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

[Jerry DeLisle]

On 03/27/2018 02:13 AM, Jakub Jelinek wrote:
> On Mon, Mar 26, 2018 at 03:03:11PM -0600, Jeff Law wrote:
>> On 03/26/2018 01:42 AM, Jakub Jelinek wrote:
>>> On Sun, Mar 25, 2018 at 08:44:41PM -0700, Steve Kargl wrote:
>>>> Now that you mention it, -std=dec would prevent a user from
>>>> specifically requesting, say, only Fortran 95 with DEC
>>>> extensions (i.e, -std=f95 -fdec).
>>>>
>>>> So, to prevent a bikeshed and micro-engineering, I think you
>>>> should go with using bit 28 to comunicate with the runtime
>>>> and put everything under -fdec in the FE.
>>>
>>> In that case, we would have two bits that are always set based on flag_dec
>>> in the compiler.
>> Steve might have been using -fdec generically -- there's a -fdec as well
>> as various sub-options.
> 
> There is, but e.g. the default exponent stuff is guarded solely by -fdec, not by
> some sub-option.  If the default width would be also just -fdec, then having
> two bits that do the same thing would be a waste of bits.
> 
> That said, I don't care that much, there are 3 roughly equivalent ways to
> propagate this info (this bit 27, bit 28 and GFC_STD_DEC_EXT on
> allow_std/warn_std), let the libgfortran maintainers choose.
> 
> The patch I've posted with s/IOPARM_DT_DEC_EXP/IOPARM_DT_DEC_EXT/ to fix
> one typo I've made passed bootstrap/regtest on x86_64-linux and i686-linux.
> 
> 	Jakub
> 

Yes, please go ahead and commit. No need for mutually exclusive bits.

Regards,

Jerry