c++/8209: Failure to detect negative bit-field size (!)

[wwieser@gmx.de]

>Number:         8209
>Category:       c++
>Synopsis:       Failure to detect negative bit-field size (!)
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          accepts-illegal
>Submitter-Id:   net
>Arrival-Date:   Sun Oct 13 02:06:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     wwieser@gmx.de
>Release:        3.2.1 20021007 (prerelease) and many more
>Organization:
>Environment:
linux-elf
>Description:
The bug was verified to be still present in yesterday's
CVS (Oct 12): 

If you compile the following code: 
  struct A
  {
      int : (-1);
  };
you get the (correct) _error_ 
  negative width in bit-field `A::<anonymous>'

Now, if you compile
  struct A
  {
    int : (sizeof(int)-5);
  };
then you just get the _warning_
warning: width of `A::<anonymous>' exceeds its type
which is incorrect. 

As a result, sizeof(A) turns out to be 536870912
(500Mb). 
>How-To-Repeat:
Just compile the four-liner above. 
>Fix:
Should be fairly trivial, but I don't know. 
>Release-Note:
>Audit-Trail:
>Unformatted: