Re: Overloading on rvalue and lvalue references

From:

SG <s.gesemann@gmail.com>

Newsgroups:

comp.lang.c++.moderated

Date:

Sun, 13 Sep 2009 14:17:26 CST

Message-ID:

<71370264-fbcd-4058-b441-889f5539c934@k19g2000yqc.googlegroups.com>

I missed an error.

On 11 Sep., 20:59, Paul Bibbings wrote:

    template<typename T>
    void bar(T&) { std::cout << "bar(T&)\n"; }

    template<typename T>
    void bar(T&&) { std::cout << "bar(T&&)\n"; }

    int main()
    {
       int i = 0;

[...]

       bar(0); // #3
       //bar(i); // #4 Error: ambiguous
       return 0;
    }

[...]

For the attempted call bar(i) (#4, lvalue), however, it seems
there will exist the two instantiations:
- void bar<int>(int& &); and
- void bar<int&>(int& &&)

The first is actually void bar<int>(int &).

tohava wrote:

Shouldn't it be impossible to have a reference to a reference?

Yes. It still is. You won't be able to write the type "int& &" for
example. But you will be able to write T& or T&& even if T is a
reference disguised behind a name. "Reference collapsing" kicks in to
determine the actual type. Here's a little table as example for
reference collapsing:

     T T&& T&
   ------------------
   int int&& int&
   int&& int&& int&
   int& int& int&

--
SG

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