🚀 go-pugleaf

I am having trouble deciding what the meaning of a cast of an object
to a reference should be, in the context of user-defined conversion
functions.  For example:

    class representation {
     public:
       int i;
    };

    class foo {
       int x;
       representation rep;
     public:
       operator const representation& () const;
       operator representation () const;
    };

    int main()
    {
       // What does this do?
       foo xx;
       representation &ref = (representation&)xx;
    }

I have tried it with a number of C++ compilers, which variously call
operator representation(), cast the address of xx, or give an error.
Those that call the operator would seem to be breaking the rule about
non-const references to temporaries; those that cast the address are
being somewhat unhelfpul: this code is surely a mistake by the
programmer.

My old copy of the ARM says [5.4] "conversion functions are not called
as the result of a cast to a reference", which flies in the face of
experience.  The same sort of wording appears in the DWP
[expr.static.cast], but after conversion functions are mentioned.

According to my reading of the DWP the compiler should prefer a
static_cast over a reinterpret_cast , but I am not sure whether this
means it should ignore a "close match" static_cast which would be in
error.

Help!

Bryan Boreham, Front Office Development, Credit Suisse Financial Products
1 Cabot Square, London E14 4QJ, phone: +44 171 516 2058, fax:+44 171 516 2688
email: bboreham@csfp.co.uk

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