Re: is_explicitly_convertible

[Daniel Frey <d dot frey at gmx dot de>]

Hi Paolo,

after reading the new standard's draft once again, I tried to implement is_constructible (which has two cases) and I used that to implement is_explicitly_convertible on top of it (which is a no-brainer, really).

The draft (N3000) requires the two-argument-form to test for

  static_cast<To>(create<From>())

to be valid, using

  template<typename T> typename add_rvalue_reference<T>::type create();

The other forms of is_constructible require

  To(create<From>()...)

instead. While trying to implement that, I got stuck with another ICE for GCC 4.4 and I can't test GCC 4.5 - if it works, we could have both, otherwise it might be worth to send another bug report against 4.5? Note that the code does work for two-argument forms (like is_explicitly_convertible) on GCC 4.4, though.

I attached the code which I think *should* work. If for GCC 4.5 it actually works, we could add both is_constructible and is_explicitly_convertible (well, at least as good as it gets until front-end support arrives...)

Thanks for taking the time to test and adapt this for GCC, I really appreciate it :)

Regards, Daniel

Attachment: is_constructible.cpp
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