[Bug c++/23480] New: default-initializing variable size array new expression does not work

[Bug c++/23480] New: default-initializing variable size array new expression does not work

[avi at argo dot co dot il]

the following function 
 
  int* f(int n) { return new int[n](); } 
 
translates to 
 
_Z1fi: 
.LFB2: 
        pushl   %ebp 
.LCFI0: 
        movl    %esp, %ebp 
.LCFI1: 
        sall    $2, 8(%ebp) 
        leave 
.LCFI2: 
        jmp     _Znaj 
 
which does not default-initialize the array.

-- 
           Summary: default-initializing variable size array new expression
                    does not work
           Product: gcc
           Version: 4.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: avi at argo dot co dot il
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i386-redhat-linux
  GCC host triplet: i386-redhat-linux
GCC target triplet: i386-redhat-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23480

[Bug c++/23480] default-initializing variable size array new expression does not work

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-08-19 13:04 -------
new int[2] () is broken in 3.4.x, see PR 20427.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23480

[Bug c++/23480] default-initializing variable size array new expression for basic types does not work

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|default-initializing        |default-initializing
                   |variable size array new     |variable size array new
                   |expression does not work    |expression for basic types
                   |                            |does not work


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23480

[Bug c++/23480] default-initializing variable size array new expression for basic types does not work

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-08-20 02:30 -------
Testcase which was attached on PR 20427:


#include <iostream>
void f(int n)
{
    int * a = new int [n] () ;
    for (int i = 0; i < n; ++i)
    {
        std::cout << a[i]++ << ' ';
    }
    std::cout << '\n';
    delete[] a;
}

int main()
{
    f(5);
    f(5);
    f(5);
    f(5);
}

Which shows the issue more clearer.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23480

[Bug c++/23480] default-initializing variable size array new expression for basic types does not work

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-08-20 02:37 -------
3.2.3 and 3.0.4 rejected the code:
t.cc: In function `void f(int)':
t.cc:4: variable-sized object of type `int[n]' may not be initialized

No recent (from 2.95.3 and above) GCC version got this right (well at least the versions I tested).

Here is a self contained testcase which fails and should not:
extern "C" void abort ();
void f(int n)
{
    int * a = new int [n] () ;
    for (int i = 0; i < n; ++i)
    {
        if (a[i])
                abort ();
        a[i]++;
    }
    delete[] a;
}
int main()
{
    f(5);
    f(5);
    f(5);
    f(5);
}

Even ICC 8.1 gets this wrong :).

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |wrong-code
      Known to fail|                            |3.3.3 3.4.0 4.0.0 4.1.0
                   |                            |2.95.3
   Last reconfirmed|0000-00-00 00:00:00         |2005-08-20 02:37:17
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23480