[Emacs-diffs] emacs-25 fe27e03: Fix rx matcher overflow without limiting

[Tassilo Horn]

branch: emacs-25
commit fe27e037663d36be3e5741c2ce86ab4ee8017db1
Author: Tassilo Horn <address@hidden>
Commit: Tassilo Horn <address@hidden>

    Fix rx matcher overflow without limiting
    
    * lisp/textmodes/reftex-vars.el (reftex-label-regexps): Improve last
    change to the regexp without imposing a limit on the length of the
    options.
---
 lisp/textmodes/reftex-vars.el |   12 +++++++++++-
 1 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/lisp/textmodes/reftex-vars.el b/lisp/textmodes/reftex-vars.el
index fcab136..9bc1d2d 100644
--- a/lisp/textmodes/reftex-vars.el
+++ b/lisp/textmodes/reftex-vars.el
@@ -877,7 +877,17 @@ DOWNCASE    t:   Downcase words before using them."
       "\\\\label{\\(?1:[^}]*\\)}"
       ;; keyvals [..., label = {foo}, ...] forms used by ctable,
       ;; listings, minted, ...
-      
"\\[[^][]\\{0,2000\\}\\<label[[:space:]]*=[[:space:]]*{?\\(?1:[^],}]+\\)}?")
+      ;;
+      ;; If you think the first shy group is a bit strange, it is like
+      ;; that in order not to overflow the regexp matcher stack in the
+      ;; presence of unbalanced brackets, i.e., a [ and then no
+      ;; closing bracket anymore.  In "[^[],]*,", the "*" repetition
+      ;; will be done without any need to record state for eventual
+      ;; backtracking because the "," is mutually exclusive with the
+      ;; "[^][,]", and the regexp matcher includes a special
+      ;; optimization for that case since it's common and very
+      ;; useful).  (Hint by Stefan Monnier)
+      "\\[\\(?:[^][,]*,\\)*[ 
\t]*\\<label[[:space:]]*=[[:space:]]*{?\\(?1:[^],}]+\\)}?")
     "List of regexps matching \\label definitions.
 The default value matches usual \\label{...} definitions and
 keyval style [..., label = {...}, ...] label definitions.  It is