http://d.puremagic.com/issues/show_bug.cgi?id=3389

           Summary: gdb: using -gc is mandatory but not well documented
           Product: D
           Version: unspecified
          Platform: All
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: www.digitalmars.com
        AssignedTo: nobody@puremagic.com
        ReportedBy: llucax@gmail.com


--- Comment #0 from Leandro Lucarella <llucax@gmail.com> 2009-10-12 14:23:14 PDT ---
-g is known to be broken when using GDB (I don't know if this is how it's supposed to be or if it's a bug). -gc usually works (there are a few bugs still), but it's not very well documented that when using GDB you should use -gc (which is supposed to mean, "pretend to be C", so it's not very easy to figure out that that flag should be used instead of -g).

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Robert Clipsham <robert@octarineparrot.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |robert@octarineparrot.com


--- Comment #1 from Robert Clipsham <robert@octarineparrot.com> 2010-04-01 13:37:35 BST ---
-g not working is how it's meant to be, at least until gdb adds support for the D extensions to DWARF. I've hopefully fixed the remaining bugs with -gc (on linux at least). My solution to this would be to add in a -gd, and make -g an alias to -gc until better support for debug info is added to debuggers. This way users get working debug output with -g, and don't blame it on a buggy dmd :)

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--- Comment #2 from Leandro Lucarella <llucax@gmail.com> 2010-04-28 09:31:36 PDT ---
Seems reasonable.

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dawg@dawgfoto.de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |dawg@dawgfoto.de
         Resolution|                            |FIXED


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Leandro Lucarella <leandro.lucarella@sociomantic.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |


--- Comment #3 from Leandro Lucarella <leandro.lucarella@sociomantic.com> 2012-02-01 02:25:52 PST ---
Copying comment in bug 4149 and reopening because I don't think this is really closed.

In that bug some standard DWARF issues were moved to -g, and now I think -g works with debuggers not supporting D extensions.

*BUT*, in bug 4149 Walter agreed about this comment by Brad Roberts:

> Depends on if gc implies c, c++, or 'as much as is supported in the built-in debug format without extension'.
> 
> I'd argue for the last definition.  Given that dwarf supports it without extension, I'd argue that it should use it.  I'd argue that -g should be built-in + d extensions.

AFAIK this pull request works for -g instead of -gc, even when it uses standard DWARF features, which goes against that comment.

Also there is the point made by Robert Clipsham in comment 1, which for me makes a lot of sense. At least this will be more familiar with people used to GCC command line arguments (which is probably 100% of the *nix world), where -g is the default for debug and you have, for example -ggdb for GDB extensions.

AFAIK there is no clear direction about this and it would be nice to have one, so the debugging stuff is as consistent as possible.

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--- Comment #4 from dawg@dawgfoto.de 2012-02-01 11:27:20 PST ---
Thats a wrong comparision because neither -g not -ggdb make the compiler fake C++ debug information as C. The -gc flag is a hack to masquerade as C which should not be the default if -g works for most platforms.

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--- Comment #5 from dawg@dawgfoto.de 2012-02-01 11:34:57 PST ---
GDB already has D specific extensions (demangling and arrays). Using -g makes
use of them, -gc does not.
There won't be D specific DWARF extensions any time soon.
What we wanted to add can be modeled by newer DWARF versions but adapting them
would break older debuggers.

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Brad Roberts <braddr@puremagic.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
                 CC|                            |braddr@puremagic.com
         Resolution|                            |WONTFIX


--- Comment #6 from Brad Roberts <braddr@puremagic.com> 2012-02-01 20:54:51 PST ---
The bottom line is that -g needs to 'just work' with the standard debuggers on
the supported platforms.  Assuming that -g works, -gc is a left over appendage.
 A whole lot of progress has been made in a number of commits over the last
year.

Some quick testing on linux shows that it works quite well with just -g now.

With that in mind, I'm resolving this bug report as wontfix since -gc isn't mandatory any more.

Chances are that there's more bugs left, so please feel encouraged to distill repro cases where -g doesn't "just work", file them, and we'll work on them.

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--- Comment #7 from Leandro Lucarella <leandro.lucarella@sociomantic.com> 2012-02-02 02:51:50 PST ---
(In reply to comment #4)
> Thats a wrong comparision because neither -g not -ggdb make the compiler fake C++ debug information as C. The -gc flag is a hack to masquerade as C which should not be the default if -g works for most platforms.

That's not what Walter said (agreeing with Brad's comment) in the comment I pointed out. But it seems that's not longer the position about -g/-gc (at least for Brad). I don't care that much about what should be the meaning of -g/-gc as long as there is one that works (and will keep working) with standard debuggers.

(In reply to comment #6)
> The bottom line is that -g needs to 'just work' with the standard debuggers on
> the supported platforms.  Assuming that -g works, -gc is a left over appendage.
>  A whole lot of progress has been made in a number of commits over the last
> year.
> 
> Some quick testing on linux shows that it works quite well with just -g now.
> 
> With that in mind, I'm resolving this bug report as wontfix since -gc isn't mandatory any more.
> 
> Chances are that there's more bugs left, so please feel encouraged to distill repro cases where -g doesn't "just work", file them, and we'll work on them.

OK, so -gc should be just deprecated and there should be only -g, right? Will -gc be the same as -g? If not, why?

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