[Bug debug/33537] New: [4.0/4.1/4.2/4.3 regression] C++ arguments passed by invisible reference have wrong type

[Bug debug/33537] New: [4.0/4.1/4.2/4.3 regression] C++ arguments passed by invisible reference have wrong type

[drow at gcc dot gnu dot org]

Compile the code below using g++ -g, load the object into gdb, and 'ptype foo'.
 You will see that the type of foo is 'int (Obj &)'.  If this function is
called from GDB, and the called function modifies its argument, it will end up
modifying the original copy.  It's supposed to get a temporary copy.

This changed sometime between g++ 3.3 and g++ 4.0.

class Obj {
public:
  Obj ();
  Obj (const Obj &);
  ~Obj ();
  int var[2];
};

int foo (Obj arg)
{
  return arg.var[0] + arg.var[1];
}

int main() { return 0; }

Obj::Obj ()
{
  var[0] = 1;
  var[1] = 2;
}

Obj::Obj (const Obj &obj)
{
  var[0] = obj.var[0];
  var[1] = obj.var[1];
}

Obj::~Obj ()
{

}


-- 
           Summary: [4.0/4.1/4.2/4.3 regression] C++ arguments passed by
                    invisible reference have wrong type
           Product: gcc
           Version: 4.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: drow at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33537

[Bug debug/33537] [4.0/4.1/4.2/4.3 regression] C++ arguments passed by invisible reference have wrong type

[bangerth at dealii dot org]

------- Comment #1 from bangerth at dealii dot org  2007-09-23 17:07 -------
I get the same output
  (gdb) ptype foo
  type = int (Obj &)
for all compilers I tried here, i.e. gcc versions 2.95, 3.2.3, 3.3.6, 3.4.6
and 4.1.2. This is with gdb 6.5.

On the other hand, when using icc10 and Sun Studio, I get this:
  (gdb) ptype foo
  type = int (Obj)
which appears correct. So I can confirm that this appears to be a bug.

I'm not sure yet about the regression status: Can you re-check whether you
indeed got the correct results with pre-4.0 versions of gcc?

W.


-- 

bangerth at dealii dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bangerth at dealii dot org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-09-23 17:07:02
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33537

[Bug debug/33537] [4.0/4.1/4.2/4.3 regression] C++ arguments passed by invisible reference have wrong type

[drow at gcc dot gnu dot org]

------- Comment #2 from drow at gcc dot gnu dot org  2007-09-23 17:49 -------
I got the correct result on amd64 with g++-3.3 (GCC) 3.3.6 (Debian 1:3.3.6-15).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33537

[Bug debug/33537] [4.0/4.1/4.2/4.3 regression] C++ arguments passed by invisible reference have wrong type

[pluto at agmk dot net]

------- Comment #3 from pluto at agmk dot net  2007-09-23 18:31 -------
(In reply to comment #0)

> If this function is called from GDB, and the called function modifies
> its argument, it will end up modifying the original copy.
> It's supposed to get a temporary copy.

compiler does the temporary copy. please look at this example:

$ cat 33537.cpp
struct X
{
    X();
    X( X const& );
    int var;
};
int f( X arg )
{
    arg.var = 0;
    return arg.var;
}
int main()
{
    X x;
    f( x );
    return 0;
}

at tree dump we see the temporary object passed to f(X) by reference:

int f(X) (arg)
{
  arg->var = 0;
  return 0;
}
int main() ()
{
  struct X x;
  struct X D.2360;
  __comp_ctor  (&x);
  __comp_ctor  (&D.2360, &x);
  f (&D.2360);
  return 0;
}


-- 

pluto at agmk dot net changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pluto at agmk dot net


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33537

[Bug debug/33537] [4.0/4.1/4.2/4.3 regression] C++ arguments passed by invisible reference have wrong type

[drow at gcc dot gnu dot org]

------- Comment #4 from drow at gcc dot gnu dot org  2007-09-23 18:40 -------
Subject: Re:  [4.0/4.1/4.2/4.3 regression] C++ arguments
        passed by invisible reference have wrong type

On Sun, Sep 23, 2007 at 06:31:42PM -0000, pluto at agmk dot net wrote:
> > If this function is called from GDB, and the called function modifies
> > its argument, it will end up modifying the original copy.
> > It's supposed to get a temporary copy.
> 
> compiler does the temporary copy. please look at this example:

That's why the bug report said "from GDB".  It's a debug info bug, not
a C++ wrong-code bug.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33537

[Bug debug/33537] [4.1/4.2/4.3 regression] C++ arguments passed by invisible reference have wrong type

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.0/4.1/4.2/4.3 regression]|[4.1/4.2/4.3 regression] C++
                   |C++ arguments passed by     |arguments passed by
                   |invisible reference have    |invisible reference have
                   |wrong type                  |wrong type
   Target Milestone|---                         |4.1.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33537

[Bug debug/33537] [4.1/4.2/4.3 regression] C++ arguments passed by invisible reference have wrong type

[mmitchel at gcc dot gnu dot org]

-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33537

[Bug debug/33537] [4.1/4.2/4.3 regression] C++ arguments passed by invisible reference have wrong type

[jakub at gcc dot gnu dot org]

------- Comment #5 from jakub at gcc dot gnu dot org  2007-10-31 15:58 -------
dwarf2out.c needs to handle DECL_BY_REFERENCE PARM_DECLs (and perhaps also
RESULT_DECLs).


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jakub at gcc dot gnu dot org
                   |dot org                     |
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2007-09-23 17:07:02         |2007-10-31 15:58:54
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33537

[Bug debug/33537] [4.1/4.2/4.3 regression] C++ arguments passed by invisible reference have wrong type

[jakub at gcc dot gnu dot org]

------- Comment #6 from jakub at gcc dot gnu dot org  2007-11-01 10:17 -------
Subject: Bug 33537

Author: jakub
Date: Thu Nov  1 10:17:42 2007
New Revision: 129820

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=129820
Log:
        PR debug/33537
        * dwarf2out.c (gen_formal_parameter_die, gen_variable_die,
        gen_decl_die): Use TREE_TYPE (TREE_TYPE (decl)) as type
        rather than TREE_TYPE (decl) if DECL_BY_REFERENCE (decl).

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/dwarf2out.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33537

[Bug debug/33537] [4.1/4.2 regression] C++ arguments passed by invisible reference have wrong type

[jakub at gcc dot gnu dot org]

------- Comment #7 from jakub at gcc dot gnu dot org  2007-11-01 10:19 -------
Fixed on the trunk so far.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.1/4.2/4.3 regression] C++|[4.1/4.2 regression] C++
                   |arguments passed by         |arguments passed by
                   |invisible reference have    |invisible reference have
                   |wrong type                  |wrong type


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33537

[Bug debug/33537] [4.1/4.2 regression] C++ arguments passed by invisible reference have wrong type

[jan dot kratochvil at redhat dot com]

------- Comment #8 from jan dot kratochvil at redhat dot com  2007-11-01 17:37 -------
ptype testcase is now in GDB as: gdb/testsuite/gdb.cp/arg-reference.exp 
(GDB still does not create the temporary copy during a call from GDB itself.)


-- 

jan dot kratochvil at redhat dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jan dot kratochvil at redhat
                   |                            |dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33537

[Bug debug/33537] [4.2 regression] C++ arguments passed by invisible reference have wrong type

[jsm28 at gcc dot gnu dot org]

------- Comment #9 from jsm28 at gcc dot gnu dot org  2008-07-04 22:18 -------
Closing 4.1 branch.


-- 

jsm28 at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.1/4.2 regression] C++    |[4.2 regression] C++
                   |arguments passed by         |arguments passed by
                   |invisible reference have    |invisible reference have
                   |wrong type                  |wrong type
   Target Milestone|4.1.3                       |4.2.5


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33537

[Bug debug/33537] [4.2 regression] C++ arguments passed by invisible reference have wrong type

[jsm28 at gcc dot gnu dot org]

------- Comment #10 from jsm28 at gcc dot gnu dot org  2009-03-30 22:26 -------
Closing 4.2 branch, fixed in 4.3.


-- 

jsm28 at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
      Known to fail|                            |4.2.5
      Known to work|                            |4.3.0
         Resolution|                            |FIXED
   Target Milestone|4.2.5                       |4.3.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33537