GNU bug report logs - #76759
[PATCH] 31.0.50; makefile-mode: incorrectly highlights make-instructions as make targets

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Message #33 received at 76759-done <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Jostein Kjønigsen <jostein <at> secure.kjonigsen.net>
Cc: "Dr. Arne Babenhauserheide" <arne_bab <at> web.de>, "Ergus via Emacs
 development discussions." <emacs-devel <at> gnu.org>,
 Mauro Aranda <maurooaranda <at> gmail.com>, 76759-done <at> debbugs.gnu.org
Subject: Re: bug#76759: [PATCH] 31.0.50; makefile-mode: incorrectly
 highlights make-instructions as make targets
Date: Sun, 09 Mar 2025 22:08:04 -0400

> Any news on this one?

Looks OK, tho I think it's a bit more strict than necessary: the TABs we
need to avoid can be only at the beginning of the line, so not inside
the $(...).

So it's only one of the [^...] that needs the \t.

Here's what I did:

- Start from the current monster:

    "^\\(\\(?:\\$\\(?:[({]\\(?:\\$\\(?:[({]\\(?:\\$\\(?:[^({]\\|.[^\n$#})]+?[})]\\)\\|[^\n$#)}]\\)+?[})]\\|[^({]\\)\\|[^\n$#)}]\\)+?[})]\\|[^({]\\)\\|[^\n$#:=]\\)+?\\)\\(:\\)\\(?:[ \t]*$\\|[^=\n]\\(?:[^#\n]*?;[ \t]*\\(.+\\)\\)?\\)"

- Change the `\\(?:[^({]\\|.` to `\\(?:[^({]\\|[({]` because I think
  the `.` was just an optimization.  And since the two alternatives are
  now mutually exclusive, swap them:

    \\(?:[^({]\\|.[^\n$#})]+?[})]\\)

=>

    \\(?:[({][^\n$#})]+?[})]\\|[^({]\\)

- Now the regexp has become:

    "^\\(\\(?:\\$\\(?:[({]\\(?:\\$\\(?:[({]\\(?:\\$\\(?:[({][^\n$#})]+?[})]\\|[^({]\\)\\|[^\n$#)}]\\)+?[})]\\|[^({]\\)\\|[^\n$#)}]\\)+?[})]\\|[^({]\\)\\|[^\n$#:=]\\)+?\\)\\(:\\)\\(?:[ \t]*$\\|[^=\n]\\(?:[^#\n]*?;[ \t]*\\(.+\\)\\)?\\)"

- Make the nested construction explicit, so it's a bit more manageable:

    (letrec ((elems-re
              (lambda (n &optional outer)
                (if (< n 1)
                     "[^\n$#})]+?"
                  (concat "\\(?:\\$\\(?:"
                          "[({]" (funcall elems-re (- n 1)) "[})]"
                          "\\|[^({]\\)"
                          "\\|[^\n$#" (if outer ":=" ")}") "]\\)+?")))))
      (concat
       ;; Allow for two nested levels $(v1:$(v2:$(v3:a=b)=c)=d)
       "^\\(" (funcall elems-re 3 'outer)
       "\\)\\(:\\)\\(?:[ \t]*$\\|[^=\n]\\(?:[^#\n]*?;[ \t]*\\(.+\\)\\)?\\)"))

- Disallow TABs in the outer case by replacing ":=" with "\t:=" (that's
  one of the TABs you added in your version of the patch).

This is still not quite right, since AFAIK TABs are allowed to appear
outside of $(...) as long as they're not at BOL, but I think it's better
than what we've had so far (and the regexp still has several other
limitations anyway).

Pushed to `master`.


        Stefan

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