bug#20806: 25.0.50; `string-match' is confused???

[Vaidheeswaran C <vaidheeswaran.chinnaraju@gmail.com>]

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On Saturday 13 June 2015 03:03 PM, Vaidheeswaran C wrote:

> Here is how I ended up with this bug.
> 
> Debugger entered--Lisp error: (error "Regexp cannot match an empty string")
>   signal(error ("Regexp cannot match an empty string"))
>   error("Regexp cannot match an empty string")
>   hi-lock-regexp-okay("\\(.*\\)")
>   byte-code("\300\301\302\303\"!\304 D\207" [hi-lock-regexp-okay
> read-regexp "Regexp to highlight" regexp-history-last
> hi-lock-read-face-name] 4)
>   call-interactively(highlight-regexp nil nil)
>   command-execute(highlight-regexp)
> 


The attached patch solves the above issue.  I hope it is OK.

(Stupid me got the title wrong.  Apologies.)

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From dd0786d3caa8ca83276dbc8ecd363c590cbccdbb Mon Sep 17 00:00:00 2001
From: Vaidheeswaran C <vaidheeswaran.chinnaraju@gmail.com>
Date: Sat, 13 Jun 2015 15:48:10 +0530
Subject: [PATCH] * lisp/hi-lock.el (hi-lock-regexp-okay): Minor change

---
 lisp/hi-lock.el |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lisp/hi-lock.el b/lisp/hi-lock.el
index 0255585..deb827c 100644
--- a/lisp/hi-lock.el
+++ b/lisp/hi-lock.el
@@ -658,7 +658,7 @@ not suitable."
   (cond
    ((null regexp)
     (error "Regexp cannot match nil"))
-   ((string-match regexp "")
+   ((string= regexp "")
     (error "Regexp cannot match an empty string"))
    (t regexp)))
 
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1.7.10.4