Hi Steve,

On 11/19/23 01:04, Steve Kargl wrote:
> On Sat, Nov 18, 2023 at 11:12:55PM +0100, Harald Anlauf wrote:
>> Regtested on x86_64-pc-linux-gnu.  OK for mainline?
>>
>
> Not in its current form.
>
>>   {
>> +  int first_int_kind = -1;
>> +  bool f2023 = ((gfc_option.allow_std & GFC_STD_F2023) != 0
>> +		&& (gfc_option.allow_std & GFC_STD_GNU) == 0);
>> +
>
> If you use the gfc_notify_std(), then you should not need the
> above check on GFC_STD_GNU as it should include GFC_STD_F2023.

this is actually the question (and problem).  For all new features,
-std=gnu shall include everything allowed by -std=f2023.

Here we have the problem that the testcase is valid F2018 and is
silently accepted by gfortran-13 for -std=gnu and -std=f2018.

I prefer to keep it that way also for gfortran-14, and apply the
new restrictions only for -std=f2023.  Do we agree on this?

Now that should happen for -std=gnu -pedantic (-w)?

I have thought some more and came up with the revised attached
patch, which still has the above condition.  It now marks the
diagnostics as GNU extensions beyond F2023 for -std=f2023.

The mask f2023 in the above form suppresses new warnings even
for -pedantic; one would normally use -w to suppress them.

Now if you remove the second part of the condition, we will
regress on testcases system_clock_1.f90 and system_clock_3.f90
because they would emit GNU extension warnings because the
testsuite runs with -pedantic.

The options I see:

- use patch-V1 (although diagnostics are better in V2),

- use patch-V2,

- use patch-V2, but enable -pedantic warnings for previously
   valid code, and adjust the failing testcases

- ???

> Elsewhere in the FE, gfortran uses gfc_notify_std() to enforce
> requirements of a Fortran standard.  The above would be
>
>        if (count->ts.kind < gfc_default_integer_kind
>            && gfc_notify_std (GFC_STD_F2023, "COUNT argument to SYSTEM_CLOCK "
>                               "at %L must have kind of at least default integer",
>                               &count->where))

I tried this first, and it did not do the job.

The logic in gfc_notify_std is:

   estd = std & ~gfc_option.allow_std;  /* Standard to error about.  */
   error = (estd != 0);
   if (error)
     msg = notify_std_msg (estd);
...

So for -std=f2023 we get estd=0, error=false, and *NO* error.
For -std=f2018 we get error=true and an error message.
This is the opposite of what is needed.

Can you please try yourself?

> Note, gfc_notify_std() should add the 'Fortran 2023: ' string,
> if not, that should be fixed.

This I did fix.

> Of course, I seldom provide patches if others don't have a comment
> then do as you like.

Thanks for your feedback!

Harald