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copied!<p>Interestingly, when I compile your code (Visual C++ 10 Express) I get errors, but also when I try this simpler case:</p> <pre><code>int main(int argc, char* argv[]) { C<int> x; // OK C<const int> x1; // error C2535: 'void C<T>::f(T &)' : member function // already defined or declared return 0; } </code></pre> <p>Seems like the ref-to-ref collapsing defined in the DR you mentioned means that <code>const</code> ref becomes a simple non-const ref within the template. My problem with this is that I don't understand why the second <code>f</code> is not just ignored.</p> <p>If I change C so that the second f is <code>const</code>-qualified, this now compiles:</p> <pre><code>template <typename T> struct C { void f(T&) { } void f(const T& t) const {} }; </code></pre> <p>The implication seems to be that when <code>C</code> is instantiated with <code>const</code> anything (ref or not), the two <code>C::f</code> overloads are simply identical, and result in compile-time duplicate detection.</p> <p>Perhaps somebody smarter than me can decipher the chain more definitively here.</p> <p>EDIT: On reflection, it's not surprising here that <code>T = const int&</code> results in the <code>f</code> overloads being identically instantiated as </p> <pre><code>void f(const int&) {} </code></pre> <p>That's what the compiler is telling me:</p> <pre><code>#include "stdafx.h" template <typename T> struct C { void f(T&) { } void f(const T&) { } }; int main() { C<const int&> z; // compile error: f cannot be overloaded return 0; } </code></pre> <p>gives this error:</p> <pre><code>1>test.cpp(6): error C2535: 'void C<T>::f(T)' : member function already defined or declared 1> with 1> [ 1> T=const int & 1> ] 1> test.cpp(5) : see declaration of 'C<T>::f' 1> with 1> [ 1> T=const int & 1> ] 1> test.cpp(10) : see reference to class template instantiation 'C<T>' being compiled 1> with 1> [ 1> T=const int & 1> ] </code></pre> <p>I'm not even convinced this has anything to do with the DR.</p>

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