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From: kilgallen@eisner.decus.org (Larry Kilgallen)
Subject: Re: Gnat on OpenVMS
Date: 1999/05/22
Message-ID: <1999May22.193351.1@eisner>#1/1
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References: <7hshfq$5tc$1@front1.grolier.fr> <FC3wGF.AFz@news.boeing.com>
 <7i6aur$i1g$1@nnrp1.deja.com> <7i74fa$9e2$1@front6.grolier.fr>
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Date: 1999-05-22T00:00:00+00:00
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In article <7i74fa$9e2$1@front6.grolier.fr>, "Thierry Lelegard" <lelegard@club-internet.fr> writes:

> However, just allow me to think that crashing with "ACCVIO,
> access violation" is an "unaesthetic" and "unfriendly" reply to
> valid commands ;-)

Actually it is an inappropriate response to even invalid commands.
Of course I do not think anyone claims this response was a design
goal, so thus it is a bug, susceptible to a fix.  I have seen such
bugs even in the DEC debugger.

> So, each OS defines its own concepts of a debugger. If a
> debugger fits in this model, it can be very powerful. If
> it refuses this model, it will always be inferior to native
> debuggers.

There may be some economics at work here, as GDB folk are accustomed
to moving readily between many operating systems so long as they are
all some form of Unix.  GDB would not be so pervasive if the great
debugger support was provided as first priority on VMS, HP-MPE, MacOS,
MVS, OS/400, and all those flavors of Windows.

> Honestly, I hardly understand why it was so difficult to
> integrate with the VMS debugger. The format of the debug tables
> is public (appendix of the linker manual). All GNAT-specific
> features could have been implemented by GNAT using a DBGEXT
> entry in the GNAT RTL. The syntax of data is similar in Ada
> 83 and 95 and is already supported by the VMS debugger.

It certainly is legally difficult if the contract from DEC said not
to integrate with the VMS debugger.  Of course that contract is only
binding on ACT (and DEC), so somebody else could make changes to GNAT,
although for Robert to suggest such an action would probably be bad
form.

Larry Kilgallen