From: Basil L. Contovounesios <contovob@tcd.ie>
Date: Tue, 6 Jul 2021 00:05:41 +0000 (+0100)
Subject: Avoid invalid regexp in wide docstring check
X-Git-Tag: emacs-28.0.90~1938
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=044742bfe8c7c22e303242c40e16fbe9e564727a;p=emacs.git

Avoid invalid regexp in wide docstring check

* lisp/emacs-lisp/bytecomp.el (byte-compile--wide-docstring-p):
Avoid constructing an invalid regexp during byte-compilation by
limiting the number of columns to the current RE_DUP_MAX of 65535.
This protects against pathological values of fill-column, for
example (bug#49426).
---

diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index 70999648d47..6970c8a5055 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -1627,7 +1627,7 @@ the `\\\\=[command]' ones that are assumed to be of length
 `byte-compile--wide-docstring-substitution-len'.  Also ignore
 URLs."
   (string-match
-   (format "^.\\{%s,\\}$" (int-to-string (1+ col)))
+   (format "^.\\{%d,\\}$" (min (1+ col) #xffff)) ; Heed RE_DUP_MAX.
    (replace-regexp-in-string
     (rx (or
          ;; Ignore some URLs.