comp.lang.ada Google Group

Re: Operation can be dispatching in only one type

2009-11-22T18:41:14Z

On Nov 22, 6:28 pm, "Dmitry A. Kazakov" <mail...@dmitry-kazakov.de>
wrote:
Ok, thanks for the explanation.
I made the change you suggest to initialize ("save") the archive and
the crash
doesn't occur. I've closed the bug on the GCC due to the discussion of
the
bug becoming confused between two issues (one of them - this one -

Re: Operation can be dispatching in only one type

2009-11-22T18:28:32Z

The problem semantically is that you convert type, which would/should
create a copy of a limited object.
Within a declaration ":=" denotes initialization. You may not convert
anything initializing a limited object.
Proper ways to go:
O : constant Archiver.Archive_t'Class :=
Archiver.Open_Archive (A, "file.zip");

Re: Operation can be dispatching in only one type

2009-11-22T18:08:38Z

If it's not already obvious, I'm aware that there's a bug in the above
code but am
not currently convinced that it's the cause of *this* crash as the
crash occurs
before the archive is finalized.

Re: Operation can be dispatching in only one type

2009-11-22T18:03:22Z

On Nov 22, 5:41 pm, "Dmitry A. Kazakov" <mail...@dmitry-kazakov.de>
wrote:
The design is both irrelevant and obsolete. I'm just trying to find
out if
the problem is *definitely* that code so that I can close a bug in the
GCC tracker.
Is it possible to save the return value of Open_Archive, or not?
Regards,

Re: Operation can be dispatching in only one type

2009-11-22T17:41:02Z

And I don't understand your design. If Archive is a Stream derive then it
from Root_Stream_Type. If it deals with a stream then pass
Root_Stream_Type'Class to the operations that need it.
But never ever return pointers to components without an urgent need.

Re: Operation can be dispatching in only one type

2009-11-22T16:52:05Z

On Nov 22, 4:42 pm, "Dmitry A. Kazakov" <mail...@dmitry-kazakov.de>
wrote:
Ah, I see what you mean.
In the process of trying to save the result of Open_Archive so that I
can test
if this problem still occurs, I've run into another problem:
A : Archiver.Archiver_t;
O : constant Archiver.Archive_t := Archiver.Archive_t

Re: Operation can be dispatching in only one type

2009-11-22T16:42:40Z

The function Open_Archive returns a new object. In Main you call it and
then apply the function Stream to the result. Stream returns an access to
the component File of the temporal object created by Open_Archive. Then
this object is destroyed and a dangling pointer is assigned to S. When you
call Integer'Inpit on S, it accesses a garbage.

Re: Operation can be dispatching in only one type

2009-11-22T16:27:59Z

On Nov 22, 4:25 pm, "Dmitry A. Kazakov" <mail...@dmitry-kazakov.de>
wrote:
Not sure which part of the code you're referring to here.
Regards,
xw

Re: Operation can be dispatching in only one type

2009-11-22T16:25:36Z

The code is broken. It creates a temporal object and takes an access to its
component. The obtained pointer is dangling.

Re: Operation can be dispatching in only one type

2009-11-22T11:30:43Z

On Nov 22, 11:25 am, Georg Bauhaus <rm-
Yes, I actually always compile code with the following:
-O2 -g -fstack-check -gnatw.eHeFT -gnatVa -gnato -gnata
-gnatW8 -gnatiw -gnaty2aAbdefhiklnprStu
(Although without -O2 when actually writing code, though).
No change, unfortunately.
Regards,
xw

Re: Operation can be dispatching in only one type

2009-11-22T11:25:40Z

Do you get segmentation fault with GNAT run in Ada mode?
(Currently, this would mean options -gnato -fstack-check
and no -gnatp, I think.)
What happens if you name the access-to-String type used for
a component of Archive_t, i.e. something like
type String_a is access String;
subtype File_Name_a is String_a;

Re: How do I debug/fix this

2009-11-22T07:51:23Z

Or this one:
[link]
Version 3.1a is now available as a Debian package in unstable.

Re: Operation can be dispatching in only one type

2009-11-22T05:45:52Z

I have to say I'm quite impressed that my question started so much
discussion.
For this (minor) project, I tried a multitude of different approaches
and ended up
with one that appeared safe, right until it ended up causing GNAT to
have some
sort of heart attack:
[link]

Re: How do I debug/fix this

2009-11-21T17:24:51Z

In article
<b3ac62eb-a230-45b5-9220-960f7 facc...@r5g2000yqb.googlegroup s.com>,
For reference, the OP might also like to see this other parser:
<[link]>

Re: How do I debug/fix this

2009-11-21T15:46:45Z

If the syntax is not trivial you may want to build a parser, e.g. by
using ayacc.
I did it to read another kind of file in another game - works fine...
Gautier