Compiler Bug or what I'm doing wrong?

Compiler Bug or what I'm doing wrong?

[M E Leypold]

Hi all,

the following happens with GNAT 3.15p on Debian. My impression is,
that finalization during reading with the compiler generated
'Read-Attribute is not handled right in variant records, but I might
be wrong. Let me first expose the problem and my sample code.

I have the following Program (explanations below):


    with Sf.Cases;
    use  Sf.Cases;

    with Sf.Fieldtypes;
    use  Sf.Fieldtypes;

    with Ada.Streams.Stream_IO;
    use  Ada.Streams.Stream_IO;


    procedure Demo.Bug3 is

       procedure Write_Record
       is
         R : Fall_Datensatz;

         F : File_Type;
         S : Stream_Access;
       begin
          Create( F , Name => "tmp-bug3" );
          S := Stream(F);
          Set_Zugang(R, SelbstMelderIn);          -- [**]
          -- Fall_Datensatz'Output(S,R); -- [2a]
          Fall_Datensatz'Write(S,R);     -- [1a]
          Close(F);
       end;

       Function Get_Record return Fall_Datensatz
       is
          R: Fall_Datensatz;
          F : File_Type;
          S : Stream_Access;
       begin
          Open( F , Mode => In_File, Name => "tmp-bug3" );
          S := Stream(F);

          -- R := Fall_Datensatz'Input(S); -- [2b]
          Fall_Datensatz'Read(S,R);        -- [1b]
          Close( F );
          return R;
       end;

       R : Fall_Datensatz;

    begin
       Write_Record;
       R := Get_Record;
    end;


It instantiated a record with default initialization, changes a
discriminant in a which controls a variant part in the record (at [**]
Set_Zugang will be explained later), and then stores the record in a
file. When rereading the file (Get_Record), I get the following
exception:


   "raised PROGRAM_ERROR : demo-bug3.adb:38 finalize raised exception"

Running it under debugger control I get 

   (gdb) exec-file demo-bug3
   (gdb) run
   Starting program: /home/mel/cvswork/statfix/src2/demo-bug3

   Program received signal SIGSEGV, Segmentation fault.
   0x4098d354 in mallopt () from /lib/libc.so.6
   (gdb)

   (gdb) bt 5
   #0  0x4098d354 in mallopt () from /lib/libc.so.6
   #1  0x4098c15f in free () from /lib/libc.so.6
   #2  0x408f4e84 in __gnat_free () from /usr/lib/libgnat-3.15p.so.1
   #3  0x4082ac79 in ada__strings__unbounded__finalize__2 ()
      from /usr/lib/libgnat-3.15p.so.1
   #4  0x080c9fe5 in <demo__bug3__get_record___read654___read1116___read1147> (
       s=0x80e2e00, v=@0xbfffc39c, <sF>=0) at demo-bug3.adb:38
   (More stack frames follow...)
   (gdb)

which makes me suspect that a finalizer is run on non-appropriate data
(i.e. on the wrong part of a variant). I'll attach more stack traces
below, but first let me explain the data structure Fall_Datensatz
(which is defined in SF.Cases). I'm showing only the parts that are
actually touched by the program:


   type PA_Kontakt_Ergebnis ( Erfolg : Di_State := Keine_Angabe ) is record

      case Erfolg is
         when Ja     => Kontakt_Ergebnis : Auswahl_Kontakt_Ergebnis := Keine_Angabe;         
         when others => null;
      end case;
   end record;


   type PA_Kontakt_Verlauf
     ( Kontakt_Methode : Auswahl_Kontakt_Methode := Keine_Angabe )
   is record
      case Kontakt_Methode is
         when Keine_Angabe => null;
         when Keinen       => null;
         when Others       => Ergebnis : PA_Kontakt_Ergebnis;
      end case;
   end record;


   type Zugangs_Daten( KlientIn_Zugang : Auswahl_KlientIn_Zugang := Keine_Angabe ) is record

      case KlientIn_Zugang is

         when  Proaktiver_Kontakt  =>

            Kontakt_Vermittlung : Angabe_Kontakt_Vermittlung ;
            PA_Kontakt          : PA_Kontakt_Verlauf         ;

         when      SelbstmelderIn  =>

            KlientIn_Aufmerksamkeit : Angabe_Klientin_Aufmerksamkeit;

         when              others  =>  null;
      end case;
   end record;




   type Fall_Datensatz
     ( KJB_Verf�gbar : Boolean := True ; Notizen_Verf�gbar : Boolean := True )
   is record

      Aktenzeichen  : Fall_Aktenzeichen;
      Tat           : Fall_Merkmale     (Notizen_Verf�gbar);

      Opfer         : Personen_Merkmale (Notizen_Verf�gbar);
      T�ter         : Personen_Merkmale (Notizen_Verf�gbar);

      Zugang        : Zugangs_Daten;
      Polizei       : Angaben_Polizei_Einsatz;

      Beratung      : Beratungsverlauf  (Notizen_Verf�gbar);

      Kinder        : Kinder_Daten; -- (KJB_Verf�gbar, Notizen_Verf�gbar);

      case KJB_Verf�gbar is
         when  True   => null; -- KJB : ...
         when  False  => null;
      end case;
   end record;


The Unbounded Strings are hidden in Angabe_Kontakt_Vermittlung and
Angabe_Klientin_Aufmerksamkeit which are actually Types defined via a
generic package as an enumeration type with an optional comment (only
to be given in some cases):


   type Data is record
      Choice  : Choice_Type      := Choice_Type'First;
      Comment : Unbounded_String := Null_Unbounded_String;
   end record;


(I'll give the complete interface below, but this post becomes pretty
longish, so I'll restrict myself to what I consider the relevant parts).

The procedure Set_Zugang modifies the diosriminant of Zugangs_Daten in
the following way:


   procedure Set_Zugang ( D :  in out Zugangs_Daten ; Z : Auswahl_KlientIn_Zugang )
   is begin

      if Z /= D.KlientIn_Zugang then

         case Z is

            when Selbstmelderin      =>
               declare New_D : Zugangs_Daten(Selbstmelderin);
               begin
                  D := New_D ;
               end;

            when Proaktiver_Kontakt  =>
               declare New_D : Zugangs_Daten(Proaktiver_Kontakt);
               begin   D := New_D ; end;

            when Keine_Angabe        => D := (KlientIn_Zugang => Keine_Angabe ) ;
         end case;
      end if;
   end;


   procedure Set_Zugang ( DS :  in out Fall_Datensatz ; Z : Auswahl_KlientIn_Zugang) is begin

      Set_Zugang( DS.Zugang, Z );
   end;

(The idea is to have the initialisation defaults if and only if the
discrimant is changed).

If  (in gdb) I step up some stackframes and print the record R in
Get_Record I get the following


  (...)  zugang => (klientin_zugang => selbstmelderin,
         klientin_aufmerksamkeit => ( choice => keine_angabe, comment
         => (prev => 0x0, next => 0x0, reference => Cannot access
         memory at address 0x7a9f08

This is also what led me to the impression that first the discriminant
is overwritten and the the finalizer(s) for the new variant part
("when SelbstMelderIn") are run (on random bit patterns) instead of
the finalizers for the default variant part ("when Keine_Angabe
..."). 

(Actually I'd have expected in the case of discriminant records that
the whole thingy works like this: Run all finalizers in variant parts
if any, only then read the discriminant, run the initializers in the
new variant parts, then read the rest of the record).

After having a look into Barnes "Programming in Ada 95" again, I
thought, that perhaps I should use 'Input and 'Output instead of 'Read
an 'Write. This fixed the problem in the case above (options [2a] and
[2b]), but unfortunately failed to fix the the problem in the larger
program from which these fragments come.

Of course the bug is a Heisenbug so small changes in Fall_Datensatz or
the order of code execuation in the larger program make it disappear
which made it difficult in the first place to construct a relatively
small example w/o GUI which succeeds in reproducing the bug. 

Therefore I think (but again I'm not sure) that the fact that the bug
goes away with 'Input and Output instead of 'Read/'Write is just part
of it's elusive character not evidence of a fix. Also, since records
with default discriminants are definite I think 'Read and 'Write
should be OK for IO. Am I not right?

I've googled a bit, but didn't find anything on that, eehm,
"effect". But maybe I didn't use the right keywords. 

Is this a known bug with GNAT 3.15p or am I doing anything wrong?

Your help/input (also suggestions for workaround or confirmation that
this indeed a GNAT bug) would be greatly appreciated.

(Ludovico: I'll file an entry into Debian bug tracking soon. Just
looking for confirmation here first).

Regards -- Markus



ATTACHEMENTS: Backtraces and more code
--------------------------------------

  Sf.Single-Choices (Unit interface from which the types Angabe_* are instantiated) 
  ------------------
  
     with Ada.Strings.Unbounded;
     use  Ada.Strings.Unbounded;

     generic

        type Choice_Type   is (<>);
        type Choice_List   is array (Integer range <>) of Choice_Type;

        Allow_Comment_List : Choice_List;

     package Sf.Single_Choice is

        type Data is private;

        procedure Set( D : in out Data ; C : Choice_Type );
        function  Get( D : Data ) return Choice_Type;
        function  ID ( D : Data ) return Integer;

        function  Get_Comment( D : Data ) return String;
        procedure Set_Comment( D : in out Data; S : String );

        procedure Set_From_Integer( D : in out Data ; I : Integer );

        procedure Set( D : in out Data ; I : Integer ) renames Set_From_Integer;

        procedure Reset ( D : in out Data );

     private

        type Flags is array (Choice_Type) of Boolean;

        function Get_Comment_Allowed_Vector return Flags;

        Comment_Allowed : constant Flags := Get_Comment_Allowed_Vector;

        type Data is record
           Choice  : Choice_Type      := Choice_Type'First;
           Comment : Unbounded_String := Null_Unbounded_String;
        end record;
     end;



  complete backtrace
  ------------------

  #0  0x4098d354 in mallopt () from /lib/libc.so.6
  #1  0x4098c15f in free () from /lib/libc.so.6
  #2  0x408f4e84 in __gnat_free () from /usr/lib/libgnat-3.15p.so.1
  #3  0x4082ac79 in ada__strings__unbounded__finalize__2 ()
     from /usr/lib/libgnat-3.15p.so.1
  #4  0x080c9fe5 in <demo__bug3__get_record___read654___read1116___read1147> (
      s=0x80e2e00, v=@0xbfffc39c, <sF>=0) at demo-bug3.adb:38
  #5  0x080ca136 in <demo__bug3__get_record___read654___read1116> (s=0x80e2e00,
      v=@0xbfffc384, <sF>=0, <vF>=false) at demo-bug3.adb:38
  #6  0x080d5997 in <demo__bug3__get_record___read654> (s=0x80e2e00, v=@0xbfffc108,
      <sF>=0, <vF>=false) at demo-bug3.adb:38
  #7  0x080d869f in demo.bug3.get_record () at demo-bug3.adb:38
  #8  0x080dd625 in demo.bug3 () at demo-bug3.adb:48
  #9  0x080640dd in main (argc=1, argv=(system.address) 0xbffff8a4,
      envp=(system.address) 0xbffff8ac) at b~demo-bug3.adb:244
  #10 0x40930e36 in __libc_start_main () from /lib/libc.so.6


  more information
  ----------------

  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.

Re: Compiler Bug or what I'm doing wrong?

[Ludovic Brenta]

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

-- 
Ludovic Brenta.

Re: Compiler Bug or what I'm doing wrong?

[M E Leypold]

"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

Re: Compiler Bug or what I'm doing wrong?

[Alex R. Mosteo]

M E Leypold wrote:

> 
> "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).

Indeed, for me the most frustrating part of bug reporting is obtaining a
sufficiently small test case. I usually hit bugs in a large project I'm
involved. Once you start to chop off, you know that the bug will disappear
along the way. When you're not even sure if you're the culprit and not the
compiler, the frustration is even bigger.

I'm now, for example, facing a spurious exception case when switching from
GNAT GPL'05 to GPL'06, only when certain compiler switches are used. I have
already found a workaround, and I even know that the problem is related
with interfaces, but I fear that the effort to isolate it will be a waste
of time. So the temptation to move on is big...

This post is really just to show my "condolences" and support. Best luck,

A. Mosteo.

Re: Compiler Bug or what I'm doing wrong?

[M E Leypold]

"Alex R. Mosteo" <devnull@mailinator.com> writes:

> I'm now, for example, facing a spurious exception case when switching from
> GNAT GPL'05 to GPL'06, only when certain compiler switches are used. I have

Have you tried to run that with a debugger? In my case I had
exceptions first and only when running that with the debugger, I found
that it was a SIGSEGV which got translated into a PROGRAM_ERROR by the
signal handler and the run time since this happened in a finalizer.

> already found a workaround, and I even know that the problem is related
> with interfaces, but I fear that the effort to isolate it will be a waste
> of time. So the temptation to move on is big...

In my case: I think I have found a workaround (if my guess on the
nature of the error is correct) and I'll post it here as a reference
for the next users if it actually works.

In my opinion, documentation of "known bugs" and "proved workarounds"
are almost as valuable as fixes. At least they'll spare other users
the time (a) to form suspicions themselves and (b) to think about
workarounds themselves.

It's a pity that GNAT (at least 3.15p? I'm repeating myself ...),
doesn't have some kind of community support side where things as these
could be collected. Or is there such a site?

For now I'm "misusing" c.l.a. for that but I wonder wether that was
right.

> This post is really just to show my "condolences" and support. Best luck,

Hey, thanks :-)). And good luck with your problem too.

Regards -- Markus

Re: Compiler Bug or what I'm doing wrong?

[James Dennett]

Alex R. Mosteo wrote:
> M E Leypold wrote:
> 
>> "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).
> 
> Indeed, for me the most frustrating part of bug reporting is obtaining a
> sufficiently small test case. I usually hit bugs in a large project I'm
> involved. Once you start to chop off, you know that the bug will disappear
> along the way. When you're not even sure if you're the culprit and not the
> compiler, the frustration is even bigger.

The "delta" tool can largely automate the task of reducing
a test case to something closer to minimal, though some
manual intervention helps:

http://gcc.gnu.org/wiki/A%20guide%20to%20testcase%20reduction

I've used it only a couple of times, but it saved me a *lot*
of effort.  (On the other hand, it might need tweaking to
support Ada; I don't know, I used it on C++ code.)

-- James

Re: Compiler Bug or what I'm doing wrong?

[Duncan Sands]

> 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.

This looks to be the same bug that we ran into with GNAT 3.15p some
time ago; it has long since been fixed, so I suggest you try a more
recent version of the compiler.

Best wishes,

Duncan.

Re: Compiler Bug or what I'm doing wrong?

[M E Leypold]

Duncan Sands <baldrick@free.fr> 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.
> 

> This looks to be the same bug that we ran into with GNAT 3.15p some
> time ago;

Is there a report on that somewhere? Did you have a workaround?


> it has long since been fixed, so I suggest you try a more

Ah. "long since". Gnat 3.15p is now just 20 months old. 


> recent version of the compiler.


There is a number of reasons to stay with 3.15p yet. 

 - There is AFAIK no packaged version of a (free as in GMGPL) post
   3.15p Gnat fpr Windows.

 - Debian has 3.15p and will only switch to Gnat/Gcc in some months.

 - Changing now would mean, I have to build the compiler / toolchain
   myself (and that on both platforems) and if things get bad, also a
   number of libraries. Since experience is, that Gnat never builds
   out of the box I'd rather forfeit the experience for the time being
   -- not because I couldn't, but because it would eat up valuable
   time, probably much more than I have put into debugging and will
   have to put into writing a workaround.


Regards -- Markus

Re: Compiler Bug or what I'm doing wrong?

[Pascal Obry]

M E Leypold a �crit :

> Ah. "long since". Gnat 3.15p is now just 20 months old. 

Hum! No it was out on nov 18th 2002 so it is almost 4 years old.

Pascal.

-- 

--|------------------------------------------------------
--| Pascal Obry                           Team-Ada Member
--| 45, rue Gabriel Peri - 78114 Magny Les Hameaux FRANCE
--|------------------------------------------------------
--|              http://www.obry.net
--| "The best way to travel is by means of imagination"
--|
--| gpg --keyserver wwwkeys.pgp.net --recv-key C1082595

Re: Compiler Bug or what I'm doing wrong?

[Dmitry A. Kazakov]

On 22 Jun 2006 18:53:18 +0200, M E Leypold wrote:

> There is a number of reasons to stay with 3.15p yet. 
> 
>  - There is AFAIK no packaged version of a (free as in GMGPL) post
>    3.15p Gnat fpr Windows.
> 
>  - Debian has 3.15p and will only switch to Gnat/Gcc in some months.
> 
>  - Changing now would mean, I have to build the compiler / toolchain
>    myself (and that on both platforems) and if things get bad, also a
>    number of libraries. Since experience is, that Gnat never builds
>    out of the box I'd rather forfeit the experience for the time being
>    -- not because I couldn't, but because it would eat up valuable
>    time, probably much more than I have put into debugging and will
>    have to put into writing a workaround.

+ GPL editions compilers still look more buggy than 3.15p. GPL 2005 is
definitely worse. As for GPL 2006, I've tried it shortly today, it promptly
has shown the infamous GNAT bug-report shield...

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de

Re: Compiler Bug or what I'm doing wrong?

[Simon Wright]

M E Leypold <development-2006-8ecbb5cc8aREMOVETHIS@ANDTHATm-e-leypold.de> writes:

> It's a pity that GNAT (at least 3.15p? I'm repeating myself ...),
> doesn't have some kind of community support side where things as
> these could be collected. Or is there such a site?

What about the GNU Ada wiki at Sourceforge? http://gnuada.sourceforge.net/

Re: Compiler Bug or what I'm doing wrong?

[Jeffrey R. Carter]

On 22 Jun 2006 18:53:18 +0200, M E Leypold wrote:
> 
>  - There is AFAIK no packaged version of a (free as in GMGPL) post
>    3.15p Gnat fpr Windows.

What do you mean by "packaged"? There's the MinGW version of gcc 3.4.2 
including GNAT.

-- 
Jeff Carter
"Blessed are they who convert their neighbors'
oxen, for they shall inhibit their girth."
Monty Python's Life of Brian
83

Re: Compiler Bug or what I'm doing wrong?

[Ludovic Brenta]

M E Leypold writes:
> In my opinion, documentation of "known bugs" and "proved workarounds"
> are almost as valuable as fixes. At least they'll spare other users
> the time (a) to form suspicions themselves and (b) to think about
> workarounds themselves.
>
> It's a pity that GNAT (at least 3.15p? I'm repeating myself ...),
> doesn't have some kind of community support side where things as these
> could be collected. Or is there such a site?
>
> For now I'm "misusing" c.l.a. for that but I wonder wether that was
> right.

Use the Debian bug tracking system, it is public for precisely that
reason, even for people who do not use Debian.

-- 
Ludovic Brenta.

Re: Compiler Bug or what I'm doing wrong?

[M E Leypold]

Pascal Obry <pascal@obry.net> writes:

> M E Leypold a �crit :
> 
> > Ah. "long since". Gnat 3.15p is now just 20 months old. 
> 
> Hum! No it was out on nov 18th 2002 so it is almost 4 years old.

Ouch. I stand corrected.

I looked at the time stamps of files in a mirror (since the nyu server
is not carrying the files any more). Furthermore I was mislead by the
fact that debian/woody only had 3.14p, so the time stamps seemed
reasonable. Of course they weren't. My mistake.

But my other arguments still stand: 3.15p is not gone and should not
be considered so as long as major distributions have not upgraded
(yet) and as long as there is not a newer pre-packaged compiler for
windows.

Regards -- Markus

Re: Compiler Bug or what I'm doing wrong?

[M E Leypold]

Dear All,

I'd like to augment by recent post with following statements and
requests in case that got lost in the overwhelming amount of details:

 - This was no attempt ro actually "report a bug" to c.l.a. but rather
 
 - a request wether I have missed some glaring error of my own or
 
 - wether anybody has seen/documented something like this before.


My apologies that I'm still using Gnat 3.15p :-). I'm not asking you
to fix my problem (which is after all partly rooted in my stubborn
refusal to consider a newer compiler version just now), but only want
to tap your memory.

A shorter test case has been posted.

Regards (and thanks for all the help so far) -- Markus

Re: Compiler Bug or what I'm doing wrong?

[Stephen Leake]

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> + GPL editions compilers still look more buggy than 3.15p. GPL 2005 is
> definitely worse. 

Well, that may be true for your applications.

I encountered no bugs with GPL 2006; while 3.15p has significant bugs.

In a system as complex as a compiler, different people will have
different problems.
-- 
-- Stephe

Re: Compiler Bug or what I'm doing wrong?

[Dmitry A. Kazakov]

On Fri, 23 Jun 2006 08:26:32 -0400, Stephen Leake wrote:

> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
> 
>> + GPL editions compilers still look more buggy than 3.15p. GPL 2005 is
>> definitely worse. 
> 
> Well, that may be true for your applications.
> 
> I encountered no bugs with GPL 2006; while 3.15p has significant bugs.
> 
> In a system as complex as a compiler, different people will have
> different problems.

Yes. Note, I didn't say "is more boggy." I did "looks more buggy."

BTW, my experience with GCC 4.0.2 (20051125) GNAT was rather positive. Guys
at sourceforge are doing a great job. Many thanks to them.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de

Re: Compiler Bug or what I'm doing wrong?

[Alex R. Mosteo]

M E Leypold wrote:

> "Alex R. Mosteo" <devnull@mailinator.com> writes:
> 
>> I'm now, for example, facing a spurious exception case when switching
>> from GNAT GPL'05 to GPL'06, only when certain compiler switches are used.
>> I have
> 
> Have you tried to run that with a debugger? In my case I had
> exceptions first and only when running that with the debugger, I found
> that it was a SIGSEGV which got translated into a PROGRAM_ERROR by the
> signal handler and the run time since this happened in a finalizer.

I rarely use the debugger, I've got really used not to depend on it, though
certainly it's another tool not to be despised.

>> already found a workaround, and I even know that the problem is related
>> with interfaces, but I fear that the effort to isolate it will be a waste
>> of time. So the temptation to move on is big...
> 
> In my case: I think I have found a workaround (if my guess on the
> nature of the error is correct) and I'll post it here as a reference
> for the next users if it actually works.
> 
> In my opinion, documentation of "known bugs" and "proved workarounds"
> are almost as valuable as fixes. At least they'll spare other users
> the time (a) to form suspicions themselves and (b) to think about
> workarounds themselves.

Completely agree. When one has suffered from obscure bugs, it's inevitable
not to think that way. One would desire that they were listed in the
compiler documentation.

> It's a pity that GNAT (at least 3.15p? I'm repeating myself ...),
> doesn't have some kind of community support side where things as these
> could be collected. Or is there such a site?

Well, as pointed there's the debian tracker. Though it's no use if you don't
know about it, and even then I wonder how much it can help for other
platforms like windows.

My worst experience was when I got hit by the "sleeping tasks" bug which
only affected windows 3.15p version. After many hours of hunting with the
help of the Gnat list users (it existed by then), it turned out that it was
a real bug (I doubted it for some time) and that several people here knew
about it (but none in the gnat list!). I had been hesitant to ask in c.l.a.
for a gnat-specific question. After the experience I wouldn't be so timid.

Certainly, the http://gnuada.sf.net site seems a good place to centralize
reports (apart, of course, of reporting them to debian for the linux
branches). I guess I'll start to send there too my reports.

> For now I'm "misusing" c.l.a. for that but I wonder wether that was
> right.

It's right in my oppinion to discuss it here, maybe others disagree.
Although, for history, I'd prefer if everyone used the site mentioned
above, for example.

>> This post is really just to show my "condolences" and support. Best luck,
> 
> Hey, thanks :-)). And good luck with your problem too.

Thanks, it's already solved.

Re: Compiler Bug or what I'm doing wrong?

[Alex R. Mosteo]

Stephen Leake wrote:

> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
> 
>> + GPL editions compilers still look more buggy than 3.15p. GPL 2005 is
>> definitely worse.
> 
> Well, that may be true for your applications.
> 
> I encountered no bugs with GPL 2006; while 3.15p has significant bugs.

I guess you've not tried to make significant use of interfaces? In a week of
gpl2006 usage I've hit three bugs there.

On the other hand, dot notation for tagged objects seems much more robust,
not a single quirk for now (whereas 2005 was plagued).

I had (as noted in another thread) very bad experiences with 3.15p for
windows because of a single hidden bug so, in comparison, bugs that blow
right in your face don't bother me that much.

Apart from that, I'd say that gnat is getting better and better fast with
each release, and now that Ada05 is being frozen I bet in few time the gcc
branch will get really interesting.

> In a system as complex as a compiler, different people will have
> different problems.

Re: Compiler Bug or what I'm doing wrong?

[Alex R. Mosteo]

Alex R. Mosteo wrote:

> It's right in my oppinion to discuss it here, maybe others disagree.
> Although, for history, I'd prefer if everyone used the site mentioned
> above, for example.

After inspecting more carefully the gnuada site, I believe that the bug
tracker is for their installation packages, right?

Maybe the 3rd party bugs section could serve.

Re: Compiler Bug or what I'm doing wrong?

[Anh Vo]

>>> "Alex R. Mosteo" <devnull@mailinator.com> 6/23/2006 6:15:05 AM >>>
>> Stephen Leake wrote:
> > I encountered no bugs with GPL 2006; while 3.15p has significant
bugs.
>
> I guess you've not tried to make significant use of interfaces? In a
week of
> gpl2006 usage I've hit three bugs there.

Have you submitted them to report@adacore.com yet? If not, please cc to
this group when you do. So, we can be aware of them. In addition, we
will not report them if encountered in the future.

AV

Re: Compiler Bug or what I'm doing wrong?

[Simon Wright]

"Alex R. Mosteo" <devnull@mailinator.com> writes:

> Alex R. Mosteo wrote:
>
>> It's right in my oppinion to discuss it here, maybe others
>> disagree.  Although, for history, I'd prefer if everyone used the
>> site mentioned above, for example.
>
> After inspecting more carefully the gnuada site, I believe that the
> bug tracker is for their installation packages, right?

Yes

> Maybe the 3rd party bugs section could serve.

I would have thought something starting at the GNATP page (== 3.15p)
would be appropriate for that compiler, similar for others. This is at
http://gnuada.sourceforge.net/pmwiki.php/Packages/GNATP reached from
the Packages section of the first page.

Re: Compiler Bug or what I'm doing wrong?

[M E Leypold]

Simon Wright <simon@pushface.org> writes:

> "Alex R. Mosteo" <devnull@mailinator.com> writes:
> 
> > Alex R. Mosteo wrote:
> >
> >> It's right in my oppinion to discuss it here, maybe others
> >> disagree.  Although, for history, I'd prefer if everyone used the
> >> site mentioned above, for example.
> >
> > After inspecting more carefully the gnuada site, I believe that the
> > bug tracker is for their installation packages, right?
> 
> Yes
> 
> > Maybe the 3rd party bugs section could serve.
> 
> I would have thought something starting at the GNATP page (== 3.15p)
> would be appropriate for that compiler, similar for others. This is at
> http://gnuada.sourceforge.net/pmwiki.php/Packages/GNATP reached from
> the Packages section of the first page.


I agree and possibly will post my bug report there. This site isn't
used for bugtracking currently, so I asked wether there is a better
place. If not, that sit will do and we'll see what comes from it.

Regards -- Markus

Re: Compiler Bug or what I'm doing wrong?

[Alex R. Mosteo]

Anh Vo wrote:

>>>> "Alex R. Mosteo" <devnull@mailinator.com> 6/23/2006 6:15:05 AM >>>
>>> Stephen Leake wrote:
>> > I encountered no bugs with GPL 2006; while 3.15p has significant
> bugs.
>>
>> I guess you've not tried to make significant use of interfaces? In a
> week of
>> gpl2006 usage I've hit three bugs there.
> 
> Have you submitted them to report@adacore.com yet? If not, please cc to
> this group when you do. So, we can be aware of them. In addition, we
> will not report them if encountered in the future.

Yep, I routinely report all the bugs I find. In the future I'll write a
short testcase to c.l.a. also.

Re: Compiler Bug or what I'm doing wrong?

[Ludovic Brenta]

M E Leypold writes :
> > > After inspecting more carefully the gnuada site, I believe that the
> > > bug tracker is for their installation packages, right?
> >
> > Yes
> >
> > > Maybe the 3rd party bugs section could serve.
> >
> > I would have thought something starting at the GNATP page (== 3.15p)
> > would be appropriate for that compiler, similar for others. This is at
> > http://gnuada.sourceforge.net/pmwiki.php/Packages/GNATP reached from
> > the Packages section of the first page.
>
> I agree and possibly will post my bug report there. This site isn't
> used for bugtracking currently, so I asked wether there is a better
> place. If not, that sit will do and we'll see what comes from it.

I would suggest the Debian bug tracker instead; not because I'm trying
to promote Debian, but because the Debian BTS already has 200 bugs
filed in it or so. The community will be better served by one central
bug database than by several disjoint ones. I specifically encourage
anyone to submit bugs there, even if they do not use Debian. Similarly,
my patches that fix several bugs in 3.15p are available to all.

The only reason why I started using the Debian BTS back in 2003 was
because no other public database existed at that time. So, I claim
precedence :)

To use the Debian BTS, you only need a mail client; each bug is a
mailing list and the archives are available in mbox format.

-- 
Ludovic Brenta.

Re: Compiler Bug or what I'm doing wrong?

[M E Leypold]

"Ludovic Brenta" <ludovic@ludovic-brenta.org> writes:

> M E Leypold writes :
> > > > After inspecting more carefully the gnuada site, I believe that the
> > > > bug tracker is for their installation packages, right?
> > >
> > > Yes
> > >
> > > > Maybe the 3rd party bugs section could serve.
> > >
> > > I would have thought something starting at the GNATP page (== 3.15p)
> > > would be appropriate for that compiler, similar for others. This is at
> > > http://gnuada.sourceforge.net/pmwiki.php/Packages/GNATP reached from
> > > the Packages section of the first page.
> >
> > I agree and possibly will post my bug report there. This site isn't
> > used for bugtracking currently, so I asked wether there is a better
> > place. If not, that sit will do and we'll see what comes from it.
> 
> I would suggest the Debian bug tracker instead; not because I'm trying
> to promote Debian, but because the Debian BTS already has 200 bugs
> filed in it or so. 

I'll try to file the bug in both places. IMHO gnuada.sourceforge.net
would be the logical place for tracking bugs in community supported
Ada software, but since nobody has reported anything there yet, one
can hardly expect anyone looking there for solutions.

> The community will be better served by one central
> bug database than by several disjoint ones. 

I completely agree. I think the situation is a bit confused presently
because of the transition between p-releases and gcc gnat: For gcc
gnat the upstream source for the debian releases would come from
http://gcc.gnu.org/ and their BTS would be the first to report bugs
to. Debian BTS would either mostly refer to bugs in the gcc BTS or to
packaging defects.

(A propos packaging defects: libgtkada2-dev in Sarge absolutely
insists on getting 3.15p installed with it, despite the fact that
gnat-3.4 also "provides gnat". Superficially, from the dependencies
listing, I cannot understand why that is so and I also wonder wether
this is intended (that gtkada can only be used with 3.15p at debian).

I think the situation wrt to where to report bugs will become more
clearly defined when the transition to gccada has been done.

> I specifically encourage anyone to submit bugs there, even if they
> do not use Debian. Similarly, my patches that fix several bugs in
> 3.15p are available to all.

Yes, I already perceived that Debian is the only open platform where
I'd say that Gnat is actually supported in sense.

> The only reason why I started using the Debian BTS back in 2003 was
> because no other public database existed at that time. So, I claim
> precedence :)

You'll get it.

Regards -- Markus

Re: Compiler Bug or what I'm doing wrong?

[Simon Wright]

"Ludovic Brenta" <ludovic@ludovic-brenta.org> writes:

> M E Leypold writes :
>> > > After inspecting more carefully the gnuada site, I believe that the
>> > > bug tracker is for their installation packages, right?

I wrote:

>> > Yes
>> >
>> > > Maybe the 3rd party bugs section could serve.
>> >
>> > I would have thought something starting at the GNATP page (== 3.15p)
>> > would be appropriate for that compiler, similar for others. This is at
>> > http://gnuada.sourceforge.net/pmwiki.php/Packages/GNATP reached from
>> > the Packages section of the first page.
>>
>> I agree and possibly will post my bug report there. This site isn't
>> used for bugtracking currently, so I asked wether there is a better
>> place. If not, that sit will do and we'll see what comes from it.
>
> I would suggest the Debian bug tracker instead; not because I'm
> trying to promote Debian, but because the Debian BTS already has 200
> bugs filed in it or so. The community will be better served by one
> central bug database than by several disjoint ones. I specifically
> encourage anyone to submit bugs there, even if they do not use
> Debian. Similarly, my patches that fix several bugs in 3.15p are
> available to all.

The only reason I suggested the gnuada site was that it's a wiki so
people could post their workrounds/experiences. If the Debian bug
tracker will do that, fine (and it's obviously better that bugs should
eb posted _somewhere_!)

Re: Compiler Bug or what I'm doing wrong?

[Ludovic Brenta]

Simon Wright <simon@pushface.org> writes:
> The only reason I suggested the gnuada site was that it's a wiki so
> people could post their workrounds/experiences. If the Debian bug
> tracker will do that, fine (and it's obviously better that bugs
> should eb posted _somewhere_!)

Yes, as I said, every bug is a mailing list.  Just send mail to
nnn@bugs.debian.org (replace nnn with the bug number), and voilà.

More at http://www.debian.org/Bugs/Reporting and
http://www.debian.org/Bugs/Access

-- 
Ludovic Brenta.