"Unqualified lookup in templates" build failure(s) — clang 2.9

This code is accepted by g++. On purpose, clang does not accept this syntax.
// Uncomment this line will fix the issue.
// template<typename Value_t> void b(Value_t value)

template<typename Value_t> void a(Value_t value)
{
    b(value);
}

template<typename Value_t> void b(Value_t value)
{
}

void foo(int y)
{
    a(y);
}

No error detected for version 2.9