Eli Zaretskii <eliz@gnu.org> writes:

Date: Mon, 24 Mar 2025 06:45:27 -0300
From: Mauro Aranda <maurooaranda@gmail.com>

+(defun project-customize-dirlocals ()
+ "Run `customize-dirlocals' in current project's root."
+ (interactive)
+ (customize-dirlocals (concat (project-root (project-current t))
".dir-locals.el")))
+

Would you change it to use file-name-concat or expand-file-name? From
past discussions, I think that using concat for file names is
discouraged.

Yes, but file-name-concat is also not right here. Please use
expand-file-name.

Done.