Deprecated attribute not honoured on partial template specialization

[ldionne]

Bugzilla Link	45151
Version	trunk
OS	All
CC	@dwblaikie,@zygoloid

Extended Description

In the following code, the deprecated attribute does not fire. I believe that is because it is applied to a partial specialization:

cat <<EOF | clang++ -xc++ -
template <typename T> class function { };
template <typename A>
class __attribute__((deprecated)) function<void(A)> { };
int main() { function<void(int)> f; }
EOF

Live repro: https://wandbox.org/permlink/5IAXzJOYCpPuCbok

[frederick-vs-ja]

What's worse, Clang currently implements [[deprecated]] and __attribute__((deprecated)) in a self-suppressing manner (Godbolt link).

#ifdef USE_GNU_SYNTAX // It doesn't matter whether the standard syntax is used.
#define DEPRECATED __attribute__((deprecated))
#else
#define DEPRECATED [[deprecated]]
#endif

// Additional [[deprecated]] on a partial specialization possibly suppresses deprecation warnings with Clang!
#ifdef USE_ANOTHER_DEPRECATED
#define ANOTHER_DEPRECATED DEPRECATED
#else
#define ANOTHER_DEPRECATED
#endif 

template<class>
struct my_template {
    using type = void;
};

template<class T>
struct DEPRECATED deprecated_type_identity { using type = T; }; // workaround for Clang, but...

template<class T>
struct ANOTHER_DEPRECATED my_template<volatile T> : deprecated_type_identity<volatile T> {};

template<class T>
using my_template_t = typename my_template<T>::type;

int main()
{
    using X [[maybe_unused]] = my_template<volatile int>; // Clang doesn't seem able to warn, sadly.
    using Z [[maybe_unused]] = my_template_t<volatile int>; // Here!
}