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Subject: [Bug libstdc++/48113] [4.6/4.7 Regression] [C++0x] bind with tuple argument fails
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48113

--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-03-14 18:10:19 UTC ---
here's one even closer to what we actually have in the library, where the
default template argument R involves the deduced type A as well:

template<typename T> T declval();

struct tuple { };

struct F1
{
    void operator()(tuple, int);
};

typedef void (*F2)(tuple, int);

template<typename F, typename T>
struct Bind
{
    template<typename A,
             typename R = decltype( F()(declval<T&>(), A()) )>
    R f(A);

    template<typename A,
             typename R = decltype( F()(declval<volatile T&>(), A()) )>
    R f(A) volatile;
};

int main()
{
    Bind<F1, tuple>().f(0);  // OK

    Bind<F2, tuple>().f(0);  // ERROR
}