[Bug fortran/50937] STAT option with ALLOCATE statement on large arrays

["sgk at troutmask dot apl.washington.edu" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50937

--- Comment #7 from Steve Kargl <sgk at troutmask dot apl.washington.edu> 2011-10-31 19:50:41 UTC ---
On Mon, Oct 31, 2011 at 07:25:38PM +0000, fwi at inducks dot org wrote:
> 
> Has the bug been corrected in recent versions of gfortran, or do you really
> mean it's OK that gfortran claims an array has been allocated when it really
> has not been?
> 

Yes, the problem of integer overflow that Janne mentioned has
been corrected.

As to gfortran claiming "that an array has been allocated when
it really has not been", suggests that you may not understand
how your operating system works.  The concise story is that
gfortran asks your OS for a gazillion bytes of memory and
please confirm the status.  The OS tells gfortran (actually
your compiled code), here's your gazillion bytes of virtual
memory and everything is a-okay.  As long as you do not 
actually touch the pages of allocated virtual memory, no
physical memory has been allocated to your program.  Once
you start touching pages, at some point the OS notices a
shortage of physical memory.  This shortage leads to swapping
other (idle) processes out to secondary storage, utilizing
swap space as the backing storage for your virtual memory,
evidently your process exceeds its limits or the system
limits and the process segfaults.