The following bit of code compiles okay on MSVC 7, but fails on IBM
VACPP 5.x, Sunpro 5.3, HP aCC 3.30.

template <typename T>
class A
{
public:
    T t;
};

template <typename C>
class ATraits
{
public:
    typedef A<C> a_type;
};

class B
{
public:
    template <typename C>
    static void foo(const typename ATraits<C>::a_type&) {}
};

int main()
{
    A<char> a;
    B::foo(a);
    return 0;
}

If I change the call to B::foo by making the template parameter
explicit, everything works okay, as expected, i.e.

B::foo<char>(a);

Wondering if this kind of template parameter deduction (ala MSVC 7) is
supposed to be valid according to the standard?

Thanks,
Samar Lotia

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Samar Lotia wrote:
> Wondering if this kind of template parameter deduction (ala MSVC 7) is
> supposed to be valid according to the standard?

No. Conceptually, the compiler would need to search through an
infinite set of types C to find those for which ATraits<C>::a_type
was an A<char>.

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