[Bug libstdc++/70607] The return type of std::conj must be std::complex<T>

[Alexander.Voigt at desy dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70607

--- Comment #2 from Alexander Voigt <Alexander.Voigt at desy dot de> ---
I absolutely agree, that the definition of the std::conj() overloads in C++11
is problematic.  However, in my opinion one has to be strict when implementing
the standard.  Otherwise, people might accidentally write non-portable C++11
code and g++ does not complain.