VS2012 SP1 (+november pack) unknown-type errors (alike C::a(T &&…) )-Collection of common programming errors

[This answer has been updated. See the EDIT at the end of the text]

I brought this down to an SSCCE:

#include 

struct A { A g(int) { return A(); } };
struct B { B g() { return B(); } };

struct C
{
    template
    auto f(Ts... ts) -> decltype(A().g(ts...)) 
    { std::cout

Originally posted 2013-11-09 23:29:45.