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[May be a BUG] clang++ 14.0.0: "undefined reference error" for an inline consteval function. #54578

@yaoxinliu

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@yaoxinliu
inline consteval unsigned char operator""_UC(const unsigned long long n)
{
    return static_cast<unsigned char>(n);
}

inline consteval char f1(auto const octet)
{
    return char(octet >> 4_UC);
}

inline constexpr char f2(auto const octet)
{
    return char(octet >> 4_UC);
}

int main()
{
    auto c1 = f1('A'); // ok
    auto c2 = f2('A'); // error

    return c1 + c2;
}

Compiled with: clang++-14 -std=c++20 -stdlib=libc++, and the error message is:

undefined reference to `operator"" _UC(unsigned long long)'

See online demo: https://godbolt.org/z/WarbWYcfP

StackOverflow question link: https://stackoverflow.com/questions/71634835/why-does-consteval-not-behave-as-expected

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    c++20clang:frontendLanguage frontend issues, e.g. anything involving "Sema"confirmedVerified by a second party

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