Why is the template argument deduction not working here?

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Just as first note, typename name is used when you mention a dependent name. So you don’t need it here.


template <class T>
struct S
{
    typedef T& type;
};

Regarding the template instantiation, the problem is that typename S<A>::type characterizes a nondeduced context for A. When a template parameter is used only in a nondeduced context (the case for A in your functions) it’s not taken into consideration for template argument deduction. The details are at section 14.8.2.4 of the C++ Standard (2003).

To make your call work, you need to explicitly specify the type:


temp<char>(c);

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