying to use the new treesit-language-remap-alist and so far
> I understand your idea of how to make it work for the basics. But it is
> not clear how can I use the new var to add the new syntax entries.
> 
> I mean, looking at the grammar:
> 
> https://github.com/tree-sitter-grammars/tree-sitter-cuda/blob/master/grammar.js
> 
> You can see that it is the inherited C++ syntax, with extra entries in
> some fields (like _declaration_modifiers or delete_expression). For this
> part the new variable may work perfectly.
> 
> However there are a few "new" entries like: kernel_call_expression,
> kernel_call_syntax and launch_bounds that will need special handling.
> 
> What's your suggestion?
> 
> I mean, for the latest what we really need is to extend (partially
> redefine) the c-ts-mode--indent-styles, c-ts-mode--keywords and so on.
> 
> Is that the intended approach?

Yeah, you can define your own cuda-indent-styles by grabbing 
c-ts-mode—indent-styles and adding your rules on top of it, something like

(append your-styles
        (c-ts-mode--indent-styles 'c++))

For font-lock, something like

(append (treesit-font-lock-rules
         :language 'cuda
         :faeture 'xxx
         '(queries))
        (c-ts-mode--font-lock-settings 'c++))

The new treesit-language-remap-alist will ensure that even though the config 
you borrow from c-ts-mode calls for c++, Emacs will actually use cuda grammar 
in your major mode.

Yuan