Why in this context can a non-type template parameter not be auto?

Question

The simplest snippet I managed to get to reproduce the problem is as follows:

#include <variant>

template <auto V>
using ic = std::integral_constant<decltype(V), V>;

enum { shake }; 
int milk(ic<shake>);

template <class...>
struct context {
    template <auto V>
    decltype(milk(ic<V>{})) get() {
        return std::get<decltype(milk(ic<V>{}))>(value);
    }
    std::variant<int> value;
};

int main(){
    context<int> c;
    c.get<shake>();
}

There is something fishy going on here in [clang] as it suggests that:

prog.cc:13:42: error: a non-type template parameter cannot have type 'auto'
        return std::get<decltype(milk(ic<V>{}))>(value);
                                         ^
prog.cc:3:16: note: template parameter is declared here
template <auto V>
               ^
1 error generated.

When we change the ic to an aliased type or use the untemplated version of context everything works as expected. So is it really clang's bug or am I missing something obvious here?

PS. In [gcc] everything works as expected...

Answer 1

Clang bug as commented by xskxzr