Re: [PATCH, fortran] Fix Bug 124543 - INQUIRE: Sometimes returns incorrect values

On 3/29/26 1:08 PM, Harald Anlauf wrote:
> Hi Jerry,
> 
> thanks for your efforts!
> 
> I played with the testcase, threw the NAG compiler on it, and
> found a few minor nits:
> 
> 1)
> 
> ! Make sure there is no file with the name we will be using
>    open (lun, file=lfn, status='old', iostat=iostat)
>    if (iostat /= 0) then
>      close (lun, status='delete')
>    end if
> 

Fixed.

> Here the logic seems backwards to me: you want to delete an
> existing file.  It should rather read:
> 
>    if (iostat == 0) then
> ...
> 
> 2)
> 
>    inquire (file=lfn, id=id, pending=pending, recl=recl)  ! SEGV at run-time w/ 
> gfortran
> 
> This crashes with NAG, because there is *no* pending asynchronous
> transfer.

It also crashed with gfortran before the patch.

> 
> I recommend to replace that with
> 
>    inquire (file=lfn, id=id, pending=pending, recl=recl,iostat=iostat)
> 
> and I also wonder if we should set iostat to non-zero (like NAG) and
> test it with:
> 
>    if (iostat == 0) stop 80

It did not fail for me here, regardless I set it in the init_vars subroutine.

> 
> (This fails after your patch).
> 
> Similarly later on:
> 
>    inquire (unit=lun, id=id, pending=pending, recl=recl,iostat=iostat)
>    if (iostat == 0) stop 123
> 
> 
> The other differences I saw may be issues with NAG or an interpretation
> issue.

I have noticed a lot of variation across several compilers.

Doing INQUIRE on things that do not exist or are not connected is a bit unusual.

I will commit after some final testing here.

Thanks for the review.

Jerry

PS Also found "+  if  (pending) print *, pending" ;)

> 
> So the patch is OK with the above addressed and suitably resolved.
> 
> Thanks,
> Harald
> 
> 
> On 3/29/26 04:38, Jerry D wrote:
>> Hello All,
>>
>> The attached patch fixes numerous return values or missing checks.
>>
>> There were at least two places where we segfaulted on checking a gfc_unit 
>> value when the unit did not exist.
>>
>> I have not implemented inquire (unit=lun, leading_zero=leading_zero) since 
>> this is rather new and I prefer to add it after this patch. It is one of those 
>> examples of a new feature added that does not have a lot of value AFAICT. It 
>> will require some front-end work.
>>
>> The new test case is very busy. It is not too difficult to adjust if we miss 
>> anything there.
>>
>> Regression tested on X86_64.
>>
>> OK for mainline?
>>
>> Regards,
>>
>> Jerry
>> -----
>>      fortran: Fix several issues with INQUIRE and unconnected units.
>>
>>              PR libfortran/124543
>>
>>      libgfortran/ChangeLog:
>>
>>              * io/inquire.c (inquire_via_unit): Fix return value for
>>              NAMED. Add check for ACTION. Fix return values for
>>              ENCODING, PENDING, READ, WRITE, READWRITE.
>>              (inquire_via_filename): Add checks for ACTION, DELIM,
>>              ASYNCHRONOUS, and PENDING. Fix return value for
>>              ENCODING.
>>              * io/unix.c (inquire_access): Change return value from no
>>              to unknown.
>>
>>      gcc/testsuite/ChangeLog:
>>
>>              * gfortran.dg/pr124543.f90: New test.
>>
>