[patch, Fortran] Fix some string temporaries

[Thomas Koenig]

Hi Mikael,

>> Do we actually want to backport this? Technically, it is a regression,
>> but people are not likely to notice much.
>>
> It is not an ICE, neither a code correctness issue as far as I can see,
> so I would rather not backport.

Fine with me.

>>
>> +        case GFC_DEP_FORWARD:
>> +          return 0;

> This is doubtfull, but not worse than before I guess.

0 in this case means that you need no array temporary.  This is fine.

>> +        case GFC_DEP_BACKWARD:
>> +          return 1;
>> +
>> +        case GFC_DEP_OVERLAP:
>> +          return 1;
>> +
>> +        case GFC_DEP_NODEP:
>> +          return 0;
>> +
>> +        case GFC_DEP_ERROR:
>> +          return 0;
> Can we put a gcc_unreachable here instead?

Unfortunately not.  The original code (before I lifted out the
functionality) sometimes had GFC_DEP_ERROR at the end of the
function, which was then removed by

   return fin_dep == GFC_DEP_OVERLAP;

(In other words, if you put a gcc_unreachable there, you get
regressions.).

I can add a comment that this is intentional.

>> +
> same here, make it unreachable please.
>
> OK with this and the other unreachable change above.

So, OK with a comment why this appears?  Or should I simply
rename GFC_DEP_ERROR to GFC_DEP_NODEPFOUND to make this a bit
clearer?

Regards

	Thomas