[Bug c++/34196] New: [4.3 Regression] uninitialized variable warning in dead exception region

[Bug c++/34196] New: [4.3 Regression] uninitialized variable warning in dead exception region

[rguenth at gcc dot gnu dot org]

#include <string>

template <class _Tp> class AutoPtr {
  _Tp* _M_ptr;

public:
  explicit AutoPtr(_Tp* __p = 0)  : _M_ptr(__p) {}

  ~AutoPtr() { delete _M_ptr; }

  _Tp* operator->() const  {
    return _M_ptr;
  }
};

struct A {
    virtual ~A();
    virtual A * unserialise(const std::string &s) const = 0;
};

A * wtx;

void
func(const std::string & s)
{
    AutoPtr<A> wt(wtx->unserialise(s.c_str()));
}


g++ -O -Wuninitialized -c remoteserver.cc
remoteserver.cc: In function 'void func(const std::string&)':
remoteserver.cc:9: warning: 'wt.AutoPtr<A>::_M_ptr' is used uninitialized in
this function
remoteserver.cc:26: note: 'wt.AutoPtr<A>::_M_ptr' was declared here


because in the late uninitalized variable pass we discover

<L1>:;
  save_filt.37_16 = <<<filter object>>>;
  save_eptr.36_17 = <<<exception object>>>;
  if (wt$_M_ptr_40(D) != 0B)
    goto <bb 12>;
  else
    goto <bb 13>;

<bb 12>:
  D.13202_23 = wt$_M_ptr_40(D)->_vptr.A;
  D.13203_24 = D.13202_23 + 8;
  D.13204_25 = *D.13203_24;
  OBJ_TYPE_REF(D.13204_25;wt$_M_ptr_40(D)->1) (wt$_M_ptr_40(D));

which hasn't been deleted here.  4.2 was either able to delete these BBs
or didn't create this exception region.


-- 
           Summary: [4.3 Regression] uninitialized variable warning in dead
                    exception region
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rguenth at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34196

[Bug c++/34196] [4.3 Regression] uninitialized variable warning in dead exception region

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pinskia at gcc dot gnu dot
                   |                            |org
   Target Milestone|---                         |4.3.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34196

[Bug c++/34196] [4.3 Regression] uninitialized variable warning in dead exception region

[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=34196

[Bug c++/34196] [4.3 Regression] uninitialized variable warning in dead exception region

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2007-12-03 03:33 -------
This looks like a front-end/gimplifier bug.

So we have:
allocator::allocator();
try {
  char* a = s->c_str();
  t = string::string(a);
  try {
   b =  wtx-> unserialise (t);
   wt = AutoPtr::AutoPtr (b);
  } finnally {
    try {
      string::~string(t);
      } catch
      {
        AutoPtr::~AutoPtr (wt);
      }
  }
}
...


At the time we call ~AutoPtr, it does not have to be fully constructored.

I think this is related (and maybe even caused by) PR 15764.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu dot org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-12-03 03:33:45
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34196

[Bug c++/34196] [4.3 Regression] uninitialized variable warning in dead exception region

[jason at gcc dot gnu dot org]

-- 

jason at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jason at gcc dot gnu dot org
                   |dot org                     |
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2007-12-03 03:33:45         |2007-12-03 14:52:41
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34196

[Bug c++/34196] [4.3 Regression] uninitialized variable warning in dead exception region

[jason at gcc dot gnu dot org]

------- Comment #2 from jason at gcc dot gnu dot org  2008-01-14 16:15 -------
This is indeed caused by the patch for 15764.  If unserialize throws, and then
the destructor for the string temporary passed as the argument to unserialize
throws, we would then destroy wt without having constructed it.  Except that we
should call terminate() if the string destructor throws, because we were
unwinding the stack.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34196

[Bug c++/34196] [4.3 Regression] uninitialized variable warning in dead exception region

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2008-01-16 22:29 -------
*** Bug 34470 has been marked as a duplicate of this bug. ***


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |zackw at panix dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34196

[Bug c++/34196] [4.3 Regression] uninitialized variable warning in dead exception region

[jason at gcc dot gnu dot org]

------- Comment #4 from jason at gcc dot gnu dot org  2008-01-22 04:54 -------
Subject: Bug 34196

Author: jason
Date: Tue Jan 22 04:53:33 2008
New Revision: 131710

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=131710
Log:
        PR c++/34196
        * tree.h (TRY_CATCH_IS_CLEANUP): New macro.
        * cp/decl.c (wrap_cleanups_r): Set TRY_CATCH_IS_CLEANUP.
        * tree-eh.c (honor_protect_cleanup_actions): Strip TRY_CATCH_EXPR
        if it is set.

Added:
    trunk/gcc/testsuite/g++.dg/eh/init-temp2.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/decl.c
    trunk/gcc/tree-eh.c
    trunk/gcc/tree.h


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34196

[Bug c++/34196] [4.3 Regression] uninitialized variable warning in dead exception region

[rguenth at gcc dot gnu dot org]

------- Comment #5 from rguenth at gcc dot gnu dot org  2008-01-22 13:24 -------
Fixed.


-- 

rguenth at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34196