Function returning constexpr does not compile

Why doesn't this compile:

Could there be a problem with a string as a return type?

constexpr开发者_开发问答 std::string fnc()
{
    return std::string("Yaba");
}

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The constructor of std::string that takes a pointer to char is not constexpr. In constexpr functions you can only use functions that are constexpr.