c++/10427: [3.0/3.2/3.3/3.4 regression] Stack corruption with variable-length automatic arrays and virtual destructors

[Matthias Klose <doko@net.local>]

>Number:         10427
>Category:       c++
>Synopsis:       [3.0/3.2/3.3/3.4 regression] Stack corruption with variable-length automatic arrays and virtual destructors
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          wrong-code
>Submitter-Id:   net
>Arrival-Date:   Thu Apr 17 20:06:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     Toni Timonen <ttimonen@users.sourceforge.net>
>Release:        
>Organization:
The Debian Project
>Environment:
>Description:
[ Reported to the Debian BTS as report #188527.
  Please CC 188527@bugs.debian.org on replies.
  Log of report can be found at http://bugs.debian.org/188527 ]
	

Regression from 2.95, rechecked with 3.0.4, 3.2 20030415, 3.3
20030415, HEAD 20030329.

the following program compiles (compiled as "g++ stackcorrupt.cpp"), 
but crashes when run. It seems that the stack gets corrupted with that
variable-length array when A class with a virtual function is used
and the length assigning variable(foo) is being changed.

stackcorrupt.cpp:
--snip--
class A {
  public:
  virtual ~A() {}
};

int main(void) {
  int foo=1;
  A bar[foo];
  foo++;
  return 0;
}
--snip-- 

The same problem can also be reproduced by using the compiler from the 
gcc-snapshot (20030314-1) or with the g++-3.0 (3.0.4-13). The g++-2.95
(2.95.4-17) does not have the same problem.

>How-To-Repeat:
	
>Fix:
	
>Release-Note:
>Audit-Trail:
>Unformatted: