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Newsgroups: comp.lang.ada
Subject: Re: Compiler Bug or what I'm doing wrong?
References: <05lkrrojfd.fsf@hod.lan.m-e-leypold.de>
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From: M E Leypold
 <development-2006-8ecbb5cc8aREMOVETHIS@ANDTHATm-e-leypold.de>
Date: 21 Jun 2006 14:29:59 +0200
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"Ludovic Brenta" <ludovic@ludovic-brenta.org> writes:

> M E Leypold writes :
> >   I've generated a core and also can reproduce the SIGSEGV in this
> >   configuration 100% of the time. Don't hesitate to ask for more
> >   debugger output or more code.
> 
> I'd ask for *less* code :-)
> 
> It would be nice if you could write a minimal test case that reproduces
> the problem. Yes, it takes time. I cannot do that for you, for various

I've already done that (it took me 10 hours so far to isolate the
problem from a larger program): The original program was much
larger. I'll be trying to even strip the example furter, but the
problem with the bug seems to be that it's a Heisenbug which vanishes
when you delete some fields in the datastructure, then turns up again
if you delete more fields and so on. The malloc() implementation of
libc which the GNAt runtime uses is unchecked so obviously one gets
sometimes away when freeing unvalid pointers and (as we know from C
programming).

Whatever: I'll try to produce an even smaller test case.

> reasons. Please have a look at Debian's bug tracking system (package
> gnat) or GCC's bugzilla for examples of good test cases.

Yes, I know what a good test case is and I know the debian bug
tracking system. You might consider my post to c.l.a. as a kind of
preliminary report: Basically I wanted to be sure that I haven't
overlooked anything glaringly obvious.

Regards -- Markus