template<int num>
struct Foo
{
    static constexpr int blarg = num;
};

template<Foo<int> foo> // Error: Template argument for non-type template parameter must be an expression
struct Bar
{
    static constexpr Foo<int> bar = foo; // Error: Template argument for non-type template parameter must be an expression
};

struct MyStruct
{
    static constexpr Foo<5> myFoo();
    static constexpr Bar<myFoo> myBar(); // Error: Value of type 'Foo<5> ()' is not implicitly convertible to 'int'
};