[patch, libgfortran] Fix PR20257 End of record occurs when writing large arrays

[Steve Kargl]

On Sat, Apr 22, 2006 at 09:53:18PM +0200, FX Coudert wrote:
> >We can reserve a few numbers for internal use - say, 2**31-1024 to 2**31-1
> >(the maximum positive GFC_INTEGER_4).  Attempts to open or otherwise use
> >these should be an error, and inquire(exist) could return false, like
> >negative numbers right now.
> 
> It might be a stupid suggestion (I don't have access to the code right 
> now): why not use negative numbers?
> 

A negative number would work.  In 9.3 of Fortran 95, we find
"A scalar integer expression that identifies an external file
unit shall be zero or positive."  In F2003, the statement 
involves "a nonnegative number" where the implication is that
negative unit numbers can be used by the implementation.

-- 
Steve