@achow101 noted we don't reject them therefore they must be silently accepted. This is not part of the specs, we should remove them. Also cc @sipa.

I can take care of this.
{
        std::string extra = ToStringExtra();
        size_t pos = extra.size() > 0 ? 1 : 0;
        std::string ret = m_name + "(" + extra;
        for (const auto& pubkey : m_pubkey_args) {
            if (pos++) ret += ",";
            std::string tmp;
            switch (type) {
                case StringType::NORMALIZED:
                    if (!pubkey->ToNormalizedString(*arg, tmp, cache)) return false;
                    break;
                case StringType::PRIVATE:
                    if (!pubkey->ToPrivateString(*arg, tmp)) return false;
                    break;
                case StringType::PUBLIC:
                    tmp = pubkey->ToString();
                    break;
                case StringType::COMPAT:
                    tmp = pubkey->ToString(PubkeyProvider::StringType::COMPAT);
                    break;
            }
            ret += tmp;
        }
        std::string subscript;
        if (!ToStringSubScriptHelper(arg, subscript, type, cache)) return false;
        if (pos && subscript.size()) ret += ',';
        out = std::move(ret) + std::move(subscript) + ")";
        return true;
    }
    std::string ToString(bool compat_format) const final