DWARF: C++ namespace support

DWARF: C++ namespace support

[Devang Patel]

Hi All,

Dan Berlin has proposed patch in past to add C++ namespace support in 
DWARF
debugging information. GDB engineer, David Carlton is using one 
variation
of that patch (with bug fixes) in his local tree for GDB testing. I am
working on to add other features like using directives, using 
declarations
etc... to complete C++ lang support. But original namespace patch is 
still
not in FSF GCC 3.4. What is the reason to hold it back ?

Thanks,
--
Devang

Re: DWARF: C++ namespace support

[Daniel Berlin]

On Nov 25, 2003, at 2:42 PM, Devang Patel wrote:

> Hi All,
>
> Dan Berlin has proposed patch in past to add C++ namespace support in 
> DWARF
> debugging information. GDB engineer, David Carlton is using one 
> variation
> of that patch (with bug fixes) in his local tree for GDB testing. I am
> working on to add other features like using directives, using 
> declarations
> etc... to complete C++ lang support. But original namespace patch is 
> still
> not in FSF GCC 3.4. What is the reason to hold it back ?

I never got a chance to update it for the current CVS head.

Full namespace support will require moving some trees from C++ specific 
to common, or other magic to deal with the trees that can appear in 
USING_STMT and whatnot that we need to be able to deal with.
>
> Thanks,
> --
> Devang
>

Re: DWARF: C++ namespace support

[Devang Patel]

On Nov 25, 2003, at 11:48 AM, Daniel Berlin wrote:

>
> On Nov 25, 2003, at 2:42 PM, Devang Patel wrote:
>
>> Hi All,
>>
>> Dan Berlin has proposed patch in past to add C++ namespace support in 
>> DWARF
>> debugging information. GDB engineer, David Carlton is using one 
>> variation
>> of that patch (with bug fixes) in his local tree for GDB testing. I am
>> working on to add other features like using directives, using 
>> declarations
>> etc... to complete C++ lang support. But original namespace patch is 
>> still
>> not in FSF GCC 3.4. What is the reason to hold it back ?
>
> I never got a chance to update it for the current CVS head.

Would it be possible for you to get it in 3.4 before door closes?
Or is it already too late ? Thanks.

> Full namespace support will require moving some trees from C++ 
> specific to common, or other magic to deal with the trees that can 
> appear in USING_STMT and whatnot that we need to be able to deal with.

So far I've managed to get 'using declaration' support without tree 
movements.
I have tested sample programs only until now. Once I build libstdc++, 
I'll know
more about my approach.

--
Devang

Re: DWARF: C++ namespace support

[Daniel Berlin]

>> I never got a chance to update it for the current CVS head.
>
> Would it be possible for you to get it in 3.4 before door closes?

Errr, part of it was approved ages ago (the basic support for 
generating namespace dies), i was just waiting for gdb to commit it.
But if we are going to do it, we should probably do it right and submit 
it all at once.

> Or is it already too late ? Thanks.
>
>> Full namespace support will require moving some trees from C++ 
>> specific to common, or other magic to deal with the trees that can 
>> appear in USING_STMT and whatnot that we need to be able to deal 
>> with.
>
> So far I've managed to get 'using declaration' support without tree 
> movements.

Well, how do you deal with USING_STMT's that contain OVERLOAD trees (or 
were those appearing in USING_DECL or something, i can't remember.)

It's possible these issues are moot, this patch was originally worked 
on before the new C++ parser came into being.


> I have tested sample programs only until now. Once I build libstdc++, 
> I'll know
> more about my approach.
>
> --
> Devang
>

Re: DWARF: C++ namespace support

[David Carlton]

On Tue, 25 Nov 2003 16:26:23 -0500, Daniel Berlin <dberlin@dberlin.org> said:

>>> I never got a chance to update it for the current CVS head.
>> 
>> Would it be possible for you to get it in 3.4 before door closes?

> Errr, part of it was approved ages ago (the basic support for
> generating namespace dies), i was just waiting for gdb to commit it.
> But if we are going to do it, we should probably do it right and
> submit it all at once.

I think that there is significant benefit in having the
DW_TAG_namespace support even without the support for using directives
and using declarations.  Without DW_TAG_namespace, there is simply no
reliable way for GDB to tell what the fully-qualified name of a type
is, which makes it impossible to reliably get nested types right (and
which gives rise to some quite unfortunate hacks within GDB).  Whereas
without, say, using directives, it just means that users have to do a
little more typing, which isn't nearly as big a deal.

Also, there's the more pragmatic consideration that a patch that
seriously uses DW_TAG_namespace (if it is present) is awaiting
approval for GDB as we speak, whereas nobody has written a patch for
GDB that uses DW_TAG_imported_declaration or whatever the other tags
are called.  I certainly can't write such a patch until I have access
to patches to GCC to generate the information in question, and while
it sounds like I might soon have that from Devang, I'm also not sure
when I'll have the necessary free time.

David Carlton
carlton@kealia.com

Re: DWARF: C++ namespace support

[David Carlton]

On Tue, 25 Nov 2003 15:12:18 -0800, David Carlton <carlton@kealia.com> said:

> Also, there's the more pragmatic consideration that a patch that
> seriously uses DW_TAG_namespace (if it is present) is awaiting
> approval for GDB as we speak

Also (I know Daniel and Devang are aware of this, but other readers
may not be), both GDB 5.3 and 6.0 are perfectly happy with seeing any
of these DWARF tags, so there's no active technical barrier on GDB's
side to adding these to GCC.

David Carlton
carlton@kealia.com

Re: DWARF: C++ namespace support

[Daniel Berlin]

On Wed, 26 Nov 2003, Benjamin Kosnik wrote:

>
> >> debug/11114 GCC doesn't generate DW_TAG_namespace entries
> >>
> >> It's mustfix for 3.4.
> >
> >Is it now?
>
> Yes. If you want to take another crack at it, I'm sure the rest of us
> would appreciate it.

Sure, i can revise it again according to his comments (i'll probably not
have much luck trying to find the patch).
I'll do it saturday when i get back (It's evry hard to edit patches over a
14.4k link :P)

>
> >> Yes; I reviewed it, but Dan never revised the patch based on my
> >> comments.
> >
> >I did, it's somewhere.
> >Like I said, it was never high on my priority list.
>
> Well, that's a bummer.

Well, at the time, GDB didn't support it.
Now that it does, and supprot for other things related to debug info seems
to be improving at a good rate, i'll probably get back into trying to make
us generate spectacular debug info.

Re: DWARF: C++ namespace support

[Benjamin Kosnik]

>> debug/11114 GCC doesn't generate DW_TAG_namespace entries
>>
>> It's mustfix for 3.4.
>
>Is it now?

Yes. If you want to take another crack at it, I'm sure the rest of us
would appreciate it.

>> Yes; I reviewed it, but Dan never revised the patch based on my 
>> comments.
>
>I did, it's somewhere.
>Like I said, it was never high on my priority list.

Well, that's a bummer. 

-benjamin

Re: DWARF: C++ namespace support

[Daniel Berlin]

On Nov 26, 2003, at 1:53 AM, Benjamin Kosnik wrote:

>> Errr, part of it was approved ages ago (the basic support for 
>> generating
>> namespace dies), i was just waiting for gdb to commit it. But if we 
>> are
>> going to do it, we should probably do it right and submit it all at
>> once.
>
> I am also wondering about the complete absence of this patch in 
> mainline gcc.
>
> This has been tracked in bugzilla as:
>
> debug/11114 GCC doesn't generate DW_TAG_namespace entries
>
> It's mustfix for 3.4.

Is it now?

>
> The last time I talked to Jason about this, he said:
>
>> Have you seen this patch?
>> http://gcc.gnu.org/ml/gcc-patches/2002-11/msg01616.html
>
> Yes; I reviewed it, but Dan never revised the patch based on my 
> comments.

I did, it's somewhere.
Like I said, it was never high on my priority list.

Re: DWARF: C++ namespace support

[Benjamin Kosnik]

> Errr, part of it was approved ages ago (the basic support for generating
> namespace dies), i was just waiting for gdb to commit it. But if we are
> going to do it, we should probably do it right and submit it all at
> once.

I am also wondering about the complete absence of this patch in mainline gcc.

This has been tracked in bugzilla as:

debug/11114 GCC doesn't generate DW_TAG_namespace entries

It's mustfix for 3.4. 

The last time I talked to Jason about this, he said:

> Have you seen this patch? 
> http://gcc.gnu.org/ml/gcc-patches/2002-11/msg01616.html

Yes; I reviewed it, but Dan never revised the patch based on my comments.

I'm not quite sure what's up with it now.

-benjamin