From ac9bc819bc438f21bd38a995812d756727ed8e2a Mon Sep 17 00:00:00 2001
From: Yuan Fu <casouri@gmail.com>
Date: Sat, 19 Nov 2022 17:59:14 -0800
Subject: Fix tree-sitter comment indentation for C-like languages

The goal is to indent like this:

/* comment
   comment  --> This line aligns with the beginning of the first line
 */         --> This line aligns with the opening comment token

* lisp/treesit.el (treesit-comment-start)
(treesit-comment-end): New variables.
(treesit-simple-indent-presets): New preset comment-end,
comment-start, comment-start-skip

* lisp/progmodes/c-ts-mode.el (c-ts-mode--indent-styles)
(c-ts-mode)
* lisp/progmodes/java-ts-mode.el (java-ts-mode--indent-rules)
(java-ts-mode)
* lisp/progmodes/js.el (js--treesit-indent-rules)
(js-ts-mode)
* lisp/progmodes/ts-mode.el (ts-mode--indent-rules)
(ts-mode): Add identical indent rules to each mode, and set identical
treesit-comment-start/end's.

* doc/lispref/modes.texi (Parser-based Indentation)
* doc/lispref/parsing.texi (Tree-sitter major modes): Update manual.
---
 lisp/progmodes/c-ts-mode.el | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

(limited to 'lisp/progmodes/c-ts-mode.el')

diff --git a/lisp/progmodes/c-ts-mode.el b/lisp/progmodes/c-ts-mode.el
index f8e809bb43f..43668a56d96 100644
--- a/lisp/progmodes/c-ts-mode.el
+++ b/lisp/progmodes/c-ts-mode.el
@@ -84,8 +84,8 @@ MODE is either `c' or `cpp'."
            ((node-is "else") parent-bol 0)
            ((node-is "case") parent-bol 0)
            ((node-is "preproc_arg") no-indent)
-           ((node-is "comment") no-indent)
-           ((parent-is "comment") no-indent)
+           ((and (parent-is "comment") comment-end) comment-start -1)
+           ((parent-is "comment") comment-start-skip 0)
            ((node-is "labeled_statement") parent-bol 0)
            ((parent-is "labeled_statement") parent-bol c-ts-mode-indent-offset)
            ((match "preproc_ifdef" "compound_statement") point-min 0)
@@ -503,6 +503,8 @@ the subtrees."
   (setq-local comment-start "/* ")
   (setq-local comment-start-skip "\\(?://+\\|/\\*+\\)\\s *")
   (setq-local comment-end " */")
+  (setq-local treesit-comment-start (rx "/" (or (+ "/") (+ "*"))))
+  (setq-local treesit-comment-end (rx (+ (or "*")) "/"))
 
   (setq-local treesit-simple-indent-rules
               (c-ts-mode--set-indent-style 'c))
-- 
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