RFC: patch to add ISO_FORTRAN_ENV intrinsic module

[Paul Thomas]

FX,

I'll give this my attention as son as I have extricated myself from the 
mess I got into whilst moving to new machines; progress is such that it 
should be tomorrow morning. :-)

I now have working trees on both machines - what a pain in the beeehind 
this has been!
Paul
>> How about leaving it to e.g. 32 and spitting out a warning when one
>> loads the module and has -fdefault-integer-8 XOR -fdefault-integer-8 
>> set.
>
> I'll go for issuing a warning if -fdefault-integer-8 OR 
> -fdefault-integer-8. After all, even when both flags are specified, 
> chances are slim that the compiler is Standard compliant :)
>
> As for the second part of my RFC, I'd very much like some advice. 
> Paul, would you have a few minutes? Here's my question:
>
>>  -- I've used the attr.intrinsic bit for the module symbol to
>> specifiy that it's an intrinsic module. Except one line in resolve.c
>> (see diff), it seems to be safe. However, I'd like
>>    a) to be sure that, for every user module symbol created, the
>> intrinsic bit is set to 0, so that we check that a non-intrinsic and
>> an intrinsic module of the same name aren't used
>>    b) the code USEing non-intrinsic modules (in module.c) to issue an
>> error if an intrinsic module of the same name was already USEd; ie,
>> I'd like the following to error out (while, with my patch, it does
>> not):
>>
>> module iso_fortran_env
>> end module iso_fortran_env
>>
>> program foo
>>  use, intrinsic :: iso_fortran_env
>>  use, non_intrinsic :: iso_fortran_env ! This should issue an error
>> end program foo
>
> Thanks all,
> FX
>
>