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From: "Alex R. Mosteo" <devnull@mailinator.com>
Newsgroups: comp.lang.ada
Subject: GNAT Spitbol segmentation fault
Date: Thu, 18 Jan 2007 13:33:21 +0100
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Date: 2007-01-18T13:33:21+01:00
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Hello,

before filing a bug report I'd like to hear your opinion to rule out a
mistake on my part. I'm using the excellent Gnat.Spitbol.Patterns package
to extract some patterns from large bodies of text. I'm doing it with this
scheme:

declare
   Text   : aliased Vstring := <initial text>;
   Target : aliased Vstring;
   
   Patt   : constant Pattern := Some_Patterns ** Target;
begin
   while Match (Text, Target, "") loop
      --  This extracts a Target string and removes it from the text.
      --  It doesn't matter if the surrounding text causes new aftermatches.
      Do_Something_With (Target);
   end loop;
end;

Very rarely I get a Storage_Error and segment violation that kills the
program. Running inside gdb I get this backtrace:

#0  0xb7ddf37c in memcpy () from /lib/tls/i686/cmov/libc.so.6
#1  0x081b7d8d in ada.strings.fixed.replace_slice ()
#2  0x081bd6cf in ada.strings.unbounded.replace_slice ()
#3  0x081d4f5e in gnat.spitbol.patterns.match ()

Unfortunately, address2line doesn't make any valid source lines from these
addresses, I suppose because the gdb wrapping (but this is just a guess).

If you have used Gnat Spitbol before, could you comment if I'm doing
something risky? This is with gnat gpl 2006 in linux x86