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* [Bug varobj/10687] New: Printing c++ class with static array (of same type) can produce infinite output in gdb 6.8
@ 2009-09-23  8:00 linde at acc dot umu dot se
  2010-02-17 19:31 ` [Bug c++/10687] " tromey at redhat dot com
                   ` (2 more replies)
  0 siblings, 3 replies; 5+ messages in thread
From: linde at acc dot umu dot se @ 2009-09-23  8:00 UTC (permalink / raw)
  To: gdb-prs

How to reproduce:

Test program (v2.cpp):

---clip--
class vec2 
{
  public:
    vec2() { _v[0] = _v[1] = 0; }
    vec2(int x, int y) { _v[0] = x; _v[1] = y; }
    static vec2 axis[2];
  private:
    int _v[2];
};

vec2 vec2::axis[2] = { vec2(1,0), vec2(0,1) };

int main(int argc, char*argv[])
{
  vec2 a;

  return 0;
}
--clip--

Compile: "g++ -g -o v2 v2.cpp" (I used gcc 4.3.3)

GNU gdb 6.8
....
(gdb) break main
Breakpoint 1 at 0x400563: file v2.cpp, line 16.
(gdb) r
Starting program: /home/linde/v2 

Breakpoint 1, main (argc=1, argv=0x7fff734e7018) at v2.cpp:16
16	  vec2 a;
(gdb) p a
$1 = {static axis = {{static axis = {{static axis = {{static axis = {{static
axis = {{static axis = { ....

If using gdb directly one will get
---Type <return> to continue, or q <return> to quit---
after a certain amount of output. However, if using gdb through a frontend 
such as cgdb or ddd, gdb will crash with segfault.


IF the array is removed and the following is added to the class:
static vec2 t;

and futher down
vec2 vec2::t = vec2(1,1);

Then gdb will show the following when printing a:
{static t = {static t = <same as static member of an already seen type>, _v =
{1, 1}}, _v = {0, 0}}
(after a:s constructor has ran).

So the problem seems to be that gdb can not detect that it's an already seen
type when there is an array involved. And if the type is not recognized, the
recursion will not break and the type vec2 kept being expanded because of "axis".

-- 
           Summary: Printing c++ class with static array (of same type) can
                    produce infinite output in gdb 6.8
           Product: gdb
           Version: 6.8
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: varobj
        AssignedTo: unassigned at sourceware dot org
        ReportedBy: linde at acc dot umu dot se
                CC: gdb-prs at sourceware dot org


http://sourceware.org/bugzilla/show_bug.cgi?id=10687

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^ permalink raw reply	[flat|nested] 5+ messages in thread
[parent not found: <bug-10687-4717@http.sourceware.org/bugzilla/>]
end of thread, other threads:[~2014-11-05  3:21 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2009-09-23  8:00 [Bug varobj/10687] New: Printing c++ class with static array (of same type) can produce infinite output in gdb 6.8 linde at acc dot umu dot se
2010-02-17 19:31 ` [Bug c++/10687] " tromey at redhat dot com
2010-04-07 17:41 ` cmoller at redhat dot com
2010-04-21 11:21 ` cmoller at redhat dot com
     [not found] <bug-10687-4717@http.sourceware.org/bugzilla/>
2014-11-05  3:21 ` amodra at gmail dot com

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