bug#4175: 23.1; nxml-mode: Internal error in rng-validate-mode triggered

[Eli Zaretskii]

> From: Stephen Berman <stephen.berman@gmx.net>
> Cc: Andrew Hyatt <ahyatt@gmail.com>,  4175@debbugs.gnu.org
> Date: Fri, 12 Feb 2016 11:12:23 +0100
> 
> I can reproduce it in a91b4b51ddf2575d821adb8b84fdf32cff83886e (GNU
> Emacs 25.0.90.2 (x86_64-suse-linux-gnu, GTK+ Version 3.14.15) of
> 2016-02-11).

How large is the run-time stack on that system?

> Here's the backtrace:
> 
> Debugger entered--Lisp error: (error "Stack overflow in regexp matcher")
>   
> looking-at("\\(\\(?:\\(xmlns\\)\\|[_[:alpha:]][-._[:alnum:]]*\\)\\(:[_[:alpha:]][-._[:alnum:]]*\\)?\\)[
>  
>       \n]*=\\(?:[ 
>       \n]*\\('[^<'&
> \n    ]*\\([&
> \n    ][^<']*\\)?'\\|\"[^<\"&
> \n    ]*\\([&
> \n    ][^<\"]*\\)?\"\\)\\(?:\\([ 
>       \n]*>\\)\\|\\(?:\\([ 
>       \n]*/\\)\\(>\\)?\\)\\|\\([ 
>       \n]+\\)\\)\\)?")
>   xmltok-scan-attributes()
>   xmltok-scan-after-lt()
>   xmltok-forward()
>   rng-forward()
>   rng-do-some-validation-1(rng-validate-while-idle-continue-p)
>   rng-do-some-validation(rng-validate-while-idle-continue-p)
>   rng-validate-while-idle(#<buffer url25099xa>)

Thanks.  Perhaps some regexp guru could suggest how to make this
regexp less greedy.