Re: [PATCH, v2] Fortran: ordering of hidden procedure arguments [PR107441]

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

Le 03/11/2022 à 23:03, Harald Anlauf a écrit :
> Am 03.11.22 um 11:06 schrieb Mikael Morin:
>> Le 02/11/2022 à 22:19, Harald Anlauf via Fortran a écrit :
>>> I do see what needs to be done in gfc_get_function_type, which seems
>>> in fact very simple.  But I get really lost in create_function_arglist
>>> when trying to get the typelist right.
>>>
>>> One thing is I really don't understand how the (hidden_)typelist is
>>> managed here.  How does that macro TREE_CHAIN work?  Can we somehow
>>> chain two typelists the same way we chain arguments?
>>>
>> TREE_CHAIN is just a linked list "next" pointer like there is in the
>> fortran frontend a "next" pointer in gfc_ref or gfc_actual_arglist
>> structures.
>> Yes, we can chain typelists; the implementation of chainon in tree.cc is
>> just TREE_CHAIN appending under the hood.
>>
>>> (Failing that, I tried to split the loop over the dummy arguments in
>>> create_function_arglist into two passes, one for the optional+value
>>> variant, and one for the rest.  It turned out to be a bad idea...)
>>>
>> Not necessarily a bad idea, but one has to be careful to keep linked
>> lists synchronized with argument walking.
>>
>> The most simple, I think, is to move the hidden_typelist advancement for
>> optional, value presence arguments from the main loop to a preliminary
>> loop.
>>
>> I hope it helps.
>>
> 
> I've spent some time not only staring at create_function_arglist,
> but trying several variations handling the declared hidden parms,
> and applying the necessary adjustments to gfc_get_function_type.
> (Managing linked trees is not the issue, just understanding them.)
> I've been unable to get the declarations in sync, and would need
> help how to debug the mess I've created.  Dropping my patch for
> the time being.
> 
If you want, we can meet on IRC somewhen (tonight?).