Fontify all comment delimiters in 'lua-ts-mode'

* lisp/progmodes/lua-ts-mode.el (lua-ts--comment-font-lock):
Apply 'font-lock-comment-delimiter-face' to the entire span of
initial dashes.  In particular, this improves the appearance of
LuaCATS and EmmyLua style annotations which use "---".
* test/lisp/progmodes/lua-ts-mode-resources/font-lock.lua:
Add tests.  (Bug#79258)

2 files changed, 10 insertions, 2 deletions

diff --git a/lisp/progmodes/lua-ts-mode.el b/lisp/progmodes/lua-ts-mode.el
index 1c1812a7c30..35700255ba4 100644
--- a/lisp/progmodes/lua-ts-mode.el
+++ b/lisp/progmodes/lua-ts-mode.el
@@ -168,10 +168,13 @@ values of OVERRIDE."
   (let* ((node-start (treesit-node-start node))
          (node-end (treesit-node-end node))
          (node-text (treesit-node-text node t))
-         (delimiter-end (+ 2 node-start)))
+         (delimiter-end (progn
+                          (goto-char node-start)
+                          (while (looking-at-p "-") (forward-char))
+                          (point))))
     (when (and (>= node-start start)
                (<= delimiter-end end)
-               (string-match "\\`--" node-text))
+               (string-match "\\`---*" node-text))
       (treesit-fontify-with-override node-start
                                      delimiter-end
                                      'font-lock-comment-delimiter-face
diff --git a/test/lisp/progmodes/lua-ts-mode-resources/font-lock.lua b/test/lisp/progmodes/lua-ts-mode-resources/font-lock.lua
index 93d589e3825..5a36bcad10b 100644
--- a/test/lisp/progmodes/lua-ts-mode-resources/font-lock.lua
+++ b/test/lisp/progmodes/lua-ts-mode-resources/font-lock.lua
@@ -11,6 +11,11 @@ Multi-line comment
 -- <- font-lock-comment-face
 local line_comment = "comment" -- comment
 --                                ^ font-lock-comment-face
+---@alias MyNumber integer
+-- <- font-lock-comment-delimiter-face
+------Calculate new number
+-- ^ font-lock-comment-delimiter-face
+function calc() end
 
 -- Definition
 local function f1() end