def METHOD_NAME(self):
    if self.real_version < Version("8.0"):
        raise spack.compiler.UnsupportedCompilerFlag(
            self, "the C++20 standard", "cxx20_flag", "< 8.0"
        )
    elif self.real_version < Version("11.0"):
        return "-std=c++2a"
    else:
        return "-std=c++20"