On Wed, Nov 20, 2024 at 6:21 PM mauro russo via Std-Discussion <
std-discussion_at_[hidden]> wrote:

> sorry, the previous message started as incomplete.
>
> First, about the wrong examples: here is a godbolt link:
> https://godbolt.org/z/vf5q6nTKq
> where you can find all compilers set with C++20 (but C++23 or C++2c works
> the same).
>
>
> About the additional doubt, I cannot see where [over.match.class.deduct]
> states that
> the selected overloaded notional constructor for CTAD must lead to deduce
> all
> parameters of the class template, based on the arguments in the return
> type of the selected constructor,
>
Each guide has, at minimum, all the template parameters of the class. Under
[over.match.class.deduct]/5, overload resolution is done with all the
guides. In any one particular guide, if any template argument fails to be
deduced in a guide, that guide does not produce a candidate
([over.match.funcs.general]/8). If no guide allows deduction of all
template parameters, there are no candidates and overload resolution fails,
resulting in an ill-formed program ([over.match.best.general]/3).


> as well as that the final selected type is the template specialization
> with those arguments .
>
[dcl.class.type.deduct]/1


>
> Maybe, p4 is aimed to this goal, but the way is not clear to me, as it
> seems a general statement,
> not mentioned in p5. Hope you may provide any hint.
> I am asking it as side point after having found the problems discussed
> above for the examples.
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-- 
*Brian Bi*