Re: [PATCH, v3] Fortran: ordering of hidden procedure arguments [PR107441]

[Mikael Morin <morin-mikael@orange.fr>]

Le 08/11/2022 à 21:31, Harald Anlauf a écrit :
> Hi Mikael,
> 
> Am 08.11.22 um 11:32 schrieb Mikael Morin:
>> this is mostly good.
>> There is one last corner case that is not properly handled:
>>
>>> diff --git a/gcc/fortran/trans-decl.cc b/gcc/fortran/trans-decl.cc
>>> index 63515b9072a..94988b8690e 100644
>>> --- a/gcc/fortran/trans-decl.cc
>>> +++ b/gcc/fortran/trans-decl.cc
>> (...)
>>> @@ -2619,6 +2620,15 @@ create_function_arglist (gfc_symbol * sym)
>>>      if (f->sym != NULL)    /* Ignore alternate returns.  */
>>>        hidden_typelist = TREE_CHAIN (hidden_typelist);
>>>
>>> +  /* Advance hidden_typelist over optional+value argument presence
>>> flags.  */
>>> +  optval_typelist = hidden_typelist;
>>> +  for (f = gfc_sym_get_dummy_args (sym); f; f = f->next)
>>> +    if (f->sym != NULL
>>> +    && f->sym->attr.optional && f->sym->attr.value
>>> +    && !f->sym->attr.dimension && f->sym->ts.type != BT_CLASS
>>> +    && !gfc_bt_struct (f->sym->ts.type))
>>> +      hidden_typelist = TREE_CHAIN (hidden_typelist);
>>> +
>>
>> This new loop copies the condition guarding the handling of optional
>> value presence arguments, except that the condition is in an "else if",
>> and the complement of the condition in the corresponding "if" is
>> missing, to have strictly the same conditions.
> 
> I know, and I left that intentionally, as it is related to
> PR107444, assuming that it doesn't lead to a new ICE.  Bad idea.
> 
>> Admittedly, it only makes a difference for character optional value
>> arguments, which are hardly working.  At least they work as long as one
>> doesn't try to query their presence.  Below is a case regressing with
>> your patch.
> 
>> With that fixed, I think it's good for mainline.
>> Thanks for your patience.
>>
>>
>> ! { dg-do compile }
>> !
>> ! PR fortran/107441
>> ! Check that procedure types and procedure decls match when the procedure
>> ! has both character-typed and character-typed optional value args.
>> !
>> ! Contributed by M.Morin
>>
>> program p
>>    interface
>>      subroutine i(c, o)
>>        character(*) :: c
>>        character(3), optional, value :: o
>>      end subroutine i
>>    end interface
>>    procedure(i), pointer :: pp
>>    pp => s
>>    call pp("abcd", "xyz")
>> contains
>>    subroutine s(c, o)
>>      character(*) :: c
>>      character(3), optional, value :: o
>>      if (o /= "xyz") stop 1
>>      if (c /= "abcd") stop 2
>>    end subroutine s
>> end program p
> 
> Well, that testcase may compile with 12-branch, but it gives
> wrong code.  Furthermore, it is arguably invalid, as you are
> currently unable to check the presence of the optional argument
> due to PR107444.  I am therefore reluctant to have that testcase
> now.
> 
> To fix that, we may have to bite the bullet and break the
> documented ABI, or rather update it, as character,value,optional
> is broken in all current gfortran versions, and the documentation
> is not completely consistent.  I had planned to do this with the
> fix for PR107444, which want to keep separate from the current
> patch for good reasons.
> 
> I have modified my patch so that your testcase above compiles
> and runs.  But as explained, I don't want to add it now.
> 
> Regtested again.  What do you think?
> 
Let's proceed with the v3 then.  Character optional value arguments are 
corner cases anyway.