Desire to allocate bit in DT_PARM bitmask for DEC FORMAT compatibility purposes

[Jeff Law]

On 03/23/2018 02:38 AM, Jakub Jelinek wrote:
> On Fri, Mar 23, 2018 at 09:12:21AM +0100, Jakub Jelinek wrote:
>>> I have some philosophical questions.
>>>
>>> 1) Why do you want 15, 7, 2? Why is this so critical?
>>
>> Because that is what all those compilers document and agree on.
>> See e.g.
>> https://software.intel.com/en-us/node/678750#32937290-265D-4805-B2B7-4E78F6AAD0D8
>> for Intel documentation, I'm sure Jeff has links to other documentations.
> 
> BTW, it seems libgfortran already has a similar extension, at least my
> reading of the standards (checked 97 and 2003) is that for Lw the standard
> doesn't allow omitting the width, but we allow that as extension:
>           else
>             {
>               fmt->saved_token = t;
>               notify_std (&dtp->common, GFC_STD_GNU,
>                           "Positive width required with L descriptor");
>             }
>           fmt->value = 1;       /* Default width */
> (and sadly different from what Intel Fortran does, because it uses 2).
> Wonder about other compilers, if they all agree on 2, perhaps we should
> behave above differently based on the new bit?
Yup.  I saw that too in my wanderings.  I was hoping it was actually
more general and that we could piggy-back a bit.  But that wasn't the
case AFAICT.

jeff