Re: "info locals" -- is variable initialized

[Daniel Jacobowitz <drow@false.org>]

On Fri, Sep 02, 2005 at 05:18:46PM +0400, Vladimir Prus wrote:
> On Friday 02 September 2005 17:13, Daniel Jacobowitz wrote:
> > On Fri, Sep 02, 2005 at 01:53:41PM +0400, Vladimir Prus wrote:
> > > So, there's a window there variable does not exists according to C++, but
> > > exists according to gdb.
> >
> > With better debug information, this doesn't happen (or the window is
> > reduced to an instruction or two in the call sequence for the
> > constructor).  GCC 4's variable tracking feature does this passably
> > well, IIRC, by use of dwarf2 location lists.
> 
> Do I need for extra flags for gcc? I've tried with gcc-4.0 before posting the
> message, and it did printed all vars.

I think it's activated with optimization, but with -O0 you may need
-fvar-tracking.  I don't know for sure.

> > In general no there is nothing gdb can do.
> 
> How about using decl_line. Here's what debug info says
> 
>    <2><2188c>: Abbrev Number: 140 (DW_TAG_variable)
>      DW_AT_name        : url
>      DW_AT_decl_file   : 1
>      DW_AT_decl_line   : 14
>      DW_AT_type        : <1d555>
>      DW_AT_location    : 3 byte block: 91 98 7f         (DW_OP_fbreg: -104)
> 
> If gdb could tell the value of 'decl_line' via some command, that might be a 
> good approximation.

Using line numbers for this sort of thing is really not a good idea. 
They're useful for displaying source to the user, but for anything
else, there are too many potential strangenesses...

-- 
Daniel Jacobowitz
CodeSourcery, LLC