Re: Initial fontification in sh-mode with tree-sittter

[Yuan Fu]

> On Nov 4, 2022, at 1:44 PM, João Paulo Labegalini de Carvalho 
> <jaopaulolc@gmail.com> wrote:
> 
> All you need to do is capture these contextual nodes in a special name 
> “contextual”.
> 
> (heredoc_body) @contextual
> (string) @contextual
> 
> I see. I'll give that a try.
>  
> But I don’t know about the bleeding you described in the very beginning. Do 
> you still see it? Is there a recipe to reproduce it?
> 
> It might just be because of how the tree-sitter-bash grammar defines heredoc 
> strings.
> 
> This are the steps to reproduce the issue on sh-mode:
> 
> ;; build emacs from head of feature/tree-sitter branch
> ;; apply the attached patch.
> ;; launch emacs with: emacs -nw -Q
> ;;Write the forms bellow on *scratch* buffer)
> 
> (require 'treesit)
> (add-to-list 'treesit-settings '(sh-mode t t))
> (find-file "/tmp/heredoc-issue.sh")
> 
> ;; contents of /tmp/heredoc-issue.sh file (also attached)
> 
> #!/usr/bin/env bash
> 
> cat <<EOF
> heredoc string
> EOF
> echo "<<HELLO>>"
> 
> ;; Then execute the commands below
> 
> ESC <                   ;; beginning-of-buffer
> C-s                     ;; isearch-forward
> heredoc                 ;; self-insert-command * 7
> RET                     ;; newline
> C-a                     ;; move-beginning-of-line
> C-k                     ;; kill-line
> C-n                     ;; next-line (At this point the echo command after 
> EOF is fontified as heredoc string)
> C-_                     ;; undo (After a short delay, the whole buffer is 
> correctly fontified)

I see. This is tree-sitter-bash’s problem. When there are only newlines between 
two EOF’s, the parser erroneously marks everything that follows as 
heredoc_body. I tried tree-sitter’s online demo and it gives the same 
result[1]. We should report this to tree-sitter-bash’s author.

Also, when defining sh-mode--treesit-settings, instead of using the value 
sh-shell as the language, it’s better to just use ‘bash. Here is what happened 
to me: my default value for sh-shell is fish, so sh-mode--treesit-settings was 
defined with language = fish. When I open heredoc-issue.sh, sh-mode parses the 
shebang and sets sh-shell to bash. Since bash does have a parser, 
(treesit-ready-p ’sh-mode sh-shell) returns t, and tree-sitter is activated. 
However when font-lock tries to use the query, it errors because query tries to 
load a parser for fish.

[1] https://tree-sitter.github.io/tree-sitter/playground

Yuan