X-Spam-Check-By:	sourceware.org
Message-ID:	<ba40711f0611301041j24166272g2c6964d71973cbf3@mail.gmail.com>
Date:	Thu, 30 Nov 2006 13:41:01 -0500
From:	"Lev Bishop" <lev DOT bishop AT gmail DOT com>
To:	cygwin AT cygwin DOT com
Subject:	Re: isnan() causes segfault
In-Reply-To:	<ba40711f0611301030o1c685b27hbbd7620b3cd2f473@mail.gmail.com>
MIME-Version:	1.0
References:	<ekmm5a$fcm$1 AT sea DOT gmane DOT org> <ba40711f0611301030o1c685b27hbbd7620b3cd2f473 AT mail DOT gmail DOT com>
Mailing-List:	contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id:	<cygwin.cygwin.com>
List-Unsubscribe:	<mailto:cygwin-unsubscribe-archive-cygwin=delorie DOT com AT cygwin DOT com>
List-Subscribe:	<mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive:	<http://sourceware.org/ml/cygwin/>
List-Post:	<mailto:cygwin AT cygwin DOT com>
List-Help:	<mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender:	cygwin-owner AT cygwin DOT com
Mail-Followup-To:	cygwin AT cygwin DOT com
Delivered-To:	mailing list cygwin AT cygwin DOT com

On 11/30/06, Lev Bishop wrote:
> On 11/30/06, Eric Lilja wrote:
> > If compiled with:
> > $ g++ -Wall -Wextra -std=c++98 -pedantic -g isnantest.cpp -o run
> > (those are the flags we have been using in this course).
> > But it doesn't stackdump if compiled simply with:
> > $ make isnantest
> > g++     isnantest.cpp   -o isnantest
>
> I was able to reproduce this behaviour.
>
> There seems to be a difference in the generated assembler.
> The -std=c++98 seems to be the only switch that matters.
> Here is a diff. File isnantest2.s is the stackdumping one (ie the one
> with -std=c++98)

<snip>

And the cause of the failure seems to be mutual recursion in
/usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/cmath

where at line 458:
  template<typename _Tp>
    int
    __capture_isnan(_Tp __f) { return isnan(__f); }

which calls at line 532:
  template<typename _Tp>
    int
    isnan(_Tp __f) { return __capture_isnan(__f); }

which calls back to __capture_isnan().

Incidentally, the stackdump file produced here is empty, so addr2line
can't help...

Lev

--
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
Problem reports:       http://cygwin.com/problems.html
Documentation:         http://cygwin.com/docs.html
FAQ:                   http://cygwin.com/faq/

- Raw text -