Re: breakpoints and symbol examination problems

["Brian Budge" <brian.budge@gmail.com>]

So here is a minimal repro case on my system:

foo.h
---------------------------------------------
template<typename joe>
struct Class1 {
    joe a;

    Class1(int b) : a(b) {}
};

template<typename joe>
struct Class2 {
    joe a;

    Class2(const Class1<joe> &rhs) {
        a = 0;
        for(int i = 0; i < 10; ++i) {
            a += rhs.a;
        }
    }
};

----------------------------------------------------
foo.cpp
--------------------------------------------------
#include <iostream>
#include "foo.h"

int main() {

    Class1<float> c1(15);

    Class2<float> c2(c1);

    std::cout << "value is " << c2.a << std::endl;

    return 0;
}
--------------------------------------------------------------

I'm compiling foo.cpp with
> g++ -g foo.cpp

Here's my gdb session:

GNU gdb 6.7.90.20080311-cvs
Copyright Stuff (removed for brevity)
This GDB was configured as "x86_64-unknown-linux-gnu"...
(gdb) b 8
Breakpoint 1 at 0x40093b: file foo.cpp, line 8.
(gdb) run
Starting program: /home/budge/projects/rt_suite/apps/RtBatch/a.out

Breakpoint 1, main () at foo.cpp:8
8	    Class2<float> c2(c1);
(gdb) s
Class2 (this=0x7fff23e32c20, rhs=@0x7fff23e32c30) at foo.h:13
13	        a = 0;
(gdb) n
14	        for(int i = 0; i < 10; ++i) {
(gdb)
15	            a += rhs.a;
(gdb) p i
No symbol "i" in current context.


g++ reports version "Gentoo 4.1.1-r3".  I'm running on amd64.

Hopefully that will help a little in figuring out what is happening.

Thanks,
  Brian

On Tue, Mar 11, 2008 at 2:20 PM, Brian Budge <brian.budge@gmail.com> wrote:
> Hi Michael, Daniel, all -
>
>  I built gdb from CVS gdb_6_8-branch, and indeed it fixed my breakpoint
>  problem.  Unfortunately, I still can't examine local variables.  I get
>  this interaction, for example:
>
>  207             vector< dopVertex<T> > tmpVerts;
>  (gdb)
>  208             vector< dopEdge > tmpEdges;
>  (gdb) p tmpVerts
>  No symbol "tmpVerts" in current context.
>
>  Needless to say, not being able to examine your local variable makes
>  debugging fairly tricky ;)
>
>  So, one down, one to go... not too shabby.  Any more ideas?
>
>  Thanks,
>   Brian
>
>
>
>  On Tue, Mar 11, 2008 at 8:24 AM, Brian Budge <brian.budge@gmail.com> wrote:
>  > Actually, this is already with -O0... at least I think.  I'm not
>  >  passing any optimization flags.  For debug symbols I'm passing -ggdb.
>  >
>  >  I'll try the CVS current top of tree a bit later today.
>  >
>  >  Thanks,
>  >   Brian
>  >
>  >
>  >
>  >  On Mon, Mar 10, 2008 at 5:52 PM, Michael Snyder <msnyder@specifix.com> wrote:
>  >  > On Mon, 2008-03-10 at 20:32 -0400, Daniel Jacobowitz wrote:
>  >  >  > On Mon, Mar 10, 2008 at 05:05:17PM -0700, Brian Budge wrote:
>  >  >  >
>  >  >
>  >  > > > Additionally, I can't seem to examine any "stack" variables once in
>  >  >  > > these template functions.  I can see member variables, global
>  >  >  > > variables, and function parameters.
>  >  >  >
>  >  >  > This may be fixed, or it may be a compiler bug.  GCC is not very good
>  >  >  > about emitting local variable information in optimized code.
>  >  >
>  >  >  Can you compile with -O0?
>  >  >
>  >  >
>  >  >
>  >
>