gfortran question about optional subroutine arguments
Thu Mar 14 13:39:00 GMT 2013
On 3/14/2013 8:30 AM, Tobias Burnus wrote:
> Mark Hounschell wrote:
>> c the old fortran77 call would have been
>> c call sub1(arg1,)
> Hmm, I have not seen the ",)" syntax before. I assume that that is
> some vendor extension, where the compiler does something - or a typo
> and it should be "arg1)" without ",".
I think I recall something like this from long before the f77 days.
With certain compilers, this resembled optional argument, although it
may have passed a machine zero value (and reserved a safe slot for
discarding a returned value). Certainly, there is no way for
-std=legacy to know which prehistoric compiler you wish to emulate. g77
had a variety of optional argument scheme which worked differently from
this, but I don't think anyone made a case for continuing it in
gfortran. f90 requires a compiler to complain about such non-standard
usage, and to use explicit interface for optional arguments.
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