Can deduced return type for defaulted three-way comparison operator be concept-constrained in C++?

Question

In the following program spaceship comparison operator with default implementation is declared with concept-constrained auto return type:

template<class T>
concept C = std::same_as<T, std::strong_ordering>;

struct A { 
    C auto operator <=>(const A &) const = default; 
};

This is accepted finely in GCC, however Clang complains:

error: deduced return type for defaulted three-way comparison operator must be 'auto', not 'C auto'

Demo: https://gcc.godbolt.org/z/4PEYMax1q

Which compiler is right here?