[patch, libgfortran] PR46733 fflush called when reading from a string

[Jerry DeLisle]

On 11/09/2010 10:37 AM, Janne Blomqvist wrote:
> On Tue, Nov 9, 2010 at 15:54, Jerry DeLisle<jvdelisle@frontier.com>  wrote:
>> Committed as obvious.
>>
>> Sending        ChangeLog
>> Sending        io/transfer.c
>> Transmitting file data ..
>> Committed revision 166490.
>>
>>
>> Index: io/transfer.c
>> ===================================================================
>> --- io/transfer.c       (revision 166469)
>> +++ io/transfer.c       (working copy)
>> @@ -2646,7 +2646,8 @@
>>      }
>>
>>    /* Bugware for badly written mixed C-Fortran I/O.  */
>> -  flush_if_preconnected(dtp->u.p.current_unit->s);
>> +  if (!is_internal_unit (dtp))
>> +    flush_if_preconnected(dtp->u.p.current_unit->s);
>>
>>    dtp->u.p.current_unit->mode = dtp->u.p.mode;
>
> Thanks for fixing this bug.
>
> Generally though, I think this flush_if_preconnected() function should
> be removed. Either we
>
> 1) Never buffer the preconnected units (or, we have mandatory line
> buffering via the use of fbuf.h, but no more than that), in which case
> we should remove GFORTRAN_UNBUFFERED_PRECONNECTED and modify the
> checks in unix.c:fd_to_stream() such that we always call raw_init()
> for preconnected units. This would be practically equivalent to the
> status quo.
>
> 2) Potentially buffer preconnected units if they are redirected
> to/from a regular file, and tell users to use GFORTRAN_UNBUFFERED_ALL
> if they wish to prevent said buffering.
>
> In neither of the above cases is flush_if_preconnected() needed. Any
> opinions on which approach is preferred?
>
>
I agree we should get rid of it.  I am leaning a bit toward 1) above. Do you 
think we should wait until after 4.6 release?  After 4.6 release we plan to 
break ABI in a lot of places and this little tweak would be insignificant.  (Of 
course by itself it does not break ABI)

Jerry