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Re: Defect Report: Direct class initialization via explicit conversion function to arbitrary class type

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Am 18.09.2012 17:24, schrieb Edward Catmur:
>
> The resolution of issue 1087[1] was intended to permit the use of an explicit
> conversion function in direct-initialization of a class type object via a copy-,
> move- or template constructor.  Unfortunately, the language used is sufficiently
> lax to permit the use of a converting constructor taking class type:
>
>       struct X {};
>       struct Y { Y(const X&); };    // converting constructor
>       struct Z { explicit operator X() const; };
>       void h(Z z) {
>         Y y1(z);    // should not be permitted
>       }
>
> The converting constructor of Y is considered for direct-initialization
> (13.3.1.3 [over.match.ctor]), and to initialize the temporary X to be bound to
> the first parameter of the constructor (13.3.1.4 [over.match.copy]), the
> explicit conversion function of Z is considered.  13.3.1.4 should be tightened
> to not apply to converting constructors.
>
> When discussing this issue[2], it became apparent that the definition of
> conversion functions in 12.3.2 [class.conv.fct] does not make it clear that the
> validity of explicit conversion functions in a direct-initialization expression
> is governed by the semantics of overload resolution. A cross-reference to the
> relevant sections would help here.


I forwarded this to the core language working group.

Thanks & Greetings from Bremen,

Daniel Kr�gler



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Defect Report: Direct class initialization via explicit conversion   function to arbitrary class type Edward Catmur<ed@catmur.co.uk> - 2012-09-18 08:24 -0700
  Re: Defect Report: Direct class initialization via explicit conversion   function to arbitrary class type Daniel Krügler <daniel.kruegler@googlemail.com> - 2012-09-18 13:06 -0700

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