As for your proposal, I see that it requires more syntax changes, and as a
result, it seems to me that there is less chance of being approved.

On Wed, Aug 25, 2021, 10:41 Valery Osheter <valery.o_at_[hidden]> wrote:

> The virtual functions are for sure not a part of this feature, because it
> involves the virtual tables that are based on potentially complex classes
> hierarhy.
>
> In my example
>
> struct foo;
> void foo::bar();
>
> foo is only the typename.
> Then when compiler gots
>
> foo& f;
> f.bar();
>
> It translates to methid call with reference this parameter &f.
> No additional information about struct foo is required to generate that
> method call, therefore full foo struct definition is unnecessery
> restriction of the language.
> My main cocern is that in some architectures, when real foo struct is
> small, ABI passes *this parameter by value. I do not have a solution for
> this problem.
>
> On Wed, Aug 25, 2021, 10:24 Lénárd Szolnoki via Std-Proposals <
> std-proposals_at_[hidden]> wrote:
>
>> What about virtual functions? Do you want these to be declarable outside
>> the class? I think those would have similar ABI issues.
>>
>> Personally I like the "partial type definition" idea. If we want to
>> protect against different orders in different TUs then maybe we could
>> mandate to give each part a name, and each part should refer to the
>> previous part, if there is any. The part that completes the type shouldn't
>> have a name.
>>
>> class C/part1 {
>> int i;
>> };
>>
>> class C/part2 extends(part1) {
>> int j;
>> };
>>
>> class C extends(part2) {
>> int k;
>> }; //completes the type
>>
>> This is just a dummy syntax.
>>
>> Cheers,
>> Lénárd
>>
>>
>> ------------------------------
>> *From:* Valery Osheter via Std-Proposals <std-proposals_at_[hidden]>
>> *Sent:* August 25, 2021 5:28:41 AM GMT+01:00
>> *To:* Ville Voutilainen <ville.voutilainen_at_[hidden]>
>> *Cc:* Valery Osheter <valery.o_at_[hidden]>, sotrdg sotrdg via
>> Std-Proposals <std-proposals_at_[hidden]>
>> *Subject:* Re: [std-proposals] Partial type definition
>>
>> I see that the discussion goes to the direction I did not expect.
>> So maybe the caption should be changed from "partial type definition" to
>> "declaration of methods outside of the class definition". This is my real
>> intent. I think it does not hurt ODR, because ODR requires only one
>> definition and allows several equvalent declarations. If the declarations
>> are not equal, the linker fails just like in case of plain function in C++.
>>
>> I hope that this feature so simple and attractive, the compilers can do
>> it literally tomorrow.
>>
>> On Tue, Aug 24, 2021, 23:08 Ville Voutilainen <
>> ville.voutilainen_at_[hidden]> wrote:
>>
>>> On Tue, 24 Aug 2021 at 23:05, Ville Voutilainen
>>> <ville.voutilainen_at_[hidden]> wrote:
>>> > I doubt it's viable to allow the real definition of X to omit the
>>> > things defined in the partial definition. A translation
>>> > unit that sees the real definition might not see the partial
>>> > definition, and then you have a serious ODR problem.
>>>
>>> ..which is not to say that this idea isn't riddled with different ODR
>>> problems to begin with, though. :)
>>>
>> --
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>>
>