bug#18577: Regexp I-search: [(error Stack overflow in regexp matcher)]

[Alan Mackenzie]

Good afternoon, Andreas!

On Sun, Sep 28, 2014 at 12:56:48PM +0200, Andreas Schwab wrote:
> Alan Mackenzie <acm@muc.de> writes:

> > With point at BOB, do C-M-s and enter this regular expression at the
> > prompt:

> > /\*\(\([^'*]\|\*[^/']\)*\*?'\([^'*]\|\*[^/']\)*\*?'\)*\([^'*]\|\*[^'/]\)*\*?'\([^'*]\|\*[^/']\)*\*?\*/

> \(...\(...\)*...\)* is bad.  \(...\)*\(...\)* is also bad.

But they both seem essential to the regexp's purpose.

> Both can cause combinatorial explosions in backtracking.

Is this a defect in my regexp or in the regexp engine?  If the former,
how could I rewrite the regexp so that it would not hit these problems?

> Andreas.

> -- 
> Andreas Schwab, schwab@linux-m68k.org
> GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
> "And now for something completely different."

-- 
Alan Mackenzie (Nuremberg, Germany).