Re: Re: Re: Crash at startup of DDD for Fortran programs

From: 	Peter Wainwright
Subject: 	Re: Re: Crash at startup of DDD for Fortran programs
Date: 	Thu, 18 Dec 2008 17:08:14 +0000

> A couple of other points I found out:
>
> (1) The problem I had in 2005 had the same symptoms, but it seems it was
> related to a Red Hat (Fedora) patch, not found on upstream GDB.  So,
> unless Mandriva made the same changes, it is probably not the same issue
> and my patch won't help you.
>
> (2) Reading your original message more carefully I understand why when
> you saw the "segmentation fault" message might have concluded that DDD
> had crashed. That was my first thought, too. However, reading the error
> message more carefully you can see it says that "*GDB* terminated
> abnormally (Segmentation fault)".  DDD also issues dialogs if it
> crashes, but they look slightly different:
>
>              DDD: Oops
> Internal error: Segmentation fault (core dumped)
> Restart    Exit    Ignore    Help
>
> In fact DDD is taking the only action it can in the desperate situation
> when its inferior debugger has vanished.
>
> (3) The problem is most likely due to some error in gdb when you use
> "info line xx" to query a symbol which does not exist. I believe that
> DDD is trying to find the source line corresponding to the program entry
> point so it can display it in the source view window. However, each
> language creates a different symbol for the entry point: C programs, as
> we know, call it "main"; Fortran programs call it "MAIN__". Therefore,
> DDD tries a series of different names until it finds one which works.
> For example, if I try it on your program:
>
> address@hidden:tmp$ gdb a.out
> GNU gdb 6.8-debian
> Copyright (C) 2008 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later
> <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show
> copying"
> and "show warranty" for details.
> This GDB was configured as "x86_64-linux-gnu"...
> (gdb) info line main
> No line number information available for address 0x400860 <main>
> (gdb) info line MAIN__
> Line 1 of "plouf.f" starts at address 0x4007b8 <MAIN__> and ends at
> 0x4007c3 <MAIN__+11>.
>
> It looks like instead of saying "No line number information" your GDB is
> crashing on the underined symbol.
>
> Hope this helps,
>
> Peter

OK. Thank you for all your messages. You have found the problem. The problem 
is with the version 6.3 of GDB. I upgraded to version 6.8 of GDB and now DDD 
works. What was misleading me was that some commands of GDB worked 
fine: "breakpoint", "run", "continue". But, as you pointed out, "info line 
main" crashes GDB 6.3.
Sincerely,
Lionel GUEZ